Abstracts
The objective of this work was to determine productive and fertility responses of Holstein-Friesian heifers and cows to supplementation with extruded linseed and soybean as sources of polyunsaturated fatty acids (PUFAs). Supplementation had a positive effect on profitability, with significant increases in milk yield in supplemented cows, but not in heifers. Treatments had no effect on milk fat content, but higher milk protein contents were observed with supplementation. A higher conception rate was found for supplemented heifers, but not for cows. Fat sources containing PUFAs are recommended for dairy cattle supplementation, since they improve fertility in heifers and milk yield in cows.
extruded linseed; extruded soybean; fertility; long-chain fatty acids; milk composition; PUFA.
O objetivo deste trabalho foi determinar a resposta produtiva e de fertilidade, de novilhas e vacas Holandesas, à suplementação com extratos de linhaça e soja como fontes de ácidos graxos poli-insaturados (PUFAs). A suplementação teve efeito positivo sobre a rentabilidade, com aumento significativo na produção de leite de vacas suplementadas, mas não na de novilhas. Os tratamentos não tiveram efeito sobre o conteúdo de gordura no leite, mas maiores conteúdos de proteína láctea foram observados com a suplementação. Houve maior taxa de concepção em novilhas suplementadas, mas não em vacas. Fontes de gordura contendo PUFAs são recomendadas para suplementação do gado leiteiro, uma vez que melhoram a fertilidade de novilhas e a produção de leite de vacas.
linhaça extruída; soja extruída; fertilidade; ácidos graxos de cadeia longa; composição do leite; PUFA.
Introduction
During the last decades, long-chain fatty acids (LCFA) have been incorporated into
cattle feed with the intention of enhancing the energy density of the diet, mostly to
improve energy balance for postpartum cows. The addition of LCFA to feed, in moderate
quantities (2-3% dry matter, DM) during early postpartum of dairy cows, increases milk
yield and improves cow reproduction, with a positive response on conception rate of up
to 17% (Staples et al., 1998STAPLES, C.R.; BURKE, J.M.; THATCHER, W.W.Influence of supplemental fats
on reproductive tissues and performance of lactating cows. Journal of Dairy Science,
v.81, p.856-871, 1998. DOI: 10.3168/jds.S0022-0302(98)75644-9.
https://doi.org/10.3168/jds.S0022-0302(9...
).
The main polyunsaturated fatty acid (PUFA) in most seed lipids is linoleic acid (C18:2
n-6), whereas linolenic acid (C18:3 n-3) predominates in most forage lipids (Palmquist & Jenkins, 1980PALMQUIST, D.L.; JENKINS, T.C. Fat in lactation rations: review. Journal
of Dairy Science, v.63, p.1-14, 1980. DOI:
10.3168/jds.S0022-0302(80)82881-5.
https://doi.org/10.3168/jds.S0022-0302(8...
). PUFAs from the n-6
and n-3 families seem to have their most remarkable effects on cattle reproductive
performance (Mattos et al., 2000MATTOS, R.; STAPLES, C.R.; THATCHER, W.W.Effects of dietary fatty acids
on reproduction in ruminants. Reviews of Reproduction, v.5, p.38-45, 2000. DOI:
10.1530/ror.0.0050038.
https://doi.org/10.1530/ror.0.0050038....
). However, it is
not completely clear whether those effects are mediated by the PUFAs themselves or by
intermediate metabolites produced during biohydrogenation in the rumen (Santos et al., 2008SANTOS, J.E.P.; BILBY, T.R.; THATCHER, W.W.; STAPLES, C.R.; SILVESTRE,
F.T.Long chain fatty acids of diet as factors influencing reproduction in cattle.
Reproduction in Domestic Animals, v.43, p.23-30, 2008. DOI:
10.1111/j.1439-0531.2008.01139.x.
https://doi.org/10.1111/j.1439-0531.2008...
).
Fat sources rich in n-3 fatty acids are inhibitors of cyclooxygenase in the endometrial
tissue of dairy cows (Staples et al., 1998STAPLES, C.R.; BURKE, J.M.; THATCHER, W.W.Influence of supplemental fats
on reproductive tissues and performance of lactating cows. Journal of Dairy Science,
v.81, p.856-871, 1998. DOI: 10.3168/jds.S0022-0302(98)75644-9.
https://doi.org/10.3168/jds.S0022-0302(9...
