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Research Article| Volume 96, ISSUE 5, P3238-3246, May 2013

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Time-dependent variations in milk fatty acid content of goats fed 3 different plant oils

Open ArchivePublished:March 18, 2013DOI:https://doi.org/10.3168/jds.2012-6313
Time-dependent variations in milk fatty acid content of goats fed 3 different plant oils
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      Abstract

      The effect of sampling time on milk fatty acid (FA) composition after separately adding 3 plant oils to an oil-free control diet (67% cereal-soybean-based concentrate and 33% alfalfa hay) was studied in 12 Malagueña goats. Individual animals were randomly allocated to 1 of the 4 treatments: control, 48 g/d of added high oleic (OSO) or regular (RSO) sunflower oil, or linseed oil (LO). Individual milk samples were taken at 0 (covariate), 1, 12, 24, 72, 120, 192, 312, and 504 h after the beginning of the experiment. Milk FA contents (g/100 g of total FA methyl esters) were analyzed in a completely randomized design with repeated measures using PROC MIXED of SAS (SAS Institute Inc., Cary, NC). Comparing results of 15 chosen FA (for example, medium-chain saturated FA trans-11 C18:1, cis-9,trans-11 C18:2, trans-10 C18:1, and C18:3n-3) indicated that throughout the duration of the experiment, feeding the control diet had little influence on the concentrations of most FA in milk. Most changes in milk FA composition due to oil supplementation had occurred within 192 h since the beginning of the experiment. However, the concentrations of 2 FA (trans-10 C18:1 in RSO and C18:3n-3 in LO treatments) continued to change until 504 h. By comparing FA values in milk fat from oil treatments with those of the control at the same sampling times, typical value differences for the 3 supplementary oils found at 504 h (21 d) were also observed at 312 h from the beginning of the experiment (13 d) and even earlier in some FA, such as medium-chain saturated FA at 120 h in RSO and LO and at 72 h in OSO, cis-9,trans-11 C18:2 and trans-10 C18:1 at 24 h in RSO, trans-11 C18:1 at 12 h in RSO and LO, and C18:3n-3 at 1 h in LO. In the conditions assayed in these experiments, reliable results of milk FA changes were obtained at sampling times shorter than 21 d. Monitoring early changes in milk FA after the addition of plant oils to diets could help in the study of rumen and mammary metabolism of dietary FA.

      Key words

      Introduction

      There is a scarcity of information dealing with the kinetics of milk FA composition responses to plant oil inclusions in the diet of dairy ruminants. Most information corresponds to work carried out with cows (
      • Dhiman T.R.
      • Satter L.D.
      • Pariza M.W.
      • Galli M.P.
      • Albright K.
      • Tolosa M.X.
      Conjugated linoleic acid (CLA) content of milk from cows offered diets rich in linoleic and linolenic acid.
      J. Dairy Sci. 2000; 83: 1016-1027
      ;
      • Roy A.
      • Ferlay A.
      • Shingfield K.J.
      • Chilliard Y.
      Examination of the persistency of milk fatty acid composition responses to plant oils in cows given different basal diets, with particular emphasis on trans-C18:1 fatty acids and isomers of conjugated linoleic acid.
      Anim. Sci. 2006; 82: 479-492
      ) and ewes (
      • Gómez-Cortés P.
      • Frutos P.
      • Mantecón A.R.
      • Juárez M.
      • de la Fuente M.A.
      • Hervás G.
      Milk production, conjugated linoleic acid content, and in vitro ruminal fermentation in response to high levels of soybean oil in dairy ewe diet.
      J. Dairy Sci. 2008; 91 (a): 1560-1569
      ,
      • Gómez-Cortés P.
      • Frutos P.
      • Mantecón A.R.
      • Juárez M.
      • de la Fuente M.A.
      • Hervás G.
      Addition of olive oil to dairy ewe diets: Effect on milk fatty acid profile and animal performance.
      J. Dairy Sci. 2008; 91 (b): 3119-3127
      ;
      • Hervás G.
      • Luna P.
      • Mantecón A.R.
      • Castañares N.
      • de la Fuente M.A.
      • Juárez M.
      • Frutos P.
      Effect of diet supplementation with sunflower oil in milk production, fatty acid profile and ruminal fermentation in lactating dairy ewes.
      J. Dairy Res. 2008; 75: 399-405
      ). To our knowledge, only

      Chilliard, Y., J. Rouel, P. Guillouet, K. Raynal-Ljutovac, L. Leloutre, and A. Ferlay. 2005. Kinetics of responses of goat milk fatty acids to dietary forage:concentrate ratio and/or high doses of sunflower or linseed oil, or extruded mixture of seeds. Page 268 in Book of Abstracts, 56th Annual Meeting of European Association for Animal Production. Wageningen Academic Publishers, Uppsala, Sweden.

