lamb performance, milk production and composition from ewes supplemented with soybean oil partially...

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Livestock Science

Livestock Science 163 (2014) 51–61

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Lamb performance, milk production and composition fromewes supplemented with soybean oil partially replaced by fishoil blend

Evandro Maia Ferreira a, Alexandre Vaz Pires b,n, Ivanete Susin b,Renato Shinkai Gentil b, Susana Gilaverte b, Michelle de Oliveira Maia Parente b,Marcos Vinicius Biehl b, Claudio Vaz Di Mambro Ribeiro c

a Department of Animal Science, State University of Ponta Grossa, General Carlos Cavalcanti Avenue, n 4748, Ponta Grossa 84.030-900,Paraná, Brazilb Department of Animal Science, College of Agriculture “Luiz de Queiroz”, University of São Paulo, Pádua dias Avenue, n 11, PO Box 09,Piracicaba 13418-900, São Paulo, Brazilc Department of Animal Science, Federal University of Bahia, Adhemar de Barros Avenue, n 500, Salvador 40170-110, Bahia, Brazil

a r t i c l e i n f o

Article history:Received 1 October 2013Received in revised form6 February 2014Accepted 11 February 2014

Keywords:CLAFatty acid profileLipidsSheepUnsaturated fatty acids

x.doi.org/10.1016/j.livsci.2014.02.00913 & 2014 Elsevier B.V. All rights reserved.

esponding author. Tel.: þ55 19 3429 4134;ail address: [email protected] (A.V. Pires).

a b s t r a c t

The objectives of these experiment were to evaluate the effects of small amounts of fishoil blend supply in partial replacement of soybean oil on dry matter intake (DMI),lactation performance and milk fatty acid composition of ewes and also on performance oftheir lambs. Fifty Santa Inês lactating ewes (6376 kg of initial BW; mean7SD) werepenned individually and used in a randomized complete block design with 10 blocks and 5treatments. The oils were added to a basal diet that contained 700 g/kg DM of concentrateand 300 g/kg DM of forage (fresh sugarcane bagasse). The treatments were as follows: (1)basal diet without added oil (CONT); (2) 40 g/kg DM of soybean oil (0FO); (3) 2.5 g/kg DMof fish oil blendþ37.5 g/kg DM of soybean oil (25FO); (4) 5 g/kg DM of fish oil blendþ35 g/kgDM of soybean oil (50FO); and (5) 7.5 g/kg DM of fish oil blendþ32.5 g/kg DM of soybeanoil (75FO). All diets were isonitrogen (14074 g/kg DM of CP). Once a week, from thesecond to the eighth week of lactation (weaning time), ewes were separated from theirlambs, stimulated by a 6-IU intravenous oxytocin injection, and milked to empty theudder. After 3 h, milk production was obtained after the same procedure. DMI (kg/d; % ofBW and g/kg BW0.75) was higher for ewes fed the control diets vs. fat-supplemented.However, no effect was observed on DMI when fish oil blend inclusion in the dietsincreased. Nevertheless, milk production increased linearly when fish oil blend replacedsoybean oil. As a consequence, the preweaning average daily gain (ADG) of lambsincreased linearly. Milk fat concentration was similar for all diets. Milk protein and totalsolids concentrations decreased linearly when fish oil blend addition increased. Lactosemilk concentration was higher for ewes fed the fat-supplemented diets vs. the control.Stearic acid, oleic acid, vaccenic acid, linoleic acid, linolenic acid and CLA cis-9, trans-11showed higher concentrations in milk of animals fed diets containing soybean oil and fishoil blend compared to the control diet. Vaccenic acid, CLA trans-10, cis-12, eicosapentae-noic acid (EPA) and docosahexaenoic acid (DHA) increased linearly with fish oil blendinclusion. Small amounts of fish oil supplementation does not exert an additional effect on

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E.M. Ferreira et al. / Livestock Science 163 (2014) 51–6152

the concentration of CLA C18:2 cis-9, trans-11 as compered to exclusive use of soybean oil.However, the addition of 7.5 g/kg DM of fish oil blend mixed with 32.5 g/kg DM of soybeanoil is recommended, because it increased the concentration of EPA, DHA and C18:1 trans-11 in the milk, as well increasing the performance of the ewes and their lambs.

& 2014 Elsevier B.V. All rights reserved.

1. Introduction

Due to the attribution of several health benefits that fattyacids bring (Park, 2009), many strategies have been used toimprove the lipid profile of milk from ruminant animals.Providing sources of supplemental fat to animals has shownto be a good alternative to enrich milk fat with fatty acidsimportant to human health, such as conjugated linoleic acid(CLA) and omega-3 fatty acids (n-3) (Toral et al., 2010;Whitlock et al., 2006).

The most recognizable as a biologically active isomers arecis-9, trans-11 C18:2 and trans-10, cis-12 C18:2. The cis-9,trans-11 C18:2 is the major isomer and represents about75–80% of total CLA in milk fat (Park et al., 2007). This maybe synthesized either in the rumen as a transient inter-mediate in the process of biohydrogenation of linoleic acidor directly in adipose tissue or in the mammary glandstarting with the vaccenic acid through the action of theenzyme Δ9-desaturase (Baumgard et al., 2000). However,80% (Mosley et al., 2006) to 93% (Piperova et al., 2002) ofCLA C18:2 cis-9, trans-11 present in the milk is of endo-genous origin. Thus, the accumulation of vaccenic acid inthe rumen for further absorption is desirable.

One strategy to increase the ruminal concentration ofvaccenic acid is the supplementation of fish oil (Bharathanet al., 2008; Toral et al., 2010). The docosahexaenoic acid(DHA) found in fish oil is largely responsible for the finalstep of inhibiting biohydrogenation of vaccenic acid tostearic acid (Abughazaleh and Jenkins, 2004).

Donovan et al. (2000) verified that the maximumconcentration of vaccenic acid and CLA in the cow milkwas obtained through the supplementation of 20 g/kg drymatter (DM) of fish oil as the sole source of fat supple-ment; however, starting from the inclusion of 10 g/kg DMof fish oil there was a reduction in dry matter intake (DMI)and in milk production.

In addition to the DHA, high concentrations of linoleic acidand other unsaturated fatty acids also reduce the biohydro-genation of the vaccenic acid to stearic acid. Whitlock et al.(2006) demonstrated that the inclusion of only 3.3 g/kg DM offish oil mixed with 16.6 g/kg DM of soybean oil was sufficientto optimize the synthesis of CLA in the mammary glandwithout harming the performance of lactating cows.