), and,
therefore, endometrial secretion of PGF2α may be suppressed, which can
potentially prevent early embryonic death (Silvestre et
al., 2011SILVESTRE, F.T.; CARVALHO, T.S.M.; FRANCISCO, N.; SANTOS, J.E.P.;
STAPLES, C.R.; JENKINS, T.; THATCHER, W.W.Effects of differential supplementation of
fatty acids during the peripartum and breeding periods of Holstein cows: I. Uterine
and metabolic responses, reproduction, and lactation. Journal of Dairy Science, v.94,
p.189-204, 2011. DOI: 10.3168/jds.2010-3370.
https://doi.org/10.3168/jds.2010-3370....
). Moreover, PUFAs supplied 21 days before parturition contribute to
a faster recovery of the uterus and to improve cow fertility (Ambrose & Kastelic, 2003AMBROSE, D.J.; KASTELIC, J.P. Dietary fatty acids and dairy cow
fertility. Advances in Dairy Technology, v.15, p.35-47, 2003.). Finally, the intake of n-6 fatty
acids during late gestation and early lactation contributes to improve embryo quality
and development (Fouladi-Nashta et al., 2007FOULADI-NASHTA, A.A.; GUTIERREZ, C.G.; GONG, J.G.; GARNSWORTHY, P.C.;
WEBB, R. Impact of dietary fatty acids on oocyte quality and development in lactating
dairy cows. Biology of Reproduction, v.77, p.9-17, 2007. DOI:
10.1095/biolreprod.106.058578.
https://doi.org/10.1095/biolreprod.106.0...
).
However, the effects of PUFAs on the reproductive performance of cows are still
controversial: some authors claim that it has no effect on this trait (Scott et al., 1995SCOTT, T.A.; SCHAVER, R.D.; ZEPEDA, L.; YANDELL, B.; SMITH, T.R. Effects
of rumen-inert fat on lactation, reproduction, and health of high producing Holstein
herds. Journal of Dairy Science, v.78, p.2435-2451, 1995. DOI:
10.3168/jds.S0022-0302(95)76872-2.
https://doi.org/10.3168/jds.S0022-0302(9...
; Petit & Twagiramungu, 2006PETIT, H.V.; TWAGIRAMUNGU, H. Conception rate and reproductive function
of dairy cows fed different fat sources. Theriogenology, v.66, p.1316-1324, 2006.
DOI: 10.1016/j.theriogenology.2006.04.029.
https://doi.org/10.1016/j.theriogenology...
; Juchem,
2007JUCHEM, S.O. Lipid digestion and metabolism in dairy cows: effects on
production, reproduction and health. 2007. 234f. Dissertation (Doctorate) -
University of California, Davis.; Fuentes et al., 2008FUENTES, M.C.; CALSAMIGLIA, S.; SÁNCHEZ, C.; GONZÁLEZ, A.; NEWBOLD,
J.R.; SANTOS, J.E.P.; RODRÍGUEZ-ALCALÁ, L.M.; FONTECHA, J. Effect of extruded linseed
on productive and reproductive performance of lactating dairy cows. Livestock
Science, v.113, p.144-154, 2008. DOI: 10.1016/j.livsci.2007.03.005.
https://doi.org/10.1016/j.livsci.2007.03...
), while
others maintain that it can improve fertility (McNamara
et al., 2003McNAMARA, S.; BUTLER, T.; RYAN, D.P.; MEE, J.F.; DILLON, P.; O'MARA,
F.P.; BUTLER, S.T.; ANGLESEY, D.; RATH, M.; MURPHY, J.J. Effect of offering
rumen-protected fat supplements on fertility and performance in spring-calving
Holstein-Friesian cows. Animal Reproduction Science, v.79, p.45-46, 2003. DOI:
10.1016/S0378-4320(03)00111-8.
https://doi.org/10.1016/S0378-4320(03)00...
; Ambrose et al.,
2006AMBROSE, D.J.; KASTELIC, J.P.; CORBETT, R.; PITNEY, P.A.; PETIT, H.V.;
SMALL, J.A.; ZALKOVIC, P.Lower pregnancy losses in lactating dairy cows fed a diet
enriched in α-linolenic acid. Journal of Dairy Science, v.89, p.3066-3074, 2006.
DOI: 10.3168/jds.S0022-0302(06)72581-4.
https://doi.org/10.3168/jds.S0022-0302(0...
).
Studies with dairy cows supplemented with PUFAs are also controversial as to their
effects on milk yield. Kennelly & Khorasani
(1993)KENNELLY, J.J.; KHORASANI, G.R. Influence of acid treatment of canola
meal on rumen fermentation and milk production in dairy cows. In: RESEARCH on canola
seed, oil and meal. Winnipeg: Canola Council of Canada, 1993. p.107-122. (Canola
Council of Canada. Project Report, 10). used whole flaxseed at different percentages - 0.5, 10, and 15% - of DM
intake (DMI) and found no effect on milk yield. Petit
(2003)PETIT, H.V. Digestion, milk production, milk composition, and blood
composition of dairy cows fed formaldehyde treated flaxseed or sunflower seed.