      gave data on time-related changes to cis-9,trans-11 C18:2 content after introducing sunflower or linseed oils into dairy goat diets.
      In most published papers, the first milk sample was taken 2 or 7 d after the introduction of the plant oil into the diets. However, in vitro work done by
      • Mosley E.E.
      • Powell G.L.
      • Riley M.B.
      • Jenkins T.C.
      Microbial biohydrogenation of oleic acid to trans isomers in vitro.
      J. Lipid Res. 2002; 43: 290-296
      and
      • Jouany J.P.
      • Lassalas B.
      • Doreau M.
      • Glasser F.
      Dynamic features of the rumen metabolism of linoleic acid, linolenic acid and linseed oil measured in vitro.
      Lipids. 2007; 42: 351-360
      showed changes in the accumulation of biohydrogenation (BH) intermediates and end products as soon as 0.5 h after oil inclusion in media inoculated with mixed rumen microbes.
      • Fievez V.
      • Vlaeminck B.
      • Jenkins T.
      • Enjalbert F.
      • Doreau M.
      Assessing rumen biohydrogenation and its manipulation in vivo, in vitro and in situ.
      Eur. J. Lipid Sci. Technol. 2007; 109: 740-756
      indicated that rumen microorganisms are permanently adapted to biohydrogenate unsaturated FA from plants because they are always in contact with them in most ruminant diets. Different authors (
      • Moate P.J.
      • Chalupa W.
      • Jenkins T.C.
      • Boston R.C.
      A model to describe ruminal metabolism and intestinal absorption of long chain fatty acids.
      Anim. Feed Sci. Technol. 2004; 112: 79-105
      ;
      • Harvatine K.J.
      • Allen M.S.
      Fat supplements affect fractional rates of ruminal fatty acid biohydrogenation and passage in dairy cows.
      J. Nutr. 2006; 136: 677-685
      ) have used information from in vivo experiments to build models describing rumen BH kinetics. These models predict a fast, strong lipolysis-BH reaction, which delivers unsaturated fats into the rumen and provide estimates for FA rumen passage rates. Whereas the model by
      • Moate P.J.
      • Chalupa W.
      • Jenkins T.C.
      • Boston R.C.
      A model to describe ruminal metabolism and intestinal absorption of long chain fatty acids.
      Anim. Feed Sci. Technol. 2004; 112: 79-105
      practically precludes C18:3n-3 from escaping the rumen unaltered by BH, the model by
      • Harvatine K.J.
      • Allen M.S.
      Fat supplements affect fractional rates of ruminal fatty acid biohydrogenation and passage in dairy cows.
      J. Nutr. 2006; 136: 677-685
      allows room for this to happen.
      When studying the kinetics of FA responses to the inclusion of plant oils in dairy ruminant diets, one has to bear in mind that the observed effects on milk FA changes also imply the time from FA leaving the rumen to their secretion as milk triacylglycerols. Furthermore, although several authors have studied the response of milk FA composition to abomasal/duodenal infusions of long-chain FA (
      • Drackley J.K.
      • Overton T.R.
      • Ortiz-Gonzalez G.
      • Beaulieu A.D.
      • Barbano D.M.
      • Lynch J.M.
      • Perkins E.G.
      Responses to increasing amounts of high-oleic sunflower fatty acids infused into the abomasum of lactating dairy cows.
      J. Dairy Sci. 2007; 90: 5165-5175
      ;
      • Khas-Erdene
      • Wang J.Q.
      • Bu D.P.
      • Wang L.
      • Drackley J.K.
      • Liu Q.S.
      • Yang G.
      • Wei H.Y.
      • Zhou L.Y.
      Responses to increasing amounts of free α-linolenic acid infused into the duodenum of lactating dairy cows.
      J. Dairy Sci. 2010; 93: 1677-1684
      ), their studies show changes occurring in the milk fat FA profile at 5 d from the beginning of the infusions, at the earliest. The aim of this work was to obtain information about the timing of changes in FA contents in goat milk fat from 1 to 504 h (21 d) after introducing 3 different plant oils into the diet.

