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Providing long hay in a novel pipe feeder or a bucket reduces abnormal oral behaviors in milk-fed dairy calves

Open AccessPublished:January 16, 2023DOI:https://doi.org/10.3168/jds.2022-22413

      ABSTRACT

      Many milk-fed dairy calves are not provided forage. In these settings, calves often perform abnormal repetitive behaviors (ARBs), including tongue rolling and nonnutritive oral manipulation (NNOM), which, based on their form, seem similar to movements used when processing feed. Feeding hay, typically presented as a short chop (≤5 cm) in a bucket, reduces ARBs. Our objective was to evaluate whether altering the presentation method of long hay (∼19 cm), by providing it in a bucket or a novel polyvinyl chloride (PVC) pipe feeder, could reduce ARBs. Holstein heifer calves were housed individually on sand and fed ad libitum starter grain and limited milk replacer (5.7–8.4 L/d step-up) via a bottle (Control, n = 9) or given access to mountaingrass hay in a bucket (Bucket, n = 9) or in a PVC pipe feeder (Pipe, n = 9). The 56 × 10.2 cm (length × diameter) PVC pipe feeder had 4 openings that were 6.35 cm wide, which required the calf to insert her tongue into the pipe and curl her tongue to extract hay. Treatments were applied from birth through 50 d of age, when step-down weaning began and TMR was provided to all calves. Calves were fully weaned at d 60. At wk 4 and 6, oral behaviors (eating, ruminating, drinking water, sucking milk, self-grooming, NNOM, tongue rolling, tongue flicking, and panting) were recorded by direct observation for 24 h using 1–0 sampling during 5-s intervals. Feeding long hay, regardless of presentation method, increased overall DMI, grain intake, and ADG compared with Control calves. Hay provision also increased rumination (25 vs. 15% of 24-h observations in Control) and eating time (5.5 vs. 2% in Control). Abnormal behaviors were seen in all calves. Hay provision reduced some of these, including NNOM (5 vs. 9% in Control). There was no difference in NNOM between calves fed hay in a pipe or bucket, even though Bucket calves consumed more hay (178 vs. 129 g/d in wk 6) and tended to spend more observations eating hay than Pipe calves (4.5 vs. 3%). Hay provision did not affect other behaviors: drinking water (0.5%), grooming (3%), or tongue flicking (3%). We also found evidence of other abnormal oral behaviors that have received less attention. Calves showed signs of polydipsia, and displayed excessive grooming, the latter indicated by overall duration, number of bouts per day, and duration of individual bouts (up to 25 min). Tongue rolling was expressed at low levels (up to 0.4% of intervals) but by 85% of calves. Feeding hay, both in a bucket and using novel methods, was not enough to counteract the welfare challenges associated with individual housing and limited ability to suck milk (<1% of time). Provision of long hay, regardless of presentation method, promotes rumination, improves performance (higher grain intake and ADG) and reduces at least some, but not all, of the considerable abnormal oral behaviors these calves performed.

