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Asparagopsis taxiformis (AT) is a source of multiple halogenated compounds and, in a limited number of studies, has been shown to decrease enteric CH4 emission in vitro and in vivo. Similarly, oregano has been suggested as a potential CH4 mitigating agent. This study consisted of 2 in vitro and 2 in vivo experiments. Experiment (Exp.) 1 was aimed at establishing the effect of AT on CH4 emission in vitro. Two experiments (Exp. 2 and 3) with lactating dairy cows were conducted to determine the antimethanogenic effect of AT and oregano (Exp. 3) in vivo. Another experiment (Exp. 4) was designed to investigate stability of bromoform (CHBr3) in AT over time. In Exp. 3, 20 Holstein cows were used in a replicated 4 × 4 Latin square design with four 28-d periods. Treatments were basal diet (control) or basal diet supplemented with (dry matter basis) 0.25% AT (LowAT), 0.50% AT (HighAT), or 1.77% oregano (Origanum vulgare L.) leaves. Enteric gas emissions were measured using the GreenFeed system (C-Lock Inc., Rapid City, SD), and rumen samples were collected for fermentation analysis using the ororuminal technique. In Exp.1 (in vitro), relative to the control, AT (at 1% dry matter basis, inclusion rate) decreased CH4 yield by 98%. In Exp. 3, HighAT decreased average daily CH4 emission and CH4 yield by 65% and 55%, respectively, in experimental periods 1 and 2, but had no effect in periods 3 and 4. The differential response to AT among experimental periods was likely a result of a decrease in CHBr3 concentration in AT over time, as observed in Exp. 4 (up to 84% decrease in 4 mo of storage). In Exp. 3, H2 emission was increased by AT and, as expected, the proportion of acetate in the total volatile fatty acids in the rumen was decreased and those of propionate and butyrate were increased by HighAT compared with the control. Compared with the control, HighAT decreased dry matter intake, milk yield, and energy-corrected milk yield in Exp. 3. Milk composition was not affected by treatment, except lactose percentage and yield were decreased by HighAT. Concentrations of iodine and bromide in milk were increased by HighAT compared with the control. Milk CHBr3 concentration and its organoleptic characteristics were not different between control and HighAT. Oregano had no effect on CH4 emission or lactational performance of the cows in Exp. 3. Overall, AT included at 0.50% in the ration of dairy cows can have a large mitigation effect on enteric CH4 emission, but dry matter intake and milk production may also decrease. There was a marked decrease in the CH4 mitigation potential of AT in the second half of Exp. 3, likely resulting from CHBr3 decay over time.
Climate Change and Land: An IPCC Special Report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems.
). Therefore, identifying effective and feasible GHG mitigation practices is becoming increasingly important. One of the main sources of anthropogenic CH4 in the United States and globally is enteric fermentation from ruminant animals. Methanogenic archaea in the rumen are responsible for the production of enteric CH4, which is released into the atmosphere primarily through eructation, with a small proportion being emitted from the hindgut with flatus (
). Hydrogen gas and CO2 are by-products of microbial fermentation in the rumen, and methanogens prevent accumulation of H2 by reducing CO2 to CH4. With CH4 being a short-lived air pollutant (
in: Stocker T.F. Qin D. Plattner G.-K. Tignor M. Allen S.K. Boschung J. Nauels A. Xia Y. Bex V. Midgley P.M. Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press,
New York, NY2013: 659-740
Mitigation of greenhouse gas emissions in livestock production: A review of technical options for non-CO2 emissions.
in: Gerber P.J. Henderson B. Makkar H.P.S. Food and Agriculture Organization of the United Nations (FAO), Animal Production and Health Paper No. 177. FAO,
Rome, Italy2013
). The mitigation effect of some feed additives (i.e., plant-derived bioactive compounds such as tannins and essential oils; EO) has been inconsistent, whereas others (e.g., CH4 inhibitor 3-nitrooxypropanol) have shown a mitigation effect of up to 30% in long-term studies (
Mitigation of greenhouse gas emissions in livestock production: A review of technical options for non-CO2 emissions.
in: Gerber P.J. Henderson B. Makkar H.P.S. Food and Agriculture Organization of the United Nations (FAO), Animal Production and Health Paper No. 177. FAO,
Rome, Italy2013
). Recently, seaweeds have emerged as a potential feed additive in ruminant diets to lower CH4 emission. The use of seaweeds in livestock feed is dependent on the chemical composition of the various genera and species. Some species of seaweeds have gained popularity as a source of nutrients, such as chelated minerals, PUFA, AA, and carbohydrates with prebiotic activities (
). As with any terrestrial or aquatic plant, composition of seaweeds is dependent on external factors such as temperature, nutrient availability, and presence and intensity of light in the aquatic environment (
). When fed to ruminants, these compounds will likely induce shifts in rumen microbiota and consequently alter fermentation pattern. One example is the red seaweed Asparagopsis spp. that have antifungal and antibacterial properties due to the presence of low molecular weight halogenated compounds, of which the brominated halomethane bromoform (CHBr3) is dominant (
). Other brominated metabolites, such as dibromochloromethane, dibromoacetic acid, and bromochloroacetic acid, are also produced in these seaweeds, but CHBr3 is the most abundant (
). The antimethanogenic mode of action of CHBr3 is similar to bromochloromethane (BCM), a synthetic compound, which has been tested in vitro and in vivo and demonstrated a strong CH4-inhibiting effect (
). It has been hypothesized that these halogenated metabolites bind to reduced vitamin B12, which hinders the cobamide-dependent methyltransferase reaction, a terminal step in CH4 synthesis (
Two species of red seaweed, Asparagopsis taxiformis (AT) and Asparagopsis armata, have been shown to decrease CH4 emission in vitro and in vivo. In vitro studies have shown that AT has the ability to reduce enteric CH4 up to 99% at 2% inclusion rate on a OM basis (
The red macroalgae Asparagopsis taxiformis is a potent natural antimethanogenic that reduces methane production during in vitro fermentation with rumen fluid.
). Asparagopsis armata has been observed to decrease enteric CH4 emission in lactating dairy cattle by more than 65% at a 1.0% inclusion level on an OM basis; however, DMI was decreased by 38% (
Similar to the secondary metabolites produced in seaweeds, EO from plants have antimicrobial properties and have been shown to reduce enteric CH4 through modification of rumen fermentation (
included oregano leaf (OL) material in lactating dairy cow diets at 500 g/d by top dressing and reported a 39% reduction in enteric CH4 emission within 8 h after feeding, using a modification of the sulfur hexafluoride (SF6) tracer method. Similarly,
observed a linear decrease in enteric CH4 emission with increasing concentration of OL in the diet of dairy cows, again using a modified SF6 technique. Other studies, however, reported no CH4 mitigation effect of oregano (
Effect of dried oregano (Origanum vulgare L.) plant material in feed on methane production, rumen fermentation, nutrient digestibility, and milk fatty acid composition in dairy cows.
Feeding oregano oil and its main component carvacrol does not affect ruminal fermentation, nutrient utilization, methane emissions, milk production, or milk fatty acid composition of dairy cows.