      Materials and Methods

      The experiments were carried out on the premises of the Animal Production Department of Córdoba University (Córdoba, Spain). Animals were kept in accordance with Spanish regulations relative to the treatment of experimental animals. Twelve Malagueña goats were used (45 ± 5 DIM, 47 ± 4.2 kg live weight, and 2,287 ± 512 g of milk production/d at the beginning of the experiment). They were placed in individual cages of 1.0 × 1.4 m with slatted floors equipped with water and feeding troughs. All goats were fed a general-purpose diet without added fat (maize, oats, horsebeans, and alfalfa hay) from kidding until the beginning of the experiment.
      Goats were randomly assigned to 1 of 4 treatments (3 goats per treatment): a basal control diet (67% concentrate and 33% alfalfa hay) with no added oil or a basal diet supplemented with 48 g/d of either high oleic sunflower oil (OSO), regular sunflower oil (RSO), or linseed oil (LO) as shown in Table 1. The experiments lasted 21 d. Milk samples were taken from milkings at 0 h (before oil supplementation) and 1, 12, 24, 72, 120, 192, 312, and 504 h after the addition of the corresponding oil. Milkings at 0 (covariate), 1, and 12 h were stripped out by hand after giving an i.v. dose of 2 to 3 IU of oxytocin to the goats. Daily DMI, BW changes, milk production and sampling, and diet analysis were carried out as in
      • Martínez Marín A.L.
      • Gómez-Cortés P.
      • Gómez Castro G.
      • Juárez M.
      • Pérez Alba L.
      • Pérez Hernández M.
      • de la Fuente M.A.
      Effects of feeding increasing dietary levels of high oleic or regular sunflower or linseed oil on fatty acid profile of goat milk.
      J. Dairy Sci. 2012; 95: 1942-1955
      .
      Table 1Ingredients, chemical composition, and nutritive value of the experimental diets
      ItemTreatment
      Control=basal diet with no added oil; OSO, RSO, and LO=diets enriched with 48g/d of high-oleic sunflower oil, regular sunflower oil, and linseed oil, respectively.
      Control
      Control diet supplied 5.1, 0.8, 6.9, 18.9, and 6.5g/d of C16:0, C18:0, cis-9 C18:1, cis-9,cis-12 C18:2, and C18:3n-3, respectively; calculated according to INRA (2002).
      		OSORSOLO
      Diet (g/d)
       Alfalfa hay600600600600
       Concentrate
      Composition (g/kg, as fed): maize, 375; barley, 374.9; soybean meal, 200; vitamin and mineral premix (Maxi Nutral Ovejas; Nutral SA, Madrid, Spain), 30; binder (Exal; Tolsa S.A., Madrid, Spain), 20; antioxidant (Luctanox; Lucta S.A., Barcelona, Spain), 0.1.
      		1,2001,2001,2001,200
       OSO
      Included in the respective concentrates. High-oleic sunflower oil and RSO were purchased from Carrefour S.A. (Madrid, Spain). Linseed oil was supplied by Gustav Heess S. L. (Barcelona, Spain).
      		—48——
       RSO
      Included in the respective concentrates. High-oleic sunflower oil and RSO were purchased from Carrefour S.A. (Madrid, Spain). Linseed oil was supplied by Gustav Heess S. L. (Barcelona, Spain).
      		——48—
       LO
      Included in the respective concentrates. High-oleic sunflower oil and RSO were purchased from Carrefour S.A. (Madrid, Spain). Linseed oil was supplied by Gustav Heess S. L. (Barcelona, Spain).
      		———48
      Chemical composition
       DM (%)90.690.591.091.2
       CP (% of DM)17.016.416.416.5
       NDF (% of DM)28.227.527.026.9
       AHEE
      Acid hydrolysis ether extract.
      (% of DM)      		2.45.65.55.8
       Ash (% of DM)7.67.57.57.5
      Nutritive value
      Calculated from NRC (2007).
       ME (Mcal/kg of DM)2.672.772.772.77
       MP (g/kg of DM)123119119119
      FA from oil (g/d)
       C16:0—1.82.92.6
       C18:0—1.42.01.8
       cis-9 C18:1—41.014.210.0
       C18:2n-6—2.727.98.0
       C18:3n-3———23.9
      1 Control = basal diet with no added oil; OSO, RSO, and LO = diets enriched with 48 g/d of high-oleic sunflower oil, regular sunflower oil, and linseed oil, respectively.
      2 Control diet supplied 5.1, 0.8, 6.9, 18.9, and 6.5 g/d of C16:0, C18:0, cis-9 C18:1, cis-9,cis-12 C18:2, and C18:3n-3, respectively; calculated according to
      INRA (Institut National de la Recherche Agronomique)
      Tables de composition et de valeur nutritive des matières premières destinées aux animaux d’élevage. INRA, Paris, France2002
      .
      3 Composition (g/kg, as fed): maize, 375; barley, 374.9; soybean meal, 200; vitamin and mineral premix (Maxi Nutral Ovejas; Nutral SA, Madrid, Spain), 30; binder (Exal; Tolsa S.A., Madrid, Spain), 20; antioxidant (Luctanox; Lucta S.A., Barcelona, Spain), 0.1.
      4 Included in the respective concentrates. High-oleic sunflower oil and RSO were purchased from Carrefour S.A. (Madrid, Spain). Linseed oil was supplied by Gustav Heess S. L. (Barcelona, Spain).
      5 Acid hydrolysis ether extract.
      6 Calculated from
      NRC
      Nutrient Requirements of Small Ruminants. National Academy Press, Washington DC2007
      .
      Milk fats were extracted as described by
      • Gómez-Cortés P.
      • Frutos P.
      • Mantecón A.R.
      • Juárez M.
      • de la Fuente M.A.
      • Hervás G.
      Milk production, conjugated linoleic acid content, and in vitro ruminal fermentation in response to high levels of soybean oil in dairy ewe diet.
      J. Dairy Sci. 2008; 91 (a): 1560-1569
      . Fatty acid methyl esters (FAME) were prepared by base-catalyzed methanolysis of the glycerides (

      ISO-IDF (International Organization for Standardization-International Dairy Federation). 2002a. Milk fat—Preparation of fatty acid methyl esters. International Standard ISO 15884:2002 (IDF 182: 2002). IDF, Brussels, Belgium.

      ). Analysis of FAME was performed on a gas-liquid chromatograph (Agilent 6890 N Network System; Agilent Technologies Inc., Santa Clara, CA) onto a CP-Sil 88 fused silica capillary column (100 m × 0.25 mm; Varian BV, Middelburg, the Netherlands) under similar conditions to those reported by
      • Luna P.
      • Bach A.
      • Juárez M.
      • de la Fuente M.A.
      Effect of a diet enriched in whole linseed and sunflower oil on goat milk fatty acid composition and conjugated linoleic acid isomer profile.
      J. Dairy Sci. 2008; 91 (): 20-28
      . Individual FAME quantification was performed according to

      ISO-IDF (International Organization for Standardization-International Dairy Federation). 2002b. Milk fat—Determination of the fatty acid composition by gas-liquid chromatography. International Standard ISO 15885:2002 [IDF 184:2002 (E)].