Journal of Dairy Science, v.86, p.2637-2646, 2003. DOI:
10.3168/jds.S0022-0302(03)73859-4.
https://doi.org/10.3168/jds.S0022-0302(0...
also did not find differences in milk yield using different
PUFA-supplemented diets. However, Petit et al.
(2004)PETIT, H.V.; GERMIQUET, C.; LEBEL, D.Effect of feeding whole,
unprocessed sunflower seeds and flaxseed on milk production, milk composition, and
prostaglandin secretion in dairy cows. Journal of Dairy Science, v.87, p.3889-3898,
2004. DOI: 10.3168/jds.S0022-0302(04)73528-6.
https://doi.org/10.3168/jds.S0022-0302(0...
reported higher milk yield in cows fed with PUFAs. Similar results were
obtained by Dirandeh et al. (2013)DIRANDEH, E.; TOWHIDI, A.; ZEINOALDINI, S.; GANJKHANLOU, M.; PIRSARAEI,
Z.A.; FOULADI-NASHTA, A. Effects of different polyunsaturated fatty acid
supplementations during the postpartum periods or early lactating dairy cows on milk
yield, metabolic responses and reproductive performances. Journal of Animal Science,
v.91, p.713-721, 2013. DOI: 10.2527/jas.2012-5359.
https://doi.org/10.2527/jas.2012-5359....
, with higher
milk yield in cows fed on unsaturated dietary fat.
The objective of this work was to determine productive and fertility responses of Holstein-Friesian heifers and cows to supplementation with extruded linseed and soybean as sources of PUFAs.
Materials and Methods
The study was done at a high-producing dairy farm in Galicia, in northwest Spain. The experiment was conducted with lactating Holstein-Friesian cows (n=51) and heifers (n=61). Multiparous cows had a preceding lactation of over 11,959 kg of milk, according to the official milk recording data collected in 2010, during 305 days. The animals were milked twice a day and housed in free stalls with straw beds.
Cows and heifers were randomly assigned to two experimental groups: 66 animals (36 heifers and 30 cows), which were subjected to a commercial concentrate (Fertilac, Núter Feed, Aranda de Duero, Spain) containing fat supplements based on extruded linseed (source of linolenic acid) and soybean oil (source of linoleic acid); and 46 animals (25 heifers and 21 cows), which did not receive the fat supplements, but otherwise received the same diet as the supplemented animals (Table 1). The diets were isocaloric and isoproteic (Table 2), and calculated to meet the total energy and protein requirements of animals with 650-kg mean body weight, producing 37 kg per day of milk, with 3.2% fat and 3.1% protein (National Research Council, 2001NATIONAL RESEARCH COUNCIL. Nutrient requirements of dairy cattle. 7th ed. Washington: National Academy Press, 2001. 408p.). For the first group, the supplement was offered from 3 weeks before calving until 2 months of lactation. During the pretrial period (3 months), all animals received the same total mixed feed, without any supplement, and were housed in the same barn.
Milk daily yield was recorded, and milk samples were taken for analysis of fat and protein contents. The milk samples were stored at 0-8ºC, before being sent to a certified laboratory. In the laboratory, the milk samples were cooled to 4ºC, and azidiol 0.33% was added as a preservative, until analysis. Before analysis, the samples were heated in a water bath (37-42ºC) and further processed in an infrared spectrophotometer MilkoScan FT 6000 (Foss, Hillerod, Denmark) to determine fat and protein contents.
After 28 days of calving, transrectal ultrasonography examination of ovaries and uterus was performed in all animals, fortnightly, using a real-time, full-digital B mode veterinary ultrasound scanner, equipped with a 6.5 MHz multi-frequency linear rectal probe KX 5200V (Kaixin Electronic Instrument Co., Ltd., Xuzhou, Jiangsu, China). Uterine involution after calving, follicular dynamics, and pregnancy diagnostic were assessed in this procedure.
In order to eliminate possible variations in estrus detection between groups, ovulation
was synchronized in all animals according to Pursley et
al. (1995)PURSLEY, J.R.; MEE, M.O.; WILTBANK, M.C. Synchronization of ovulation in
dairy cows using PGF2α and GnRH. Theriogenology, v.44, p.915-923, 1995. DOI:
10.1016/0093-691X(95)00279-H.
https://doi.org/10.1016/0093-691X(95)002...
, using two GnRH treatments Gonadorelin diacetate 0.05 mg (Ceva
Salud Animal, Barcelona, Spain), with an interval of 9 days; and a PGF2α
treatment Luprostiol 7.5 mg (Virbac España S.A., Barcelona, Spain), 7 days after the
first GnRH treatment. Then, all synchronized animals were inseminated, always by the
same technician, at 14-16 hours after the second dose of GnRH, with frozen-thawed semen.