There is an apparent need to investigate the effects of AT on CH4 emission and production variables in lactating dairy cows. In addition, the conflicting results for oregano require further investigation. Therefore, the objectives of the present experiments were to determine the effect of AT and OL on enteric gas emissions and production variables in lactating dairy cows. The objective of experiment (Exp.) 1 was to establish the CH4 mitigation effect of AT in vitro. The objective of Exp. 2 (see Supplemental File S1, https://doi.org/10.26208/f7rk-3805) was to determine, based on in vitro data (Exp. 1), optimal AT doses (i.e., maximum CH4 mitigation effect without decreasing DMI) to be used in Exp. 3. The objectives of Exp. 3 were to investigate the effects of AT and OL on enteric gas emissions, milk production and composition, and rumen VFA profile in lactating dairy cattle. We hypothesized that the inclusion of AT at 0.50% or OL at 1.77% (both on a DMI basis) would decrease daily enteric CH4 emission, yield, and intensity without negatively affecting DMI or milk production. The objective of Exp. 4 was to determine the effect of light and storage temperature on CHBr3 stability in AT.
MATERIALS AND METHODS
Animals involved in these experiments were cared for according to the guidelines of The Pennsylvania State University Institutional Animal Care and Use Committee. The committee reviewed and approved the experiments and all procedures involving animals.
Animals and Experimental Design
The study consisted of 4 experiments: an in vitro AT experiment (Exp. 1), a preliminary AT dosage experiment (Exp. 2; see Supplemental File S1, https://doi.org/10.26208/f7rk-3805), a replicated Latin square experiment (Exp. 3), and an AT storage experiment (Exp. 4). Cows used in Exp. 1, 2, and 3 were housed in the tiestall barn at The Pennsylvania State University's Dairy Teaching and Research Center (University Park, PA). All animals were fed TMR ad libitum, targeting 10% refusals (as-is basis) from previous day's intake, and had unrestricted access to drinking water. In all experiments, cows were fed once daily at around 0800 h. Individual feed intake, milk yield, and BW (Exp. 3 only; AfiFarm3.04E scale systems; S.A.E. Afikim, Rehovot, Israel) of the cows were recorded daily throughout the experiments. Cows were milked twice daily at 0600 and 1800 h. Milk from cows receiving AT was discarded for the duration of the experiments and for an additional 7-d withdrawal period.
AT Material
Asparagopsis taxiformis in the gametophyte lifecycle stage was harvested at Angústias, Faial Island, Azores, Portugal (38°31′45″N, 28°37′09″W) between April 10 and May 2, 2018, by seaExpert (Feteira, Ilha Do Faial, Portugal). Biomass was collected at a depth of 3 to 6 m by scuba divers and stored in a dark cooled container in a supporting boat before reaching land, where it was rinsed and immediately frozen at −40°C and then stored at −25°C. The frozen material was shipped to The Pennsylvania State University in a reefer container preset at −25°C. Once the AT was received, it was stored at −20°C until being freeze-dried (Kuhlis Freeze Dry, Bedford, OH). The freeze-dried AT was ground in a Wiley mill (1-mm screen, Thomas Scientific, Swedesboro, NJ) and stored in plastic 190-L barrels with airtight locking lids at 4°C. This AT was used in Exp. 1, 2, and 3. A separate 1-kg (dry weight) batch of AT, harvested from the same area and supplied by seaExpert, was used in Exp. 4. The AT material was analyzed for nutrient composition by Cumberland Valley Analytical Services Inc. (Waynesboro, PA) using wet chemistry methods (
; for details see Sampling and Measurements). Briefly, the AT contained (% of DM unless otherwise indicated) the following: CP, 14.6; ADF, 11.3; amylase-treated NDF, 18.5; starch, 0.80; crude fat, 0.89; ash, 55.5; Ca, 3.31; P, 0.22; Mg, 1.56; K, 2.48; Na, 10.2; Fe, 4,964 mg/kg; Mn, 92 mg/kg; Zn, 21 mg/kg; Cu, 7 mg/kg; estimated TDN, 29.4%; and estimated NFC, 10.6%.
In Vitro Experiment (Exp. 1)
A series of 8 in vitro incubations were carried out to determine the CH4 mitigation potential of AT. Three multiparous ruminally cannulated (10.2 cm i.d. cannulas; Bar Diamond Inc., Parma, ID) cows were used as donors of ruminal inoculum. Cows (mean ± SD: 189 ± 95 DIM, 40.2 ± 13.8 kg of milk yield/d, and 24.0 ± 2.2 kg of DMI/d) were fed the same basal (control) diet as in Exp. 3 (Table 1). Whole ruminal contents were collected from 4 locations in the rumen (reticulum, ventral sac, and 2 samples from the feed mat of the dorsal rumen) at 0500 h before milking. Ruminal inoculum was prepared as described in
, except the buffer did not contain dl-glucose. The inoculum was transported back to the laboratory with prewarmed thermoses within 10 min of collection and was used to inoculate the incubation flasks within 45 min of its preparation. The Ankom RF Gas Production System (Ankom Technology, Macedon, NY) was used to measure total gas production and collect samples for gas composition analysis. Incubations were carried out for 24 h in a New Brunswick Innova 44 incubator/shaker (Eppendorf North America, Enfield, CT) at 39°C and 75 rpm agitation. There were 2 treatments (in triplicate) in each incubation: control and 1.0% AT (TMR DM basis). A TMR sample that was ground through a 1-mm sieve (Wiley mill, Thomas Scientific) served as the basal substrate, included at 1.5 g/150 mL of incubation medium. The TMR was the same basal (control) TMR fed in Exp. 3 (Table 1). For the AT treatment, freeze-dried AT was pulverized using a Mixer Mill MM 200 (Retsch GmbH, Haan, Germany) and was added to the TMR at 1.0% (DM basis) in each treatment vessel. The incubation medium contained 75 mL of buffer (
) and 75 mL of a 1:1 buffer–rumen fluid mix. At the termination of each incubation, total gas pressure was recorded and gas samples were collected from each bottle and analyzed for gas composition (CH4 and H2) using gas chromatography (Agilent 7980B, Agilent Technologies, Santa Clara, CA). For this, 2 samples of gas (2 mL each) were collected into vacuumed 20-mL vials (Agilent Headspace screw-top, Agilent Technologies), separately for H2 and CH4 analysis. Vials were filled with 22 mL of N2 gas and analyzed immediately or stored at 2°C and analyzed within 24 h. Vials were agitated for 10 s at 40°C before analysis. Ultra-high purity He (999.99 g/kg He; Praxair Inc., Danbury, CT) was used as a carrier gas for CH4 analysis. Methane separation was achieved using a HayeSep Q 80–100 mesh column (1.83 m × 2 mm; Agilent Technologies) operated at 310 kPa. A 3 m × 320-µm deactivated fused silica restrictor operating at 58.6 kPa was used, leading to the flame ionization detector, which was set at 300°C. Ultrahigh purity N2 (999.99 g/kg N2; Praxair Inc.) was used as a carrier for H2 analysis. Separation was achieved through a HayeSep Q 80–100 mesh column (1.83 m × 2 mm; Agilent Technologies) at a flow rate of 5 and 12 mL/min pre- and postrun, respectively. A thermal conductivity detector was used at 250°C and a flow rate of 5 mL/min. Because there were effectively 2 ranges in concentrations (high and low), interpretation of the results was through handmade standards (35–7,000 mg/m3 for CH4 and 4–900 mg/m3 for H2). Serial dilutions were made using ultrahigh purity N2 and chemically pure CH4 (99.0% purity; Praxair Inc.) or 4.5-grade H2 (99.995%; Praxair Inc.). For Exp. 2 Materials and Methods, see Supplemental File S1 (https://doi.org/10.26208/f7rk-3805).