      using a milk fat with known composition (CRM 164; European Community Bureau of Reference, Brussels, Belgium). Individual FA were identified by comparison with standards distributed by Nu-Chek Prep Inc. (Elysian, MN), whereas trans-11,cis-15 C18:2, trans-11,trans-15 C18:2, cis-9,trans-11,cis-15 C18:3, and cis-9,trans-11,trans-15 C18:3 had previously been identified by gas chromatography-tandem mass spectrometry (
      • Gómez-Cortés P.
      • Tyburczy C.
      • Brenna J.T.
      • Juárez M.
      • de la Fuente M.A.
      Characterization of cis-9 trans-11 trans-15 C18:3 in milk fat by GC and covalent adduct chemical ionization tandem MS.
      J. Lipid Res. 2009; 50: 2412-2420
      ).
      Data of milk fat FA content were analyzed by repeated measurement analysis (
      • Littell R.C.
      • Milliken G.A.
      • Stroup W.W.
      • Wolfinger R.D.
      • Schabenberger O.
      SAS for Mixed Models. 2nd. SAS Institute Inc., Cary NC2006
      ) using PROC MIXED of SAS (

      SAS Institute. 2004. SAS/STAT 9.1 User’s Guide. SAS Institute Inc., Cary, NC.

      ). The statistical model included the fixed effects of diet, time, their interaction, the covariate, and the random effect of goat nested within treatment. For each FA, the covariance structure of goat nested within treatment [compound symmetry, ANTE(1) or spatial power] was chosen on the basis of the Schwarz Bayesian information model fit criteria. Least squares means (adjusted by the covariate) of the diet × time interaction were compared using the CONTRAST statement in PROC MIXED. Within treatments, the least squares means were compared with their respective 504-h values. Least squares means from samples of goats fed with added oil were also compared, by sampling times, with the respective control mean. Statistical differences were declared at P < 0.05.

