西门塔尔杂交后备母牛日粮植物源磷进食量对表观可消化磷的影响

Effect of Botanical Phosphorus Intake in the Diet of Simmental Hybrid Replacement Heifers on the Apparent Digestible Phosphorus

旨在采用消化试验研究后备母牛日粮植物源磷进食量与磷表观消化率的关系。试验选用体况良好、体重一致的西杂后备母牛[西门塔尔牛(♂)×中国黄牛(♀)]24头,随机分为6组,即试验1组、2组、3组、4组、5组和6组,每组4头,分别定量(3.50kg/d)饲喂6种不同磷水平的精料日粮,粗料(青贮)自由采食。使用麸皮调节日粮精料磷水平,各试验组精料磷水平分别为0.36%、0.40%、0.42%、0.46%、0.50%和0.54%;总试验期为30d,预饲期20d后进入正试期,试验最后7d全收集粪样和尿样。饲料样及粪样均测定其中磷和干物质含量,计算粪磷排泄量与日粮磷进食量的回归关系。结果表明,不同日粮处理间消化道磷的表观消化量和表观消化率有显著差异(P<0.05),并随进食磷量的增加而增加,但消化道表观消化的磷量与磷的进食不是直线关系,而是呈现抛物线关系,在日粮磷水平为0.42%时,消化量和消化率达最大,即分别为10.5g/d和40.8%。

The relationship between botanical phosphorus intake in the diet of Simmental hybrid replacement heifers and the apparent digestible phosphorus. 24 healthy Simmental hybrid replacement heifers were randomly divided into 6 groups,and there were 4 heifers in each group. The concentrate diet with 6 different levels of phosphorus was fed to each heifer according to 3.50 kg/d,while crude fodder was fed freely. The dietary P content was 0.36%,0.40%,0.42%,0.46%,0.50% and 0.54% on a dry matter（DM） basis,respectively. The total experimental period was 30 d;the normal test comes after 20 d raise period,and fecal samples and urine samples were collected during the last 7 days. The contents of phosphorus and dry matter in diet and fecal samples were determined,and then the regression relationship between phosphorus excretion in fecal samples and botanical phosphorus intake in diet. Results showed that the apparent digestible phosphorus in digestive tract were significantly different（P0.05） from the different treatment of dietary phosphorus intake. To increase dietary phosphorus would be increased fecal phosphorus excretion. However,the apparent digestible phosphorus in digestive tract possessed a parabola function relation with phosphorus intake. The maximum amount of apparent digestion and apparent digestibility in the total tract were 10.5 g/d and 40.8%,respectively.