Table 1Ingredient and nutrient composition (% of DM unless indicated) of diets in experiment 3
Values were calculated using the chemical analysis (Cumberland Valley Analytical Services Inc., Waynesboro, PA) of the individual feed ingredients and their inclusion in the diets.
12 Values were calculated using the chemical analysis (Cumberland Valley Analytical Services Inc., Waynesboro, PA) of the individual feed ingredients and their inclusion in the diets.
This experiment was a replicated 4 × 4 Latin square design balanced for residual effects. A total of 20 (4 primiparous and 16 multiparous) Holstein cows, averaging (±SD) 2.6 ± 1.19 lactations, 95 ± 22.0 DIM, and 42.2 ± 2.59 kg of milk yield/d at the beginning of the experiment, were grouped into 5 squares based on parity, DIM, and milk yield. The experiment consisted of 4 periods; each experimental period lasted 28 d, of which 21 d were allowed for adaptation and 7 d for data and sample collection. Cows within square were randomly assigned to 1 of 4 treatments: control (basal diet, no additives) or (DM basis) 0.25% AT (LowAT), 0.50% AT (HighAT), or 1.77% OL. Inclusion of AT was determined based on results from Exp. 2 and literature data. The OL used in the experiment was carvacrol type (see Supplemental File S1 and Supplemental Table S1, https://doi.org/10.26208/f7rk-3805) from Starwest Botanicals Inc. (Sacramento, CA) and was imported from Turkey. The OL contained (analysis provided by the manufacturer; % on as-is basis) the following: total carbohydrates, 69 (including dietary fiber, 43, and sugars, 4.1); CP, 9; and total fat, 4.3. The inclusion rate of OL was based on
. All cows were fed the same basal diet (Table 1) and received the AT and OL in a premix containing ground corn grain and wheat middlings mixed daily with the TMR. The premix was prepared twice weekly and was kept at 4°C. Cows received the full dose of AT and OL from d 1 of each experimental period.
AT Storage Experiment (Exp. 4)
This experiment was conducted to determine the effect of storage time, temperature, and light exposure on CHBr3 concentration in AT. Approximately 1 kg of AT was lyophilized and used in the experiment. The AT was ground using a hand-held mixer (NutriBullet Nutrient Extractor, 600W; NutriBullet LLC, Pacoima, CA). The AT material was then subjected to 1 of 6 storage treatments for 4 mo: −20°C dark (no light); −20°C with continuous fluorescent light; 4°C dark; 4°C with continuous fluorescent light; 23°C dark; or 23°C with continuous fluorescent light. Samples were stored in 30-cm3 clear (light treatments) or brown (dark treatments) glass bottles with plastic lids (Qorpak, Berlin Packaging, Clinton, PA). Stored AT material was analyzed monthly for CHBr3 and was tested for CH4 mitigation effect in duplicated incubations following the procedures described for Exp. 1. All incubations included a blank, control, and AT dosed at 1.0% DM. The AT used in these in vitro incubations was from the pool of AT stored in the dark at 4°C.
Sampling and Measurements
Diet and Feed Ingredients
For Exp. 3, the basal diet was prepared using a stationary mixer (Electra-Mix, model 1062; I. H Rissler, Mohnton, PA). A mobile mixer (Rissler mobile TMR mixer, model 1050; I. H. Rissler) was used to mix the premixes and incorporate them into the TMR. The basal diet was formulated according to
to meet the NEL and MP requirements for a lactating cow with 640 kg of BW, 45 kg of milk yield/d, 3.50% milk fat, and 3.00% milk true protein at 27 kg of DMI/d.
Samples of TMR and refusals were collected twice weekly, stored at −20°C, and later composited (on an equal-weight basis) per period for further analysis. Forages and concentrate feed samples were collected weekly, stored at −20°C, and later composited for further analysis. All samples were oven-dried at 55°C for 72 h for DM determination and ground through a 1-mm sieve (Wiley mill, Thomas Scientific) before being analyzed.
Composite samples were submitted to Cumberland Valley Analytical Services Inc. for wet chemistry analyses of CP (
). The nutrient analyses of the individual feed ingredients and their inclusion rate were used to calculate nutrient content of the TMR (Table 1). Averaged DMI, milk yield and composition, and BW of cows during the experiment were used to determine MP and NEL balance using
. Two GreenFeed units were used and were calibrated at the beginning of each measurement period based on manufacturer recommendations. Gas measurements were collected 8 times over 3 consecutive days (d 22, 23, and 24) at 0900, 1500, and 2100 h (d 1), 0300, 1200, and 1600 h (d 2), and 0000 and 0400 h (d 3) during each experimental period. A pelletized bait feed (Stocker Grower 14, Purina Animal Nutrition LLC, Shoreview, MN) was used to attract cows to the GreenFeed system; the weight of pellets dispensed was recorded and included in the daily DMI estimation. A total of 4,000 g of bait feed/cow was consumed over the 3-d sampling period. GreenFeed is equipped with a head position sensor, and gas emission data were rejected when the cow's head position criteria were not met. Individual breath samples were collected for 5 min per sampling event followed by a 2-min background air sample. Enteric gas emissions were also calculated based on DMI (CH4 emission yield; g/kg of DMI) and ECM yield (CH4 emission intensity; g/kg of ECM).
Milk Production and Composition
In Exp. 3, milk production was recorded at each milking. Milk samples were collected from 2 consecutive p.m. and a.m. milkings on d 23 and 24 of each experimental period. Milk was preserved with 2-bromo-2-nitropropane-1,3-diol and submitted to DairyOne Cooperative Inc. (Ithaca, NY) for analysis of milk fat, true protein, lactose, SCC, MUN, and SNF using Milkoscan models 6000, FT+, or 7 and Fossomatic models 5000 or FC (Foss Electric A/S, Hiller⊘d, Denmark). Composition data were weighted for corresponding p.m. and a.m. milk yields.
