Resumo

VIEYRA-ALBERTO, Rodolfo et al. Effect of soybean oil on the concentration of vaccenic and rumenic fatty acids in grazing cow milk. Agrociencia [online]. 2017, vol.51, n.3, pp.299-313. ISSN 2521-9766.

Soybean oil is rich in linoleic acid, and -in addition to the contribution of major linolenic acid in fodder- can improve the production of unsaturated fatty acids (AG) in the milk of grazing cows. The objective of this study was to evaluate the effect of adding soybean oil (0, 3 and 6 % BS) in partial total mixed rations (pTMR) of six multiparous Holstein grazing cows on the AG performance, production, composition, and profile, with emphasis on the content of vaccenic (VA) and rumenic AG (RA) AG in milk. The experimental design was a 3×3 replicated Latin square with three 21 d experimental periods each one, with the following treatments (T): T1=pTMR-0, T2=pTMR-3, and T3=pTMR-6. The data were analyzed with the MIXED procedure and orthogonal polynomials to find out the linear and quadratic effects (p≤0.05). The TMR intake decreased linearly (p≤0.05) as the soybean oil content of the diet increased. Milk from cows with pTMR-6 and pTMR-3 had 20.8 and 7.6 % lower contents of saturated AG compared to pTMR-0 (p≤0.05): mainly a decrease in the C12, C14, and C16 AGs. VA increased 50.3 and 128.7 % in cow milk with pTMR-3 and pTMR-6, compared to pTMR-0; RA was higher (p≤0.05) in pTMR-3. In conclusion, adding 6 % soybean oil in the grazing Holstein cows’ TMR increased the production efficiency, modified milk composition, and increased VA and RA contents.

Palavras-chave : Soybean oil; fatty acids; grazing; bovines; milk; conjugated linoleic acid.

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