Our hypothesis is that if the mixture provided has a richsource of linoleic acid, low levels of fish oil blend (r7.5 g/kgDM) will be sufficient to optimize synthesis of vaccenic acidand CLA in milk without adversely affecting the DMI andmilk production of sheep.

In order to test this hypothesis, we assessed the effectsof small inclusions of fish oil blend in the diets of lactatingewes in partial replacement of soybean oil on the DMI,milk production, milk fatty acid profile and the perfor-mance of the ewes and their lambs.

2. Materials and methods

This study was conducted between the months of Octoberand December of 2008 at the System facilities of the IntensiveProduction of Sheep and Goats (SIPOC) of Animal ScienceDepartment, “Luiz de Queiroz” College of Agriculture, SãoPaulo University, located in Piracicaba – São Paulo (221 420

24″ S and 471 370 53″ W), Brazil.

2.1. Animals and experimental facilities

Fifty lactating Santa Inês ewes with an initial body weight(BW) of 63.675.9 kg, were housed indoor and individuallyallotted with their lambs in pens (1.3 m�3.5 m), with aconcrete floor, feed bunk, mineral box, and waterer. Thirty-five ewes had single births and fifteen had twin births.All the lambs were F1 (Dorper� Santa Inês), with 30females and 35 males. The day of lambing, all ewes weredewormed with 1.0% moxidectin (Cydectin, Fort DodgeAnimal Health, Campinas, São Paulo, Brazil) at a dosage of1 mL/50 kg BW.

2.2. Experimental design and treatments

After 11.072.0 days of lactation, all of the animals weredivided into a randomized complete block design with 10blocks and 5 treatments. The blocks were defined accordingto date of birth, type of birth (single or twin), sex of theoffspring and weight of the ewes.

The treatments were defined by the addition of increas-ing levels of fish oil blend (59.7 g/kg DM of DHA pluseicosapentaenoic acid (EPA) and 4.1 n-6/n-3 ratio; AzevedoIndústria e Comércio de Óleos LTDA, São Paulo, SP, Brazil;Table 2) as a replacement for soybean oil (CampestreIndústria e Comércio de Óleos Vegetais LTDA, São Paulo,SP, Brazil; Table 2) in the diet, maintaining the content ofsupplemental fatty acid at 40 g/kg DM (Table 1). The oilswere added to a basal diet that contained 700 g/kg DM ofconcentrate and 300 g/kg DM of forage (fresh sugarcanebagasse). The treatments were as follows: (1) basal dietwithout added oil (CONT); (2) 40 g/kg DM of soybean oil(0FO); (3) 2.5 g/kg DM of fish oil blendþ37.5 g/kg DM ofsoybean oil (25FO); (4) 5 g/kg DM of fish oil blendþ35 g/kg DM of soybean oil (50FO); and (5) 7.5 g/kg DM of fish oilblendþ32.5 g/kg DM of soybean oil (75FO). The diets wereformulated according to the recommendations of the“National Research Council” – NRC (2007). The proportionof the ingredients and the chemical composition of thediets are presented in Table 1. The composition of fattyacids of the soybean and fish oil blend used is shown inTable 2.

Table 1Proportions of the ingredients and chemical composition of the experimental diets, g/kg DM.

Item Dietsa

CONT 0FO 25FO 50FO 75FO

IngredientsSugar cane bagasse in natura 300 300 300 300 300Corn 452 401 401 401 401Soybean meal 129 138 138 138 138Soybean hulls 98 100 100 100 100Urea 6 6 6 6 6Limestone 5 5 5 5 5Mineral Mixb 10 10 10 10 10Fish oil blend – – 2.5 5.0 7.5Soybean oil – 40 37.5 35.0 32.5

Chemical compositionDry matter (g/kg, as-fed basis) 755 758 758 758 758Organic material 959 958 958 958 958Crude protein 137 142 142 142 142Ether extract 29 67 67 67 67Non-fibrous carbohydrate 345 296 296 296 296Neutral detergent fiber 448 453 453 453 453Metabolizable energy, Mcal/kg DMc 2.6 2.8 2.8 2.8 2.8

a CONT¼diet without added oil; 0FO¼40 g/kg DM of soybean oil; 25FO¼2.5 g/kg DM of fish oil blendþ37.5 g/kg DM of soybean oil; 50FO¼5 g/kg DMof fish oil blendþ35 g/kg DM of soybean oil; 75FO¼7.5 g/kg DM of fish oil blendþ32.5 g/kg DM of soybean oil.

b Composition: 5.5% P, 22% Ca, 3.5% Mg, 2,2% S, 7,0% Na, 500 ppm Fe, 450 ppm Cu, 1550 ppm Z, 20 ppm Se.c Estimated using the Small Ruminant Nutrition System, v. 1.8.6 (Cannas et al., 2004).

Table 2Composition of the fatty acids of the soybean oil and fish oil blend.

Fatty acids, g/100 g FAMEa Soybean oilb Fish oil blendc

C12:0 (lauric) n.dd n.d.C14:0 (myristic) 0.08 1.31C16:0 (palmitic) 11.32 12.07C16:1 (palmitoleic) n.d. 1.29C18:0 (stearic) 4.05 3.46C18:1 n-9 (oleic) 23.38 21.96C18:2 n-6 (linoleic) 54.79 47.55C18:3 n-3 (linolenic) 4.90 5.19C20:5 n-3 (EPA – eicosapentaenoic) n.d. 2.86C22:6 n-3 (DHA – docosahexaenoic) n.d. 3.11Saturated 15.64 17.55PUFAe 60.98 59.06MUFAf 23.38 23.39PUFA n-6 56.08 47.55PUFA n-3 4.90 11.51

a FAME¼ fatty acid methyl esters.b Azevedo Indústria e Comércio de Óleos LTDA”, São Paulo, Brazil.c Azevedo Indústria e Comércio de Óleos LTDA”, São Paulo, Brazil.d n.d.¼not detected.e PUFA¼polyunsaturated fatty acids.f MUFA¼monounsaturated fatty acids.

E.M. Ferreira et al. / Livestock Science 163 (2014) 51–61 53

2.3. Feed management and data collection

After entering the experiment, all the ewes were fedwith a control diet for one week. This period served toadapt the animals to the basal diet and to the experimentalfacilities. Following the adaptation period, the experimen-tal period began, elapsing between the 18th72.0 days oflactation and the 60th72 days of lactation, completing 7weeks of data collection.