Pregnancy diagnosis was performed 30 days after the insemination. The nonpregnant
animals were resynchronized and inseminated at a fixed time.
The following reproductive parameters were considered: conception rate (%) at first artificial insemination (AI); interval (days) from calving to first AI; insemination/conception rate; and number of open days (interval from calving to a new conception).
Considering the differences in lactation physiology of heifers and cows, statistical analyses were performed for both animals classes separately. Productive and reproductive parameters were tested for normality, according to the Kolmogorov test. All productive parameters (milk yield, milk corrected yield at 3.5% fat/3.2% protein, milk fat, milk protein, and milk fat/protein ratio) were normalized by log transformation. Descriptive statistics for all variables were tabulated. Differences between normalized means were established using the t-Student test, taking into account the Levene test to assess the equality of variances. Conception rate at first AI was evaluated using a chi-square test. All statistical analyses were performed using the SPSS 18 package. Significance for differences was declared at 5% probability; and for tendency, at 10% probability.
Results and Discussion
A better conception rate was obtained in supple-mented heifers (Table 3). Days from calving to first AI did not differ between treatments in the heifer group; however, a tendency (p=0.052) for a lower AI/conception rate was observed in the supplemented group, whereas open days were higher in the non-supplemented group. The cows, however, did not show differences between treatments in their reproductive parameters.
Total milk yield was higher in supplemented cows (Table 4). In the analyzed period (17 months), supplemented cows produced 6.3% more milk than the control cows. Total milk production, however, did not differ between heifers.
Supplementation with PUFAs resulted in increased milk protein content both in
supplemented heifers and cows, but did not have any effect on fat content (Table 4). Consequently, the milk fat/protein ratio
was significantly lower in supplemented animals. The use of PUFAs in dairy cow diets has
revealed benefits in fertility performance (Mattos et
al., 2000MATTOS, R.; STAPLES, C.R.; THATCHER, W.W.Effects of dietary fatty acids
on reproduction in ruminants. Reviews of Reproduction, v.5, p.38-45, 2000. DOI:
10.1530/ror.0.0050038.
https://doi.org/10.1530/ror.0.0050038....
, 2002MATTOS, R.; STAPLES, C.R.;WILLIAMS, J.; AMOROCHO, A.; McGUIRE, M.A.;
THATCHER, W.W.Uterine, ovarian, and production responses of lactating dairy cows to
increasing dietary concentrations of menhaden fish meal. Journal of Dairy Science,
v.85, p.755-764, 2002. DOI: 10.3168/jds.S0022-0302(02)74133-7.
https://doi.org/10.3168/jds.S0022-0302(0...
; Ambrose & Kastelic, 2003AMBROSE, D.J.; KASTELIC, J.P. Dietary fatty acids and dairy cow
fertility. Advances in Dairy Technology, v.15, p.35-47, 2003.) and in milk production (Petit et al., 2004PETIT, H.V.; GERMIQUET, C.; LEBEL, D.Effect of feeding whole,
unprocessed sunflower seeds and flaxseed on milk production, milk composition, and
prostaglandin secretion in dairy cows. Journal of Dairy Science, v.87, p.3889-3898,
2004. DOI: 10.3168/jds.S0022-0302(04)73528-6.
https://doi.org/10.3168/jds.S0022-0302(0...
; Dirandeh et al., 2013DIRANDEH, E.; TOWHIDI, A.; ZEINOALDINI, S.; GANJKHANLOU, M.; PIRSARAEI,
Z.A.; FOULADI-NASHTA, A. Effects of different polyunsaturated fatty acid
supplementations during the postpartum periods or early lactating dairy cows on milk
yield, metabolic responses and reproductive performances. Journal of Animal Science,
v.91, p.713-721, 2013. DOI: 10.2527/jas.2012-5359.
https://doi.org/10.2527/jas.2012-5359....
). It was observed that the supplementation of dairy
cattle with extruded linseed and soybean as sources of linoleic and linolenic acids
increased total milk yield, but this benefit was not extended to heifers. The supplement
also increased the milk protein content in all animals. Supplemented heifers showed a
tendency of improving reproductive performance, but this effect was not seen in
multiparous cows.
Improved conception rates of heifers have been reported as a consequence of the
additional dietary energy provided by the fat supplement, which leads to a higher
fertility at first insemination (Staples et al.,
1998STAPLES, C.R.; BURKE, J.M.; THATCHER, W.W.Influence of supplemental fats
on reproductive tissues and performance of lactating cows. Journal of Dairy Science,
v.81, p.856-871, 1998. DOI: 10.3168/jds.S0022-0302(98)75644-9.
https://doi.org/10.3168/jds.S0022-0302(9...
