Dietary Whole Cottonseed Percentage Affects Lactation Performance and Fatty Acid Composition of Milk Fat in Dairy Cows

This experiment was conducted to study the effects of dietary whole cottonseed(WCS) percentage on lactation performance and fatty acid composition of milk fat in dairy cows.A 4×4 Latin square design was used.Eight Holstein cows in early lactation with similar milk yield,parity and time of parturition were selected and assigned randomly into four groups with two replicates in each group and one cow per replicate.Cows in group A were fed a basal diet,and cows in groups B,C and D were fed experimental diets conteined 5%,10% and 15% WCS,respectively.Each period lasted for 28 d with 7-d adaptation period and 21-d formality period.The results showed as follows: with the increasing of WCS percentage,milk yield of dairy cows tended to be increased(P0.05),and FCM yield was significantlly increased(P0.01).Milk fat percentage was significantly increased by WCS(P0.01),and percentages of milk protein,lactose and milk non-fat milk solids(SNF) were not significantly affected(P0.05).Saturated fatty acid(SFA) content was significantly decreased by WSC(P0.01),contents of poly-unsaturated fatty acid(PUFA) and monounsaturated fatty acid(MUFA)were also significantly increased(P0.05 or P0.01);short-chain fatty acid(SCFA) and middle-chain fatty acid(MCFA) were significantly decreaed(P0.05);long-chain fatty acid(LCFA) content was significantly increased(P0.05 or P0.01).These results indicate that dietary WCS can increase milk yield,optimize fatty acid compositon of milk fat and improve milk fat quality.For dairy cows in early lactation period,the optimal percentage of WCS in the diet is 10%.