      Results and Discussion

      To study the effect of time after introducing the oils into the diets, 15 FA were selected (Table 2) on the basis of their significant differences in diet × time interaction and relevance in current knowledge of rumen and mammary metabolism as well as in human nutrition.
      Table 2Fatty acid content (g/100 g of FA methyl esters) at different sampling times in milk fat from goats fed control (basal diet with no added oil) or oil-supplemented diets
      FA
      Short-chain SFA (SCSFA)=sum of C4:0, C6:0, and C8:0; medium-chain SFA (MCSFA)=sum of C12:0, C14:0, and C16:0.
      		TreatmentHourSEM
      1122472120192312504
      SCSFAControl10.009.629.849.449.629.538.988.950.118
      OSO9.959.319.547.66
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		8.679.009.438.990.191
      RSO9.64
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		9.57
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		9.51
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		9.37
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		9.50
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		10.3210.13
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		10.97
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.169
      LO9.629.4310.0210.5010.6510.5010.52
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		9.810.163
      SEM0.1720.1460.1190.3910.3010.2560.2460.384
      MCSFAControl44.8445.0043.0341.7343.2745.4746.8346.470.672
      OSO45.42
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		45.50
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		40.1432.11
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		37.63
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		38.04
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		39.24
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		36.73
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		1.272
      RSO45.08
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		45.69
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		40.06
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		36.7634.75
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		34.70
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		34.96
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		33.40
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		1.015
      LO45.85
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		45.48
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		40.4636.0434.68
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		33.34
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		35.66
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		36.71
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		1.336
      SEM1.0301.1600.9741.1611.3922.0111.8922.180
      C18:0Control7.888.578.679.118.237.957.837.1780.143
      OSO7.58
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		8.22
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		10.47
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		13.72
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		10.5410.9111.00
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		13.88
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.583
      RSO7.998.6110.67
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		11.4010.299.099.768.780.391
      LO7.637.598.7511.1011.0611.83
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		10.148.2200.499
      SEM0.2880.2730.3800.6730.7240.6960.5310.953
      cis-9 C18:1Control15.2016.3017.2319.3518.2716.1015.8615.310.516
      OSO14.82
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		15.12
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		18.45
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		27.2921.4420.2818.07
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		21.94
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		1.139
      RSO15.1514.1917.1518.6718.6616.3517.1416.240.488
      LO14.79
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		13.6814.2316.8817.2017.9015.3314.980.510
      SEM0.4740.6900.6341.7100.8641.2160.5220.840
      trans-10 C18:1Control0.190.130.150.130.150.160.200.360.027
      OSO0.190.240.320.300.290.290.280.220.018
      RSO0.18
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		0.24
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		0.40
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.44
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.69
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.78
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.72
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		1.33
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.088
      LO0.17
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.260.43
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.250.190.200.240.330.035
      SEM0.0400.0350.0490.0320.0760.0780.0630.162
      trans-11 C18:1Control0.780.610.690.720.730.690.640.890.050
      OSO0.810.871.161.391.391.341.291.460.129
      RSO0.81
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		1.14
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		1.87
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		3.18
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		4.32
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		5.15
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		4.95
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		5.51
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.467
      LO0.78
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		1.65
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		3.06
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		3.28
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		3.65
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		3.64
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		3.46
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		3.49
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.312
      SEM0.1290.1470.2990.4290.5840.6540.5500.680
      trans-15 (+cis-11) C18:1Control0.300.300.310.320.270.240.270.250.012
      OSO0.310.320.340.40
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		0.340.340.270.270.015
      RSO0.320.320.40
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.380.370.380.330.340.014
      LO0.30
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		0.33
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		0.49
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.53
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.55
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.55
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.54
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.61
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.048
      SEM0.0280.0260.0330.0340.0380.0410.0450.061
      cis-15 C18:1Control0.050.060.070.040.050.040.040.050.002
      OSO0.040.03
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.050.050.050.040.050.030.002
      RSO0.04
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		0.04
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		0.070.06
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		0.070.070.07
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		0.100.005
      LO0.05
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		0.10
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.21
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.23
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.31
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.29
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.30
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.30
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.034
      SEM0.0030.0080.0190.0240.0360.0360.0350.038
      trans-11,trans-15 C18:2Control0.010.010.030.010.010.010.0100.010.001
      OSO0.01
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.010.01
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.020.02
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.020.010.020.001
      RSO0.01
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.010.020.010.010.02
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.02
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.020.001
      LO0.010.01
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		0.01
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.010.010.010.010.030.002
      SEM0.0010.0010.0030.0010.0010.0010.0010.004
      trans-11,cis-15 C18:2Control0.030.020.040.040.030.030.030.030.002
      OSO0.030.030.040.050.050.040.040.030.003
      RSO0.020.020.040.06
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		0.080.080.070.130.009
      LO0.04
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		0.34
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.57
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.54
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.66
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.76
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.73
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.87
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.094
      SEM0.0030.0370.0640.0670.0840.1030.1010.120
      cis-9,cis-12 C18:2Control1.421.461.551.761.851.801.851.720.047
      OSO1.33ª1.281.361.581.601.421.321.350.036
      RSO1.40
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		1.51
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		1.97
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		2.272.62
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		2.71
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		2.58
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		2.82
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.129
      LO1.38
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		1.50
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		1.681.801.822.022.062.330.119
      SEM0.0510.0620.1100.1320.1720.1950.1940.244
      cis-9,trans-11 C18:2Control0.390.300.360.340.390.330.310.460.027
      OSO0.380.370.430.490.510.470.430.600.034
      RSO0.42
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		0.44
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		0.79
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		1.19
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		1.71
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		2.09
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		1.99
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		2.27
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.201
      LO0.39
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		0.60
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.97
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.94
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		1.20
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		1.21
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		1.24
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		1.60
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.115
      SEM0.0550.0580.1030.1610.2290.2670.2310.294
      C18:3n-3Control0.130.130.150.170.180.160.170.150.007
      OSO0.120.120.130.170.170.140.130.160.008
      RSO0.150.120.180.150.170.140.14
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		0.180.006
      LO0.18
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.34
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.50
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.54
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.61
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.65
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.73
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.83
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.068
      SEM0.0070.0250.0410.0440.0510.0620.0780.112
      cis-9,trans-11,trans-15 C18:3ControlTr
      Tr=concentrations below 0.01g/100g of FA methyl esters.
      		TrTrTrTrTrTrTr0.000
      OSOTrTrTrTrTrTrTrTr0.000
      RSOTrTrTrTrTrTrTrTr0.000
      LO0.01
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		0.01
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		0.02
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		0.03
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		0.03
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		0.040.040.040.004
      SEM0.0000.0010.0020.0030.0040.0050.0040.006
      cis-9,trans-11,cis-15 C18:3Control0.050.06
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		0.05
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		0.05
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		0.040.04
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		0.040.030.005
      OSO0.040.050.050.040.040.040.030.030.002
      RSO0.040.040.040.050.040.040.040.040.001
      LO0.03
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		0.07
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      		0.09
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.09
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.09
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.11
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.14
      Within an FA, the means in a treatment with superscript “A” differ significantly (P<0.05) from the 504-h mean in the same treatment.
      ,
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.10
      Within an FA, the means in OSO, RSO, or LO (diets enriched with 48g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P<0.05) from the same mean in the control treatment.
      		0.012
      SEM0.0050.0070.0080.0080.0080.0110.0170.013
      A Within an FA, the means in a treatment with superscript “A” differ significantly (P < 0.05) from the 504-h mean in the same treatment.
      a Within an FA, the means in OSO, RSO, or LO (diets enriched with 48 g/d of high oleic sunflower oil, regular sunflower oil, or linseed oil, respectively) treatments with superscript “a” differ significantly (P < 0.05) from the same mean in the control treatment.
      1 Short-chain SFA (SCSFA) = sum of C4:0, C6:0, and C8:0; medium-chain SFA (MCSFA) = sum of C12:0, C14:0, and C16:0.
      2 Tr = concentrations below 0.01 g/100 g of FA methyl esters.