      Key words

      INTRODUCTION

      Calves perform oral abnormal repetitive behaviors (ARBs), or inappropriate behaviors indicative of compromised welfare (
      • Garner J.P.
      Perseveration and stereotypy—Systems-level insights from clinical psychology.
      ), in settings where feed availability is limited (
      • Horvath K.C.
      • Miller-Cushon E.K.
      Evaluating effects of providing hay on behavioral development and performance of group-housed dairy calves.
      ;
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.
      ). In many cases, it appears that these behaviors do not solely stem from hunger. Limited ability to perform the physical actions associated with food processing, including sucking, chewing, and ruminating, may also be a key component of these ARBs. Calves fed milk via esophageal feeders (
      • de Passillé A.M.B.
      • Rushen J.
      Motivational and physiological analysis of the causes and consequences of non-nutritive sucking by calves.
      ) or buckets (e.g.,
      • Hammell K.L.
      • Metz J.H.M.
      • Mekking P.
      Sucking behaviour of dairy calves fed milk ad libitum by bucket or teat.
      ) increase oral manipulation of pen fittings following feeding compared with calves fed via teats, even when meal sizes and daily allowances are kept constant. Similarly, calves fed via slow-flow teats, which increase sucking time, show less nonnutritive oral manipulation (NNOM) than calves fed the same amount of milk at a faster flow rate (e.g.,
      • Haley D.B.
      • Rushen J.
      • Duncan I.J.H.
      • Widowski T.M.
      • de Passillé A.M.B.
      Effects of resistance to milk flow and the provision of hay on nonnutritive sucking by dairy calves.
      ). These same patterns are evident in relation to solid feed. Calves will consistently choose a proportion of hay in their diets (e.g.,
      • Castells L.
      • Bach A.
      • Aris A.
      • Terré M.
      Effects of forage provision to young calves on rumen fermentation and development of the gastrointestinal tract.
      ; Miller-Cushon et al., 2013;
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.
      ), despite it containing less energy per kilogram of DM than grain (
      • Drackley J.K.
      Calf nutrition from birth to breeding.
      ). They will also sort in favor of forage when fed a mixed diet (e.g.,
      • Montoro C.
      • Miller-Cushon E.K.
      • DeVries T.J.
      • Bach A.
      Effect of physical form of forage on performance, feeding behavior, and digestibility of Holstein calves.
      ;
      • Terler G.
      • Poier G.
      • Klevenhusen F.
      • Zebeli Q.
      Replacing concentrates with a high-quality hay in the starter feed in dairy calves: I. Effects on nutrient intake, growth performance, and blood metabolic profile.
      ). Forage is often not provided to young calves [e.g., provided around d 36 (
      • USDA
      Dairy 2014: Dairy cattle management practices in the United States. Report No. 1.
      ); not required before d 14 under EU legislation (
      • European Council
      Council Directive 2008/119/EC of 18 December 2008. Laying down minimum standards for the protection of calves.
      )]. In these settings, calves will consume fibrous bedding as early as 6 d after birth (e.g.,
      • Phillips C.J.C.
      The effects of forage provision and group size on the behavior of calves.
      ;
      • Wang S.
      • Diao Q.Y.
      • Hu F.M.
      • Bi Y.L.
      • Piao M.Y.
      • Jiang L.S.
      • Sun F.
      • Li H.
      • Tu Y.
      Development of ruminating behavior in Holstein calves between birth and 30 days of age.
      ). Forage requires more chewing and ruminating than grain (e.g.,
      • Khan M.A.
      • Weary D.M.
      • von Keyserlingk M.A.G.
      Hay intake improves performance and rumen development of calves fed higher quantities of milk.
      ;
      • Castells L.
      • Bach A.
      • Araujo G.
      • Montoro C.
      • Terré M.
      Effect of different forage sources on performance and feeding behavior of Holstein calves.
      ), and cattle seem to seek out opportunities for these behaviors. For example, when cows have their rumens artificially filled, they spend more time searching for feed and manipulating their environment than those who are able to ingest food themselves (
      • Lindström T.
      • Redbo I.
      Effect of feeding duration and rumen fill on behaviour in dairy cows.
      ). Dairy calves also appear to perform sham rumination in the absence of forage (
      • Webb L.E.
      • Bokkers E.A.M.
      • Engel B.
      • Gerrits W.J.J.
      • Berends H.
      • van Reenen C.G.
      Behaviour and welfare of veal calves fed different amounts of solid feed supplemented to a milk replacer ration adjusted for similar growth.
      ;
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.
      ), similar to sham chewing in sows (e.g.,
      • Terlouw E.M.C.
      • Lawrence A.B.
      • Illius A.W.
      Influences of feeding level and physical restriction on development of stereotypies in sows.
      ), which may suggest rumination is a highly motivated behavior. Calves that are able to consume hay, and engage in more chewing and ruminating than those reared without forage, in turn perform less NNOM (e.g.,
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.
      ;
      • Horvath K.C.
      • Miller-Cushon E.K.
      The effect of milk-feeding method and hay provision on the development of feeding behavior and non-nutritive oral behavior of dairy calves.
      ,
      • Horvath K.C.
      • Miller-Cushon E.K.
      Evaluating effects of providing hay on behavioral development and performance of group-housed dairy calves.
      ). Food processing behaviors may thus represent a behavioral need for cattle, that is, one that animals are highly motivated to perform regardless of functional consequences, which can have negative implications if prevented (e.g.,
      • Jensen P.
      • Toates F.
      Who needs “behavioural needs”? Motivational aspects of the needs of animals.
      ).
      The physical actions associated with food acquisition also seem to matter. Cattle work to gain access to food that is otherwise freely available (
      • Van Os J.M.C.
      • Mintline E.M.
      • DeVries T.J.
      • Tucker C.B.
      Domestic cattle (Bos taurus taurus) are motivated to obtain forage and demonstrate contrafreeloading.
      ). In some cases, when cattle on pasture are fed ad libitum TMR, they still choose to spend time grazing (
      • Tuomisto L.
      • Ahola L.
      • Martiskainen P.
      • Kauppinen R.
      • Huuskonen A.
      Comparison of time budgets of growing Hereford bulls in an uninsulated barn and in extensive forest paddocks.
      ). This may be because cattle use their tongue to encircle and rip grass on pasture before chewing it (
      • Sambraus H.H.
      Mouth-based anomalous syndromes.
      ), and provision of prechopped forage in a trough or bucket does not allow for this natural motion or effort. Indeed, prevention of these encircling motions during feeding has been hypothesized to be a factor influencing tongue rolling, a common abnormal behavior in cattle (e.g.,
      • Sambraus H.H.
      Mouth-based anomalous syndromes.
      ;
      • Seo T.
      • Sato S.
      • Kosaka K.
      • Sakamoto N.
      • Tokumoto K.
      • Katoh K.
      Development of tongue-playing in artificially reared calves: Effects of offering a dummy-teat, feeding of short cut hay and housing system.
      ). Tongue rolling is also seen in zoo-kept giraffes and okapi, who use their tongues when ripping browse in natural settings, but is not seen in species that bite grass, including goats and sheep (
      • Sambraus H.H.
      Mouth-based anomalous syndromes.
      ). Although hay provision in a bucket can reduce tongue rolling and other ARBs in calves reared in farm settings, they are still performed by most animals (e.g.,
      • Kooijman J.
      • Wierenga H.K.
      • Wiepkema P.
      Development of abnormal oral behaviour in group-housed veal calves: Effects of roughage supply.
      ;
      • Horvath K.C.
      • Miller-Cushon E.K.
      The effect of milk-feeding method and hay provision on the development of feeding behavior and non-nutritive oral behavior of dairy calves.
      ;
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.
      ). It is possible that food acquisition may be part of a broader behavioral need to forage, along with food processing. Hay acquisition, and whether it encourages natural grazing motions, may thus be an important facet to further reduce ARB development and improve welfare that is not currently addressed by providing hay in a bucket.
      When provided, forage is presented to young calves in different ways, but the influence these options have on ARB performance is not clear cut. It is common to study the effect of short chopped hay in a bucket (e.g., <5 cm;
      • Khan M.A.
      • Weary D.M.
      • von Keyserlingk M.A.G.
      Hay intake improves performance and rumen development of calves fed higher quantities of milk.
      ;
      • Horvath K.C.
      • Miller-Cushon E.K.
      The effect of milk-feeding method and hay provision on the development of feeding behavior and non-nutritive oral behavior of dairy calves.
      ;
      • Engelking L.E.
      • Matsuba T.
      • Inouchi K.
      • Sugino T.
      • Oba M.
      Effects of feeding hay and calf starter as a mixture or as separate components to Holstein calves on intake, growth, and blood metabolite and hormone concentrations.
      ;
      • Horvath K.C.
      • Allen A.N.
      • Miller-Cushon E.K.
      Effects of access to stationary brushes and chopped hay on behavior and performance of individually housed dairy calves.
      ,
      • Horvath K.C.
      • Brocious A.N.
      • Miller-Cushon E.K.
      Effects of forage presentation and addition of molasses-based liquid feed on dairy calf dietary selection and feed sorting of mixed diets.
      ;
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.
      ). Hay has also been presented by mixing it with grain (
      • Miller-Cushon E.K.
      • Montoro C.
      • Bach A.
      • DeVries T.J.
      Effect of early exposure to mixed rations differing in forage particle size on feed sorting of dairy calves.
      ;
      • Montoro C.
      • Miller-Cushon E.K.
      • DeVries T.J.
      • Bach A.
      Effect of physical form of forage on performance, feeding behavior, and digestibility of Holstein calves.
      ;
      • Horvath K.C.
      • Miller-Cushon E.K.
      Effects of hay provision and presentation on cognitive development in dairy calves.
      ), providing long particle sizes (e.g., 20–30 cm,
      • Webb L.E.
      • Bak Jensen M.
      • Engel B.
      • van Reenen C.G.
      • Gerrits W.J.J.
      • de Boer I.J.M.
      • Bokkers E.A.M.
      Chopped or long roughage: What do calves prefer? Using cross point analysis of double demand functions.
      ; 50 cm,
      • Seo T.
      • Sato S.
      • Kosaka K.
      • Sakamoto N.
      • Tokumoto K.
      • Katoh K.
      Development of tongue-playing in artificially reared calves: Effects of offering a dummy-teat, feeding of short cut hay and housing system.
      ), or offering it in hay nets (
      • Ude G.
      • Georg H.
      • Schwalm A.
      Reducing milk induced cross-sucking of group housed calves by an environmentally enriched post feeding area.
      ;
      • Zhang C.
      • Juniper D.T.
      • Meagher R.K.
      Effects of physical enrichment items and social housing on calves' growth, behaviour and response to novelty.
      ). These methods can extend eating time (e.g., mixed with grain,
      • Miller-Cushon E.K.
      • Montoro C.
      • Bach A.
      • DeVries T.J.
      Effect of early exposure to mixed rations differing in forage particle size on feed sorting of dairy calves.
      ; long particles, as reviewed in
      • Beauchemin K.A.
      Invited review: Current perspectives on eating and rumination activity in dairy cows.
      ; hay nets,
      • Rochais C.
      • Henry S.
      • Hausberger M.
      “Hay-bags” and “Slow feeders”: Testing their impact on horse behaviour and welfare.
      ), likely because they require more manipulation. This should be associated with a decrease in ARBs, given previous findings, but this is not always the case. Both NNOM and tongue rolling are reduced when calves are fed coarse hay mixed with grain compared with ground (4 vs. 2 mm;
      • Montoro C.
      • Miller-Cushon E.K.
      • DeVries T.J.
      • Bach A.
      Effect of physical form of forage on performance, feeding behavior, and digestibility of Holstein calves.
      ), but this reduction is not seen when longer lengths are fed separately (50 vs. 5 cm,
      • Seo T.
      • Sato S.
      • Kosaka K.
      • Sakamoto N.
      • Tokumoto K.
      • Katoh K.
      Development of tongue-playing in artificially reared calves: Effects of offering a dummy-teat, feeding of short cut hay and housing system.
      ). Sometimes presentation of hay is combined with multiple other provisions that may reduce ARBs (e.g., dummy teats, socialization, grooming brushes, or scented hay;
      • Ude G.
      • Georg H.
      • Schwalm A.
      Reducing milk induced cross-sucking of group housed calves by an environmentally enriched post feeding area.
      ;
      • Zhang C.
      • Juniper D.T.
      • Meagher R.K.
      Effects of physical enrichment items and social housing on calves' growth, behaviour and response to novelty.
      ), so it is not possible to isolate the effects of hay. Studies of feed presentation methods focus mostly on sorting behavior or physiological performance, and as such ARBs are not often scored (e.g.,
      • Jahani-Moghadam M.
      • Mahjoubi E.
      • Hossein Yazdi M.
      • Cardoso F.C.
      • Drackley J.K.
      Effects of alfalfa hay and its physical form (chopped versus pelleted) on performance of Holstein calves.
      ;
      • Engelking L.E.
      • Matsuba T.
      • Inouchi K.
      • Sugino T.
      • Oba M.
      Effects of feeding hay and calf starter as a mixture or as separate components to Holstein calves on intake, growth, and blood metabolite and hormone concentrations.
      ;
      • Horvath K.C.
      • Brocious A.N.
      • Miller-Cushon E.K.
      Effects of forage presentation and addition of molasses-based liquid feed on dairy calf dietary selection and feed sorting of mixed diets.
      ). More work is needed to elucidate the link between forage presentation, natural food acquisition and processing motions, and ARB reduction.
      This link between ARBs and methods of forage presentation is further complicated by how behavior is measured. Calves show circadian variation in behavior. Some behaviors peak around or after milk feeding (e.g., eating,
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.
      ; Horvath and Miller-Cushon, 2019;
      • Miller-Cushon E.K.
      • Bergeron R.
      • Leslie K.E.
      • Mason G.J.
      • DeVries T.J.
      Effect of feed presentation on feeding patterns of dairy calves.
      ; NNOM,
      • Webb L.E.
      • Bokkers E.A.M.
      • Engel B.
      • Gerrits W.J.J.
      • Berends H.
      • van Reenen C.G.
      Behaviour and welfare of veal calves fed different amounts of solid feed supplemented to a milk replacer ration adjusted for similar growth.
      ;
      • Horvath K.C.
      • Allen A.N.
      • Miller-Cushon E.K.
      Effects of access to stationary brushes and chopped hay on behavior and performance of individually housed dairy calves.
      ;
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.
      ), others overnight (e.g., rumination,
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.
      ), and others are rare, occurring sporadically throughout the day (e.g., tongue rolling,
      • Webb L.E.
      • Bokkers E.A.M.
      • Engel B.
      • Gerrits W.J.J.
      • Berends H.
      • van Reenen C.G.
      Behaviour and welfare of veal calves fed different amounts of solid feed supplemented to a milk replacer ration adjusted for similar growth.
      ;
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.
      ). However, research on ARBs is often conducted during limited windows throughout the day (
      • Bokkers E.A.
      • Koene P.
      Activity, oral behaviour and slaughter data as welfare indicators in veal calves: A comparison of three housing systems.
      ;
      • Salter R.S.
      • Reuscher K.J.
      • Van Os J.M.C.
      Milk- and starter-feeding strategies to reduce cross sucking in pair-housed calves in outdoor hutches.
      ;
      • Zhang C.
      • Juniper D.T.
      • Meagher R.K.
      Effects of physical enrichment items and social housing on calves' growth, behaviour and response to novelty.
      ), which could skew interpretations about performance. This may be particularly important in light of recent evidence that, across 24-h periods, calves perform a wide array of possibly abnormal behaviors that are often not scored. In addition to possible sham rumination, calves show polydipsia (
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.
      ), which is also seen in poultry and swine exposed to feeding restriction (
      • Savory C.J.
      • Seawright E.
      • Watson A.
      Stereotyped behaviour in broiler breeders in relation to husbandry and opioid receptor blockade.
      ;
      • Robert S.
      • Matte J.J.
      • Farmer C.
      • Girard C.L.
      • Martineau G.P.
      High-fibre diets for sows: Effects on stereotypies and adjunctive drinking.
      ), excessive grooming, and repetitive tongue flicks (
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.
      ). It is possible that providing more opportunities for natural forage acquisition and processing behaviors could have wide-ranging effects on all calf oral behaviors over 24 h.
      We set out to design a novel hay enrichment device that encouraged natural forage acquisition movements and increased effort required to obtain hay before chewing it. Devices of this nature have been created to reduce oral ARBs, including tongue rolling, in giraffes (
      • Fernandez L.T.
      • Bashaw M.J.
      • Sartor R.L.
      • Bouwens N.R.
      • Maki T.S.
      Tongue twisters: Feeding enrichment to reduce oral stereotypy in giraffe.
      ) and were the basis for our design. We predicted that calves provided with hay would eat and chew more and perform fewer oral ARBs across 24 h relative to controls, and that presenting it in a pipe feeder would result in more marked changes in these behaviors. We also expected to see fewer possibly abnormal behaviors such as tongue flicks and long or repeated bouts of grooming in calves provided hay. Panting, another oral behavior performed by calves, typically reflective of heat stress (e.g.,
      • Tresoldi G.
      • Schütz K.E.
      • Tucker C.B.
      Assessing heat load in drylot dairy cattle: Refining on-farm sampling methodology.
      ), was scored to add to a limited body of research on this behavior in calves. We did not expect that hay provision would reduce grain intake or ADG, given recent evidence that forage does not displace either one (e.g.,
      • Khan M.A.
      • Weary D.M.
      • von Keyserlingk M.A.G.
      Hay intake improves performance and rumen development of calves fed higher quantities of milk.
      ;
      • Castells L.
      • Bach A.
      • Araujo G.
      • Montoro C.
      • Terré M.
      Effect of different forage sources on performance and feeding behavior of Holstein calves.
      ;
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.
      ).

      MATERIALS AND METHODS

      This study was conducted from June to November 2019 at the University of California, Davis Dairy Facility. All procedures were approved by the University of California, Davis Institutional Animal Care and Use Committee (protocol #20466).

