Effects Of Supplemental Choline,Niacin And Vitamin C On Performance And Some Blood Biochemical Parameter In Lactating Dairy Cows

Three experiments were conducted to test the effects of dietary choline, niacin and vitamin C on performance and blood parameters in lactating dairy cows.In experiment 1,6 primiparous Holstein cows in early lactation were selected in a replicated 3X3 Latin square design to determine the effects of supplemental 0> 60, 120g/d blood梡rotected choline chloride on performance and blood biochemical parameters. The results were followed:(l) Milk yield and 4% fat corrected milk tended to increase for supplemental rumen梡rotected choline,but no significant difference (P >0. 05);Milk fat percentage of the treatment of supplementing 120g/d choline increased 5.67% (P < 0.05),and there was no significant difference between the 60g/d group and the unsupplemental control (P >0. 05) ;Dietary choline had no effect on milk protein percentage. (2)Serum cholesterol and triglyceride tended to decrease, but no significant differene (P>0. 05);The content of serum free fatty acid decreased 23.68% (P<0.05) and 19.13 (P>0. 05) respectively compared with the control group, but there was no significant difference between the 60g/d group and the 120g/d group (P>0. 05).In experiment 2,3 Hostein cows in early lactating under heat stress were selected in a 3X3 Latin square design to determine the effects of supplemental 0, 6, 12g/d nicotinic acid (niacin) on performance and blood biocheminal parameters. The results were followed: (1) Supplemental niacin had no significant effect on the rectal temperature andrespiratory rate (P>0. 05). (2) Milk yield increased 13.20% (P<0. 05K 9.39% (P<0.05) respectively , but 4% fat corrected milk yield was no significant differene (P>0. 05) ;Dietary niacin had no effect on milk fat and protein percentage. (3) The content of serum cholesterol decreasedinsignificantly (P>0. 05) ;The conten of blood sugar increased 37. 89* (P <0. 05) > 51. 93% (P<0. 05), there was no significant differene between the two groups (P > 0.05);The content of urea nitrogen decreased significantly for supplementing 12g/d niacin (P<0. 05);The content of serum triglyceride was no significant differene between the treatment of supplemental niacin and the control group (P>0.05);The content of free fatty acid decreased 23.89% (P < 0. 01) , 10.39% (P < 0. 01) respectively.In experiment 3,6 Holstein cows under heat stress were selected in a replicated 3X3 Latin square design to determine the effects of supplemental 0>5^lOg/d vitamin C on performance and blood parameters. The results were followed: (1) Rectal temperature and respiratory rate decreased for supplemental vitamin C,but there was no significant differene (P>0. 05) ;(2) Dietary vitamin C had no effect on milk yield and milk composition. (3) The serum I3^ T.( decreased and serum cortisol increased,but no significant differene (P > 0.05); (4) There was no significant effect for dietary vitamin C on serum cholesterol and triglyceride (P>0.05);The content of serum vitamin C and alkaline phosphatase activity respectively increased 46. 52% (P<0. 05) ^ 84. 04% (P <0. 01) and 34. 33% (P<0. 01) , 28. 32% (P<0. 01) ; Urea nitrogen decreased 17. 68% (P<0. 01) > 11. 44% (P<0. 05) respectively. (5) The contant of serum TgG and total antioxidation capacity respectively increased 7. 14% (P >0. 05), 21. 34% (P<0. 05) and 31. 44% (P<0. 05) , 51. 69% (P<0. 05), serum active oxygen decreased 7. 42% (P>0. 05K 3.94% (P>0. 05) respectively.