      Comparing Respective 504-h Values

      In the control treatment, sampling time did not affect the proportion of any FA in Table 2 [i.e., for a given FA, the values obtained at any sampling time were no different from the corresponding 504-h value (21 d)]. This provided a proper reference for comparing the effects of sampling time on the 3 oil treatments.
      In the OSO treatment, only 4 FA out of the 15 presented in Table 2 showed differences due to sampling time compared with the corresponding value obtained at 504 h: medium-chain SFA (MCSFA), C18:0, cis-9 C18:1, and trans-15(+cis-11) C18:1. No significant differences were observed in the percentages of MCSFA and C18:0 relative to the final samples collected after 1 and 3 d, respectively. The effect of OSO on MCSFA content in milk fat may be mediated by 2 different causes, which are not mutually exclusive: one is the negative effect of oil on VFA produced in rumen fermentation, and the other is the direct effect of long-chain FA absorbed in the small intestine on de novo FA synthesis in the mammary gland. According to
      • Martínez Marín A.L.
      • Gómez-Cortés P.
      • Gómez Castro G.
      • Juárez M.
      • Pérez Alba L.
      • Pérez Hernández M.
      • de la Fuente M.A.
      Effects of feeding increasing dietary levels of high oleic or regular sunflower or linseed oil on fatty acid profile of goat milk.
      J. Dairy Sci. 2012; 95: 1942-1955
      , who used the same diets in their experiments as those in the current work, the likelier cause is the second because the short-chain SFA (SCSFA; C4:0 to C8:0) showed no negative, or even positive, responses to oil supplementation (Table 2). The effect of OSO on C18:0 and cis-9 C18:1 milk fat content probably reflected its high level of cis-9 C18:1 and the particular rumen BH-mammary desaturation cycle of these FA.
      Five FA in the RSO treatment showed values statistically different from their corresponding 504-h values, which did not differ significantly at 72 h (MCSFA and cis-9,cis-12 C18:2), at 120 h (trans-11 C18:1 and cis-9,trans-11 C18:2; Figure 1) or at 192 h (SCSFA; i.e., between 3 and 8 d; Table 2).
      • Roy A.
      • Ferlay A.
      • Shingfield K.J.
      • Chilliard Y.
      Examination of the persistency of milk fatty acid composition responses to plant oils in cows given different basal diets, with particular emphasis on trans-C18:1 fatty acids and isomers of conjugated linoleic acid.
      Anim. Sci. 2006; 82: 479-492
      and
      • Shingfield K.J.
      • Reynolds C.K.
      • Hervás G.
      • Griinari J.M.
      • Grandison A.S.
      • Beever D.E.
      Examination of the persistency of milk fatty acid composition responses to fish oil and sunflower oil in the diet of dairy cows.
      J. Dairy Sci. 2006; 89: 714-732
      observed in cows and
      • Gómez-Cortés P.
      • Frutos P.
      • Mantecón A.R.
      • Juárez M.
      • de la Fuente M.A.
      • Hervás G.
      Milk production, conjugated linoleic acid content, and in vitro ruminal fermentation in response to high levels of soybean oil in dairy ewe diet.
      J. Dairy Sci. 2008; 91 (a): 1560-1569
      ,
      • Gómez-Cortés P.
      • de la Fuente M.A.
      • Toral P.G.
      • Frutos P.
      • Juárez M.
      • Hervás G.
      Effects of different forage:concentrate ratio in dairy ewe diets supplemented with sunflower oil on animal performance and milk fatty acid profile.
      J. Dairy Sci. 2011; 94: 4578-4588
      ) in ewes, that the contents of trans-11 C18:1 and cis-9,trans-11 C18:2 in milk fat reached maximum values between 6 and 7 d after introducing linoleic acid-rich oils into the diet, but then decreased and leveled off to values higher than those of the control diet. In the current research, the highest milk fat content values of these 2 FA were reached at 8 d, but rather than subsequently decreasing, they leveled off at these highest values. On the other hand, the sampling time values of trans-10 C18:1 were all different from the corresponding 504-h value, which was higher than the apparent plateau reached between 120 and 312 h (Figure 2). This type of response was not observed in cows [
      • Roy A.
      • Ferlay A.
      • Shingfield K.J.
      • Chilliard Y.
      Examination of the persistency of milk fatty acid composition responses to plant oils in cows given different basal diets, with particular emphasis on trans-C18:1 fatty acids and isomers of conjugated linoleic acid.
      Anim. Sci. 2006; 82: 479-492
      , with forage:concentrate ratios of 27:73 and 48:52; or by
      • Shingfield K.J.
      • Reynolds C.K.
      • Hervás G.
      • Griinari J.M.
      • Grandison A.S.
      • Beever D.E.
      Examination of the persistency of milk fatty acid composition responses to fish oil and sunflower oil in the diet of dairy cows.
      J. Dairy Sci. 2006; 89: 714-732
      , with a forage:concentrate ratio of 60:40]. Both sets of authors reported a plateau of trans-10 C18:1 content in milk fat around 10 to 12 d, up to 20 and 28 d, respectively. However,