Separate milk samples were collected from control and HighAT cows, stored at −20°C, composited (on an equal-volume basis) per treatment and period, and submitted to Michigan State University's Veterinary Diagnostics Laboratory (East Lansing, MI) for analysis of milk iodine and bromide concentrations using inductively coupled plasma mass spectrometry according to
. These samples were also submitted to Bigelow Laboratory for Ocean Sciences (East Boothbay, ME) for analysis of CHBr3 concentration. Briefly, the analysis was performed using gas chromatography with mass selective detection (
). An isotopically labeled internal standard (13CHBr3) was used to correct for variability in extraction and preconcentration efficiency and instrument sensitivity (
Rumen samples were collected from all cows in Exp. 3 during wk 4 (d 25 at 1000 h) of each experimental period using a stomach tube. The sampling device consisted of 244-cm-long polyethylene orogastric tubing with a 15-mL perforated conical tube attached. An electric vacuum pump (Gast model 0823-v13q-g608nex, Septic Solutions Inc., Dieterich, IL) was used to obtain rumen contents. During a sampling event, rumen fluid was collected by placing an oral speculum in the mouth of the animal. The tube was passed through the speculum into the reticulorumen and gently pushed through the fiber mat. Approximately 200 cm of the flexible tubing was inserted in the cow with the remainder outside, allowing for the tube to be moved. Approximately 500 mL of rumen fluid sample was collected for further analyses. Rumen contents were filtered through 2 layers of cheesecloth and immediately analyzed for pH (pH meter 59000-60 pH Tester, Cole-Parmer Instrument Company, Vernon Hills, IL) and processed and analyzed for VFA concentrations as described in
Blood samples were collected from the coccygeal vein or artery on 2 consecutive days at 0900 and 1700 h (d 1) and at 1400 and 2000 h (d 2) in Exp. 3. Samples were collected into vacuumed tubes containing EDTA (BD Biosciences, Franklin Lakes, NJ). Plasma was obtained by centrifugation at 1,500 × g at 4°C for 10 min and stored at −20°C for further analysis. Plasma samples were composited per cow and experimental period on an equal-volume basis and analyzed for blood chemistry (glucose, creatinine, BUN, total protein, albumin, globulin, alanine transaminase) using a Catalyst One Chemistry Analyzer (Idexx Laboratories Inc., Westbrook, ME). Insulin was analyzed using an enzyme-linked immunoassay kit (Bovine Insulin ELISA, Kit No. 10-1201-01, Mercodia AB, Uppsala, Sweden). The inter- and intra-assay coefficients of variation were both <10%. The minimum detection level of insulin in the kit was 0.05 μg/L.
Milk Sensory Panel Evaluation
In Exp. 3, milk from 2 consecutive milkings (a.m. and p.m.) during the last week of the last experimental period was collected from all control and HighAT cows. The milk was composited by treatment, pasteurized, and used for a milk sensory panel at the Sensory Evaluation Center in the Department of Food Science at The Pennsylvania State University (University Park, PA). Sensory properties of the milk were evaluated by a 109-subject sensory panel composed of untrained panelists. A triangle test design was used to determine whether HighAT milk was perceptibly different from control milk. Milk from both treatments was stored and served at refrigerator temperature. Panelists were presented with 3 cups of samples (2 with control and 1 with HighAT milks, or 2 with HighAT and 1 with control milks) labeled with 3-digit blinding codes. Milk was served in 60-mL cups containing 30 mL of sample. Participants were instructed to identify the code that was different. Water was provided as a palate cleanser. The tests took place in individual testing booths under white lighting using Compusense Cloud software (Compusense Inc., Guelph, ON, Canada).
Other Analyses
Details on the analysis of Origanum vulgare L. EO, CHBr3 analysis of AT samples from Exp. 4, and feces and urine collection procedures and milk fatty acid analysis for Exp. 3 are given in Supplemental File S1 (https://doi.org/10.26208/f7rk-3805).
Statistical Analysis
Unless indicated differently, data were analyzed using the MIXED procedure of SAS version 9.4 (SAS Institute Inc., Cary, NC) with the Satterthwaite option for degree of freedom and pdiff option for least squares means. Data from Exp. 1 (in vitro experiment) were analyzed with treatment, incubation, and treatment × incubation interaction in the model; all were fixed effects.
In Exp. 3, milk yield, DMI, and BW data for the last 7 d of each experimental period were averaged and the average values were used in the statistical analysis. Feed efficiency (milk yield/DMI) was calculated based on the average milk yield and DMI data. Mean milk yields were used to calculate ECM yield according to
A Nordic proposal for an energy corrected milk (ECM) formula.
in: Proc. of the 27th Session of the International Commission for Breeding and Productivity of Milk Animals, Paris, France. Wageningen Academic Publishers,
Wageningen, the Netherlands1990: 156-157
. Enteric gas (CH4, CO2, and H2) emission data were averaged by cow and period, and the averaged values were used in the statistical analysis. Methane yield and H2 emission data were also analyzed by experimental period. Averaged DMI and ECM yield were used to calculate CH4 yield and intensity. All data were analyzed with period and treatment in the model. Square and cow within square were random effects, and all others were fixed. Milk iodine, bromide, and CHBr3 concentration data were analyzed with treatment in the model.
Data from Exp. 4 were analyzed with storage time, storage temperature, light conditions, and the 2- and 3-way interactions in the model; interactions were nonsignificant (P ≥ 0.38) and were removed from the final model. Data from this experiment were also fitted to a linear regression model of the type f = y0 + a × t, where f is CHBr3 concentration (mg/g of DM), y0 is the intercept, a is the rate constant (mg/g of DM per day), and t is time (d) and plotted using SigmaPlot (v. 13.0; Systat Software Inc., San Jose, CA).
Unless specified differently, data are presented as least squares means. Differences were considered significant at P ≤ 0.05, and a trend was declared at 0.05 < P ≤ 0.10.
RESULTS
Exp. 1
Total gas production was lower (P < 0.001; SEM = 1.43, n = 48) for 1% AT compared with the control (111.1 vs. 127.3 mL/g of TMR DM, respectively; data from Exp. 1 are not shown in tables or figures). Inclusion of AT decreased (P < 0.001; SEM = 0.213) CH4 yield by 98%: 0.22 vs. 10.5 mL of CH4/g of TMR for AT and control, respectively. Hydrogen emission was increased (P < 0.001; SEM = 0.232) about 7-fold with AT compared with the control (2.87 vs. 0.39 mL/g of TMR, respectively). For Exp. 2 results, see Supplemental File S1 (https://doi.org/10.26208/f7rk-3805).
Exp. 3
Total-tract apparent digestibility of nutrients and urinary and fecal N excretion data are presented in Supplemental Tables S2 and S3 (https://doi.org/10.26208/f7rk-3805).
Milk Production and Composition
Dry matter intake in Exp. 3 was lowest (P = 0.006) for cows receiving the HighAT diet and was not different among the other treatments (Table 2). Milk and ECM yields were decreased (P ≤ 0.01) by HighAT compared with control and LowAT; OL had no effect on milk production. Milk and ECM feed efficiencies were not different among treatments. Milk fat, true protein, and SNF percentages were also not affected by treatment. Lactose percentage was lower (P < 0.001) for HighAT, followed by LowAT and OL, and was greatest for the control. Milk fat yield was decreased by HighAT (P = 0.03) compared with all other treatments. Milk protein, lactose, and SNF yields were decreased (P ≤ 0.05) by HighAT compared with control and LowAT but were not different from OL. Milk urea nitrogen, SCC, and BW of the cows were not different among treatments.
Table 2Effects of Asparagopsis taxiformis and oregano leaves on feed intake, milk yield and composition, and BW of lactating dairy cows in experiment 3
Highest SEM shown in table; n = 80 for DMI, milk yield, milk composition data, ECM, and ECM feed efficiency; n = 79 for BW (n represents number of observations used in the statistical analysis).
Statistical analysis was performed on log-transformed data.
× 103 cells/mL
67.9
94.8
98.7
60.4
21.65
0.32
BW, kg
642
645
635
642
17.3
0.13
a–c Means within a row with different superscripts differ at P ≤ 0.05.
1 Treatments were basal diet (control) and basal diet plus (DM basis) 0.25% Asparagopsis taxiformis (LowAT), 0.50% Asparagopsis taxiformis (HighAT), and 1.77% Origanum vulgareL. leaves (OL).