Corn and soybean hulls were coarsely ground using agrinder (Nogueiras DPM – 4, Itapira, Brazil) devoid ofsieve, and mixed with soybean meal, urea, limestone,mineral mixture and monensin (Elanco of Brazil, SãoPaulo, Brazil) using a horizontal mixer with a capacity of500 kg (Lucatos, Limeira, Brazil). The monensin (Rumen-sins 100, Elanco Animal Health, Greenfield, IN) was addedin the proportion of 25 mg/kg of diets (as-fed basis). Oilmixes were added to the concentrate just before feeddelivery. The concentrateþoil(s) and the sugar canebagasse were weighed separately on an electric scale withan accuracy of 1 g (Martes, LC 100, São Paulo, Brazil),mixed, and offered daily in the form of total mixed ration.The animals had ad libitum access to the feed and freshwater. Amounts of feed offered to animals were calculatedaccording to previous DMI, and adjustments were madewhen needed so that refused feed did not exceed 0.10 ofdaily intake. Orts were recorded every week to determinethe animal DMI. Feeds and orts were sampled weekly andfrozen at �20 1C for later analysis. All of the ewes wereweighed, for three consecutive days, without fasting, inthe beginning and end of the experimental period todetermine BW change.

To measure the milk production, once a week the eweswere separated from their lambs and milked mechanically

(Camp Agri, model GL300, São Paulo, Brazil). The ejectionof the milk was stimulated by the intravenous applicationof 6 international units (IU) of oxytocin (Univet, São Paulo,Brazil). The consecutive machine milkings were performedat 10:00 am and 1:00 pm. The first milking served toempty the udder and the milk obtained was discarded.In the second milking, each animal's milk was weighed toquantify the production of milk during the 3 h interval, asdescribed by Susin et al. (1995). Two samples of milkper ewe (20 mL each), were collected weekly, one of the


samples was conserved in Bronopol Broad Spectrum Micro-tabss II (2-bromo-2-nitropropano-1,3-diol, D & F ControlSystemss, Inc., Dublin, CA, USA) and the other storedat �20 1C.

The lambs received the initial concentrate starting at2572 days old. The ingredients of the initial concentratewere: 700 g/kg DM of corn; 238 g/kg DM of soybean meal;15 g/kg DM of limestone; 10 g/kg DM of mineral mix; and37 g/kg DM of molasses. The chemical compositions (g/kgDM) of the initial concentrate were: 885 g DM (g/kg, as-fedbasis), 186 g CP, 126 g NDF and 53 g Ash. The feed wasoffered in a private feeder permitting access only to thelambs. In order for them not to have access to the ewe'strough, the lambs were tied with a rope to the feeder. Thelength of the cord permitted free access to the water andthe ewe. The lambs were weighted weekly after a 3 h fast.On the weighing day, the orts of the initial feed werequantified for the determination of the DMI by the lambs.

2.4. Chemical analysis

Samples of feeds and orts were ground through a1-mm Wiley Mill screen (Marconi, Piracicaba, Brazil). TheDM content of feed offered and orts was determined afteroven-drying the samples at 105 1C for 24 h according tothe method of the Association of Official Analytical Che-mists (AOAC, 1990; #934.01). Ash was determined byincinerating the samples in a muffle furnace at 550 1C for4 h (AOAC, 1990; #942.05). Total nitrogen (N) concentra-tion was determined using a LECOs FP-528 Total NitrogenAnalyzer (LECOs Corporation, St. Joseph, MI, USA; AOAC,1990; #968.06). Crude protein (CP) was obtained by multi-plying the total N content by 6.25. Neutral detergent fiber(NDF) was determined according to Van Soest et al. (1991),using heat-stable alpha-amylase and sodium sulfite withan Ankom 200 Fiber Analyzer (Ankom Tech. Corp., Fair-port, NY, USA). The ether extract (EE) was determinedusing a LECOs TFE-2000 Fat Analyzer (LECOs Corporation,St, Joseph, MI, USA). Nonfiber carbohydrates (NFC) werecalculated according to equation: NFC (%)¼100�(%NDFþ%CPþ%ether extractþash).

The milk samples, previously conserved in bronopol,were analyzed for the quantification of protein, fat, lactoseand total solids via infrared with a Bentley 2000 instru-ment (Bentley Instruments, Chaska, MN, USA, AOAC, 1990).

2.5. Fatty acid composition of the milk fat

The total lipids were extracted following the metho-dology described by Feng et al. (2004). One aliquot of thelipid extract was methylated in two steps with 2 mL of0.5 M sodium methoxide (10 min at 50 1C), followed by theaddition of methanoic HCL (10 min at 80 1C), according toKramer et al. (1997) and stored at �20 1C in 1.5 mL ambervials containing nitrogen to prevent possible oxidation.

The quantification and determination of fatty acidswere performed using Agilent 7890A gas chromatographequipped with a flame ionization detector (7683B), and afused-silica capillary column (J&W 112-88A7, Agilent Tech-nologies, Santa Clara, CA, USA), 100 m in length and250 μm internal diameter, containing 0.20 μm cyanopropyl

policiloxane. The data acquisition was performed usingChemStation software (Agilent Technologies, Santa Clara, CA,USA). The total chromatographic run time was 87.5 mindivided into four heating ramps, as follows: 70 1C (1 min),100 1C (5 1C/min, 2 min), 175 1C (10 1C/min, 40 min), 225 1C(5 1C/min) and 245 1C (20 1C/min, 20 min). The H2 was usedas carrier gas at a flow rate of 1.0 mL/min, the temperature ofthe injector and detector was 260 1C. The N2 gas was used asMakeup with a flow of 30 mL/min. A split ratio of 50:1 wasused. The identification of the fatty acids of the samples wasperformed based on the retention time of the fatty acidmethyl esters. A mix standard Supelcos (Sigma Aldrich,Bellefonte, EUA) of 37 compounds and individual standardsto identify fatty acids C18:0, C18:2 cis-9, trans-11 and C18:2trans-10, cis-12 (Nu-Chek Prep, Inc., Elysian, MN, USA)were used.

