Effects Of Infusing Milk Fat And Milk Protein Precursor To External Pudic Artery On The Uptake Rule Of Short Chain Fatty Acid In Dairy Cows Mammary Gland Under The Condition Of Corn Straw Diet

This experiment was conducted to study the promoting effects of infusing milk fat precursor and milk protein precursor on the production performance and milk quality of mid lactation Holstein cows. By analyzing the main reason in the difference of milk performance and the quality of milk between corn Straw and alfalfa groups to provide the theoretical and scientific basis for effective improvement in the utilization efficiency of straw feed and the quality of milk.The experiment of this paper included two parts.Expement 1 was conducted to effects of infusing milk fat precursor to external pudic artery on the uptake rule of short chain fatty acid in mammary gland of dairy cows.Expement 2 was conducted to effects of infusing milk protein precursor to external pudic artery on the uptake rule of short chain fatty acid in mammary gland of dairy cows.The two expements all used the 2x2 cross experiment design, Eight healthy Holstein cows with similar parity, body weight, multiparous(2～3 parities), lactation period (99±11 d), and milk yield (20.17±1.28 kg/d) were randomly assigned in 2 groups, each group had 4 cows. Dairy cows of two groups were fed different diets, respectively, alfalfa group (MF) and corn straw (CS). The expement was divided into two stages, each stage lasted 20 days, including the diet adjustment period (pre feeding period) 14 days, carrier perfusion phase 3 days, formal perfusion phase 3 days. During carrier perfusion phase, the dairy cows of alfalfa group had received carrier perfusion (positive control group 1), the dairy cows of corn straw group also received carrier perfusion (control group); during formal perfusion, the dairy cows of alfalfa group continued to receive carrier perfusion (positive control group 2), and the dairy cows of corn straw group received milk fat precursor perfusion (treatment group). In the second phase, interchange cows of two groups. In expement 2,the dairy cows of corn straw group were infused milk protein precursor during formal perfusion, and the other is the same as the experiment 1. During the experimental period, blood and milk samples were taken from dairy cows to measure the concentration and proportion of short chain fatty acids in caudal artery and internal mammary vein, the uptake of short chain fatty acid in mammary gland, milk performance of dairy cows.Under the condition of this experiment it is concluded:(1) Before infusing milk fat precursor, the milk yield, standard milk yield, milk fat and protein yield of the cows in the straw group were significantly lower than alfalfa group (P<0.05), and infusing milk fat precursor for the cows in the straw group could significantly increase milk fat rate, the production efficiency of milk fat and milk protein rate(P<0.05), and those parameters could close to the level of alfalfa group.It could improve the milk yield, milk protein and fat yield of the cows in the straw group, but it was still lower than alfalfa group(P<0.05).(2) Infusing milk fat precursor to external pudic artery of cows in the straw group might significantly increase the concentration of acetic acid, propionic acid, butyric acid and short chain fatty acids in the blood of caudal artery (P< 0.05).(3) Infusing milk fat precursor had no significant effect on the uptake,uptake efficiency and arteriovenous difference of acetic acid, propionic acid, butyric acid, short chain fatty acid in mammary gland (P> 0.05),but these indicators were higher than alfalfa group in numerical.(4) Infusing milk protein precursor to external pudic artery could significantly improve milk protein rate (P< 0.05), and it had certain promoting effect on milk yield standards milk yield, milk fat rate and milk fat and protein yield, but it was still lower than alfalfa group.(5) It had a tendency to significantly increase the concentration of acetic acid in the blood of internal mammary vein (P< 0.10), reduce arteriovenous difference of acetic acid and the difference of the uptake and uptake efficiency of acetic acid in the mammary glands between corn straw and alfalfa group(6) Infusing milk protein precursor to external pudic artery had certain promoting effect on increasing C2/C3,(C2+C3)/C4 in the blood of caudal artery.