Effects of Whole Cottonseed on Performance and Blood Biochemical Paramaters of Dairy Cows

This experiment was conducted to study the effects of dietary whole cottonseed(WCS) on performance and blood biochemical paramaters of dairy cows.A 4×4 Latin square design was used.Eight multiparity Holstein cows in early lactation were selected and assigned randomly into 4 groups with 2 replicates in each group and 1 cow per replicate.Cows in group A(control group) were fed a basal diet,and cows in groups B,C and D were fed experimental diets contained 5%,10% and 15% WCS,respectively.The experiment contained four period,and each period lasted for 28 d with 7-d adaptation period and 21-d formality period.The results showed as follows: 1) with the increasing of WCS percentage,milk yield of dairy cows tended to be increased(P0.05),and the milk fat percentage and 4% fat corrected milk(FCM) was significantly increased(P0.01).Deitary WCS had no effects on the milk protein percentage,lactose percentage and milk NFS percentage(P0.05).2) Dietary WCS level had no effects on the apparent digestibilities of crude protein,ether extract and acid detergent fiber(P0.05),but it significantly increased the apparent digestibility of neutral detergent fiber(P0.05),the apparent digestibility of neutral detergent fiber in group C were increased by 8.4%,and higher than that in the control group(P0.05).3) Dietary WCS level had no effects on contents of albumin and glucose in serum(P0.05),but it significantly affected the contents of cholesterol and urea nitrogen in serum(P0.05).Serum cholesterol content in group C was significantly lower than that in other groups.Serum urea nitrogen content in groups B and C was significantly lower than that in groups A and D.4) The free gossypol content in serum and milk was significantly increased with the WCS percentage increasing(P0.01).Milk free gossypol content had no significant difference among groups B,C and D(P0.05),In conclusion,for dairy cows in early lactation period,the optimal percentage of WCS in the diet is 10%.