Abstract #W415

# W415
Effect of rubber seed oil and flaxseed oil on milk performance, fatty acid composition and oxidative stability of milk fat.
Y. Pi1, J. Q. Wang1, D. P. Bu*1,3, L. Ma1,2, Y. X. Zhu4, J. C. Xu4, 1Institute of Animal Science, State Key Laboratory of Animal Nutrition, Chinese Academy of Agricultural Sciences, Beijing, China, 2CAAS-ICRAF Joint Lab on Agroforestry and Sustainable Animal Husbandry, World Agroforestry Centre, East and Central Asia, Beijing, China, 3Synergetic Innovation Center of Food Safety and Nutrition, Harbin, China, 4Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Kunming, China.

The experiment was conducted to investigate the effect of rubber seed oil compared with flaxseed oil when fed alone or in combination on the milk yield, milk composition, fatty acid composition and oxidative stability of milk fat from dairy cows. Forty-eight mid-lactation Holstein dairy cows were randomly assigned to one of 4 treatments according to a completely randomized block design. Cows were fed a basal diet (Control) or the basal diet supplemented with 4% rubber seed oil (RO), 4% flaxseed oil (FO), or 2% rubber seed oil plus 2% flaxseed oil (RFO) on a dry matter (DM) basis for 9 weeks. Feed intake (DMI), milk protein percentage, and milk fat levels did not differ among the treatments. Cows fed the RO, FO or RFO treatments had a higher (P < 0.001) milk yield than the control group (up to 6.5% more), while milk fat percentages were decreased. Compared with the Control, milk concentration of α-linolenic acid (ALA) content was substantially higher in cows receiving RO or RFO, and was double in cows receiving FO (P < 0.001). Both C18:1trans-11 (VA) and C18:2cis-9,trans-11 (CLA) levels were higher (P < 0.001) in cows fed added flaxseed or rubber seed oil. The increasing in VA, ALA, and CLA was greater in cows fed RFO than in cows fed RO alone. Compared with the Control, the milk fat from cows fed any of the dietary supplements had a higher concentration of unsaturated fatty acids (UFA), monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA), while the average saturated fatty acids (SFA) levels in milk fat were 30% lower. Compared with the Control, the superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities were all decreased (P > 0.05) in RO, FO and RFO treatments, while the catalase (CAT) activity was decreased (P < 0.05) in FO and RFO groups. The concentration of malondialdehyde (MDA) tended to increase (P < 0.10) in RO, FO and RFO treatments. These results indicated that the supplement of rubber seed oil and flaxseed oil in dairy diet could increase milk yield and the functional fatty acids content (ALA, VA, and CLA) in milk fat, while decrease the content of saturated fatty acids and oxidative stability of milk fat.

Key Words: milk fat, oxidative stability, rubber seed oil