). Heifers that receive energy supplement can develop larger follicles,
which become larger corpus luteum, producing more progesterone and favoring the
maintenance of pregnancy (Mattos et al., 2002MATTOS, R.; STAPLES, C.R.;WILLIAMS, J.; AMOROCHO, A.; McGUIRE, M.A.;
THATCHER, W.W.Uterine, ovarian, and production responses of lactating dairy cows to
increasing dietary concentrations of menhaden fish meal. Journal of Dairy Science,
v.85, p.755-764, 2002. DOI: 10.3168/jds.S0022-0302(02)74133-7.
https://doi.org/10.3168/jds.S0022-0302(0...
).
In fact, studies have shown that the diameter of the dominant follicle of lactating
dairy cows is larger when they are fed with fat supplements (Ambrose et al., 2006AMBROSE, D.J.; KASTELIC, J.P.; CORBETT, R.; PITNEY, P.A.; PETIT, H.V.;
SMALL, J.A.; ZALKOVIC, P.Lower pregnancy losses in lactating dairy cows fed a diet
enriched in α-linolenic acid. Journal of Dairy Science, v.89, p.3066-3074, 2006.
DOI: 10.3168/jds.S0022-0302(06)72581-4.
https://doi.org/10.3168/jds.S0022-0302(0...
). In addition to these benefits, PUFAs, or
their biohydrogenated metabolites, can be absorbed by the uterus and inhibit the
production and release of prostaglandin F2α in the endometrium at the
beginning of pregnancy. This would prevent the regression of the corpus luteum in the
ovary and allow the continuous production of progesterone, favoring embryo survival
(Bilby et al., 2006BILBY, T.R.; BLOCK, J.; AMARAL, B.C.; SÁ FILHO, O.; SILVESTRE, F.T.;
HANSEN, P.J.; STAPLES, C.R.; THATCHER, W.W. Effects of dietary unsaturated fatty
acids on oocyte quality and follicular development in lactating dairy cows in summer.
Journal of Dairy Science, v.89, p.3891-3903, 2006. DOI:
10.3168/jds.S0022-0302(06)72432-8.
https://doi.org/10.3168/jds.S0022-0302(0...
; Silvestre et al., 2011SILVESTRE, F.T.; CARVALHO, T.S.M.; FRANCISCO, N.; SANTOS, J.E.P.;
STAPLES, C.R.; JENKINS, T.; THATCHER, W.W.Effects of differential supplementation of
fatty acids during the peripartum and breeding periods of Holstein cows: I. Uterine
and metabolic responses, reproduction, and lactation. Journal of Dairy Science, v.94,
p.189-204, 2011. DOI: 10.3168/jds.2010-3370.
https://doi.org/10.3168/jds.2010-3370....
). It is likely that the interaction between
these mechanisms resulted in the improved tendency observed in the conception rate of
supplemented heifers (Table 3).
However, supplementation studies with calcium soap as a source of long-chain fatty acids
(Ca-LCFAs) for dairy cow diets have shown controversial results. McNamara et al. (2003)McNAMARA, S.; BUTLER, T.; RYAN, D.P.; MEE, J.F.; DILLON, P.; O'MARA,
F.P.; BUTLER, S.T.; ANGLESEY, D.; RATH, M.; MURPHY, J.J. Effect of offering
rumen-protected fat supplements on fertility and performance in spring-calving
Holstein-Friesian cows. Animal Reproduction Science, v.79, p.45-46, 2003. DOI:
10.1016/S0378-4320(03)00111-8.
https://doi.org/10.1016/S0378-4320(03)00...
observed that supplementing cows with
0.35-0.5 kg Ca-LCFA per cow per day improved fertility at first insemination of
lactating cows; however, Scott et al. (1995)SCOTT, T.A.; SCHAVER, R.D.; ZEPEDA, L.; YANDELL, B.; SMITH, T.R. Effects
of rumen-inert fat on lactation, reproduction, and health of high producing Holstein
herds. Journal of Dairy Science, v.78, p.2435-2451, 1995. DOI:
10.3168/jds.S0022-0302(95)76872-2.
https://doi.org/10.3168/jds.S0022-0302(9...
and
Juchem (2007)JUCHEM, S.O. Lipid digestion and metabolism in dairy cows: effects on
production, reproduction and health. 2007. 234f. Dissertation (Doctorate) -
University of California, Davis. found no improvement in dairy
cow fertility by supplementing them with Ca-LCFA. Scott
et al. (1995)SCOTT, T.A.; SCHAVER, R.D.; ZEPEDA, L.; YANDELL, B.; SMITH, T.R. Effects
of rumen-inert fat on lactation, reproduction, and health of high producing Holstein
herds. Journal of Dairy Science, v.78, p.2435-2451, 1995. DOI:
10.3168/jds.S0022-0302(95)76872-2.
https://doi.org/10.3168/jds.S0022-0302(9...
reported increased milk production and consequent loss in body
condition with this type of supplementation. The cows in the present study did not show
any improvement concerning fertility parameters due to supplementation with PUFAs.