      Animals and Housing

      We enrolled all healthy female Holstein calves born between June 1 and September 21, 2019 (n = 27). Calves were housed individually in outdoor plastic hutches (2 × 1.5 m, length × depth) with an attached wire-fenced pen (2 × 1.5 × 0.9 m, length × depth × height). Hutches and pens were spaced ∼0.5 m apart, allowing calves to touch the muzzle of neighboring animals. The enclosures were bedded with sand approximately 12 to 17 cm deep that was spot-cleaned daily and topped-up as needed. The sand was covered with perforated rubber mats from d 0 to 5 ± 1 to limit unintentional inhalation of sand particulate (Supplemental Figure S1, https://doi.org/10.5281/zenodo.6618168;
      • Downey B.C.
      • Tucker C.B.
      Data from: Providing long hay in a novel pipe feeder or a bucket reduces some, but not all abnormal oral behaviors in milk-fed dairy calves. Dryad, Dataset.
      ). Sand was used to limit fibrous bedding consumption (e.g.,
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.
      ).
      Calves received colostrum twice a day for 5 d with each calf consuming 18.1 ± 1.1 L (mean ± SD) total. Colostrum meals were fed via a bottle and rubber teat (Connewango) or an esophageal tube feeder (2.1% of all colostrum feedings across calves). From 5 to 9 d of age, calves were fed 1.9 L of milk replacer (26% CP, 16% fat, 15% TS, mixed as indicated at a rate of 142 g/L of hot water; Calva Products Inc.) at each of 2 daily meals at approximately 0915 and 1615 h. From 10 to 23 d of age, calves received 2.4 L of milk replacer at each of the 2 meals, and from 24 to 49 d of age, 2.8 L of milk replacer per meal. All milk meals were fed via a bottle and rubber teat. Bottles were available inside the hutch 0.6 m above the ground. Weaning began at 50 d when the 0915 h meal was removed. Calves were fully weaned at 60 d when the 1615 h meal was removed. All colostrum and milk feedings were in accordance with farm protocol.
      All calves were disbudded at 7 to 10 d (n = 14, mean birth weight = 38.7 kg) or 50 to 53 d (n = 13, mean birth weight = 38.6 kg) as part of a separate experiment balanced by feeding treatment and birth weight. Calves were given a cornual nerve block with 5 to 7 mL lidocaine hydrochloride on each side of the head and hair over the horn bud was trimmed before application of a disbudding iron until a copper ring formed. Oral meloxicam (0.5–1 mg/kg) was provided to all calves after disbudding. All calves were vaccinated with Bovishield 5 at 21 and 40 d, Spirovac at 30 d, and One Shot at 40 d (all Zoetis Inc.). Electrolyte treatments (1.9 L) were provided as per standard farm practice if loose feces were observed. Nine calves received electrolytes for 1 to 4 treatments total over the course of the experiment (2 Control, 4 Pipe, 3 Bucket); only 1 of these calves received electrolytes on consecutive days (2 feedings total). No observation days were affected by these.

      Experimental Design

      Calves were allocated to 1 of 3 treatments based on birth order, with each treatment represented in a given similarly aged cohort of 3 calves, using a random number generator. Adjustments were made to balance birth weight across treatments. Calves assigned to the Control treatment (n = 9, mean birth weight = 38.6 kg) received ad libitum water and grain (Table 1; Starter Calf Feed 901033, Associated Feed and Supply Co.; Supplemental Figures S1 and S2, https://doi.org/10.5281/zenodo.6618168;
      • Downey B.C.
      • Tucker C.B.
      Data from: Providing long hay in a novel pipe feeder or a bucket reduces some, but not all abnormal oral behaviors in milk-fed dairy calves. Dryad, Dataset.
      ) by bucket from birth. Calves assigned to the Bucket treatment (n = 9, mean birth weight = 38.6 kg) received ad libitum water, grain, and chopped (19 ± 4 cm) mountaingrass hay (mix of orchard, Dactylis glomerata, and fescue, Festuca arundinacea; Higby's Country Feed; Table 1; Table 2; Supplemental Figures S1 and S2) by bucket from birth. Calves in the Pipe treatment (n = 9, mean birth weight = 38.8 kg) received ad libitum water, grain, and the same chopped mountaingrass hay in a 56 × 10.2 cm (length × diameter) polyvinyl chloride (PVC) pipe feeder (Figure 1; Supplemental Figures S1–S3; Supplemental Videos S1–S4, https://doi.org/10.5281/zenodo.6618168;
      • Downey B.C.
      • Tucker C.B.
      Data from: Providing long hay in a novel pipe feeder or a bucket reduces some, but not all abnormal oral behaviors in milk-fed dairy calves. Dryad, Dataset.
      ). The pipe feeder had 4 equally spaced 6.35-cm (diameter) holes cut into it that were sanded down until smooth, and was fitted with 2 removable knockout end caps. Pipes were mounted 0.8 m from the ground using a 10.2-cm vent pipe hanger in all pens. All calves had 3 buckets available at all times: grain, water, hay (Bucket group), or empty bucket (Control and Pipe groups), left to right (Supplemental Figure S1), and a pipe feeder with hay (Pipe group) or kept empty (Control and Bucket groups). The assigned feeding method continued throughout the preweaning stage. On d 50, when weaning began, pipes were removed for all calves and ad libitum TMR (Table 1, Table 2; alfalfa, almond hulls, cottonseed, corn, barley, beet pulp) was provided for all calves via bucket. The TMR was placed in the bucket previously used for hay (Bucket group) or kept empty (Control and Pipe groups). All calves had access to grain and water in the same buckets as in the milk-fed period throughout weaning.
      Table 1Chemical composition of solid feeds (mean ± SD, reported as % of DM)
      Chemical compositionGrainMountaingrass hayTMR
      DM86.86 ± 0.8392.37 ± 1.089.66 ± 0.96
      CP21.76 ± 1.1110.85 ± 1.0316.08 ± 0.83
      ADF7.16 ± 0.533.97 ± 1.1426.34 ± 1.71
      NDF12.78 ± 1.3154.23 ± 1.5936.86 ± 1.78
      Ash7.55 ± 0.8710.7 ± 0.567.95 ± 0.79
      TDN61.98 ± 1.2664.94 ± 0.77
      Table 2Particle size of mountaingrass hay and TMR (mean ± SD, reported as % of diet; Penn State Particle Separator)
      Particle sizeMountaingrass hayTMR
      >1.9 cm73.9 ± 5.017.1 ± 1.6
      0.79–1.9 cm17.6 ± 2.223.0 ± 2.0
      0.41–0.79 cm5.5 ± 2.326.0 ± 0.6
      <0.41 cm3.1 ± 1.533.9 ± 1.0
      Figure thumbnail gr1
      Figure 1Calf feeding from a polyvinyl chloride (PVC) pipe feeder filled with chopped mountaingrass hay. The pipe was 56 × 10.2 cm (length × width) with 4 equally spaced 6.35-cm holes cut into it that were sanded down until smooth and was fitted with 2 removable knockout end caps. Pipes were mounted 0.8 m from the ground using a 10.2-cm vent pipe hanger in all pens.

      Data Collection

      Feed Intake and ADG

      Feed and water intake were recorded beginning on d 0 of life by providing preweighed fresh feed daily at 0800 h and subtracting the refusals on the following day at 0800 h from the initial provisions (GBK16a Bench Check Weighing Scale 8,000 g limit/0.1 g readability, Adam Equipment Inc.). Feed levels were checked at 1200, 1600, and 2000 h and fresh measured feed was added if necessary to maintain ad libitum levels. When possible, clean spilled hay was added back to the bucket at each feeding; spillage contaminated with feces or water was removed daily at 1600 h. Calves were fed to at least 115% of the previous day's intake throughout the experiment, with a minimum of 800 g of grain and 40 g of hay provided at each feeding. Water orts were recorded and fresh measured water provided at 0800, 1200, and 1600 h. If low, fresh water was added at 2000 h. If feces were present in any of the buckets, or intake did not represent a continuous 24-h period (e.g., for calves born after 0800 h), intake data for that calf for that day were discarded. Calves were weighed weekly to determine ADG during the experimental period (VS-660 Scale 300 kg limit/0.1 kg readability, A and A Scales LLC).
      To calculate DM and nutritional protein of the feed, fresh feed was sampled once a week and sent to Cumberland Valley Analytical Services Inc. for analysis of DM (1358C; method 930.15;
      • AOAC International
      Official Methods of Analysis.
      ), ash (5358C; method 942.05;
      • AOAC International
      Official Methods of Analysis.
      ), ADF (method 973.18;
      • AOAC International
      Official Methods of Analysis.
      ), NDF with heat-stable a-amylase and sodium sulfite (
      • Van Soest P.J.
      • Robertson J.B.
      • Lewis B.A.
      Methods for dietary fiber, neutral detergent fiber, and nonstarch polysaccharides in relation to animal nutrition.
      ), and CP (N × 6.25; method 990.03;
      • AOAC International
      Official Methods of Analysis.
      ; Leco FP-528 Nitrogen Analyzer, Leco]. The nutrient content of the solid feed is reported in Table 2. Samples of daily orts were taken per calf and combined weekly to determine DM. These combined samples were oven-dried at 100°C for 15 h to determine DM content. Weights were recorded with an AG104 101 g limit/0.1 mg readability scale (Mettler Toledo, LLC.). Particle sizes of mountaingrass hay and TMR were determined via a 3-sieve Penn State Particle Separator, used as directed by one trained researcher (40 total shakes, 5 in each direction;
      • Kononoff P.J.
      • Heinrichs A.J.
      • Buckmaster D.R.
      Modification of the Penn State forage and total mixed ration particle separator and the effects of moisture content on its measurements.
      ).

