Effect of dietary phosphorus level on performance and phosphorus excretion of lactating dairy cows | 日粮磷水平对泌乳奶牛生产性能及磷排放的影响

chinois. 目的研究日粮磷水平对奶牛生产性能及磷排放量的影响，为中国奶牛饲养标准中磷需要量的制定提供数据参考。方法采用单因子试验设计，30头中国荷斯坦奶牛随机被分为3组，每组10头，分别饲喂干物质基础磷含量分别为0.32%、0.44%和0.56%的日粮，试验期75 d；其中，预试期15 d，正式期60 d，正式期最后5 d为采样期。结果磷的不同摄入量对采食量、生产性能及乳成分无显著影响（P＞0.05），血清中钙、磷、碱性磷酸酶、羟脯氨酸以及唾液磷含量均处于正常值。0.32%磷日粮组每天通过粪尿向环境排磷量分别比0.44%和0.56%的磷日粮组少20.40 g（P＜0.01）和45.84 g（P＜0.01）；其中，粪中水溶性磷排放量分别比0.44%和0.56%磷日粮组少15.24 g（P＜0.01）和45.61 g（P＜0.01），奶牛的饲养成本每天分别降低了0.60元/头和0.40元/头。结论日粮干物质基础磷水平为0.32%时对中国泌乳奶牛生产性能无不利影响，且显著降低粪磷含量，增加奶牛养殖的经济效益和生态效益。

anglais. Objective The aims of the present study were to investigate the effect of dietary phosphorus level on the performance and phosphorus excretion to environment in lactating cows. Method Thirty lactating Chinese Holstein cows were randomly allocated respectively into 3 treatments with 10 duplicates each. The phosphorus contents in the dietary of each treatment were 0.32%, 0.44% or 0.56% (dry matter basis), respectively. The trial lasted 75 days with 15-d adaptation period and 60-d experimental period. Samples were collected in the last 5 days. ResultDietary phosphorus level of dairy cows showed no effects on the dry matter intake, milk yield and milk composition (P＞0.05). The contents of calcium, phosphorus, alkaline phosphatase and hydroxyproline in the serum and the saliva phosphorus content were all in the normal range. Daily phosphorus excretion to the environment through manure and urine of group fed diet with 0.32% P was decreased by 20.40 g and 45.84 g compared with the group fed diet with 0.44% P and 0.56% P, respectively. Fecal water-soluble phosphorus emissions from dairy cow fed diet with 0.32% P was respectively decreased by 15.24 g (P＜0.01) and 45.61 g (P＜0.01) compared with that fed diet with 0.44% P and 0.56% P. The daily feeding cost was respectively decreased by 0.60 yuan/cow and 0.40 yuan/cow. ConclusionTherefore, dietary phosphorus level was 0.32% (dry matter basis) not only had no negative effect on the performance, but also significantlly decreased the fecal phosphorus excretion and improved economic benefit and ecological benefit of feeding. The recommended dietary allowance of phosphorus is 0.32%-0.44%.