2 Highest SEM shown in table; n = 80 for DMI, milk yield, milk composition data, ECM, and ECM feed efficiency; n = 79 for BW (n represents number of observations used in the statistical analysis).
A Nordic proposal for an energy corrected milk (ECM) formula.
in: Proc. of the 27th Session of the International Commission for Breeding and Productivity of Milk Animals, Paris, France. Wageningen Academic Publishers,
Wageningen, the Netherlands1990: 156-157
Milk from HighAT cows had on average about 5 times greater (P < 0.001) iodine concentration compared with control milk (Table 3). Similarly, bromide concentration in HighAT milk was 8 times higher (P < 0.001) than in milk from control cows; in 3 of the 4 milk samples from control cows, bromide concentration was below the detection limit of the method (4 mg/kg). It is noted that both iodine and bromide concentrations were lower (by 20 and 27%, respectively) in milk from experimental periods 3 and 4 than in milk from periods 1 and 2 (data not shown by period). Milk CHBr3 concentration was not statistically different between control and HighAT.
Table 3Concentration of iodine, bromide, and bromoform (CHBr3) in milk of dairy cows fed a control diet or a diet supplemented with Asparagopsis taxiformis in experiment 3
Data presented are from samples composited by cow and then by treatment within each experimental period (n = 8, where n represents number of observations used in the statistical analysis).
Bromide concentration in 3 out of 4 control samples was below the detection limit of the analytical procedure (4 mg/kg), and these were included in the statistical analysis as 4 mg/kg.
40.4
2.64
<0.001
Bromoform, μg/L
16.5
28.9
10.62
0.44
1 Data presented are from samples composited by cow and then by treatment within each experimental period (n = 8, where n represents number of observations used in the statistical analysis).
2 Control = basal diet; HighAT = basal diet plus 0.50% Asparagopsis taxiformis included on a DM basis.
3 Bromide concentration in 3 out of 4 control samples was below the detection limit of the analytical procedure (4 mg/kg), and these were included in the statistical analysis as 4 mg/kg.
Analysis of the milk sensory panel results indicated that milk from HighAT cows was not organoleptically different from milk from control cows (P = 0.11; 43/109, or about 39% of participants correctly identified milk from HighAT cows as different from control cows).
Enteric Gas Emissions
Daily CH4 emission, CH4 yield, and CH4 intensity were all decreased (P ≤ 0.002) by HighAT compared with the control (by 34.4, 29.4, and 34.2%, respectively; Table 4). Daily CH4 emission, yield, and intensity were not different among control, LowAT, and OL. Hydrogen emission was increased (P < 0.001) by both LowAT and HighAT compared with the control; however, H2 emission by HighAT was 2.7 times greater than that of LowAT. Oregano had no effect on H2 emission. Carbon dioxide emission was lower (P = 0.03) for HighAT compared with LowAT, but both were not different from the control and OL.
Table 4Effects of Asparagopsis taxiformis and oregano leaves on enteric gas emissions in lactating dairy cows in experiment 3
Methane yield and H2 emission averages from each experimental period for control and HighAT are presented in Figure 1, Figure 2, respectively. During periods 1 and 2, HighAT had on average 55% lower (P ≤ 0.008) CH4 yield than control, but there was no difference (P ≥ 0.41) between the 2 treatments in periods 3 and 4. In periods 1 and 2, HighAT had approximately 10 times greater (P < 0.001) H2 emission than control; in periods 3 and 4, the difference was 3- to 6-fold (P < 0.001).
Figure 1Effect of Asparagopsis taxiformis included at 0.50% of DMI (HighAT) on enteric methane yield in dairy cows by experimental period in experiment 3 (data are mean ± SEM).
Figure 2Effect of Asparagopsis taxiformis included at 0.50% of DMI (HighAT) on hydrogen emission in dairy cows by period in experiment 3 (data are mean ± SEM).
Rumen pH and VFA data from Exp. 3 are shown in Table 5. Rumen pH tended to be greater (P = 0.10) for HighAT compared with OL. Total VFA concentration was decreased (P = 0.03) by HighAT compared with all other treatments. Molar concentration of acetate was lower (P = 0.001) for cows receiving HighAT compared with the other treatments. Compared with control and LowAT, the molar concentration of propionate was increased (P = 0.03) by HighAT. Cows receiving both AT treatments had an increased molar proportion of butyrate (P < 0.001) compared with control and OL. Molar proportion of isobutyrate was not affected by treatment. Valerate concentration was 39% greater (P < 0.001) for HighAT compared with control, and it was higher than LowAT and OL. The LowAT treatment increased (P = 0.008) the molar proportion of isovalerate compared with HighAT and OL. Acetate:propionate ratio was lower (P = 0.02) for HighAT compared with control and LowAT. Similar to the CH4 emission data, the response in VFA to AT differed between the first and second halves of Exp. 3. The decrease in total VFA concentration, molar proportion of acetate, and acetate:propionate ratio and the increase in molar proportions of propionate, butyrate, and valerate due to AT were consistent in experimental periods 1 and 2 (P ≤ 0.08), but no statistically significant differences (P ≥ 0.13) were observed for periods 3 and 4 (data not shown).
Table 5Effect of Asparagopsis taxiformis and oregano leaves on rumen pH and VFA in lactating dairy cows in experiment 3
Blood plasma glucose and insulin concentrations as well as most of the analyzed blood chemistry variables were not affected by treatment (Table 6). Compared with control and LowAT, HighAT and OL decreased (P = 0.005) plasma BUN:creatinine ratio, and HighAT cows had lower (P < 0.001) alanine transaminase concentration than cows on all other treatments. Blood urea N concentration tended to be lower (P = 0.07) for HighAT and OL compared with the control and LowAT.
Table 6Effect of Asparagopsis taxiformis and oregano leaves on insulin and blood chemistry in lactating dairy cows in experiment 3
After 4 mo of storage, CHBr3 concentration in AT was decreased (P < 0.001) by 75% (when stored in the dark) to 84% (when stored under luminescent light) across storage temperatures (Figure 3). Asparagopsis taxiformis samples exposed to light had on average 17% lower (P = 0.02) CHBr3 concentration compared with samples stored in the dark. Storage temperature did not have an effect (P = 0.82) on CHBr3 concentration in AT.
Figure 3Effect of storage conditions and storage time on concentration of bromoform (CHBr3) in Asparagopsis taxiformis (experiment 4; data are mean ± SE). Light = seaweed material exposed to continuous fluorescent light; Dark = seaweed material stored in brown glass bottles with plastic lids.
Samples of AT stored in the dark at 4°C for 1 and 2 mo decreased (P < 0.001) in vitro CH4 yield (mL of CH4/g of TMR) by an average of 98% when dosed at 1% of TMR DM (Figure 4). Samples stored for 3 and 4 mo decreased (P < 0.001) CH4 yield by 22% and 44%, respectively. The reduction in CH4 yield by AT was expressed as a percent decrease compared with control, assuming control was 100% of CH4 emission.
Figure 4Effect of Asparagopsis taxiformis (included at 1% of DM) stored in the dark at 4°C for 4 mo (experiment 4) on enteric methane yield (mL of methane/g of feed DM) in vitro. Data are mean ± SE and are expressed relative to control (control = 100%); error bar is not visible for the 30-d data.