2.6. Statistical analysis

The DMI data, production and milk composition wereanalyzed as repeated measurements over time using theSAS (1999) MIXED procedure according to the followingstatistical model: Y¼μþBiþDjþSijþTkþ(DT)jkþEijk, whereμ¼overall mean, Bi¼effect of block (i¼1 to 10), Dj¼effectof diet (j¼1 to 5), Sij¼residual error associated with theeffect of the animal (block�diet ), Tk¼effect of lactationweek (k¼1 to 7); (DT)jk¼ interaction of diet�week inlactation, and Eijk¼residual error. The blocks and animalswere included as random effects. The covariance matrix ofbest fit to the data set was the “autoregressive” (AR 1). Theaverages of each treatment were obtained using theLSMEANS command. There were two contrasts previouslydefined: 1 � control diet (CONT) vs. diet containing 40 g/kgDM of soybean oil (0FO) and 2 � CONT vs. diets containingfish oil blend (25FO, 50FO and 75FO). The effects of the fishoil blend content (0FO, 25FO, 50FO or 75FO) included inthe diets as the replacement for soybean oil were evalu-ated using linear and quadratic orthogonal contrasts. Theeffects of the week and interaction of the diet vs. weekswere defined by the F test analysis of variance.

The fatty acid composition of the milk was also ana-lyzed using the SAS (1999) “MIXED” procedure accordingto the model: Y¼μþBiþDjþEij, in which μ¼overall aver-age, Bi¼effect of the block (i¼1 to 10), Dj¼effect of thediet (j¼1 to 5), and Eij¼residual error. The block wasincluded as a random effect. The averages were obtainedthrough the LSMEANS command. The previously describedcontrasts (control diet vs. the diet containing 40 g/kg DMof soybean oil and control vs. diets containing fish oilblend) were performed. The effects of the inclusion levelsof fish oil blend in the diets in replacement of soybean oilwere evaluated using linear and quadratic orthogonalpolynomials. The effects were considered significant whenPo0.10.

3. Results

Dietary DM, CP and NDF content were similar amongtreatments. NDF was 14.5% lower in diets with oilscompared to the control. The level of ether extract of the


diets increased from 29 g/kg DM (control diet) to 67 g/kgDM (diets containing oil). Consequently, the four dietscontaining oil had a higher concentration of metabolizableenergy (ME) in relation to the control diet (2.8 vs. 2.6 Mcal/kgDM, respectively; Table 1). The fish oil blend showed anelevated concentration of linoleic acid (47.6 g/100 g fattyacids) and low concentrations of EPA (2.9 g/100 g fatty acids)and DHA (3.1 g/100 g fatty acids) (Table 2).

1.0

1.4

1.8

2.2

2.6

3.0

0 1 2 3 4 5 6 7 8

Con

sum

o de

MS,

kg/

dia

Semanas de lactação

CONT 0FO 25FO 50FO 75FO

Fig. 1. Dry matter intake (average, SE¼0.08) by the ewes during 8 weeksof lactation according to the experimental diets: CONT¼diet withoutadded oil; 0FO¼40 g/kg DM of soybean oil; 25FO¼2.5 g/kg DM of fish oilblendþ37.5 g/kg DM of soybean oil; 50FO¼5 g/kg DM of fish oilblendþ35 g/kg DM of soybean oil; 75FO¼7.5 g/kg DM of fish oilblendþ32.5 g/kg DM of soybean oil (n¼10 ewes for each diet).

3.1. Body weight, dry matter intake, milk production andcomposition

The inclusion of soybean oil or fish oil blend in theexperimental diets did not affect the variation of the ewe'sbody weight over the experimental period (Table 3). Theanimals of all the treatments presented positive changes inbody weight which indicates that there was no nutritionalrestriction for milk production.

For DMI, the effect of the diets (Po0.01), of the experi-mental week (Po0.01) and of the interaction (kg/day,P¼0.10, % of BW and g/kg BW0,75, P¼0.03) between thediets and experimental weeks were verified (Table 3,Fig.1). The animals fed the control diet have greater(Po0.01) DMI (kg/day, % of BW, g/kg BW0,75) than thosefed diets containing oil (Table 3). Throughout the experi-mental weeks, the ewes fed diets containing oil showed asimilar pattern of intake (Fig. 1). As a result, there was noeffect of increasing levels of replacement of soybean oil byfish oil blend on DMI. The interaction occurred because theinclusion of oil sources in the diet caused a reduction inDMI between the second and third experimental week.However, beginning on the second week, the animals fedthe control diet increased their DMI progressively untilreaching a peak in the 7th experimental week (Fig. 1).

Table 3Body weight, dry matter intake and milk production of the ewes fed with the e

Item Dietsa SEMb P-value

CONT 0FO 25FO 50FO 75FO CONT�

Initial BWd, kg 62.7 64.8 63.0 62.3 63.0 0.83 0.28Final BW, kg 66.9 68.1 66.2 65.3 66.6 0.89 0.56BW gain, kg 4.2 3.3 3.2 3.0 3.5 0.41 0.48DM intake

kg/day 2.33 2.12 2.14 2.07 2.10 0.03 o0.01% of BW 3.6 3.2 3.3 3.3 3.2 0.05 o0.01g/kg BW0,75 101.9 91.3 94.1 92.1 91.7 1.27 o0.01

Production, g/3 hMilk 201.7 184.8 189.5 205.4 221.6 4.16 0.21FCMe 216.1 204.1 206.2 219.9 232.5 4.85 0.46FPCMf 209.8 199.4 199.5 199.9 225.9 4.53 0.40

EAg 95.2 100.6 98.4 116.4 114.9 2.85 0.54

a CONT¼diet without added oil; 0FO¼40 g/kg DM of soybean oil; 25FO¼2.5of fish oil blendþ35 g/kg DM of soybean oil; 75FO¼7.5 g/kg DM of fish oil blen

b SEM¼standard error of the mean (n¼10 ewes for each diet).c CONT�0FO¼control diet vs. diet containing 40 g/kg DM of soybean oil; CO

vs. 25FO, 50FO and 75FO); L¼ linear effect; Q¼quadratic effect; Week¼effect ofand weeks.

d BW¼body weight.e 6.5% fat-corrected milk according to Pulina and Nudda (2004).f 6.5% fat- and 5.8% protein-corrected milk according to Pulina and Nudda (g EA¼feed efficiency (g of fat-corrected milk/g of DM intake).

Milk production, fat corrected milk (FCM) and fat-protein corrected milk (FPCM) were similar in comparisonbetween the control diet and those containing oil(Table 3). However, there was a linear increase in milkproduction (Po0.01), FCM (P¼0.07) and FPCM (P¼0.08)with increasing levels of replacement of soybean oil by fishoil blend (Table 3).

Feed efficiency (FE) (Table 3) did not differ when compar-ing the control diet and those containing oil. However, due toa linear increase in milk production, partial replacement ofsoybean oil by fish oil blend increased the FE linearly(P¼0.03).