      Behavioral Observations

      Calf behavior was recorded using 1–0 sampling (present or not present) during 5-s intervals for a continuous 24 h beginning at 0800 h at wk 4 (31 ± 3 d) and 6 (45 ± 4 d) for each calf. This methodology was similar to our previous work (e.g., 1–0 sampling during 1-min intervals,
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.
      ) but refined to 5-s intervals to improve estimates. Weeks 4 and 6 were chosen as calves are reported to consume nonnegligible amounts of hay during this period and proportion of time engaged in oral behavior stabilizes during this period (
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.
      ). Drinking water, eating hay or grain, grooming, NNOM: pipe, NNOM: other, panting, ruminating, sucking milk, tongue flicks, and tongue rolling (Table 3; Supplemental Videos S1–S12 in https://doi.org/10.5281/zenodo.5553444,
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Data from: Hay provision affects 24-h performance of normal and abnormal oral behaviors in dairy calves. Dryad.
      ; Supplemental Video S5 in https://doi.org/10.5281/zenodo.6618168,
      • Downey B.C.
      • Tucker C.B.
      Data from: Providing long hay in a novel pipe feeder or a bucket reduces some, but not all abnormal oral behaviors in milk-fed dairy calves. Dryad, Dataset.
      ) were recorded as present or not present every 5 s using the Animal Behaviour Pro app (
      • Newton-Fisher N.E.
      Animal Behaviour Pro: 1.4.4.
      ) with continuous countdown timers (Pebble Technology Corp., Fitbit). Eating overall was the sum of eating hay and eating grain. NNOM: total was the sum of NNOM: pipe and NNOM: other. Calves were watched for a continuous 24 h using a total of 16 observers. An observer watched one calf at a time in 2-h shifts. Observers were not blind to treatment because feed availability could not be masked. Observers were first trained using 1–0 sampling during 5-s intervals using a total of 1.5 h of video from 9 unique calves not used in this experiment. All possible behaviors were exhibited in these videos. Observers were then trained in live sessions using 1–0 sampling during 5-s intervals for a minimum of 3 h across 3 separate days (maximum training time = 4.75 h across 5 sessions), and reliability values were taken from these. Tongue rolling and panting were rare in these live sessions and were assessed using a 30-question video test (15 yes, 15 no). All observers were trained to reliability ≥75% on tongue flicks (Cohen's kappa, irr package version 0.84.1,
      • Gamer M.
      • Lemon J.
      • Fellows I.
      • Singh P.
      irr: Various coefficients of interrater reliability and agreement. R package version 0.84.1.
      ) and ≥80% on all other behaviors, compared with author B.C.D., before data collection began.
      Table 3Behaviors recorded during continuous 24-h observations
      For all relevant definitions, muzzle is defined as from the bottom of the eyes to the end of the mouth. See Supplemental Videos S1–S12 in https://doi.org/10.25338/B8V054, Downey et al., 2022b, and Supplemental Video S5 in https://doi.org/10.5281/zenodo.6618168, Downey and Tucker, 2022, for examples.
      BehaviorDefinition
      Drinking waterAny part of the muzzle is in the water bucket for at least 1 s, or mouth or tongue visibly enters water.
      Eating grainAny part of the muzzle is in the feed bucket while grain is present for at least 1 s, or jaw movements while the head is above the bucket or within 1 head length of the feed bucket, or jaw movements while grain is visibly held within the mouth
      Eating hayAny part of the muzzle is in the feed bucket while hay is present for at least 1 s, or mouth is directed at one of the holes of the polyvinyl chloride (PVC) pipe of at least 1 s, or jaw movements while the head is within 1 head length of the feed bucket/PVC pipe, or jaw movements while hay is visibly held within the mouth
      Grooming bodyTouching hair with the tongue or mouth on calf's own body or a neighboring animal
      Licking a neighboring animal was rare due to the positioning of the hutches.
      ; includes if mouth is not visible but directed toward body and the head moves in an up/down motion.
      NNOM: pipe
      Nonnutritive oral manipulation (NNOM) of the pipe was scored separately from all other NNOM because it was a novel addition to all pens.
      Licking, chewing, or sucking directed toward the PVC pipe, but not at any of the 4 holes, unless the pipe is empty
      NNOM: otherLicking, chewing, or sucking directed toward a nonnutritive item (includes bars, hutch, bedding, empty bucket; excludes PVC pipe): tongue or lips must be touching a nonnutritive item, or such item must be held inside the mouth
      PantingBreathing involves heavy movements of the abdomen and thorax; mouth may be open (space between the lips is visible)
      RuminatingRhythmic circular jaw movements (at least 2) that happen anywhere in the pen except over the feed buckets/PVC pipe; if only neck is visible, can be identified by visual observation of a bolus moving down/up the neck
      Sucking milkMouth around nipple of a bottle containing milk
      Tongue flicksTongue extends out of the mouth without touching other objects or forming a full or partial circular motion, or extends up to the nose before retracting back into mouth and repeating at least once more within 1 s; can occur while eating and ruminating
      Tongue rollingTongue is held in a full or partial circular position and/or moves in a full or partial circular motion; this can occur when the tongue is held within the border of the lips inside the mouth and/or extended outside the border of the lips. This cannot occur while any other behaviors are being performed (the tongue is not touching any feed/nonnutritive items), and does not need to repeat.
      1 For all relevant definitions, muzzle is defined as from the bottom of the eyes to the end of the mouth. See Supplemental Videos S1–S12 in https://doi.org/10.25338/B8V054,
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Data from: Hay provision affects 24-h performance of normal and abnormal oral behaviors in dairy calves. Dryad.
      , and Supplemental Video S5 in https://doi.org/10.5281/zenodo.6618168,
      • Downey B.C.
      • Tucker C.B.
      Data from: Providing long hay in a novel pipe feeder or a bucket reduces some, but not all abnormal oral behaviors in milk-fed dairy calves. Dryad, Dataset.
      , for examples.
      2 Licking a neighboring animal was rare due to the positioning of the hutches.
      3 Nonnutritive oral manipulation (NNOM) of the pipe was scored separately from all other NNOM because it was a novel addition to all pens.

      Statistical Analysis

      Statistical analyses were performed using R version 4.0.3 (
      • R Core Team
      R: A language and environment for statistical computing.
      ) on MacOS Big Sur 10.16 via RStudio version 1.2.5033 (
      • RStudio Team
      RStudio: Integrated Development for R.
      ) with calf as the experimental unit. Model fit was checked for normality and homogeneity of variance using QQ plots and plots of residuals vs. fitted values (plot, boxplot, resid functions in base R, ggpubr package version 0.4.0,
      • Kassambara A.
      ggpubr: ‘ggplot2’ based publication ready plots. R package version 0.4.0.
      , DHARMa package version 0.3.3.0,
      • Hartig F.
      DHARMa: Residual diagnostics for hierarchical (multi-level/mixed) regression models. R package version 0.4.1.
      ). Unless stated otherwise, all model assumptions were met. All intake and behavior models were assessed with a type 3 ANOVA (car package v 3.0–10,
      • Fox J.
      • Weisberg S.
      An R Companion to Applied Regression.
      ) to obtain P-values. If significant (P < 0.05) treatment or interaction effects were detected, P-values for individual pairwise comparisons were obtained using estimated marginal mean contrasts (emmeans package v. 1.6.1,
      • Lenth R.V.
      emmeans: Estimated Marginal Means, aka Least-Squares Means. R package version 1.6.1.
      ). The interaction term is reported if P < 0.1, otherwise the individual significant fixed effects are reported.

      Feed Intake

      Some intake data were excluded: 9.4, 23.6, 4.9, and 7.7% of calf-day values for grain, hay, water, and TMR, respectively, due to contamination with feces or saliva, spillage by calves (e.g., entire bucket spilled or kicked over), or intake covering <24 h (e.g., d 0 of life for some calves). Most of the exclusions for grain (88% of the 9.4% excluded) and hay intake (76% of the 23.6% excluded) occurred within the first 2 wk when consumption was low (<0.09 kg/d) and saliva contamination had a large effect. Data were also excluded if intake could not be calculated on a DM basis, which was due to human error in drying individual ort samples.
      Intake data were separated by age into preweaning (0–49 d) and weaning (50–59 d) periods. During the preweaning period, intake data were averaged by week. Data from d 49 were included in the wk 6 values. Grain and hay data were modeled with a linear mixed model using the REML method with an identity variance structure to account for heterogeneous variance across weeks (lme4 package version 1.1–26,
      • Bates D.
      • Mächler M.
      • Bolker B.
      • Walker S.
      Fitting linear mixed-effects models using lme4.
      ). Week was treated numerically as data were collected continuously over time. Week, treatment, and the interaction between week and treatment were fixed effects, whereas calf was a random effect.
      During the weaning period, intake was assessed by day; day was treated as a numeral. Grain, TMR, and water intake were modeled with linear mixed models (lme4 package version 1.1–26,
      • Bates D.
      • Mächler M.
      • Bolker B.
      • Walker S.
      Fitting linear mixed-effects models using lme4.
      ) with age in days, treatment, and the interaction between both as fixed effects and calf as a random effect.

      Average Daily Gain

      Average daily gain during the preweaning period was modeled with a linear mixed model using the REML method (lme4 package version 1.1–26,
      • Bates D.
      • Mächler M.
      • Bolker B.
      • Walker S.
      Fitting linear mixed-effects models using lme4.
      ). Week, treatment, and the interaction between week and treatment were fixed effects and calf was a random effect. ADG from wk 0 and 7 were not included in the model as not all calves these values, based on when they were first measured (wk 0) or weaned (wk 7), and early life stress and adjustment to the environment can lead to growth checks (e.g.,
      • Chapman C.E.
      • Erickson P.S.
      • Quigley J.D.
      • Hill T.M.
      • Bateman II, H.G.
      • Suarez-Mena F.X.
      • Schlotterbeck R.L.
      Effect of milk replacer program on calf performance and digestion of nutrients with age of the dairy calf.
      ). All calves thus had 5–6 ADG calculations, with the final preweaning measurement occurring on 45 ± 2 d.
      Average daily gain during weaning was not assessed, as calves only had 1 or 2 measurements during this period, and measurements were not taken at a consistent point in the step-down process for all calves. Instead, final weight (measured on 57 ± 2 d) and overall ADG across the entire experimental period [(final weight − birth weight)/age in days at final weight] were assessed using a one-way ANOVA (aov function in base R). If a significant treatment difference was found, Tukey pairwise comparisons were calculated and adjusted P-values are reported.

      Behavioral Observations

      Proportion of time engaged in each behavior was analyzed using a generalized linear mixed model (glmmTMB package v 1.0.2.1.3,
      • Brooks M.E.
      • Kristensen K.
      • van Benthem K.J.
      • Magnusson A.
      • Berg C.W.
      • Nielsen A.
      • Skaug H.J.
      • Maechler M.
      • Bolker B.M.
      glmmTMB balances speed and flexibility among packages for zero-inflated generalized linear mixed modeling.
      ) fit with a β distribution and logit link. Week was treated categorically as observations were conducted at 2 distinct time points. Week, treatment, and the interaction between week and treatment were fixed effects, and calf was a random effect. Tongue rolling and panting were rare and were not analyzed with a model. Behavioral data are reported as percentages hereafter in the text to facilitate readability; raw data (https://doi.org/10.25338/B8Z052,
      • Downey B.C.
      • Tucker C.B.
      Data from: Providing long hay in a novel pipe feeder or a bucket reduces some, but not all abnormal oral behaviors in milk-fed dairy calves. Dryad, Dataset.
      ) are expressed as proportions.

      Outliers

      Some data were analyzed for extreme expression. Outliers in water consumption could indicate polydipsia, whereas outliers in grooming bouts may provide insight into abnormal expression of a seemingly normal behavior. Grooming bouts were considered to be consecutive runs of 5-s intervals in which grooming occurred. For each calf in each week, we converted nongrooming intervals occurring singly or in consecutive runs of ≤3 (= 15 s) that were bordered by grooming to this behavior. Nongrooming gaps of ≥4 intervals (20 s) thus ended a consecutive run of grooming. This cutoff (20 s) was determined based on visual inspection of these data. Outliers in both water intake (preweaning and weaning, separately) and grooming were calculated using interquartile range criteria, such that values that fell more than 1.5× below or above the first and third quartiles, respectively (boxplot function in base R), were considered extreme.

      RESULTS

      All data (https://doi.org/10.25338/B8Z052), RMarkdown files for analyses and figures (https://doi.org/10.5281/zenodo.6618166), and supplemental videos, figures, and tables containing means, standard errors, confidence intervals, test statistics, degrees of freedom, and P-values for all analyses (https://doi.org/10.5281/zenodo.6618168) are available in the Dryad repository (
      • Downey B.C.
      • Tucker C.B.
      Data from: Providing long hay in a novel pipe feeder or a bucket reduces some, but not all abnormal oral behaviors in milk-fed dairy calves. Dryad, Dataset.
      ).