      • Gómez-Cortés P.
      • Frutos P.
      • Mantecón A.R.
      • Juárez M.
      • de la Fuente M.A.
      • Hervás G.
      Milk production, conjugated linoleic acid content, and in vitro ruminal fermentation in response to high levels of soybean oil in dairy ewe diet.
      J. Dairy Sci. 2008; 91 (a): 1560-1569
      found the highest value of trans-10 C18:1 on the last sampling day of their experiment (21 d) with a 20:80 forage:concentrate diet supplemented with 6% of soybean oil.
      • Gómez-Cortés P.
      • de la Fuente M.A.
      • Toral P.G.
      • Frutos P.
      • Juárez M.
      • Hervás G.
      Effects of different forage:concentrate ratio in dairy ewe diets supplemented with sunflower oil on animal performance and milk fatty acid profile.
      J. Dairy Sci. 2011; 94: 4578-4588
      also found the same type of result at 28 d when including 2% of sunflower oil in a 30:70 forage:concentrate diet. All of this suggests that temporal changes in trans-10 C18:1 milk fat content observed in cows could be different from those in ewes and goats. In these species, at least with high-concentrate diets, the potential maximum value of trans-10 C18:1 content in milk fat does not seem to have been reached at 21 or 28 d after introducing the dietary oil.
      Figure thumbnail gr1
      Figure 1Time-dependent changes of trans-11 C18:1 and cis-9,trans-11 C18:2 in milk fat of goats fed an unsupplemented diet (control) or diets enriched with high oleic sunflower oil (OSO), regular sunflower oil (RSO), or linseed oil (LO). FAME = FA methyl esters.
      Figure thumbnail gr2
      Figure 2Time-dependent changes of trans-10 C18:1 and C18:3n-3 in milk fat of goats fed an unsupplemented diet (control) or diets enriched with high oleic sunflower oil (OSO), regular sunflower oil (RSO), or linseed oil (LO). FAME = FA methyl esters.
      Nine of the 15 FA listed in Table 2 that showed statistically significant differences between their first sampling time values and those of the corresponding 504-h sampling in the LO treatment did not differ significantly at 24 h [MCSFA, trans-11 C18:1, trans-15(+cis-11) C18:1, cis-9,cis-12 C18:2, cis-9,trans-11 C18:2, and cis-9,trans-11,cis-15 C18:3], at 120 h (cis-15 C18:1), or at 192 h (trans-11,cis-15 C18:2 and cis-9,trans-11,trans-15 C18:3). The content of C18:3n-3 showed numerically increasing values with time, which were all lower than the 504-h value (Table 2), suggesting that the potential maximum content of C18:3n-3 in milk fat was not reached before or even at 504 h (21 d) after the introduction of LO in the dairy goat diets (Figure 2). A similar response was observed by
      • Luna P.
      • Fontecha J.
      • Juárez M.
      • de la Fuente M.A.
      Changes in the milk and cheese fat composition of ewes fed commercial supplements containing linseed with special reference to the CLA content and isomer composition.
      Lipids. 2005; 40: 445-454
      working with ewes fed linseed for 6 wk.
      In the current study, the final values of trans-11 C18:1 and cis-9,trans-11 C18:2 were 58 and 42% higher, respectively, in the RSO than in the LO treatment. These results indicate that the response of trans-11 C18:1 and cis-9,trans-11 C18:2 to diets supplemented with LO was faster but weaker than with RSO.
      • Bernard L.
      • Shingfield K.J.
      • Rouel J.
      • Ferlay A.
      • Chilliard Y.
      Effect of plant oils in the diet on performance and milk fatty acid composition in goats fed diets based on grass hay or maize silage.
      Br. J. Nutr. 2009; 101: 213-224
      also found higher trans-11 C18:1 and cis-9,trans-11 C18:2 contents in goat milk fat when the basal diet was supplemented with sunflower oil instead of LO.
      In the LO treatment, the contents of trans-11 C18:1 and cis-9,trans-11 C18:2 were not different from their respective 504-h values at 24 h (i.e., a plateau was reached up to the final sampling time), but in the RSO treatment, the plateau started later (120 h; Figure 1 and Table 2). Work in vitro by
      • Jouany J.P.
      • Lassalas B.
      • Doreau M.
      • Glasser F.
      Dynamic features of the rumen metabolism of linoleic acid, linolenic acid and linseed oil measured in vitro.
      Lipids. 2007; 42: 351-360
      with a mixed rumen microbial population indicated that BH of C18:3n-3 was faster, reaching a maximum at 5 h, whereas, in the case of cis-9,cis-12 C18:2, BH was still important between 5 and 24 h. According to
      • Jouany J.P.
      • Lassalas B.
      • Doreau M.
      • Glasser F.
      Dynamic features of the rumen metabolism of linoleic acid, linolenic acid and linseed oil measured in vitro.
      Lipids. 2007; 42: 351-360
      , the reason for the delayed BH of cis-9,cis-12 C18:2 could be due to the preferential uptake of 18:3n-3 by bacteria, or differences in microbial isomerase or saturase affinity between the 2 FA. Work with dairy goats by