There was no effect of the treatments on the content(g/kg) and yield (g/3 h) of milk fat.

xperimental diets.

c

0FO CONT� Fish oil blend L Q Week TRAT�Week

0.93 0.29 0.32 – –

0.65 0.43 0.32 – –

0.38 0.91 0.76 – –

o0.01 0.66 0.92 o0.01 0.10o0.01 0.92 0.45 o0.01 0.03o0.01 0.95 0.59 o0.01 0.03

0.89 o0.01 0.62 o0.01 0.460.88 0.07 0.69 o0.01 0.490.58 0.08 0.26 o0.01 0.510.12 0.03 0.96 0.12 0.52

g/kg DM of fish oil blendþ37.5 g/kg DM of soybean oil; 50FO¼5 g/kg DMdþ32.5 g/kg DM of soybean oil.

NT� Fish oil blend¼control diet vs. diets containing fish oil blend (CONTthe week; TRAT�Week¼effect of the interaction between the treatments

2004).


The protein content of the milk was similar betweenthe control diet and the diet containing 40 g/kg DM ofsoybean oil. However, it decreased (Po0.05) in the milk ofewes fed with the three diets containing fish oil blendwhen compared to that the control diet. In addition, alinear reduction (P¼0.03) was observed with the increas-ing levels of the replacement of soybean oil by fish oilblend (Table 4). Nevertheless, given the linear increase inthe milk production, the protein production of the milklinearly increased (P¼0.02) with increasing levels of fishoil blend in the diets. For the same reason, the productionof milk protein did not differ in comparison between thethree diets containing fish oil blend and the control. Theconcentration of lactose of the milk did not differ betweenthe animals fed the control diet and those fed the dietscontaining oil. However, there was a linear increase(P¼0.05) in the concentration of lactose with the inclusionof fish oil blend in the diets (Table 4). As a result of this,and the increase observed in milk production, the lactoseyield (g of lactose/3 h) also increased linearly (Po0.01) as

Table 4Composition and production of the milk components of the ewes fed with the

Item Dietsa SEMb P-valuec

CONT 0FO 25FO 50FO 75FO CONT�0F

Content, g/kgFat 74 75 71 75 70 1.00 0.98Protein 52 48 47 45 45 0.50 0.14Lactose 47 48 48 48 49 0.20 0.64Total solids 181 180 175 175 173 1.10 0.50

Production, g/3 hFat 14.7 14.0 13.8 14.8 15.4 0.36 0.55Protein 9.2 8.8 8.6 9.1 10.2 0.18 0.40Lactose 9.4 8.8 8.9 10.2 11.1 0.21 0.36Total solids 35.3 33.4 34.1 36.1 38.6 0.75 0.43


b SEM¼standard error of the mean (n¼10 samples for each diet).c CONT�0FO¼control diet vs. diet containing 40 g/kg DM of soybean oil; CO


Table 5Effect of the supply of the experimental diets to the ewes on dry matter intake

Item Dietsa SEMb P-valuec

CONT 0FO 25FO 50FO 75FO CONT�0

Initial age, days 18.0 17.4 17.9 17.1 17.3 – –

Final age, days 60.0 59.4 59.9 59.1 59.3 – –

Initial weight, kg 7.7 8.9 8.8 9.4 8.8 – –

Final weight, kg 18.4 19.2 19.1 20.5 20.6 0.55 0.57ADGd, g 256 246 249 284 279 0.01 0.54DMIe, g/day 261 219 187 188 199 0.01 0.45


b SEM¼standard error of the mean (n¼13 lambs for each diet).c CONT�0FO¼control diet vs. diet containing 40 g/kg DM of soybean oil; CO


d ADG¼average daily weight gain.e DMI¼dry matter intake of the initial concentrate.

fish oil blend was added to the diets. Given the lineardecrease of the protein concentration, the concentration oftotal milk solids was also linearly reduced (P¼0.09) withthe inclusion of increasing levels of fish oil blend. How-ever, the production of the total solids (g of total solids/3 h) increased linearly (P¼0.03) as fish oil blend wasincluded in the diets. The reduction in the concentrationof total solids was 3.9% (181 vs. 173 g/kg milk for thetreatments 0FO and 75FO, respectively), while the rate ofincrease in the production of milk was 19.9% (184.8 vs.221.6 g/3 h for the treatments 0FO and 75FO, respectively)which explains the increase in the production of totalsolids (g of total solids/3 h) even with a reduction in theconcentration of total milk solids (Table 4).

The average daily weight gain (ADG) of the lambs of theewes fed with the control diet was similar to those of theewes that received the diets containing oil (Table 5).However, the lambs of the ewes fed with the dietscontaining the increasing levels of fish oil blend had alinear increase in ADG. The supply of the experimental

experimental diets.

O CONT� Fish oil blend L Q Week TRAT�Week

0.52 0.43 0.90 o0.01 0.370.02 0.03 0.43 0.17 0.770.18 0.05 0.24 o0.01 0.360.22 0.09 0.55 o0.01 0.46

0.72 0.20 0.70 o0.01 0.430.85 0.02 0.19 o0.01 0.340.54 o0.01 0.48 o0.01 0.490.99 0.03 0.64 o0.01 0.49



of the initial concentrate and weight gain of their young.

FO CONT� Fish oil blend L Q Week TRAT�Week

– – – – –

– – – – –

– – – – –

0.19 0.20 0.89 – –

0.33 o0.01 0.70 o0.01 0.590.13 0.74 0.60 o0.01 0.96




diets to the ewes did not affect the initial concentrateintake by the lambs.

3.2. Fatty acid composition of the milk

The total concentration of the short chain fatty acids(C4:0 to C12:0) and medium (C14:0 to C16:1) in the milkdecreased (Po0.001) with the supply of the diets contain-ing oil (Table 6). Additionally, there was a linear decrease(P¼0.06) in the medium (C14:0 to C16:1) fatty acids withincreasing levels of fish oil blend in the diets. However, thereplacement of soybean oil by fish oil blend did not affectthe concentration of short chain fatty acids (C4:0 to C12:0)fatty acids in the milk.

The concentration of unsaturated fatty acids was higher(Po0.01) in the milk of animals fed the diets containingoil (Table 6). While, the addition of oil to the dietsdecreased (Po0.01) the concentration of saturated fattyacids in the milk. There was a linear increase in theunsaturated fatty acids (P¼0.01) and a linear decrease insaturated fatty acids (P¼0.01) concentrations in the milkwith increasing levels of fish oil blend in the diets.

