不同泌乳阶段奶牛饲料中N、P、Ca的生物学利用率研究
摘要
In this experiment, six high-yield Holstein cows and six transition cows which were close in body condition, births and milk yield were chosen. Determine their milk yield, feed intake, urine and faces amount in different lactation stages which are 0 d, 5 d, and 10 d. Meanwhile, collect their forage, milk, urine and faces and determine the N, P and Ca content in specimens. Figure out the Biological Value of N, P and Ca by analyzing specimens' content. This experiment provided direction for milk produce, veterinary and animal husbandry. The result indicated that early postpartum cows' apparent absorptive of N, P and Ca werre 77.21%±1.91%, 56.08%±8.22% and 47.62%±7.47% while apparent retention rate are 15.6%±9.70%, 12.38%±12.07% and 32.52%±7.93%. The high-yield cows' apparent absorptive of N, P and Ca are 76.39%±3.08%, 60.15%±8.54% and 49.58%±9.89% while apparent retention rate were 18.26%±6.35%, 23.65%±9.57% and 36.56%±10.96%. There was not remarkable difference between apparent absorptive of N, P and Ca of early postpartum cows and high-yield cows. The apparent retention rate of N, P and Ca of high-yield cows was higher than that of early postpartum cows.