      Chilliard, Y., J. Rouel, P. Guillouet, K. Raynal-Ljutovac, L. Leloutre, and A. Ferlay. 2005. Kinetics of responses of goat milk fatty acids to dietary forage:concentrate ratio and/or high doses of sunflower or linseed oil, or extruded mixture of seeds. Page 268 in Book of Abstracts, 56th Annual Meeting of European Association for Animal Production. Wageningen Academic Publishers, Uppsala, Sweden.

      indicated that the cis-9,trans-11 C18:2 increase in milk fat of goats fed sunflower and linseed oils, which was observed at 7 d, lasted up to the end of the experiment (35 d).
      • Luna P.
      • Bach A.
      • Juárez M.
      • de la Fuente M.A.
      Effect of a diet enriched in whole linseed and sunflower oil on goat milk fatty acid composition and conjugated linoleic acid isomer profile.
      J. Dairy Sci. 2008; 91 (): 20-28
      , also working with goats supplemented with whole linseed and sunflower oil, found that the maximum values in milk fat of trans-11 C18:1 and cis-9,trans-11 C18:2 were at 15 d. Unfortunately, no data was reported for the week before supplementation in those experiments.

      Comparing Oil Treatments with the Control

      Comparison of FA contents from oil treatments with the corresponding values in the control treatment at the different sampling times are shown in Table 2. Of the 45 possible comparisons (i.e., 15 selected FA and 3 oil treatments), 28 (7, 9, and 12 in OSO, RSO, and LO treatments, respectively) had significantly different values from the corresponding values in the control at 1 or more sampling times. Out of these 28 comparisons, 16 showed differences of the same algebraic sign (positive or negative) to their corresponding 312- and 504-h values in the control treatment. All 3 oils lowered the MCSFA content in milk fat, whereas increases in trans-11 C18:1 and cis-9,trans-11 C18:2 content were common to RSO and LO treatments. Specific for each oil were the increases in C18:0 in the OSO treatment; SCSFA, trans-10 C18:1, and cis-9,cis-12 C18:2 in the RSO treatment; and trans-15(+cis-11) C18:1, cis-15 C18:1, trans-11,cis-15 C18:2, C18:3n-3, and cis-9,trans-11,cis-15 C18:3 in the LO treatment.
      Some of the changes observed when comparing oil-supplemented diets with the control diet at 312 and 504 h were also detected at shorter time periods. For example, the MCSFA content in milk fat of goats fed oil-supplemented diets had the same response observed at 312 and 504 h and as soon as 120 h; that response was already present at 72 h in the OSO treatment. Other FA responded faster: cis-9,trans-11 C18:2 and trans-10 C18:1 contents in milk fat of RSO-supplemented goats and cis-9,trans-11,cis-15 C18:3 in milk fat of LO-supplemented goats were already different from the control at 24 h. Differences observed with the control treatment appeared at 12 h for trans-11 C18:1 in both RSO and LO treatments, for cis-9,cis-12 C18:2 in the RSO treatment, and for cis-15 C18:1, cis-9,trans-11 C18:2, and trans-11,cis-15 C18:2 in the LO treatment. Furthermore, only 1 h was necessary to obtain a significant increase in C18:3n-3 in the LO treatment. All the responses mentioned in the paragraph above were consistent in that the differences with control values were statistically significant at all sampling times after the earlier one observed. In contrast, other FA comparisons failed to give a continuous significant response after the first difference with the control was seen (Table 2).
      The fact that the milk FA profile can be changed shortly after dietary lipid introduction had already been observed by
      • Scott T.W.
      • Cook L.J.
      • Mills S.C.
      Protection of dietary polyunsaturated fatty acids against microbial hydrogenation in ruminants.
      J. Am. Oil Chem. Soc. 1971; 48: 358-364
      and
      • Gulati S.K.
      • Byers E.B.
      • Byers Y.G.
      • Ashes J.R.
      • Scott T.W.
      Effect of feeding different fat supplements on the fatty acid composition of goat milk.
      Anim. Feed Sci. Technol. 1997; 66: 159-164
      . Those authors introduced fat into diets and observed clear changes in milk fat FA composition at the first milk sampling at 36 h in cows and 96 h in goats. It can be argued that those authors used protected oils or oilseeds, but the relevant fact is the short time required to obtain clear results. This is not surprising, in view of the results obtained by
      • Li X.Z.
      • Yang C.G.
      • Long R.J.
      • Jing G.L.
      • Shine Khuu J.
      • Ji B.J.
      • Choi S.H.
      • Lee H.G.
      • Song M.K.
      Conjugated linoleic acid in rumen fluid and milk fat, and methane emission of lactating goats fed a soybean oil-based diet supplemented with sodium bicarbonate and monensin.
      Asian-australas. J. Anim. Sci. 2009; 22: 1521-1530
      . Those authors observed increased cis-9,trans-11 C18:2 in the rumen fluid of dairy goats fed twice daily a diet supplemented with 4% soybean oil at 1, 2, and 6 h after the morning feeding.
      The observed evolution of FA contents determined in the present work could not be necessarily identical for other types of diets (i.e., when lipid supplementation is accompanied by other changes, such as the dietary forage-to-concentrate ratio). However, a shortening of the period for assessing changes in milk fat following the introduction of dietary lipid supplements may be possible. Although the data suggest that longer periods after lipid supplementation would be required for an accurate assessment of some FA (mainly trans-10 C18:1), a stabile milk fat general profile could be achieved at shorter times than 21 d.

      Conclusions

      In summary, compared with their respective 504-h values, most FA responding to the addition of any of the 3 plant oils used in this study reached a value that did not differ greatly between 24 and 192 h (i.e., between 1 and 8 d). That means that for most of the FA studied, the time from introducing the plant oil into the diet up to having a milk fat response not different from that obtained at 21 d was 8 d. Results obtained under the conditions described in this paper show that typical changes in milk fat FA content by separately adding 3 different plant oils (OSO, RSO, or LO) to the diet of dairy goats, compared with a control diet without added fat, can be obtained as soon as 13 d after introducing the oils into the diet for most FA (earlier for many of them), although the maximum attainable values for some FA may require a longer time.

      Acknowledgments

      This work was financed by the Ministerio de Ciencia e Innovación (MICINN, Madrid, Spain; AGL2008-04805 and the Consolider Ingenio 2010 Programme; FUN-C-FOOD CSD2007-063) and the Comunidad Autónoma de Madrid (Spain; 2009-AGR-1469). The authors thank A. Jiménez Secilla and B. Garfia Catalán of Laboratorio Agropecuario Regional of Córdoba (Spain) for their help with milk composition analysis. We are also grateful to I. Andújar-Ramírez (Universidad de Córdoba, Córdoba, Spain) and M. V. Rodríguez-Pino [Consejo Superior de Investigaciones Cientificas (CSIC), Madrid, Spain] for their technical assistance in processing milk samples and J. J. Pérez-Hernández (Universidad de Córdoba) for his assistance in animal feeding and management.

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      Article info

      Publication history

      Published online: March 18, 2013
      Accepted: January 24, 2013
      Received: October 26, 2012

      Identification

      DOI: https://doi.org/10.3168/jds.2012-6313

      Copyright

      © 2013 American Dairy Science Association. Published by Elsevier Inc.

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