Table 6Composition of the fatty acids of the milk fat of the ewes fed with the experim

Fatty acids, g/100 g FAMEa Dietsb

CONT 0FO 25FO 50FO 75

C4:0 (butyric) 1.39 1.50 1.65 1.20 1C6:0 (caproic) 1.69 1.31 1.36 1.10 1C8:0 (caprylic) 1.73 1.20 1.24 0.99 1C10:0 (capric) 6.36 3.93 3.91 3.35 3C12:0 (lauric) 4.10 2.49 2.62 2.27 2C14:0 (myristic) 10.78 7.91 8.14 7.83 7C14:1 (myristoleic) 0.60 0.52 0.48 0.50 0C15:0 (pentadecanoic) 1.13 0.82 0.80 0.80 0C16:0 (palmitic) 29.43 24.39 23.97 24.61 23C16:1 (palmitoleic) 0.63 0.55 0.52 0.56 0C18:0 (stearic) 11.68 15.71 14.92 14.25 14C18:1 n-9 (oleic) 21.86 25.87 24.94 25.44 25C18:1 trans-11 (vaccenic) 1.09 2.17 2.79 3.59 3C18:2 cis-9, trans-11 (rumenic) 0.75 1.34 1.48 1.62 1C18:2 trans-10, cis-12 0.02 0.03 0.03 0.04 0C18:2 n-6 (linoleic) 2.62 3.46 3.52 3.47 3C18:3 n-6 (gamma linolenic) 0.19 0.26 0.26 0.25 0C18:3 n-3 (linolenic) 0.11 0.19 0.19 0.19 0C20:5 n-3 (EPA – eicosapentaenoic) n.dg n.d. 0.03 0.03 0C22:6 n-3 (DHA – docosahexaenoic) n.d. n.d. 0.02 0.03 0Others 3.62 6.14 7.09 8.85 8Short chain (C4:0�C12:0) 15.38 10.49 10.83 8.95 9Medium chain (C14:0�C16:1) 42.56 34.19 33.91 34.30 32Long chain (C17:0�C22:6) 41.91 55.25 55.47 57.39 57Total saturated 69.31 60.02 59.37 57.19 56Total unsaturated 30.62 39.99 40.94 43.26 43MUFAe 26.49 34.39 35.02 37.29 37PUFAf 4.18 5.62 5.85 5.99 5Total n-3 0.49 0.49 0.52 0.56 0

a FAME¼ fatty acid methyl esters.b CONT¼diet without added oil; 0FO¼40 g/kg DM of soybean oil; 25FO¼2.5

of fish oil blendþ35 g/kg DM of soybean oil; 75FO¼7.5 g/kg DM of fish oil blenc SEM¼standard error of the mean (n¼10 samples for each diet).d CONT�0FO¼control diet vs. diet containing 40 g/kg DM of soybean oil; CO

vs. 25FO, 50FO and 75FO); L¼ linear effect; Q¼quadratic effect.e MUFA¼monounsaturated fatty acids.f PUFA¼polyunsaturated fatty acids.g n.d.¼not detected.

The concentration of oleic acid (C18:1 cis-9) was higher(Po0.01) in the milk of the animals fed diets containingoil. However, it was not affected by the increasing levels ofreplacement of fish oil blend for soybean oil.

The concentration of vaccenic acid increased 178.3%(Po0.01) when the three diets containing fish oil blendwere analyzed in comparison to the control diet. Further-more, a linear increase was observed (P¼0.04) in theconcentration of vaccenic acid as a result of fish oil blendinclusion in the diets. The milk of the animals fed dietscontaining oil had a higher (Po0.01) concentration ofstearic acid. However, among the diets containing oil,there was a linear reduction (P¼0.03) in the concentrationof stearic acid in the milk according to fish oil blendsupply.

The concentration of CLA cis-9, trans-11 increased(P¼0.02) by 78.6% with the supply of the diet containing40 g/kg DM of soybean oil (Table 6). When the three dietscontaining fish oil blend were analyzed together, there wasa 101.3% increase in the concentration of CLA cis-9, trans-11 in the milk in comparison to the control diet. Thesedifferences indicate that the use of soybean oil with fish oil

ental diets.

SEMc P-valued

FO CONT�0FO CONT� Fish oil blend L Q

.55 0.06 0.59 0.64 0.66 0.48

.31 0.05 0.01 o0.01 0.51 0.31

.16 0.05 o0.01 o0.01 0.33 0.42

.57 0.20 o0.01 o0.01 0.20 0.67

.33 0.13 o0.01 o0.01 0.29 0.84

.27 0.26 o0.01 o0.01 0.16 0.27

.48 0.01 0.02 o0.01 0.41 0.73

.77 0.03 o0.01 o0.01 0.32 0.71

.20 0.39 o0.01 o0.01 0.05 0.15

.55 0.01 o0.01 o0.01 0.64 0.67

.25 0.33 o0.01 o0.01 0.03 0.45

.90 0.44 o0.01 o0.01 0.87 0.41

.72 0.26 0.13 o0.01 0.04 0.69

.43 0.09 0.02 o0.01 0.65 0.36

.04 0.01 0.18 o0.01 0.03 0.81

.41 0.10 o0.01 o0.01 0.85 0.78

.24 0.01 o0.01 o0.01 0.39 0.79

.17 0.01 o0.01 o0.01 0.42 0.57

.04 0.01 – 0.03 0.03 0.44

.03 0.01 – 0.08 o0.01 0.06

.61 0.43 0.02 o0.01 0.02 0.47

.98 0.42 o0.01 o0.01 0.22 0.57

.26 0.65 o0.01 o0.01 0.06 0.18

.61 1.07 o0.01 o0.01 0.10 0.96

.31 0.84 o0.01 o0.01 0.01 0.92

.62 0.88 o0.01 o0.01 0.01 0.78

.96 0.76 o0.01 o0.01 o0.01 0.99

.71 0.17 o0.01 o0.01 0.75 0.35

.50 0.01 0.87 0.17 0.54 0.13


NT� Fish oil blend¼control diet vs. diets containing fish oil blend (CONT


blend is more efficient in increasing the concentration ofCLA cis-9, trans-11 than when soybean oil is used alone.However, there was no effect of the levels of replacementof soybean oil with fish oil blend on the concentration ofCLA cis-9, trans-11.

The total concentration of n-3 fatty acids in the milkwas not affected by the treatments. However, as expected,the concentration of the EPA (C20:5 n-3; P¼0.03) and DHA(C22:6 n-3; P¼0.08) fatty acids in the milk increasedlinearly with the increasing levels of fish oil blend.