      Feed Intake

      During the preweaning period (d 0–49), there was a significant week by treatment interaction for grain (P < 0.001) and water intake (P = 0.004; Figure 2; Supplemental Table S1, https://doi.org/10.5281/zenodo.6618168;
      • Downey B.C.
      • Tucker C.B.
      Data from: Providing long hay in a novel pipe feeder or a bucket reduces some, but not all abnormal oral behaviors in milk-fed dairy calves. Dryad, Dataset.
      ). All calves consumed more grain and water over time, but calves fed hay (Bucket and Pipe groups) increased their consumption of these resources more than Control calves. Individual water intake varied from 0.1 to 11.05 L/d, with outliers considered to be those ≥7.35 L/d. Twelve calves (4 Control, 3 Bucket, 5 Pipe) had outlier values representing 2.5% of all calf-day measurements during the milk-fed period. For these 12 calves, these outliers represented 2 to 21% of all their values. There was also a significant week by treatment interaction for hay (P < 0.001), as calves in the Bucket group consumed more hay over time than calves in the Pipe group. Our intention was to feed hay ad libitum: 11% of calf-days for the Bucket treatment and 12% for Pipe had <10% hay refusals.
      Figure thumbnail gr2
      Figure 2Feed and water intake values throughout the treatment period of calves fed a diet of grain and milk replacer from birth (Control) or a control diet with additional mountaingrass hay from birth in a bucket (Bucket) or novel polyvinyl chloride (PVC) pipe feeder (Pipe). Total mixed ration was available for all calves at the start of step-down weaning (50–60 d), as indicated by the dashed line. Data are summarized by treatment (trt) and averaged by 7-d period (wk) across the preweaning period, and by day (d) during step-down weaning. Error bars represent SE. P-values <0.1 are reported for week (preweaning) or day (weaning), treatment, or their interactions.
      During the weaning period, all calves consumed more grain (P = 0.018; Figure 2) and TMR (P < 0.001; Figure 2) as days passed, but there was no evidence that treatment affected intake (P ≥ 0.117). There was a day by treatment interaction for water consumption (P = 0.029; Figure 2), with Bucket calves consuming more water than Pipe and Control calves as weaning continued. Individual water intake during the weaning period varied from 1.00 to 17.15 L/d, with outliers considered to be those ≥16.05 L/d. Two calves (1 Bucket, 1 Pipe) had outlier values on 5 d (1.8% of all calf-day measurements) during the weaning period.

      Average Daily Gain

      Calves fed hay increased ADG at a faster rate than Control calves during the preweaning period (mean ± SE, Control: 0.50 ± 0.04 kg/d; Bucket: 0.61 ± 0.04 kg/d; Pipe: 0.60 ± 0.05 kg/d; week by treatment interaction P = 0.020; Supplemental Table S1), with all calves increasing ADG over time (P < 0.001). Across the entire experiment, Bucket calves had higher ADG than Control calves (Control: 0.54 ± 0.03 kg/d; Bucket: 0.68 ± 0.03 kg/d; P = 0.023) but not Pipe calves (0.63 ± 0.04 kg/d; P = 0.600). Pipe calves had a similar ADG to Control (P = 0.167). Similarly, Bucket calves tended to have a higher final BW than Control (Control: 69.1 ± 1.8 kg, Bucket: 77.9 ± 2.6 kg; P = 0.077) but not Pipe calves (75.0 ± 3.5 kg; P = 0.741), whereas there was no evidence that Control and Pipe calves differed (P = 0.290).

      Oral Behaviors

      Bucket and Pipe calves ruminated in an equal percentage of observations (P = 0.981; Figure 3; Supplemental Table S2, https://doi.org/10.5281/zenodo.6618168;
      • Downey B.C.
      • Tucker C.B.
      Data from: Providing long hay in a novel pipe feeder or a bucket reduces some, but not all abnormal oral behaviors in milk-fed dairy calves. Dryad, Dataset.
      ) and spent more observations ruminating compared with Control calves (P < 0.001). Rumination was consistent across weeks (P = 0.278). All calves spent similar percentages of observations eating grain across weeks (Ptrt = 0.122; Pwk = 0.223; Figure 3), though Bucket and Pipe calves spent significantly more observations eating overall (grain and hay) compared with Control (P < 0.001) due to the additional time spent consuming hay. There was no evidence that observations spent eating overall differed across weeks (P = 0.137).
      Figure thumbnail gr3
      Figure 3Mean percentage of observations engaged in eating grain, eating hay, eating overall, ruminating, drinking water, and sucking milk across 24 h of calves fed a control diet of grain and milk replacer from birth (Control) or a control diet with additional mountaingrass hay from birth in a bucket (Bucket) or novel polyvinyl chloride (PVC) pipe feeder (Pipe). Data were collected via 1–0 live sampling at 5-s intervals for a continuous 24 h in wk 4 and 6 and are summarized by treatment (trt) and week (wk). Boxplots represent the median (black line within box) and first and third quartiles (25 and 75% of data). Whiskers extend to the lowest and highest values that are not outliers (values that are 1.5× the interquartile range); outliers (o) and means (x) are also presented. Back-transformed model predicted estimates are represented by dashed lines (means) and shaded ribbons (SE). P-values <0.1 are reported for week, treatment, or their interactions.
      Bucket calves spent more observations drinking water compared with Control calves (P = 0.031; Figure 3), but there was no evidence that either treatment differed from Pipe calves (P ≥ 0.317). Observations spent drinking water were not related to amount of water consumed (posthoc regression analysis, R2 = −0.01, Supplemental Figure S4, https://doi.org/10.5281/zenodo.6618168;
      • Downey B.C.
      • Tucker C.B.
      Data from: Providing long hay in a novel pipe feeder or a bucket reduces some, but not all abnormal oral behaviors in milk-fed dairy calves. Dryad, Dataset.
      ). All calves spent 0.7 ± 0.02% of observations (mean percentage of intervals ± SE) sucking milk in wk 4 (P ≥ 0.759; Figure 3) but by wk 6, Bucket calves tended to spend more observations sucking than Pipe calves (0.8 ± 0.03% vs. 0.7 ± 0.05%, respectively; P = 0.064) and significantly more than Control calves (0.6 ± 0.02%; P = 0.001).
      Control calves consistently spent more observations manipulating the pipe feeder (NNOM: pipe) than Pipe calves (P = 0.007; Figure 4) and tended to spend more observations manipulating the pipe compared with Bucket calves (P = 0.078). There was no evidence that Pipe and Bucket calves differed in percentage of observations manipulating the pipe (P = 0.589), and all calves manipulated the pipe less across weeks (P = 0.008). Control calves spent more intervals performing NNOM: other and NNOM: total (pipe and other) than Bucket (P = 0.003, P = 0.002, respectively; Figure 4) and Pipe (P = 0.001, P < 0.001) calves. There was no evidence that Bucket and Pipe calves differed in NNOM: other (P = 0.934) or NNOM: total (P = 0.901). Pipe calves tended to spend fewer observations eating hay than Bucket calves (P = 0.068). All calves tended to spend more observations eating hay across weeks (P = 0.099). There was no evidence that week influenced observations spent performing NNOM: (P = 0.356), or total NNOM: total (P = 0.609).
      Figure thumbnail gr4
      Figure 4Mean percentage of time engaged in nonnutritive oral manipulation (NNOM): pipe, NNOM: other, NNOM: total, grooming, and tongue flicks across 24 h of calves fed a control diet of grain and milk replacer from birth (Control) or a control diet with additional mountaingrass hay from birth in a bucket (Bucket) or novel polyvinyl chloride (PVC) pipe feeder (Pipe). Data were collected via 1–0 live sampling at 5-s intervals for a continuous 24 h in wk 4 and 6 and are summarized by treatment (trt) and week (wk). Boxplots represent the median (black line within box) and first and third quartiles (25 and 75% of data). Whiskers extend to the lowest and highest values that are not outliers (values that are 1.5× the interquartile range); outliers (o) and means (x) are also presented. Back-transformed model predicted estimates are represented by dashed lines (means) and shaded ribbons (SE). P-values <0.1 are reported for week, treatment, or their interactions.
      There was no evidence that treatment affected the percentage of observations performing tongue flicks (Ptrt = 0.184, Pwk = 0.530; Figure 4) and grooming (Ptrt = 0.735, Pwk = 0.815; Figure 4). Individuals varied in overall grooming performance (0.5–5.8% of 24-h observations). Individuals also varied in number of grooming bouts performed in a single day (31–274; average across both weeks = 150 bouts; Figure 5). Bouts ranged from 1 to 299 consecutive 5-s intervals (5 s to 24.9 min; Figure 5), with a median bout length of 2 intervals, or 10 s (mean = 4.3, or 22 s). Outliers were bouts of 12 to 299 consecutive intervals (1–24.9 min), which represented 7.3% of all grooming bouts performed across weeks. Individuals varied in how much they performed these outlier bouts (1.8–18.9% of total bouts in a 24-h day; Figure 5).
      Figure thumbnail gr5
      Figure 5Counts and durations of grooming bouts (individual dots) in wk 4 and 6 for 4 calves. Grooming bouts were evaluated over 24 h using 1–0 sampling at 5-s intervals; bouts were calculated as observations where grooming occurred consecutively, that is with 3 or fewer 5-s interval gaps of nonrooming behavior in between. Bouts with durations greater than or equal to 60 s were considered outliers, as they fell outside 1.5× the interquartile range below or above the first and third quartiles. The 4 calves chosen illustrate calves that reflect unique challenges with using repetition as a component to abnormal repetitive behaviors (ARBs). Calf 3030 has the longest outlier bout of all 27 calves sampled (1,494 s in wk 4). She spends a similar amount of time grooming overall as Calf 3038 (5.8% vs. 5.7%, respectively, in wk 6), but 3038 performs more grooming bouts, for shorter durations. Calf 3042 spends the least amount of time grooming (0.5%, wk 6), and has only 1 outlier grooming bout in each week. Calf 3043 spends a low percentage of time grooming overall (4.1% in wk 4, 3.8% in wk 6) but has the highest percentage of outlier bouts out of her total grooming bouts (18.9% in wk 4, 17.2% in wk 6).
      Tongue rolling was seen in 85% of calves (8 Control, 7 Bucket, 8 Pipe) at least once during wk 4 and 6, but for low percentages of observations (Control: 0.02 ± 0.008%; Bucket: 0.05 ± 0.03%; Pipe: 0.006 ± 0.002%, Supplemental Figure S5, https://doi.org/10.5281/zenodo.6618168;
      • Downey B.C.
      • Tucker C.B.
      Data from: Providing long hay in a novel pipe feeder or a bucket reduces some, but not all abnormal oral behaviors in milk-fed dairy calves. Dryad, Dataset.
      ). Calves that tongue rolled performed this behavior for 0.006–0.4% of observations. Similar numbers of calves tongue rolled each week (wk 4: 18 calves; wk 6: 17 calves), but not all calves tongue rolled in each week. Tongue rolling occurred throughout the day (Supplemental Figure S6, https://doi.org/10.5281/zenodo.6618168;
      • Downey B.C.
      • Tucker C.B.
      Data from: Providing long hay in a novel pipe feeder or a bucket reduces some, but not all abnormal oral behaviors in milk-fed dairy calves. Dryad, Dataset.
      ). Panting was performed by 8 calves (2 Control, 4 Bucket, 2 Pipe) infrequently across both weeks (Control: 0.003 ± 0.003%; Bucket: 0.2 ± 0.1%; Pipe: 0.006 ± 0.005%). Panting was most common around 1400 h across weeks, as in
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.
      .

