Abstract
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.
Highlights
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
polyunsaturated fatty acids (PUFAs) from the n‐6 and n‐3 families seem to have their most remarkable effects on cattle reproductive performance (Mattos et al, 2000). 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, 2008)
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 and soybean oil; 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)
Summary
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, 1998). PUFAs from the n‐6 and n‐3 families seem to have their most remarkable effects on cattle reproductive performance (Mattos et al, 2000). 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, 2008).
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