4. Discussion

4.1. Body weight, dry matter intake, milk productionand composition

The data presented in Fig. 1 clearly show that the oilsources caused a striking reduction on DMI in the firstweek of the experimental period; however, it also illus-trates the animal's capacity of adaptation to the dietswith the increase in DMI after the third week. The dietscontaining oil provided a higher energetic density than thecontrol diet (2.8 vs. 2.6 Mcal/kg BW, respectively. Table 1),which explains the reduction of DMI as a response to theuse of oil sources. When compared to the diets withoutthe addition of oil, the utilization of fish oil in amounts equalto or above 10 g/kg DM consistently reduced the DMI(Abughazaleh et al., 2002; Donovan et al., 2000; Shingfieldet al., 2003; Whitlock et al., 2002). In comparison betweendiets containing 20 g/kg DM of soybean oil or 20 g/kg DM offish oil there was less DMI with the use of fish oil. However,the inclusion of 3.3, 6.7 or 10 g/kg DM of fish oil mixed with16.7 g, 13.3 g or 10 g/kg DM of soybean oil did not affect theDMI of milking cows when compared to a diet containing20 g/kg DM of soybean oil as the sole source of supplementalfat (Whitlock et al., 2006). This is consistent with the resultsof the present experiment inwhich there was not an effect ofthe replacement of up to 7.5 g/kg DM of soybean oil by fishoil blend when the diets contained high levels of fat (40 g/kgDM). Similar results were reported by Duckett and Gillis(2010) who compared diets containing 40 g/kg DM of canolaoil or 40 g/kg DM of corn oil with diets containing 30 g/kgDM of canola oilþ10 g/kg DM of fish oil or 30 g cornoilþ10 g fish oil/kg DM and there was no difference inthe DMI.

Milk production increased by 19.9% (0FO vs. 75FO), FCMby 13.9% (0FO vs. 75FO), and FPCM by 13.3% (0FO vs. 75FO).Therefore, the insignificant reduction (P¼0.20) in thepercentage of milk fat, as well as the linear reduction inthe protein concentration of the milk can, at least in part,explain the increase in milk production with the inclusionof fish oil blend in the diet. Whitlock et al. (2006)compared diets containing 3.3 g, 6.7 g or 10 g/kg DM offish oil mixed with 16.7 g, 13.3 g or 10 g/kg DM of soybeanoil with a diet containing 20 g/kg DM of soybean oil as thesole source of supplemental fat for milking cows andobserved increased milk production in the animals thatreceived the diets containing fish oil mixed with soybeanoil. The result observed was similar to that of the presentexperiment. These results suggest an additional benefit of

providing fish oil mixed with soybean oil to milk produc-tion in comparison to providing only soybean oil.

Typically, the supply of fish oil reduces the content andmilk fat yield (Annett et al., 2009; Bharathan et al., 2008;Donovan et al., 2000; Shingfield et al., 2006; Toral et al.,2010). The decrease in the de novo synthesis of acids in themammary gland is primarily responsible for the reduct-ion in the fat content of milk (Baumgard et al., 2000;Chouinard et al., 1999). The no effect of the treatments onthe content (g/kg) and yield (g/3 h) of milk fat (Table 4)showed that the negative effect of the oil sources on theconcentration of short chain fatty acids in the milk wasadequately compensated by the increase of the incorpora-tion of long-chain fatty acids from the diet in the milk(Table 6).

The decrease in the protein content of the milk with theincreasing levels of fish oil blend in the diet can be partlyattributed to a dilution effect caused by the increasein milk production, since yield of protein in the milkincreased with increasing levels of fish oil blend. Addi-tionally, a direct effect of the polyunsaturated fatty acidsfrom the fish oil on ruminal microorganisms with aconsequent reduction in microbial protein synthesis mayhave occurred. Consistent with this idea, a reduction in thecontent of milk protein was seen in lactating cows withsimilar production in response to an infusion of 300 mL/day of fish oil in the rumen, but when the same amountwas infused into the duodenum, the protein content of themilk was not affected (Loor et al., 2005). The absence ofeffect of the diets containing 40 g/kg DM of soybean oil onthe content and yield of milk protein (Table 4) is consistentwith the available results in the literature (Abughazalehet al., 2002; Bouattour et al., 2008; Eifert et al., 2006;Freitas et al., 2010; Loor and Herbein, 2003; Ramaswamyet al., 2001). In conjunction, the results indicate that fishoil causes more damage to the synthesis of milk proteinproduction than soybean oil.

The linear increase in the ADG of the lambs was due tothe linear increase in the milk production (Table 3) inresponse to the increasing levels of inclusion of fish oilblend in the ewes diets. The probable greater milk intakeby the lambs had no substitute effect on the initialconcentrate intake. Araujo et al. (2008) also found a directrelationship between the milk production of Santa Inêsewes and the performance of the lambs in the pre-weaning phase. However, the authors observed lowerintake of the initial concentrate by the lambs of the eweswith greater milk production. One justification for thesevariations in the responses is that the lambs evaluated byAraujo et al. (2008) were of the Santa Inês breed that haslower growth potential than the crossbred Dorper� SantaInês lambs used in the present experiment.

4.2. Fatty acid composition of the milk

The decrease in the short chain fatty acids (C4:0 toC12:0) and medium chain fatty acids (C14:0 to C16:1)concentrations in the milk is a typical response by animalsfed with diets containing oil (Abughazaleh et al., 2002;Ramaswamy et al., 2001; Whitlock et al., 2006). Baumgardet al. (2002) demonstrated that the CLA trans-10, cis-12 is a


powerful inhibitor of the de novo synthesis of fatty acids inthe mammary gland by reducing the synthesis of the keylipogenesis enzymes (acetil-CoA-carboxilase and fatty acidsynthetase) (Gervais et al., 2009). The inclusion of 40 g/kgDM of soybean oil increased the concentration of trans-10,cis-12 by 50% in the milk (CONT vs. 0FO, effect notsignificant, P¼0.18) and the supplying of fish oil blendincreased the concentration of this isomer by 83.3% (CONTvs. diets with fish oil blend). Therefore, this may havecontributed to the reduction in the short chain fatty acids(Table 6). Although, the concentration of trans-10, cis-12observed for all treatments was lower than that (0.15–0.70%) associated with the decrease in concentration ofshort chain fatty acids and milk fat content (Baumgardet al., 2001). The milk incorporation of long chain fattyacids from the diet also reduced the de novo synthesis offatty acids in the mammary gland (Grummer, 1991). Theconcentration of the long chain fatty acids in the milkincreased with the supplying of the diets containing oil,which reflects the absorption and transfer of these fattyacids from the diet to the milk fat (Palmquist and Griinari,2006). This hypothesis is consistent with the fact thatapproximately 50% of milk fat is derived from plasmalipids, and that 88% of the fatty acids derived from bloodhave a dietary origin and only 12% are of endogenouscontribution (Palmquist and Mattos, 1978). Due to the fishoil blend and soybean oil having similar concentrations oflong chain fatty acids (Table 2), the increasing levels ofreplacement of soybean oil by fish oil blend did not affectthe concentration of these fatty acids in the milk. A similarresult was found by Whitlock et al. (2006).