      DISCUSSION

      Feeding Behavior

      Calves fed hay consumed relatively high levels of it (Bucket: 0.086 kg/d; Pipe: 0.064 kg/d) and more grain (Bucket: 0.31 kg/d; Pipe: 0.3 kg/d) than Control calves (0.22 kg/d) throughout the milk-fed period. Providing forage alongside grain is often found to increase overall DMI (
      • Khan M.A.
      • Weary D.M.
      • von Keyserlingk M.A.G.
      Hay intake improves performance and rumen development of calves fed higher quantities of milk.
      ;
      • Castells L.
      • Bach A.
      • Aris A.
      • Terré M.
      Effects of forage provision to young calves on rumen fermentation and development of the gastrointestinal tract.
      ;
      • Horvath K.C.
      • Miller-Cushon E.K.
      Evaluating effects of providing hay on behavioral development and performance of group-housed dairy calves.
      ). We also found that calves fed hay had higher ADG than Control during the milk-fed period (0.60–0.61 vs. 0.54 kg/d), similar to other findings (e.g.,
      • Castells L.
      • Bach A.
      • Araujo G.
      • Montoro C.
      • Terré M.
      Effect of different forage sources on performance and feeding behavior of Holstein calves.
      ;
      • Terré M.
      • Castells L.
      • Khan M.A.
      • Bach A.
      Interaction between the physical form of the starter feed and straw provision on growth performance of Holstein calves.
      ). Recent evidence demonstrates that access to forage can also increase grain consumption (e.g.,
      • Castells L.
      • Bach A.
      • Araujo G.
      • Montoro C.
      • Terré M.
      Effect of different forage sources on performance and feeding behavior of Holstein calves.
      ;
      • Terré M.
      • Castells L.
      • Khan M.A.
      • Bach A.
      Interaction between the physical form of the starter feed and straw provision on growth performance of Holstein calves.
      ). Our average grain and hay intake were higher than what is typically reported in individually housed settings (e.g., grain: 0.09–0.11 kg/d,
      • Horvath K.C.
      • Miller-Cushon E.K.
      The effect of milk-feeding method and hay provision on the development of feeding behavior and non-nutritive oral behavior of dairy calves.
      ;
      • Khan M.A.
      • Weary D.M.
      • von Keyserlingk M.A.G.
      Hay intake improves performance and rumen development of calves fed higher quantities of milk.
      ; forage: 0.02–0.04 kg/d,
      • Hepola H.
      • Hänninen L.
      • Pursiainen P.
      • Tuure V.-M.
      • Syrjälä-Qvist L.
      • Pyykkönen M.
      • Saloniemi H.
      Feed intake and oral behaviour of dairy calves housed individually or in groups in warm or cold buildings.
      ;
      • Horvath K.C.
      • Miller-Cushon E.K.
      The effect of milk-feeding method and hay provision on the development of feeding behavior and non-nutritive oral behavior of dairy calves.
      ). This could be due, in part, to the low milk provision in our study (3.8–5.6 L/d, or 10% BW). Calves will drink 9 to 13 L milk/d when given the choice (
      • Jasper J.
      • Weary D.M.
      Effects of ad libitum milk intake on dairy calves.
      ;
      • Hepola H.P.
      • Hänninen L.T.
      • Raussi S.M.
      • Pursiainen P.A.
      • Aarnikoivu A.-M.
      • Saloniemi H.S.
      Effects of providing water from a bucket or a nipple on the performance and behavior of calves fed ad libitum volumes of acidified milk replacer.
      ), and the low allowance in our experiment, likely left calves hungry, requiring increased solid feed intake in an attempt to compensate for low milk satiety. Indeed, the solid feed intake in this study is also higher than our own results using this same mountaingrass hay at a 2-cm chop length when milk was fed at 15% BW (grain: 0.18 kg/d; hay: 0.046 kg/d;
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.
      ).
      Hay intake increased over time, but Bucket calves consumed more as they aged than Pipe. Issues with maintaining ad libitum hay levels in the pipes were unlikely to play a role, as both Bucket and Pipe calves had a similar number of days (11–12% of calf-days) with orts <10%, suggesting neither treatment was more limited in total quantity of hay than the other. Instead, this could potentially reflect limitations in acquiring hay from the pipe. Hay rack slat sizes have been suggested to play a role in ease of obtaining forage and thus overall feeding time (
      • Seo T.
      • Sato S.
      • Kosaka K.
      • Sakamoto N.
      • Tokumoto K.
      • Katoh K.
      Development of tongue-playing in artificially reared calves: Effects of offering a dummy-teat, feeding of short cut hay and housing system.
      ). Calves may have preferred feeding rates that they were unable to match given the hole size in the pipe feeder, leading to lower intake levels than when hay was available in a bucket.
      Regardless of method of presentation, calves fed hay ruminated for 25% of the 24-h observations as early as 4 wk of age, compared with only 14% in Control calves. Rumination is reported to start in the first few days (e.g., <5 d;
      • Swanson E.W.
      • Harris Jr., J.D.
      Development of rumination in the young calf.
      ) or weeks (e.g., 1–3 wk;
      • Margerison J.K.
      • Preston T.R.
      • Berry N.
      • Phillips C.J.C.
      Cross-sucking and other oral behaviours in calves, and their relation to cow suckling and food provision.
      ;
      • Wang S.
      • Diao Q.Y.
      • Hu F.M.
      • Bi Y.L.
      • Piao M.Y.
      • Jiang L.S.
      • Sun F.
      • Li H.
      • Tu Y.
      Development of ruminating behavior in Holstein calves between birth and 30 days of age.
      ) of life for 15 to 27% of the day in the first 6 wk when calves have access to forage (e.g., hay as feed;
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.
      ;
      • Poier G.
      • Terler G.
      • Klevenhusen F.
      • Sharma S.
      • Zebeli Q.
      Replacing concentrates with a high-quality hay in the starter feed of dairy calves: II. Effects on the development of chewing and gut fermentation, and selected systemic health variables.
      ; straw bedding,
      • Wang S.
      • Diao Q.Y.
      • Hu F.M.
      • Bi Y.L.
      • Piao M.Y.
      • Jiang L.S.
      • Sun F.
      • Li H.
      • Tu Y.
      Development of ruminating behavior in Holstein calves between birth and 30 days of age.
      ). Feeding only grain is known to lead to less time ruminating, but can still occur in young calves for 8 to 16% of the day (e.g.,
      • Hodgson J.
      The development of solid food intake in calves. 2. Studies on the volume of rumen fluid, determined by an indirect method.
      ;
      • Liu S.
      • Ma J.
      • Li J.
      • Alugongo G.M.
      • Wu Z.
      • Wang Y.
      • Li S.
      • Cao Z.
      Effects of pair versus individual housing on performance, health, and behavior of dairy calves.
      ;
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.
      ). Some of this behavior may stem from feeding of a coarse, fibrous grain, instead of one that is pelleted or ground, and may prompt earlier rumination (e.g., 3.7 vs. 6 wk of age,
      • Porter J.C.
      • Warner R.G.
      • Kertz A.F.
      Effect of fiber level and physical form of starter on growth and development of dairy calves fed no forage.
      ), though little is known about this. High levels may also indicate pseudorumination or sham chewing, which has been suggested by others to explain periods of jaw movement in ruminants when forage is withheld (
      • Gordon J.G.
      The act of rumination.
      ;
      • Webster A.J.F.
      • Saville C.
      • Church B.M.
      • Gnanasakthy A.
      • Moss R.
      The effect of different rearing systems on the development of calf behaviour.
      ;
      • Campion D.P.
      • Leek B.F.
      Investigation of a “fibre appetite” in sheep fed a “long fibre-free” diet.
      ;
      • Webb L.E.
      • Bokkers E.A.M.
      • Engel B.
      • Gerrits W.J.J.
      • Berends H.
      • van Reenen C.G.
      Behaviour and welfare of veal calves fed different amounts of solid feed supplemented to a milk replacer ration adjusted for similar growth.
      ;
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.
      ). Additional evidence for this may be found in instances where time spent eating is constant across treatments, but calves in intensive farm environments (e.g., individually housed) ruminate for longer than calves in pasture-based, dam-nursed settings (
      • Kerr S.G.C.
      • Wood-Gush D.G.M.
      A comparison of the early behaviour of intensively and extensively reared calves.
      ). This suggests calves may use this behavior similarly to other vacuum or sham behaviors (e.g., sham dustbathing in poultry,
      • Petherick J.C.
      • Seawright E.
      • Waddington D.
      • Duncan I.J.H.
      • Murphy L.B.
      The role of perception in the causation of dustbathing behaviour in domestic fowl.
      ; sham chewing in sows,
      • Terlouw E.M.C.
      • Lawrence A.B.
      • Illius A.W.
      Influences of feeding level and physical restriction on development of stereotypies in sows.
      ) as a way of expressing a motivated behavior that is prevented by the current settings. Anecdotal evidence for pseudorumination may also be found in a description of early rumination-like behavior by
      • Wang S.
      • Diao Q.Y.
      • Hu F.M.
      • Bi Y.L.
      • Piao M.Y.
      • Jiang L.S.
      • Sun F.
      • Li H.
      • Tu Y.
      Development of ruminating behavior in Holstein calves between birth and 30 days of age.
      , which describes brief bouts of “grinding behavior” in some calves.
      Hay reduced oral manipulation of nonfeed items (NNOM: total) regardless of presentation method compared with Control calves. A small percentage of this total NNOM was directed at the pipe (0.2–0.5% of observations), likely because it was a manipulable surface for all calves. Calves fed hay spent less time manipulating the pipe regardless of hay presentation method. This pattern was also true for other NNOM, which was more prevalent than pipe manipulation (5–9% of observations) and thus made up more of the total NNOM (5–10% of observations). Hay provision is well known to reduce NNOM (e.g.,
      • Webb L.E.
      • Bokkers E.A.M.
      • Heutinck L.F.M.
      • Engel B.
      • Buist W.G.
      • Rodenburg T.B.
      • Stockhofe-Zurwieden N.
      • van Reenen C.G.
      Effects of roughage source, amount, and particle size on behavior and gastrointestinal health of veal calves.
      ;
      • Horvath K.C.
      • Miller-Cushon E.K.
      The effect of milk-feeding method and hay provision on the development of feeding behavior and non-nutritive oral behavior of dairy calves.
      ,
      • Horvath K.C.
      • Miller-Cushon E.K.
      Evaluating effects of providing hay on behavioral development and performance of group-housed dairy calves.
      ;
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.
      ), but the magnitude of this change was lower than our previous research (Hay: 16% vs. Control: 20% in
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.
      ). Hay may reduce NNOM because calves engage in more natural foraging behaviors (e.g., eating, ruminating;
      • Sambraus H.H.
      Mouth-based anomalous syndromes.
      ;
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.
      ). Indeed, earlier onset of rumination is correlated with less NNOM in calves (
      • Wang S.
      • Diao Q.Y.
      • Hu F.M.
      • Bi Y.L.
      • Piao M.Y.
      • Jiang L.S.
      • Sun F.
      • Li H.
      • Tu Y.
      Development of ruminating behavior in Holstein calves between birth and 30 days of age.
      ). Presenting solid feed in a method that promotes natural feeding behaviors has previously been found to further reduce ARBs in some cases (e.g., coarse vs. fine hay,
      • Montoro C.
      • Miller-Cushon E.K.
      • DeVries T.J.
      • Bach A.
      Effect of physical form of forage on performance, feeding behavior, and digestibility of Holstein calves.
      ; grain via a bottle vs. bucket,
      • Salter R.S.
      • Reuscher K.J.
      • Van Os J.M.C.
      Milk- and starter-feeding strategies to reduce cross sucking in pair-housed calves in outdoor hutches.
      ), but not all (e.g., 5 vs. 50 cm of hay,
      • Seo T.
      • Sato S.
      • Kosaka K.
      • Sakamoto N.
      • Tokumoto K.
      • Katoh K.
      Development of tongue-playing in artificially reared calves: Effects of offering a dummy-teat, feeding of short cut hay and housing system.
      ).

