Effect of dietary fat blend enriched in oleic or linoleic acid and monensin supplementation on dairy cattle performance, milk fatty acid profiles, and milk fat depression.

摘要: The effect of feeding increasing levels oleic and linoleic acid both independently together, with or without monensin, on milk fat depression was evaluated. Fifty-six Holstein cows were blocked by parity then divided production into 2 groups (high low) 14 each within block. A cow pair 1 high low block fed in a single electronic gate. Gates (n = 28) considered the experimental unit assigned to monensin (17.5 g/t dry matter) control as main plot each). 7 pairs fixed further sequence blend diets split plot. Seven treatments × Latin square no added (no fat) acid: C18:1 + C18:2 (LOLL); medium (LOML); (LOHL); (MOLL); C18:1+medium (MOML); C18:1+low (HOLL). Monensin did not affect yield concentration fat. Feeding decreased proportion C <16, increased total C18, trans-10 C18:1, trans-10,cis-12 conjugated fatty acids (FA). As dietary beyond present LOLL, concentration, yield, <16 all decreased, increased. quadratic noticed for feeding, but feeding. When contents FA other than similar, C18:2-rich compared C18:1-rich (LOML vs. MOLL, LOHL HOLL), indicating that is more potent depressing Increasing content from which primarily small increases C18:0 C16:0, secretion C18 milk. This suggests biohydrogenation intermediates act decrease mammary synthesis at C18:2. No significant interactions detected composition parameters analyzed; however, interaction found proportion.