DMI, Milk Production and Composition, and Blood Chemistry
Asparagopsis taxiformis included in the diet at 0.50% of DM did not seem to affect DMI in Exp. 2 (see Supplemental File S1, https://doi.org/10.26208/f7rk-3805) but decreased it in Exp. 3. This discrepancy may be due to the shorter experimental periods in Exp. 2 (10 d) versus Exp. 3 (28 d). The highest AT dose in Exp. 2 (0.75% of DM) clearly had a negative effect on DMI. The decreased DMI by HighAT in Exp. 3 was accompanied by a 6.5% decrease in milk yield.
reported an 11 and 38% decrease in DMI with inclusion of 0.5 and 1.0% (OM basis) A. armata, respectively. It is likely that the decrease in DMI with AT observed in the current study was due to low palatability of the seaweed.
supplemented finishing beef steers with increasing doses of AT (0, 0.05, 0.10, and 0.20% of OM) and reported no effect on DMI except a decrease at the 0.05% level. Unlike the present study and the study by
gradually adapted the steers to AT supplementation over 30 d; also, the highest inclusion of AT in that study (0.20%, OM basis) was lower than the lowest dose in the current study. Similar to
did not report a difference in DMI when AT was offered to sheep fed at maintenance level at increasing dosages (0, 0.5, 1.0, and 2.0% of OM). However, according to the authors, sheep fed the 2.0 and 3.0% AT diets were able to sort and avoid AT, further suggesting that reduced DMI in the current study is likely due to palatability issues. In the present study, AT was finely ground and mixed into the TMR, eliminating the possibility of sorting. Lack of effect on DMI was reported in other studies using analogous halogenated compounds to inhibit CH4 emission. When BCM was fed to dairy goats at 0.30 g/100 kg of BW, DMI was not changed, but there was an increase in milk yield (
). These authors suggested that decreased CH4 emission likely led to an increase in glucose, and subsequently lactose, synthesis from increased propionate supply, thus stimulating greater milk production. Conversely, DMI of growing steers was decreased when BCM was dosed at 2.4 g/100 kg of live weight (
hypothesized that decreased DMI in ruminants supplemented with halogenated compounds, specifically halomethane, was a result of increased metabolic H2 concentration in the rumen, thus impaired microbial production of vitamin B12, ineffective metabolism of increased proportions of propionate, or a taste aversion to the various inhibitors. As expected, OL did not affect DMI or milk yield in the current experiment. The lack of response in DMI and milk yield with OL is in line with previous reports (
Effect of dried oregano (Origanum vulgare L.) plant material in feed on methane production, rumen fermentation, nutrient digestibility, and milk fatty acid composition in dairy cows.
). These studies fed similar amounts (around 500 g/d) of OL to lactating dairy cows. When OL inclusion rate in the diet increases, a decrease in DMI may be expected, as reported in
, likely as a result of organoleptic properties (specifically flavor) of oregano.
Asparagopsis taxiformis did not affect milk composition in Exp. 3 except for a decreased lactose concentration with LowAT. The observed decrease in component yields with HighAT was a result of decreased milk yield for that treatment compared with the control. The study of
with A. armata reported a decrease in milk protein percentage but did not find any differences in other milk composition characteristics. Lactating dairy goats fed BCM at 0.30 g/100 kg of BW had increased lactose yield, but lactose percentage was not affected (
). The lack of effect of OL on milk components is generally in agreement with previous studies where a similar lack of effect on milk true protein and lactose percentages in dairy cows was reported (
Effect of dried oregano (Origanum vulgare L.) plant material in feed on methane production, rumen fermentation, nutrient digestibility, and milk fatty acid composition in dairy cows.
The increased iodine and bromide contents of milk from HighAT cows in Exp. 3 was clearly a result of AT supplementation. The iodine concentration observed for HighAT milk in the current experiment is 7.8 times greater than reference values for whole milk (average = 380, minimum = 176, and maximum = 838 ng/mL;
Incremental amounts of Ascophyllum nodosum meal do not improve animal performance but do increase milk iodine output in early lactation dairy cows fed high-forage diets.
also observed increased milk iodine concentration in cows fed Ascophyllum nodosum, a brown seaweed. Iodine consumption is necessary for production of thyroid hormones in humans; however, in some individuals, excess iodine in the diet can cause thyroid dysfunction (
Incremental amounts of Ascophyllum nodosum meal do not improve animal performance but do increase milk iodine output in early lactation dairy cows fed high-forage diets.
, however, although iodine concentrations in milk from cows fed seaweeds may be high, it is unlikely that milk that is used for retail will have high concentrations of iodine due to the pooling of milk from different farms at the processing plant (unless most or all farms use AT). Data for bromide concentration in cattle milk are scarce. Older sources reported typical bromide concentrations in the 1 to 5 mg/kg range, with some samples reaching 20 to 25 mg/kg (
). Based on these data, it can be concluded that milk from HighAT cows in Exp. 3 had elevated bromide content, which was clearly a result of AT supplementation. The milk CHBr3 data, however, were not in line with the iodine and bromide data. The reasons for this discrepancy are unclear. The CHBr3 analysis was repeated and results were confirmed by the Bigelow laboratory. It is possible that CHBr3 from AT are metabolized and, therefore, excretion with milk is low. Interestingly,
reported much lower, compared with our data, CHBr3 concentrations in milk from cows fed A. armata at 0.5 and 1% of OM: 0.15 and 0.11 µg/mL for the A. armata treatment and control, respectively.
The present study is the first to report on the effect of AT on sensory characteristics of milk.
reported no differences in tenderness, juiciness, flavor, consumer satisfaction, or overall liking of meat from beef cattle supplemented with AT during the finishing period. Although we did not observe a statistical difference in the sensory characteristics of milk samples from the study, it is worth noting that 43 out of 109 participants in the sensory panel correctly identified milk from HighAT cows as being different from control milk (with the P-value approaching a trend).
Interestingly, HighAT decreased blood alanine aminotransferase (ALT) activity in Exp. 3. Elevated levels of this enzyme have been associated with liver damage and metabolic and infectious diseases (e.g., ketosis, metritis) in dairy cows (
Changes in the blood routine, biochemical indexes and the pro-inflammatory cytokine expressions of peripheral leukocytes in postpartum dairy cows with metritis.
). The cows in Exp. 3 did not show any signs of metabolic diseases, although the ALT values appear to be somewhat higher than reference values for cattle (11–40 U/L;
also observed a decrease, although smaller, with AT of another marker of liver damage, gamma-glutamyl transpeptidase; the authors offered no explanation for these results. We are also unable to offer a plausible explanation for the marked effect of 0.50% AT on blood ALT in the current experiment, although this is unlikely to be a negative effect. Studies with challenged laboratory animals have reported protective effects of seaweed, including red and brown species, on liver function (
). The decreased BUN:creatinine ratio observed for HighAT and OL in Exp. 3 was a result of a slight decrease in BUN with these treatments compared with control and LowAT.