However, better milk yield and higher milk protein content were observed with the
treatment. Therefore, the findings of the present study seem to agree with those of the
latter authors.
Sklan et al. (1994)SKLAN, D.; KAIM, M.; MOALLEM, U.; FOLMAN, Y. Effect of dietary calcium
soaps on milk yield, body weight, reproductive hormones, and fertility in first
parity and older cows. Journal of Dairy Science, v.77, p.1652-1660, 1994. DOI:
10.3168/jds.S0022-0302(94)77107-1.
https://doi.org/10.3168/jds.S0022-0302(9...
stated that Ca-LCFAs are
responsible for a depression in the conception rate at first AI. The authors ascribed
this effect to an increased milk yield of supplemented heifers, which lead to a greater
negative energy balance. In the present study, the supplemented heifers did not increase
their milk yield, which may have favored their reproductive performance, compared to the
non-supplemented heifers. The low number of animals evaluated may have contributed to
the nonsignificant difference found in the conception rate of supplemented animals, but
the observed tendency (p=0.08) and the effect size obtained between treatments (48%
conception rate in supplemented animals vs. 25% in non-supplemented ones) were enough to
consider that supplementation has an important effect on this trait.
When cows are fed daily with 0.75 kg linseed fat, as a source of linolenic acid,
fertility is improved (Ambrose et al., 2006AMBROSE, D.J.; KASTELIC, J.P.; CORBETT, R.; PITNEY, P.A.; PETIT, H.V.;
SMALL, J.A.; ZALKOVIC, P.Lower pregnancy losses in lactating dairy cows fed a diet
enriched in α-linolenic acid. Journal of Dairy Science, v.89, p.3066-3074, 2006.
DOI: 10.3168/jds.S0022-0302(06)72581-4.
https://doi.org/10.3168/jds.S0022-0302(0...
).
Other researchers, however, did not find beneficial effects of linseed supplementation
on fertility (Petit & Twagiramungu, 2006PETIT, H.V.; TWAGIRAMUNGU, H. Conception rate and reproductive function
of dairy cows fed different fat sources. Theriogenology, v.66, p.1316-1324, 2006.
DOI: 10.1016/j.theriogenology.2006.04.029.
https://doi.org/10.1016/j.theriogenology...
;
Fuentes et al., 2008FUENTES, M.C.; CALSAMIGLIA, S.; SÁNCHEZ, C.; GONZÁLEZ, A.; NEWBOLD,
J.R.; SANTOS, J.E.P.; RODRÍGUEZ-ALCALÁ, L.M.; FONTECHA, J. Effect of extruded linseed
on productive and reproductive performance of lactating dairy cows. Livestock
Science, v.113, p.144-154, 2008. DOI: 10.1016/j.livsci.2007.03.005.
https://doi.org/10.1016/j.livsci.2007.03...
). Differential responses
to fatty acid feeding suggest that PUFAs of the n-6 and n-3 families are more beneficial
than saturated fat acids (Santos et al., 2008SANTOS, J.E.P.; BILBY, T.R.; THATCHER, W.W.; STAPLES, C.R.; SILVESTRE,
F.T.Long chain fatty acids of diet as factors influencing reproduction in cattle.
Reproduction in Domestic Animals, v.43, p.23-30, 2008. DOI:
10.1111/j.1439-0531.2008.01139.x.
https://doi.org/10.1111/j.1439-0531.2008...
).
However, it is hard to predict the amount of available PUFA for absorption in the
duodenum because most of these acids are biohydrogenated in the rumen. Juchem (2007)JUCHEM, S.O. Lipid digestion and metabolism in dairy cows: effects on
production, reproduction and health. 2007. 234f. Dissertation (Doctorate) -
University of California, Davis. pointed out that between 70 and 85% of
the PUFAs are biohydrogenated when cows are fed with unprotected oils. Furthermore,
PUFAs from extruded linseed are biohydrogenated in an even greater proportion, and the
intermediates of this biohydrogenation process, such as conjugated linoleic acid (CLA),
have been related to decreasing milk fat contents (Fuentes et al., 2008FUENTES, M.C.; CALSAMIGLIA, S.; SÁNCHEZ, C.; GONZÁLEZ, A.; NEWBOLD,
J.R.; SANTOS, J.E.P.; RODRÍGUEZ-ALCALÁ, L.M.; FONTECHA, J. Effect of extruded linseed
on productive and reproductive performance of lactating dairy cows. Livestock
Science, v.113, p.144-154, 2008. DOI: 10.1016/j.livsci.2007.03.005.
https://doi.org/10.1016/j.livsci.2007.03...
