酪蛋白对线性回归法测定磷真消化率的影响

Effect of Dietary Casein Supplementation on Estimation of True Phosphorus Digestibility by the Linear Regression Method

本试验旨在使用线性回归法研究肉鸡饲粮添加酪蛋白对豆粕中磷真消化率测定的影响。采用2×3因子完全随机区组设计将384只15日龄罗斯肉鸡随机分为6个处理,每个处理8个重复,每个重复8只鸡。试验因子包含2种饲粮类型(无酪蛋白添加和添加酪蛋白)和3个磷水平(0.22%、0.30%和0.38%),选择三氧化二铬作为指示剂测定肉鸡对豆粕中磷的利用效率。结果表明:随饲粮总磷水平增加,肉鸡采食量、体增重和饲料转化率显著线性增加,而磷表观消化率和存留率以及干物质消化率和存留率显著线性降低(P<0.01);饲粮添加酪蛋白显著减少肉鸡食糜和排泄物中总磷排泄量(P<0.01);使用线性回归法测得酪蛋白添加组豆粕中磷的真消化率71.26%和存留率60.58%显著高于无酪蛋白添加组的61.84%和48.68%(P<0.05)。由此可见,饲粮添加酪蛋白影响线性回归法对豆粕中磷真消化率的测定。

The objective of this study was to investigate the effect of dietary casein supplementation on the estimation of true phosphorus （P） digestibility in soybean meal for broiler chickens by the regression method. Three hundred eighty-four male Ross broilers were allocated to 6 diets consisting of 2 factors in a 2x3 factorial arrangement： diet type （with or without casein）and P concentrations at 3 levels （0.22%, 0.30% or 0.38%）in a randomized complete block design. There were 8 birds per cage and 8 replicate cages per diet. Chromic dioxide was used as an indicator to calculate P utilization in soybean meal for broiler chickens. The results indicated that body weight gain, feed intake, and feed efficiency increased linearly with increasing graded level of dietary P （P〈0.01）. However,dry matter digestibility,dry matter retention, apparent P digestibility and P retention decreased linearly with increased dietary P content （P〈0.01）. Casein supplementation in diets decreased P outputs in digesta and excreta of birds （P〈0.01）. Regressing P outputs in digesta and excreta against dietary P intake,the estimated true P digestibility （71.26%）and P retention （60.58%）for birds fed diets with casein supplementation were greater than the determined values of true P digestibility （61.84%）and P retention （48.68%）for birds fed diets without casein （P〈0.05）. In conclusion, dietary casein supplementation affected the estimation of true P digestibility in soybean meal by the regression method.