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The effects of parity and stage of lactation on odd- and branched-fatty acid profile in milk fat from dairy cows.

D. P. Bu

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06-23-2020

Abstract:

214
The effects of parity and stage of lactation on odd- and branched-fatty acid profile in milk fat from dairy cows.
L. L. Sun1, L. Lei2, J. T. Brenna3, Z. H. Wu1, L. Ma1, J. C. Xu4, D. P. Bu*1,5. 1State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences Beijing, China, 2Hunan Agricultural University Hunan, China, 3Dell Pediatric Research Institute and Departments of Nutrition and of Chemistry, University of Texas at Austin Austin, TX, 4Key Laboratory of Economic Plants and Biotechnology, Kunming Institute of Botany, Chinese Academy of Sciences Kunming, China, 5Hunan CoInnovation Center of Animal Production Safety, CICAPS Hunan, China.

Dairy products are the main source of odd-and branched-fatty acids (OBCFA) in the Western diet, a group of nutrients with emerging health benefits. Animal diet is known to have important influence on milk fat OBCFA; however, effects of physiological factors have received little attention. The objectives of our study were to examine the effects of parity and stage of lactation on OBCFA profiles in milk fat from Holstein dairy cows, and further to investigate the relationship between OBCFA profiles and yield of milk and milk fat. Holstein dairy cows (n = 184) with an average parity of 2.8 � 0.3 and 173 � 24 d in milk (DIM) were selected. All cows were fed the same diet, and milk samples were collected on the same day to avoid the effects of diet and season factors. Fatty acid methyl esters contents were analyzed by gas chromatography. A regression model was developed by linear model procedure (PROC GLM) of SAS to analyze the data, and the relationships between OBCFA profiles and yield of milk and milk fat were analyzed by correlation procedure (PROC CORR). Frequency distributions demonstrated that milk fat content of iso-15:0, iso-17:0, anteiso-15:0 and anteiso-17:0 varied 3-4-fold among individuals. Parity and DIM accounted for less than 25% of total individual variation of OBCFAs, except for n-15:0 (26.8%). Parity and DIM had significant effects on some OBCFAs, including n-15:0 (P < 0.001), iso-13:0 (P < 0.01), iso-15:0 (P < 0.01), iso-17:0 (P < 0.001), anteiso-15:0 (P < 0.01), and anteiso-17:0 (P < 0.01). Negative correlations existed between n-13:0 (r = −0.22, P = 0.03), iso-14:0 (r = −0.21, P = 0.03), and iso-16:0 (r = −0.22, P = 0.03) and yield of milk and milk fat. There were no relationships between milk yield or milk fat and other OBCFAs of Holstein dairy cows.

Keywords: dairy cow, odd- and branched-chain fatty acid, parity.