). Bauman & Griinari
(2003)BAUMAN, D.E.; GRIINARI, J.M. Nutritional regulation of milk fat
synthesis. Annual Review of Nutrition, v.23, p.203-227, 2003. DOI:
10.1146/annurev.nutr.23.011702.073408.
https://doi.org/10.1146/annurev.nutr.23....
reported that trans-10, cis-12-CLA is responsible for causing milk fat
reduction in dairy cows. Further studies are necessary to establish if the positive
response in heifer fertility indexes observed here might be an effect of the elevated
intake of CLA. Therefore, if specific unsaturated fatty acids are important for cattle
reproduction, it is critical that future research relating lipids and reproduction aim
to improve the extent of delivery of these acids for absorption.
The increased milk yield of supplemented cows (Table
4) agrees with the majority of studies in the literature (Scott et al., 1995SCOTT, T.A.; SCHAVER, R.D.; ZEPEDA, L.; YANDELL, B.; SMITH, T.R. Effects
of rumen-inert fat on lactation, reproduction, and health of high producing Holstein
herds. Journal of Dairy Science, v.78, p.2435-2451, 1995. DOI:
10.3168/jds.S0022-0302(95)76872-2.
https://doi.org/10.3168/jds.S0022-0302(9...
; Petit et al., 2004PETIT, H.V.; GERMIQUET, C.; LEBEL, D.Effect of feeding whole,
unprocessed sunflower seeds and flaxseed on milk production, milk composition, and
prostaglandin secretion in dairy cows. Journal of Dairy Science, v.87, p.3889-3898,
2004. DOI: 10.3168/jds.S0022-0302(04)73528-6.
https://doi.org/10.3168/jds.S0022-0302(0...
; Dirandeh et al.,
2013DIRANDEH, E.; TOWHIDI, A.; ZEINOALDINI, S.; GANJKHANLOU, M.; PIRSARAEI,
Z.A.; FOULADI-NASHTA, A. Effects of different polyunsaturated fatty acid
supplementations during the postpartum periods or early lactating dairy cows on milk
yield, metabolic responses and reproductive performances. Journal of Animal Science,
v.91, p.713-721, 2013. DOI: 10.2527/jas.2012-5359.
https://doi.org/10.2527/jas.2012-5359....
), although some authors report that the supplementation with fatty acids
does not affect milk production (Ward et al.,
2002WARD, A.T.; WITTENBERG, K.M.; PRZYBYLSKI, R. Bovine milk fatty acid
profiles produced by feeding diets containing solin, flax and canolA. Journal of
Dairy Science, v.85, p.1191-1196, 2002. DOI:
10.3168/jds.S0022-0302(02)74182-9.
https://doi.org/10.3168/jds.S0022-0302(0...
; Gonthier et al., 2005GONTHIER, C.; MUSTAFA, A.F.; OUELLET, D.R.; CHOUINARD, P.Y.; BERTHIAUME,
R.; PETIT, H.V.Feeding micronized and extruded flaxseed to dairy cows: effects on
blood parameters and milk fatty acid composition. Journal of Dairy Science, v.88,
p.748-756, 2005. DOI: 10.3168/jds.S0022-0302(05)72738-7.
https://doi.org/10.3168/jds.S0022-0302(0...
). Petit et al. (2004)PETIT, H.V.; GERMIQUET, C.; LEBEL, D.Effect of feeding whole,
unprocessed sunflower seeds and flaxseed on milk production, milk composition, and
prostaglandin secretion in dairy cows. Journal of Dairy Science, v.87, p.3889-3898,
2004. DOI: 10.3168/jds.S0022-0302(04)73528-6.
https://doi.org/10.3168/jds.S0022-0302(0...
suggest that a greater fat
mobilization contributes for a greater milk yield in cows supplemented with fatty acids.
However, the source of these acids certainly has effect on the different milk yield
responses and also on milk fat and protein production. For example, palm oil enables
higher increases in milk yield than linseed oil (Fuentes
et al., 2008FUENTES, M.C.; CALSAMIGLIA, S.; SÁNCHEZ, C.; GONZÁLEZ, A.; NEWBOLD,
J.R.; SANTOS, J.E.P.; RODRÍGUEZ-ALCALÁ, L.M.; FONTECHA, J. Effect of extruded linseed
on productive and reproductive performance of lactating dairy cows. Livestock
Science, v.113, p.144-154, 2008. DOI: 10.1016/j.livsci.2007.03.005.
https://doi.org/10.1016/j.livsci.2007.03...