      Hay Presentation and Behavioral Skill

      All calves demonstrated improved feeding and processing skills as they aged, as they consumed more solid feed, whereas observations spent eating overall and ruminating remained stable. This pattern was enhanced in calves fed hay. Faster processing time of solid feed has been documented as animals grow, due to increased experience and practice performing foraging motions (as reviewed in
      • Arnold G.W.
      • Maller R.A.
      Effects of nutritional experience in early and adult life on the performance and dietary habits of sheep.
      ;
      • Provenza F.D.
      • Balph D.F.
      Diet learning by domestic ruminants: Theory, evidence and practical implications.
      ;
      • Nielsen B.L.
      On the interpretation of feeding behaviour measures and the use of feeding rate as an indicator of social constraint.
      ). For example, veal calves fed limited quantities (250 g) of straw spend 13% of the time around milk meals chewing at 2 to 7 wk of age, but chew this same amount in <6% of time by wk 13 (
      • Mattiello S.
      • Canali E.
      • Ferrante V.
      • Caniatti M.
      • Gottardo F.
      • Cozzi G.
      • Andrighetto I.
      • Verga M.
      The provision of solid feeds to veal calves: II. Behavior, physiology, and abomasal damage.
      ). Calves also spend fewer minutes ruminating per gram of DMI as they age (
      • Poier G.
      • Terler G.
      • Klevenhusen F.
      • Sharma S.
      • Zebeli Q.
      Replacing concentrates with a high-quality hay in the starter feed of dairy calves: II. Effects on the development of chewing and gut fermentation, and selected systemic health variables.
      ), which may suggest improved efficiency with time, or could be additional support for sham rumination in young animals. Bucket and Pipe calves consumed significantly more grain than Control, but all calves spent similar amounts of observations eating grain. This efficiency or feeding skill could stem from multiple facets of forage processing. Forage allows for more practice chewing and ruminating than grain. Processing forage can also stimulate mucosa development (e.g.,
      • Suárez B.J.
      • Van Reenen C.G.
      • Stockhofe N.
      • Dijkstra J.
      • Gerrits W.J.J.
      Effect of roughage source and roughage to concentrate ratio on animal performance and rumen development in veal calves.
      ) and buffer rumen pH (as reviewed in
      • Khan M.A.
      • Weary D.M.
      • von Keyserlingk M.A.G.
      Hay intake improves performance and rumen development of calves fed higher quantities of milk.
      ;
      • Castells L.
      • Bach A.
      • Araujo G.
      • Montoro C.
      • Terré M.
      Effect of different forage sources on performance and feeding behavior of Holstein calves.
      ;
      • Beauchemin K.A.
      Invited review: Current perspectives on eating and rumination activity in dairy cows.
      ), both of which lead to better rumen development. Together, these effects could help calves consume increasingly large quantities of complex feed.
      In addition to changing presentation through provision in a bucket or pipe, we provided a relatively long chop of hay (∼19 cm) which may have affected behavior. Indeed, the magnitude of NNOM (all other) in our study was lower than in our previous work (
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.
      ), but the percent reduction in NNOM in calves fed hay compared with Control was greater (40 vs. 18%). Most other studies provide short chopped forage (e.g., <5 cm,
      • Khan M.A.
      • Weary D.M.
      • von Keyserlingk M.A.G.
      Hay intake improves performance and rumen development of calves fed higher quantities of milk.
      ;
      • Horvath K.C.
      • Miller-Cushon E.K.
      The effect of milk-feeding method and hay provision on the development of feeding behavior and non-nutritive oral behavior of dairy calves.
      ;
      • Engelking L.E.
      • Matsuba T.
      • Inouchi K.
      • Sugino T.
      • Oba M.
      Effects of feeding hay and calf starter as a mixture or as separate components to Holstein calves on intake, growth, and blood metabolite and hormone concentrations.
      ;
      • Horvath K.C.
      • Allen A.N.
      • Miller-Cushon E.K.
      Effects of access to stationary brushes and chopped hay on behavior and performance of individually housed dairy calves.
      ,
      • Horvath K.C.
      • Brocious A.N.
      • Miller-Cushon E.K.
      Effects of forage presentation and addition of molasses-based liquid feed on dairy calf dietary selection and feed sorting of mixed diets.
      ;
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.
      ), but calves demonstrate a preference for long cuts of hay over short (e.g., 20–30 vs. 2–3 cm;
      • Webb L.E.
      • Bak Jensen M.
      • Engel B.
      • van Reenen C.G.
      • Gerrits W.J.J.
      • de Boer I.J.M.
      • Bokkers E.A.M.
      Chopped or long roughage: What do calves prefer? Using cross point analysis of double demand functions.
      ). This preference has been hypothesized to stem from the processing required to break down long forage compared with short chops (
      • Webb L.E.
      • Bak Jensen M.
      • Engel B.
      • van Reenen C.G.
      • Gerrits W.J.J.
      • de Boer I.J.M.
      • Bokkers E.A.M.
      Chopped or long roughage: What do calves prefer? Using cross point analysis of double demand functions.
      ), as longer particles are correlated with more time chewing and ruminating than short ones, which may lead to greater ARB reductions. Using this long chop may have also been more effective at stimulating natural food acquisition behaviors than our pipe or bucket manipulation methods of presentation. We did not evaluate the specific movements used while acquiring hay during this experiment, and thus cannot determine if acquisition differed by treatments, as intended, or if long hay promotes functional tongue grasping motions itself.

      Hay Presentation and Sensory-Specific Satiety

      Presenting hay in a pipe feeder may have led to sensory-specific satiety. Pipe calves consumed less hay over time and tended to spend less time eating hay than Bucket calves. This may be because the extra effort and natural acquisition movements encouraged by feeding from the pipe led to satiety at a lower level of hay intake than feeding from the bucket, as may be expected if both food acquisition and processing are both part of a behavioral need to forage in cattle. Indeed, humans report altered levels of satiation and satisfaction when food is varied by texture, shape, or consumption method, even when nutrient levels are consistent (as reviewed in
      • Krop E.M.
      • Hetherington M.M.
      • Nekitsing C.
      • Miquel S.
      • Postelnicu L.
      • Sarkar A.
      Influence of oral processing on appetite and food intake – A systematic review and meta-analysis.
      ). Animals similarly perform behaviors associated with satiety (e.g., voluntary cessation of feeding, postmeal rest) when fed in ways that encourage more species-typical feeding motions (e.g., fiber for pigs,
      • Bergeron R.
      • Bolduc J.
      • Ramonet Y.
      • Meunier-Salaun M.C.
      • Robert S.
      Feeding motivation and stereotypies in pregnant sows fed increasing levels of fibre and/or food.
      ; chewing vs. stomach fistula for rats,
      • Miller N.E.
      • Kessen M.L.
      Reward effects of food via stomach fistula compared with those of food via mouth.
      ). Both Pipe and Bucket calves performed similar levels of NNOM: total, which was less than Control calves (5.2–5.5 vs. 9.7%). This meant hay provision conferred similar benefits to Pipe and Bucket calves, as they had equal reductions in NNOM compared with Control (∼4% fewer observations). However, given the differences in hay intake and eating time, Pipe calves were able to achieve this reduction with less effort (lower hay intake and less time eating) than Bucket calves. This could suggest that the extra engagement in feeding from the pipe feeder, and possible behavioral satiety due to more naturalistic tongue movements, may have reduced NNOM more efficiently.
      • Pempek J.A.
      • Eastridge M.L.
      • Proudfoot K.L.
      The effect of a furnished individual hutch pre-weaning on calf behavior, response to novelty, and growth.
      also tested a PVC pipe feeder and found no overall ARB reductions. However, this design fed ground molasses through small holes and was intended to allow for oral manipulation. This was not comparable to our intended promotion of acquisition motions used in natural foraging.

      Normal Behaviors Performed Abnormally?