The higher concentration of unsaturated fatty acids inthe milk of the ewes fed diets containing oil (Table 6) maybe attributed to the increased absorption and transfer ofunsaturated fatty acids from the diets to the milk. It isprobable that the inclusion of fish oil blend in replacementof soybean oil decreased the ruminal biohydrogenationwhich could have increased the duodenal flow of unsatu-rated fatty acids and reduced the available saturated fattyacids for absorption and incorporation in the milk, whichexplains the increase in the unsaturated fatty acids and thedecrease in the saturated fatty acids in the milk as aresponse to the increasing levels of fish oil blend in thediets. Is important to mention that the fish blend andsoybean oil used had similar concentrations of saturatedand unsaturated fatty acids (Table 2).

The increase observed in the concentration of vaccenicacid and the decrease in the concentration of stearic acidin response to the use of fish oil blend indicate that thesmall amounts used of long chain fatty acids from fish oilblend (EPA and DHA) were efficient to inhibit the finalphase of ruminal biohydrogenation of the vaccenic acid tostearic acid (Lee et al., 2005; Shingfield et al., 2003). Thisshould be understood as a benefit of the use of fish oilmixed with soybean oil, as the increase in the concentra-tion of vaccenic acid improves the lipid profile of the milkby being a precursor to the synthesis of CLA C18:2 cis-9,trans-11. Additionally, the stearoyl-CoA desaturase thatconverting C18:1 trans-11 vaccenic acid into C18:2 cis-9,trans-11 in the mammary gland of ruminants (Griinariet al., 2000), also is found in the small intestine and

adipose tissue of humans (Adlof et al., 2000). Therefore,the increase in the intake of vaccenic acid could havebeneficial effects on human health associated with CLA.

Given that the vaccenic acid increased with the supplyof oils (Table 6), a reduction in the concentration of stearicacid could be expected. Usually, fish oil greatly decreasesstearic acid in the milk fat (Ramaswamy et al., 2001). Oneexplanation for the results of the present experiment wasthe small amount of fish oil blend used and the low con-centration of EPA and DHA in the fish oil blend (Table 2).

As the vaccenic acid in the milk increased linearly withincreasing levels of replacement of fish oil blend bysoybean oil, a similar increase in the concentration ofCLA C18:2 cis-9, trans-11 was expected. However, thiseffect was not observed (Table 6), suggesting that theactivity of the enzyme stearoyl-CoA desaturase was nega-tively affected by the sources of oil and/or the flow ofvaccenic acid exceeded the desaturation capacity of themammary gland (Chilliard et al., 2001; Sessler et al., 1996).Abughazaleh et al. (2002) also found no additional benefitof diets containing 10 g fish oil mixed with 10 g soybeanoil/kg DM on the increase in the concentration of CLAC18:2 cis-9, trans-11 in comparison to providing 20 g/kgDM of soybean oil as the sole source of supplemental fat.This contradicts the results of Ramaswamy et al. (2001)and Whitlock et al. (2002) who observed a synergeticeffect from the inclusion of fish oil mixed with soybean oilin the diet on the increase of CLA cis-9, trans-11. Whitlocket al. (2006) concluded that, with lactating cows, theutilization of just 3.3 g fish oil mixed with 16.6 g/kg DMof soybean oil was enough to optimize the synthesis of CLAin the milk. These authors drew heavily on the absence ofeffect of the increasing levels of inclusion of fish oil in thediets (3.3, 6.7, and 10 g/kg DM) mixed with soybean oil(16.6, 13.3 and 10 g/kg DM, respectively) on the concentra-tion of CLA in the milk. However, in the work of Whitlocket al. (2006) there was no treatment containing onlysoybean oil as the sole source of lipids for comparisonwith the diets containing fish oil.

In the present experiment, with lactating ewes, thehypothesis that the small inclusions of fish oil blend inpartial replacement of soybean oil would increase thesynthesis of CLA (C18:2 cis-9, trans-11) in comparison tothe use of a diet containing only soybean oil was notconfirmed. The utilization of 40 g/kg DM of soybean oilinstead of 20 g/kg DM, as used by other authors thatevaluated the supply of fish oil mixed with soybean oil(Ramaswamy et al., 2001; Whitlock et al., 2002, 2006)differs this experiment from the others. The absence of theeffect of the levels of inclusion of fish oil blend mixed withsoybean oil allows us to suggest that in diets with highinclusion of soybean oil (40 g/kg DM) the use of fish oil hasno direct effect on milk CLA concentration.

In the literature, low efficiency transfer of EPA and DHAto milk has been reported (Palmquist and Griinari, 2006),which can be attributed to its high rates of ruminalbiohydrogenation. However, in this experiment, the linearincrease in concentration of these fatty acids is consistentwith their higher concentrations in the fish oil blend ascompared to soybean oil (Table 2). The observed increasein the milk fat concentrations of EPA and DHA according to


fish oil blend supply is desirable due to beneficial effects ofthese fatty acids on human health (Ruxton et al., 2007).

5. Conclusions

Small amounts of fish oil supplementation does notexert an additional effect on the concentration of CLAC18:2 cis-9, trans-11 as compered to exclusive use ofsoybean oil. However, the addition of 7.5 g/kg DM of fishoil blend mixed with 32.5 g/kg DM of soybean oil isrecommended, because it increased the concentration ofEPA, DHA and C18:1 trans-11 in the milk, as well increasingthe performance of the ewes and their lambs.

Conflict of interest statement

None of the authors have any conflicts of interest todeclare.

Acknowledgments

The authors are grateful to FAPESP (The State of SãoPaulo Research Foundation) for the first author scholar-ship. Appreciation is extended to graduate students forassistance and animal care during this study.

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