东北玉米肉鸡表观代谢能预测方程的建立

本研究旨在通过实验室分析和肉鸡代谢试验建立东北玉米养分含量与代谢能的回归方程,为生产提供便捷的玉米代谢能估算方法。试验1:选取成熟季节不同的20种东北玉米,测定养分含量和容重,分析养分含量变异范围。试验2:用玉米、玉米皮、玉米碴按照中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)含量梯度配制人工玉米,再添加一定量的维生素和矿物质,配制成人工玉米代谢饲粮。选取正常饲养的商品代爱拔益加雄性肉鸡进行代谢试验,分别在11~13日龄及25~27日龄,用全收粪法测定人工玉米代谢饲粮表观代谢能(AME)、氮校正表观代谢能(AMEn)和养分表观消化率,并采用逐步回归法建立AME及AMEn与养分含量的回归方程。结果表明:东北玉米粗脂肪(EE)、NDF及ADF含量变异系数相对较大,分别为16.72%、14.65%、14.72%。肉鸡对人工玉米代谢饲粮的养分表观消化率在11~13日龄和25~27日龄之间存在差异,25~27日龄肉鸡对人工玉米代谢饲粮粗蛋白质(CP)、EE和总淀粉(STC)的表观消化率高于11~13日龄,其中EE表观消化率差异显著(P0.05);25~27日龄肉鸡对人工玉米代谢饲粮的AME、AMEn也显著高于11~13日龄(P0.05)。采用逐步回归法建立肉鸡东北玉米代谢能的预测方程为:11~13日龄,AME=17.661-0.853ADF(R2=0.870,P0.01),AM En=17.468-0.878ADF(R2=0.873,P0.01);25~27日龄,AM E=18.102-0.792ADF(R2=0.781,P0.05),AM En=17.935-0.830ADF(R2=0.784,P0.05)。通过预测方程计算所得人工玉米代谢饲粮AME的预测值与实测值很接近,计算所得的东北玉米AME符合预期值。由此得出,不同品种东北玉米EE、NDF及ADF的含量差异相对较大;肉鸡不同阶段玉米代谢能存在差异,计算肉鸡饲粮配方时,不同阶段饲粮代谢能应采用对应的代谢能值;低于14日龄的肉鸡,东北玉米AM E、AM En预测方程分别为AM E=17.661-0.853ADF,AM En=17.468-0.878ADF;14日龄以上的肉鸡,东北玉米AME、AMEn预测方程分别为AME=18.102-0.792ADF,AMEn=17.935-0.830ADF。

Prediction Equation of Apparent Metabolizable Energy of Corn in Northeast China for Broilers

This study aimed to establish the regression equations for metabolizable energy of corn in Northeast China for broilers based on nutrient contents by the methods of laboratory analysis and metabolic test for broil?ers, in order to provide a convenient estimation method for corn metabolizable energy in production. In trial 1, twenty kinds of corn from Northeast China with different mature seasons were used to measure the nutrient con?tents and volume?weight, and to analyze the variation ranges of nutrient contents. In trial 2, artificial corn met?abolic diets were formulated by artificial corn and a certain amount of vitamins and minerals, and the artificial corn were formulated by corn, samp and corn bran based on the graded level of neutral detergent fiber ( NDF) and acid detergent fiber ( ADF) contents. Arbor Acres broilers raised as normal production were used to com?plete metabolism test at the age of 11 to 13 days and 25 to 27 days by the total collection method. The apparent metabolizable energy ( AME) , nitrogen corrected apparent metabolizable energy ( AMEn) and nutrient appar?ent digestibility of artificial corn metabolic diets for broilers were measured, and the stepwise regression method was used to establish regression equations for AME or AMEn and nutrient contents. The results showed that the variance coefficients for the contents of ether extract ( EE) , NDF and ADF of corn in Northeast China were relatively larger, and they were 16.72%, 14.65% and 14.72%, respectively. There were differences in the nu?trient apparent digestibility of artificial corn metabolic diets for broilers between 11 to 13 days of age and 25 to 27 days of age. Among them, broilers fed artificial corn metabolic diets at 25 to 27 days of age had greater crude protein ( CP) , EE and total starch ( STC) apparent digestibility, and the EE apparent digestibility was significant ( P<0.05) . The AME and AMEn of broilers at 25 to 27 days of age were significantly higher than those of broilers at 11 to 13 days of age ( P<0.05) . The prediction equations for metabolizable energy of corn in Northeast China for broilers using stepwise regression method showed as follows: AME = 17. 661-0.853ADF ( R2=0.870, P<0.01) and AMEn=17.468-0.878ADF ( R2=0.873, P<0.01) for 11 to 13 days of age; AME=18.102-0.792ADF ( R2=0.781, P<0.05) and AMEn=17.935-0.830ADF ( R2=0.784, P<0.05) for 25 to 27 days of age. The calculated values of AME for artificial corn metabolic diets using predic?tion equations were close to the measured values, and the calculated values of AME for corn in Northeast China met the expected values. In conclusion, the differences of contents of EE, NDF and ADF of corn in Northeast China are relatively larger among different varieties. Different stage diets should take the corresponding metabo?lizable energy values when calculate the feed formula for broilers, because broilers at different stage have dif?ferent corn metabolizable energy. The prediction equations of AME and AMEn of corn in Northeast China are AME=17.661-0.853ADF( R2=0.870, P<0.01) and AMEn=17.468-0.878ADF ( R2=0.873, P<0.01) for broilers less than 14 days of age, and AME=18.102-0.792ADF( R2=0.781, P<0.05) and AMEn=17.935-0.830ADF (R2=0.784, P<0.05) for broilers more than 14 days of age, respectively.