Enteric Gas Emissions
Based on Exp. 2 data (see Supplemental File S1, https://doi.org/10.26208/f7rk-3805), treatments selected for Exp. 3 were 0.25% and 0.50% AT. In Exp. 2 and 3, enteric CH4 emissions were clearly reduced when AT was included in the TMR fed to the cows. The magnitude of the response, however, was largely different between the 2 experiments, with an 80% reduction in CH4 yield in Exp. 2 and an average 30% reduction in Exp. 3 for the same (0.50%) inclusion rate of AT. Notably, there was a large difference in the mitigation effect of AT between experimental periods 1 and 2 and periods 3 and 4 in Exp. 3 (a 55% decrease vs. no effect, respectively). The reason for this discrepancy in the response to AT among periods remains unknown because we were unable to analyze CHBr3 in AT that was used in Exp. 3. Milk samples from Exp. 3 were analyzed for CHBr3, but the data were extremely variable and there was no difference between control and HighAT milks or HighAT milk from experimental periods 1 and 2 versus periods 3 and 4. It is noted, however, that there was a substantial (27%) reduction in bromide content of milk from HighAT cows in periods 3 and 4 compared with milk from periods 1 and 2. This, along with the 20% reduction in milk iodine concentration between periods, is indirect evidence that cows on AT treatments likely received less CHBr3 in the second half of Exp. 3 than in the first half, possibly due to CHBr3 decay in AT, as suggested by Exp. 4 data.
The largest decrease in daily CH4 emission, yield, and intensity in the current study was observed in Exp. 2 when AT was fed at 0.50% of TMR DM. When AT inclusion rate was increased to 0.75%, the decrease in CH4 yield and intensity were not as large as at the 0.50% inclusion rate due to decreased DMI and milk yield. These results are similar to what
observed when supplementing dairy cows with A. armata at 1.0% dietary OM (67% reduction in the daily CH4 emission) in a crossover study with 21-d periods. These authors reported CHBr3 content in A. armata to be 1.23 mg/g of DM.
reported an 80% reduction in daily CH4 emission when AT was supplemented to sheep at 3% (OM basis) in a 72-d study; the authors reported total halogen content in the AT to be 0.384 mg/g. Recently,
supplemented AT to beef steers fed a high-grain feedlot diet at 0.20% (OM basis) and observed a 98% reduction in CH4 yield, which is among the highest CH4 reductions reported in vivo. These authors indicated CHBr3 content of the AT used in their experiment at 6.55 mg/g. In Exp. 3 of the current study, the overall effect of HighAT on CH4 emission reduction (34.4%) was similar to the reduction of CH4 emission (26.4%) observed by
when supplementing cows with 0.50% A. armata. The overall treatment effect of HighAT on CH4 (daily emission, yield, and intensity basis) in Exp. 3 was less than in Exp. 2 (at the same dosage). However, the reduction in periods 1 and 2 of Exp. 3 was similar to the reduction in Exp. 2. It appears that the lack of effect of AT in periods 3 and 4 (of Exp. 3) was due to a decrease in the concentration of CHBr3 (and possibly other halogenated and brominated compounds) in AT during storage. It is estimated that approximately 100 different organohalogen compounds, mainly brominated and iodinated, are produced and stored in AT, with CHBr3 being present in the largest concentration (
suggested that CHBr3 could act synergistically with other halogenated compounds in Asparagopsis spp., which could imply that CHBr3 is not solely responsible for the CH4 mitigation effect of AT and that other brominated or halogenated compounds may also play a role.
The decrease in bromide concentration in HighAT milk from periods 3 and 4 (compared with periods 1 and 2) indicates an overall decrease in all brominated compounds in AT, not just CHBr3. The mitigation potential of Asparagopsis seaweeds is dependent on accumulation and preservation of CHBr3 and other halogenated compounds. Thus, the variation in responses among published in vitro and in vivo studies with Asparagopsis spp. may be due to varied concentrations of these compounds within Asparagopsis spp. To the best of our knowledge, in vivo studies that have used Asparagopsis spp. reported the seaweed as wild harvested, which explains the inherent variability in concentration of halogenated compounds present and, subsequently, in its CH4 mitigation potential (
reported a 26% reduction in CH4 emission (expressed on a digestible DM basis) in lactating dairy cows, which is in line with our earlier studies with OL (
Effect of dried oregano (Origanum vulgare L.) plant material in feed on methane production, rumen fermentation, nutrient digestibility, and milk fatty acid composition in dairy cows.
Feeding oregano oil and its main component carvacrol does not affect ruminal fermentation, nutrient utilization, methane emissions, milk production, or milk fatty acid composition of dairy cows.
used oregano EO and carvacrol (which is one of the main compounds in oregano EO) and reported lack of effect of both treatments on CH4 emission in dairy cows. Composition of oregano EO varies largely depending on environmental factors (
), which makes comparison of results among studies difficult. The OL used in the current study had considerably lower oil content (0.58% of DM) compared with the OL used in
Effect of dried oregano (Origanum vulgare L.) plant material in feed on methane production, rumen fermentation, nutrient digestibility, and milk fatty acid composition in dairy cows.
had 4.21% EO, but its carvacrol content was much lower (35% of the EO) than in the former studies (79–91%); however, it also contained a large proportion of thymol. Further, in the
study, the OL treatment provided 7 g of EO/cow per day (or 6.3 g of carvacrol/d), which is considerably greater than the oregano oil (1.21 g/cow per day) or carvacrol (1.19 g/d) given to the cows in
Feeding oregano oil and its main component carvacrol does not affect ruminal fermentation, nutrient utilization, methane emissions, milk production, or milk fatty acid composition of dairy cows.
Effect of dried oregano (Origanum vulgare L.) plant material in feed on methane production, rumen fermentation, nutrient digestibility, and milk fatty acid composition in dairy cows.
study provided EO and carvacrol intake from 4.2 to as high as 21.4 g/d and from 0.7 to 6.8 g/d, respectively, with still no effect on CH4 emission. Despite discrepancies in dosage, it is clear that, unlike previous results from our laboratory, OL had no effect of CH4 emission in the current experiment. The application method (i.e., inclusion in the TMR vs. direct administration in the rumen or top-dressing) may also affect the CH4 mitigation efficacy of feed supplements, as demonstrated for 3-nitrooxypropanol by
Short communication: Relationship of dry matter intake with enteric methane emission measured with the GreenFeed system in dairy cows receiving a diet without or with 3-nitrooxypropanol.
speculated that the 40% decrease in CH4 in their study could have been due to pulse dosing of OL and that CH4 would likely not be reduced to the same extent throughout the entire feeding cycle. In addition to differences in oregano EO content and composition and application method, other factors such as the short-term nature of CH4 measurements and unreliability of the SF6 technique used in
have likely contributed to the observed discrepancies in the effect of OL on CH4 emission between our earlier studies and the current experiment.
Increased H2 emission in cows receiving 0.50 and 0.75% AT (Exp. 2) and the HighAT treatment in Exp. 3 is indicative of inhibition of methanogenesis and H2 accumulation in the rumen and has been consistently observed in studies from our group with the synthetic CH4 inhibitor 3-nitrooxypropanol (
reported a 55- and 79-fold increase in H2 emission in 0.5 and 1.0% A. armata inclusion, respectively. Similarly, large increases in H2 emission were reported for feedlot cattle receiving up to 0.20% AT by
. It is noted that these authors observed H2 emission of up to 2 g/kg of DMI, which is much greater than the 0.3 to 0.5 g/kg of DMI observed in the current study or reported by
; up to 0.2 g/kg). In the current experiments, the range of H2 emissions varied. Even when CH4 emission was not suppressed (i.e., 0.25% AT in Exp. 2 or LowAT in Exp. 3), H2 emission was increased compared with the control. During periods 3 and 4 of Exp. 3, when no CH4 reduction was observed, HighAT H2 emission was on average approximately 30% to 3.5 times less than emissions in periods 1 and 2, when there was a substantial reduction of CH4 emission. Oregano did not affect H2 emission in the current study, which is in line with the lack of effect on CH4 and in agreement with previous reports (
Effect of dried oregano (Origanum vulgare L.) plant material in feed on methane production, rumen fermentation, nutrient digestibility, and milk fatty acid composition in dairy cows.