      Hay provision did not influence tongue rolling or tongue flicks. Tongue rolling was performed for short periods (0.006–0.02% of a 24-h day), but by most calves. This common prevalence but low performance of the behavior is similar to other findings (
      • Hepola H.
      • Hänninen L.
      • Pursiainen P.
      • Tuure V.-M.
      • Syrjälä-Qvist L.
      • Pyykkönen M.
      • Saloniemi H.
      Feed intake and oral behaviour of dairy calves housed individually or in groups in warm or cold buildings.
      ;
      • Veissier I.
      • Caré S.
      • Pomiès D.
      Suckling, weaning, and the development of oral behaviours in dairy calves.
      ;
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.
      ). Tongue rolling has been reported to appear after weaning in calves (
      • Seo T.
      • Sato S.
      • Kosaka K.
      • Sakamoto N.
      • Tokumoto K.
      • Katoh K.
      Development of tongue-playing in artificially reared calves: Effects of offering a dummy-teat, feeding of short cut hay and housing system.
      ), and thus it may still be developing during the milk-fed period and better captured by additional observation days. Indeed, veal calves are reported to tongue roll for 3 to 5% of observations when observed at 12 to 14 wk of age (
      • Veissier I.
      • Ramirez de la Fe A.R.
      • Pradel P.
      Nonnutritive oral activities and stress responses of veal calves in relation to feeding and housing conditions.
      ;
      • Webb L.E.
      • Bokkers E.A.M.
      • Engel B.
      • Gerrits W.J.J.
      • Berends H.
      • van Reenen C.G.
      Behaviour and welfare of veal calves fed different amounts of solid feed supplemented to a milk replacer ration adjusted for similar growth.
      ;
      • Leruste H.
      • Brscic M.
      • Cozzi G.
      • Kemp B.
      • Wolthuis-Fillerup M.
      • Lensink B.J.
      • Bokkers E.A.M.
      • van Reenen C.G.
      Prevalence and potential influencing factors of non-nutritive oral behaviors of veal calves on commercial farms.
      ), and up to 15% at 22 wk (
      • Webb L.E.
      • Bokkers E.A.M.
      • Heutinck L.F.M.
      • Engel B.
      • Buist W.G.
      • Rodenburg T.B.
      • Stockhofe-Zurwieden N.
      • van Reenen C.G.
      Effects of roughage source, amount, and particle size on behavior and gastrointestinal health of veal calves.
      ), suggesting tongue rolling may also relate to time kept in feed-restrictive settings, or may increase with age. It is possible that tongue rolling may develop from tongue flicks, which often share similar motions to tongue rolling, or that they may be different responses to a shared underlying problem. Calves spent 3% of observations performing tongue flicks. This is in contrast to the only other study known to measure tongue flicks, where calves performed this behavior for 13 to 18% of a 24-h day (
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.
      ). Our previous 60-s sampling approach may have overestimated duration of tongue flicks, which typically occur for less than 5 s at a time (
      • Downey B.C.
      • Gfeller J.S.
      • Tucker C.B.
      Validation of 1 – 0 and instantaneous sampling for quantifying oral behaviors in milk-fed dairy calves.
      ). There was no effect of hay on tongue flicks, despite our previous findings, which could stem from the low milk allowance provided in this study. Calves spent <1% of the day sucking milk, compared with 3% of time that they would naturally suckle the dam on pasture (as reviewed by
      • de Passillé A.M.B.
      Sucking motivation and related problems in calves.
      ). This 67% reduction in time spent sucking may have been such a severe limitation for calves that it washed out any possible effects of hay on reducing tongue flicks, particularly because they occur for a small percentage of time. However, tongue flicks could also represent normal behavior, as animals may lick the nose to clear mucus, water, or feed from the nostrils (
      • Meltzer S.J.
      • Githens T.S.
      The nose-licking reflex and its inhibition.
      ). If tongue flicks fall on a spectrum of normal to abnormal behavior, they thus may not be consistently affected by hay provision or enrichment.
      Percentage of time spent grooming also was not affected by treatment. Similar to tongue flicks, grooming is a normal behavior that may be performed at abnormal levels or out of context (e.g., displacement behavior) during periods of motivational conflict (e.g.,
      • Manning A.
      • Dawkins M.S.
      An Introduction to Animal Behaviour.
      ). In normal scenarios, grooming can maintain cleanliness (e.g.,
      • Panivivat R.
      • Kegley E.B.
      • Pennington J.A.
      • Kellogg D.W.
      • Krumpelman S.L.
      Growth performance and health of dairy calves bedded with different types of materials.
      ) or facilitate social bonds in group settings (
      • Færevik G.
      • Andersen I.L.
      • Jensen M.B.
      • Bøe K.E.
      Increased group size reduces conflicts and strengthens the preference for familiar group mates after regrouping of weaned dairy calves (Bos taurus).
      ). However, higher levels of self-grooming are also found when natural feeding opportunities are reduced (e.g., bucket vs. bottle feeding,
      • Pempek J.A.
      • Eastridge M.L.
      • Botheras N.A.
      • Croney C.C.
      • Bowen Yoho W.S.
      Effects of alternative housing and feeding systems on the behavior and performance of dairy heifer calves.
      ; no hay vs. hay,
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.
      ), and when cattle are reared in more barren environments (e.g., indoor pen vs. pasture,
      • Ishiwata T.
      • Uetake K.
      • Kilgour R.J.
      • Eguchi Y.
      • Tanaka T.
      Comparison of time budget of behaviors between penned and ranged young cattle focused on general and oral behaviors.
      ; individual vs. group,
      • Andrighetto I.
      • Gottardo F.
      • Andreoli D.
      • Cozzi G.
      Effect of type of housing on veal calf growth performance, behaviour and meat quality.
      ;
      • Babu L.K.
      • Pandey H.N.
      • Sahoo A.
      Effect of individual versus group rearing on ethological and physiological responses of crossbred calves.
      ). Extreme levels of self-grooming may thus indicate abnormality, reflecting redirected or displacement behavior, or a desire to self-soothe and reduce arousal during motivational conflict (e.g., when social grooming is restricted, as suggested in the review by
      • Boissy A.
      • Manteuffel G.
      • Jensen M.B.
      • Moe R.O.
      • Spruijt B.
      • Keeling L.J.
      • Winckler C.
      • Forkman B.
      • Dimitrov I.
      • Langbein J.
      • Bakken M.
      • Veissier I.
      • Aubert A.
      Assessment of positive emotions in animals to improve their welfare.
      ).
      “Abnormal” grooming could be expressed in multiple dimensions, such as overall duration of grooming, location of grooming (e.g., repetitive focus on an easily reached body part), and number or duration of individual grooming bouts. Grooming in this study typically lasted for fewer than four 5-s intervals (∼20 s duration) suggesting “functional” grooming, as required to maintain cleanliness, could be reflected by bouts around or below four 5-s intervals. However, grooming duration is known to vary across individuals (e.g., 34–1,080 s, Horvath and Miller-Cushon, 2019), and we saw a similar pattern with grooming bouts (Figure 5). This led us to question what we consider to be “repetitive” in describing ARBs. Repetition within a single bout, leading to a long 24.9 min bout of grooming (Figure 5), may be considered a more concerning expression of behavior than short bouts, and indeed, ARBs are sometimes described by whether a motion in a bout repeats (e.g., “repetition of an identical pattern of movement … 2 or more times,”
      • Meehan C.L.
      • Garner J.P.
      • Mench J.A.
      Environmental enrichment and development of cage stereotypy in orange-winged Amazon parrots (Amazona amazonica).
      ; “3 or more consecutive repetitions,”
      • Dallaire J.A.
      • Meagher R.K.
      • Díez-León M.
      • Garner J.P.
      • Mason G.J.
      Recurrent perseveration correlates with abnormal repetitive locomotion in adult mink but is not reduced by environmental enrichment.
      ). We did not apply formal bout criteria due to our 1–0 sampling methodology, but others using continuous durations have found that self-licking and scratching have a bout criterion of 50 s in milk-fed calves (
      • Horvath K.C.
      • Miller-Cushon E.K.
      Characterizing grooming behavior patterns and the influence of brush access on the behavior of group-housed dairy calves.
      ). This bout criterion was higher than our decision of using continuous grooming including any pauses of ≤3 intervals (15 s). Using a higher criterion would likely have increased all bout durations, including the extreme outliers, showing similar repetition. Repetition could also be described by a high number of bouts performed throughout a day, even if they are short (Figure 5). In contrast, some animals also performed low levels of grooming, and had very little repetition within bouts (Figure 5). Inactivity has been correlated with negative welfare states in other species (e.g., mink,
      • Meagher R.K.
      • Mason G.J.
      Environmental enrichment reduces signs of boredom in caged mink.
      ), but less is known about this than excessive repetition of behavior. Low grooming could thus reflect a concern related to inactivity, but more work is needed to determine if extreme low performance of behavior is a problem. These findings suggest that “normal” behaviors, such as grooming, may be expressed in a wide variety of potentially concerning and repetitive ways, and that analyzing overall group-level durations may miss important insights.
      Defining abnormal behavior based on individual extremes is used in describing polydipsia, or excessive water drinking. Water consumption is an essential normal behavior but can reflect welfare concerns at high levels. For example, frustrated feeding opportunities have been suggested to lead to polydipsia in broiler breeders (
      • Savory C.J.
      • Seawright E.
      • Watson A.
      Stereotyped behaviour in broiler breeders in relation to husbandry and opioid receptor blockade.
      ) and sows (
      • Robert S.
      • Matte J.J.
      • Farmer C.
      • Girard C.L.
      • Martineau G.P.
      High-fibre diets for sows: Effects on stereotypies and adjunctive drinking.
      ). In calves, water intake has an inverse relationship with milk intake (e.g., as reviewed in
      • Jensen M.B.
      • Vestergaard M.
      Invited review: Freedom from thirst—Do dairy cows and calves have sufficient access to drinking water?.
      ), and is thus higher in calves who are limit-fed milk compared with ad libitum provision. In addition, polydipsia has recently been identified in individual calves. We previously described 1 calf who consistently drank up to 20 L water/d (
      • Downey B.C.
      • Jensen M.B.
      • Tucker C.B.
      Hay provision affects 24-h performance of normal and abnormal oral behaviors in individually housed dairy calves.
      ), and in the present research found 13 calves that consumed outlier amounts of water (preweaning: ≥7.35 L/d, weaning: ≥16.05 L/d). The increased prevalence of polydipsic calves in the current study likely reflects feeding differences, as the 13 calves were in more restrictive environments than in our previous work (milk fed at 10% BW vs. 15%, <1% observations sucking vs. 3%, respectively). Polydipsia may serve as an additional indicator of compromised welfare in dairy calves kept in restrictive environments. However, time spent drinking water was not corelated to amount of water consumed (Supplemental Figure S4), suggesting polydipsia cannot be identified through behavioral observations alone.

      CONCLUSIONS

      Provision of long hay, regardless of presentation method, promoted rumination, improved performance, and reduced at least some, but not all, of the considerable abnormal oral behaviors these calves performed. Calves of all treatments performed a wide variety of abnormal behaviors, including possible pseudorumination, polydipsia, repetitive tongue movements and excessive grooming.

      ACKNOWLEDGMENTS

      We thank University of California Davis Dairy Facility (Davis, CA) manager Doug Gisi, assistant manager Maria Patino, and the dairy interns for animal care and support. We are grateful to those who assisted with data collection: Ana Calderon, Jesica Calderon, Ajanee Evans, McKenna Farnham, Rowan Farrell, Meliza Guox, Megan Harmon, Christopher Lingga, Alicia Marzolf, Isabelle McDonald-Gilmartin, Chelsea Morrow, Erin Nemivant, Theodore Oentoro, Gretchen Peckler, Alexis Roccia, Sabrina Sankus, Joshua Shaw, and Arden Uy, all affiliated with UC Davis at the time of the study, and Julie Gfeller, affiliated with AgroSup Dijon. Special thanks to Mark Rubio and José Villasenor (UC Davis Farm Crew) for helping build the pipe feeders. We also thank Margit Bak Jensen (Aarhus University, Aarhus, Denmark) for valuable feedback on earlier versions of this manuscript. This study was supported by USDA Multistate Research Project NC1029, and a Henry A. Jastro Research Scholarship Award to B.C.D. We gratefully acknowledge the infrastructure support of the Department of Animal Science, College of Agricultural and Environmental Sciences, and the UC Davis California Agricultural Experiment Station. The authors have not stated any conflicts of interest.

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