Aviagen Inc., Huntsville, AL 35806, USA.
Arbiom Inc., Durham, NC 27703, USA.
Poult Sci. 2019 Sep 1;98(9):3994-4007. doi: 10.3382/ps/pez142.
Digestibility coefficients of nutrients, metabolizable energy (ME), net energy (NE) and the ratio of NE to ME (NE/ME) of 20 diets were measured in broiler chickens (1 to 21 d). Dietary nutrients were formulated to keep similar ME/nutrient ratios, except for dietary protein, fat, and fiber using corn, soybean meal, animal protein blend, barley, poultry oil and an enzyme mixture of xylanase, glucanase, and phytase. Digestibility coefficients of nutrients and ME were measured in battery cages under free-access of feed, while NE was measured in floor pens feeding 75% of recommended ME intake each day. NE for maintenance was calculated on basis of mean metabolic weight using a coefficient from a previous study and NE for gain was calculated by body protein and fat gains using dual-energy x-ray absorptiometry. Digestibility coefficients of protein and neutral detergent fiber (NDF) were curvilinearly related to dietary protein and NDF, respectively, while digestibility coefficients of fat and starch were linearly correlated to dietary fat and starch, respectively. The inclusion of enzymes increased the digestion coefficient of NDF to predict the digestibility of protein, NDF, fat, and starch. MEn/gross energy ratio averaged 72.5% and was correlated to protein, fat, NDF, and starch. ME values were accurately predicted from chemical characteristics, where best equations were obtained from digestible nutrients. Energetic efficiencies of ME were 72% (NE/MEn) and 68% (NE/ME) and varied by about 20 and 18%, respectively. Ratios of energetic efficiency were 68% for digestible carbohydrates; 86% for digestible fat; and 76% (NE/MEn) and 59% (NE/ME) for digestible protein. According to the lowest residual standard deviation the best nutrient components to predict energy were digestible nutrients for predicting ME values (41 kcal/kg); digestible protein intake, fecal organic matter, and body fat and protein for predicting heat increment values (111 kcal/kg); and combination of ME and crude nutrient for predicting NE values (140 kcal/kg).
20 种饲粮的养分消化率、代谢能（ME）、净能（NE）和 NE 与 ME 的比值（NE/ME）在肉鸡（1 至 21 日龄）中进行了测定。饲粮营养素的配方保持相似的 ME/营养素比值，除了使用玉米、豆粕、动物蛋白混合物、大麦、禽油和木聚糖酶、葡聚糖酶和植酸酶的酶混合物来调节饲粮蛋白质、脂肪和纤维。在自由采食的笼中测定养分和 ME 的消化率，而在每天饲喂 75%推荐 ME 摄入量的地板笼中测定 NE。维持的 NE 是根据之前研究的系数，用平均代谢体重计算的，而增重的 NE 是用双能 X 射线吸收法测定的体蛋白和体脂肪增长计算的。蛋白质和中性洗涤纤维（NDF）的消化率与饲粮蛋白质和 NDF 呈曲线相关，而脂肪和淀粉的消化率与饲粮脂肪和淀粉呈线性相关。添加酶提高了 NDF 的消化率，从而预测蛋白质、NDF、脂肪和淀粉的消化率。总能/粗能比平均为 72.5%，与蛋白质、脂肪、NDF 和淀粉相关。ME 值可通过化学特性准确预测，其中最佳方程来自可消化养分。ME 的能量效率为 72%（NE/MEn）和 68%（NE/ME），分别变化约 20%和 18%。能量效率比分别为可消化碳水化合物 68%；可消化脂肪 86%；可消化蛋白质 76%（NE/MEn）和 59%（NE/ME）。根据最低剩余标准差，预测 ME 值的最佳营养素成分是可消化养分（41 千卡/千克）；预测热增耗值的最佳营养素成分是可消化蛋白摄入量、粪便有机物、体脂肪和体蛋白（111 千卡/千克）；预测 NE 值的最佳营养素成分是 ME 和粗养分的组合（140 千卡/千克）。