In Exp. 3 of the current study, CO2 emissions were decreased by HighAT compared with control, which was clearly associated with a 7% decrease in DMI. Similarly, inclusion of A. armata at 1.0% OM decreased CO2 emission in the study of
reported a decrease in CO2 emission with 3-nitrooxypropanol and suggested that the decrease was likely due to a numerical decrease in DMI. Oregano did not affect CO2 emission in Exp. 3, which is in agreement with previous reports (
Effect of dried oregano (Origanum vulgare L.) plant material in feed on methane production, rumen fermentation, nutrient digestibility, and milk fatty acid composition in dairy cows.
Methane inhibition by HighAT in Exp. 3 was accompanied by a decrease in total VFA concentration and, subsequently, a numerically greater rumen pH. Similar effects were reported in other CH4 inhibition studies (
). In the present study, the relative proportion of acetate was decreased and those of propionate, butyrate, and valerate were increased by HighAT, reflecting changes in the fermentation pattern as a result of inhibited methanogenesis. Cows fed LowAT also had an increased molar proportion of butyrate. In agreement with the CH4 emission data, AT supplementation did not affect VFA total concentration and molar proportions in periods 3 and 4. Similar effects of AT on rumen VFA were reported in vitro.
observed a decrease in acetate with an increase in propionate and butyrate proportions with AT dosed at 2% of OM. The few published in vivo studies, where rumen samples were collected, also demonstrated a shift in VFA proportion in favor of propionate and butyrate while decreasing acetate proportion (
). The latter authors also reported decreased acetate:propionate ratio. In Exp. 3. of the present study, the acetate:propionate ratio was the lowest when cows received the HighAT diet. A decreased proportion of acetate was accompanied by an increase in propionate and butyrate when methanogenesis was inhibited by 3-nitrooxypropanol across several studies (
The effects of feeding 3-nitrooxypropanol at two doses on milk production, rumen fermentation, plasma metabolites, nutrient digestibility, and methane emissions in lactating Holstein cows.
Processing and drying methods and storage conditions can reportedly affect concentrations and bioactivity of halogenated compounds in Asparagopsis spp. (
Drying process, storage conditions, and time alter the biochemical composition and bioactivity of the anti-greenhouse seaweed Asparagopsis taxiformis..
conducted a processing and drying experiment with fresh AT to determine effects on CHBr3 concentration. Three different methods of drying were tested: freeze-drying (lyophilization), dehydration (in a food dehydrator at 45°C), and kiln-drying (at 45°C). Frozen and lyophilized AT yielded the greatest concentrations of CHBr3, dibromoacetic acid, bromochloromethane, and dibromocloroacetic acid.
Drying process, storage conditions, and time alter the biochemical composition and bioactivity of the anti-greenhouse seaweed Asparagopsis taxiformis..
conducted an experiment that evaluated how drying method (lyophilization vs. oven-drying), storage conditions (15°C vs. −20°C), and time (0 to 3 mo) affect fatty acid profile, phenolic content, and other compounds relevant to bioactivities of AT. When AT was lyophilized, total phenolic content was greater than that in AT that was oven-dried. In the current study, we observed, a 75 to 80% decrease in CHBr3 concentration over 4 mo. In concert with decreasing CHBr3 concentration in AT, in mo 3 and 4 of Exp. 4, the CH4 mitigation potential of AT diminished. Our data suggest that light exposure does affect CHBr3 concentration in AT over time, but the effect of storage temperature appears to be small.
CONCLUSIONS
Inclusion of A. taxiformis at 0.5% of DM in lactating cow diets has the potential to decrease daily enteric CH4 emission and emission yield and intensity; at this inclusion rate, however, A. taxiformis may decrease DMI, which will result in decreased milk production. Our data suggest that the CH4 inhibitory effect of A. taxiformis is at least partially related to its concentration of CHBr3. We observed a large decrease in the CH4 mitigation potential of A. taxiformis, likely resulting from CHBr3 decay over time. Ideal storage conditions of A. taxiformis to preserve CHBr3 and other halogenated compounds or brominated compounds have yet to be determined. We also observed large increases in concentrations of iodine and bromide in milk of cows receiving 0.50% A. taxiformis, although CHBr3 content and organoleptic characteristics of the milk did not seem to be affected. In this study, OL had no effect of enteric CH4 emission and animal production variables.
ACKNOWLEDGMENTS
The authors have not stated any conflicts of interest.
REFERENCES
Abdel-Raouf N.
Al-Enazi N.M.
Ibraheem I.B.M.
Al-Harbie R.M.
Antibacterial and anti-hyperlipidemic activities of the brown alga Hormophysa cuneiformis from Ad Dammam Seashore.
Incremental amounts of Ascophyllum nodosum meal do not improve animal performance but do increase milk iodine output in early lactation dairy cows fed high-forage diets.
Feeding oregano oil and its main component carvacrol does not affect ruminal fermentation, nutrient utilization, methane emissions, milk production, or milk fatty acid composition of dairy cows.
Changes in the blood routine, biochemical indexes and the pro-inflammatory cytokine expressions of peripheral leukocytes in postpartum dairy cows with metritis.
The effects of feeding 3-nitrooxypropanol at two doses on milk production, rumen fermentation, plasma metabolites, nutrient digestibility, and methane emissions in lactating Holstein cows.
Short communication: Relationship of dry matter intake with enteric methane emission measured with the GreenFeed system in dairy cows receiving a diet without or with 3-nitrooxypropanol.
Mitigation of greenhouse gas emissions in livestock production: A review of technical options for non-CO2 emissions.
in: Gerber P.J. Henderson B. Makkar H.P.S. Food and Agriculture Organization of the United Nations (FAO), Animal Production and Health Paper No. 177. FAO,
Rome, Italy2013
Climate Change and Land: An IPCC Special Report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems.
The red macroalgae Asparagopsis taxiformis is a potent natural antimethanogenic that reduces methane production during in vitro fermentation with rumen fluid.
in: Stocker T.F. Qin D. Plattner G.-K. Tignor M. Allen S.K. Boschung J. Nauels A. Xia Y. Bex V. Midgley P.M. Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press,
New York, NY2013: 659-740
Effect of dried oregano (Origanum vulgare L.) plant material in feed on methane production, rumen fermentation, nutrient digestibility, and milk fatty acid composition in dairy cows.
Drying process, storage conditions, and time alter the biochemical composition and bioactivity of the anti-greenhouse seaweed Asparagopsis taxiformis..
A Nordic proposal for an energy corrected milk (ECM) formula.
in: Proc. of the 27th Session of the International Commission for Breeding and Productivity of Milk Animals, Paris, France. Wageningen Academic Publishers,
Wageningen, the Netherlands1990: 156-157
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