).
The increase in milk protein content in the supplemented groups (Table 4) is in agreement with Petit
(2003)PETIT, H.V. Digestion, milk production, milk composition, and blood
composition of dairy cows fed formaldehyde treated flaxseed or sunflower seed.
Journal of Dairy Science, v.86, p.2637-2646, 2003. DOI:
10.3168/jds.S0022-0302(03)73859-4.
https://doi.org/10.3168/jds.S0022-0302(0...
, who reported higher milk protein contents in cows fed with linseed,
and attributed this result to a better energy balance in the diet. However, other
authors did not find changes in milk protein when linseed was included in the diet
(Kennelly & Khorasani, 1993KENNELLY, J.J.; KHORASANI, G.R. Influence of acid treatment of canola
meal on rumen fermentation and milk production in dairy cows. In: RESEARCH on canola
seed, oil and meal. Winnipeg: Canola Council of Canada, 1993. p.107-122. (Canola
Council of Canada. Project Report, 10).; Petit et al., 2004PETIT, H.V.; GERMIQUET, C.; LEBEL, D.Effect of feeding whole,
unprocessed sunflower seeds and flaxseed on milk production, milk composition, and
prostaglandin secretion in dairy cows. Journal of Dairy Science, v.87, p.3889-3898,
2004. DOI: 10.3168/jds.S0022-0302(04)73528-6.
https://doi.org/10.3168/jds.S0022-0302(0...
; Ambrose et al., 2006AMBROSE, D.J.; KASTELIC, J.P.; CORBETT, R.; PITNEY, P.A.; PETIT, H.V.;
SMALL, J.A.; ZALKOVIC, P.Lower pregnancy losses in lactating dairy cows fed a diet
enriched in α-linolenic acid. Journal of Dairy Science, v.89, p.3066-3074, 2006.
DOI: 10.3168/jds.S0022-0302(06)72581-4.
https://doi.org/10.3168/jds.S0022-0302(0...
). Furthermore, several studies reported that fat milk
content was not affected by linseed supplement (Petit,
2003PETIT, H.V. Digestion, milk production, milk composition, and blood
composition of dairy cows fed formaldehyde treated flaxseed or sunflower seed.
Journal of Dairy Science, v.86, p.2637-2646, 2003. DOI:
10.3168/jds.S0022-0302(03)73859-4.
https://doi.org/10.3168/jds.S0022-0302(0...
; Petit et al., 2004PETIT, H.V.; GERMIQUET, C.; LEBEL, D.Effect of feeding whole,
unprocessed sunflower seeds and flaxseed on milk production, milk composition, and
prostaglandin secretion in dairy cows. Journal of Dairy Science, v.87, p.3889-3898,
2004. DOI: 10.3168/jds.S0022-0302(04)73528-6.
https://doi.org/10.3168/jds.S0022-0302(0...
), which agrees
with results of the present study.
Supplementation had an additional feed cost of €0.30 per animal per day. Considering that supplemented cows had a mean increase in milk yield of 2.4 kg per animal per day, supplementation allowed for an additional income of €0.72 per cow per day, at the current milk price of €0.30 kg-1. The increased milk protein contents may also provide protein premium in prices. According to the current milk quota system in Europe, milk protein production means a bonus, whereas the excess of fat means a penalty.
Regarding the economic analysis of reproductive efficiency, the higher AI/conception rate observed in supplemented heifers may account for a reduction of one insemination, compared to the control group, which means a saving of €30 per heifer per year in semen.
Conclusions
-
The supplementation with polyunsaturated fatty acids (PUFAs) improves fertility in heifers and milk yield in cows.
-
Although supplementation does not affect milk fat contents, it increases milk protein contents, both in heifers and cows.
-
Supplementation of dairy cattle with PUFAs, at moderate amounts, up to 2-3% dry matter, has a positive effect on farm profitability.
Acknowledgment
To the Sat Vilar-Alaxe farm, in Galicia, Spain, for the cooperation in the execution of the present study.
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» https://doi.org/10.3168/jds.S0022-0302(06)72581-4. - BAUMAN, D.E.; GRIINARI, J.M. Nutritional regulation of milk fat synthesis. Annual Review of Nutrition, v.23, p.203-227, 2003. DOI: 10.1146/annurev.nutr.23.011702.073408.
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Publication Dates
-
Publication in this collection
Apr 2015
History
-
Received
29 May 2014 -
Accepted
17 Mar 2015