菜籽粕肉鸭标准回肠可消化氨基酸含量预测模型

Prediction Equations of Standardized Ileal Digestible Amino Acid Contents of Rapeseed Meal of Meat Ducks

本试验旨在通过逐步回归法,以菜籽粕化学成分、蛋白质溶解度(PS)及赖氨酸(Lys)∶粗蛋白质(CP)等为指标建立肉鸭菜籽粕标准回肠可消化氨基酸含量的预测模型。采用套算法进行代谢试验,选用22个不同来源的菜籽粕,试验饲粮菜籽粕替代比例为15%。选用1 168只1日龄肉公鸭,随机分为23个组(每组6个重复,每个重复8只肉鸭)和1个无氮饲粮组(每组8个重复,每个重复8只肉鸭)。所有饲粮均添加0.5%二氧化钛(TiO2)作为外源指示剂。16~18日龄开始饲喂试验饲粮,试验期3 d。结果表明:1)22种菜籽粕的Lys∶CP的变化范围为0.028~0.074,且随着菜籽粕PS增加而增加。2)22种菜籽粕标准回肠可消化CP、必需氨基酸、非必需氨基酸和总氨基酸含量差异显著(P<0.05)。3)标准回肠可消化CP和Lys含量分别为226.9~288.6 g/kg[平均值254.6 g/kg;变异系数(CV) 17.3%]和5.61~18.83 g/kg(平均值13.97 g/kg;CV 30.45%)。4)中性洗涤纤维(NDF)含量(R2=0.809 2,P<0.001)、Lys∶CP(R2=0.948 2,P<0.001)和PS(R2=0.654 2,P<0.001)是一元线性回归法预测标准回肠可消化Lys含量较好的预测因子。5)根据菜籽粕常规养分(干物质、CP、粗灰分、NDF、粗脂肪和酸性洗涤纤维)含量并结合PS和Lys∶CP,利用多元回归模型预测出的标准回肠可消化Lys、精氨酸、异亮氨酸、亮氨酸、苏氨酸、缬氨酸、苯丙氨酸、组氨酸、天冬氨酸、丝氨酸、谷氨酸、甘氨酸、丙氨酸、半胱氨酸、酪氨酸和脯氨酸的决定系数(R2)为0.736 7~0.992 6(P<0.001),拟合度高。结果提示,根据菜籽粕常规养分含量结合热加工敏感指标(PS和Lys∶CP)可成功预测肉鸭菜籽粕标准回肠可消化氨基酸含量。

This study is conducted to establish prediction models to estimate standardized ileal digestible amino acid content in rapeseed meal for meat ducks based on chemical components,protein solubility(PS)and lysine(Lys)∶crude protein(CP)by stepwise regression analysis.A substitution method was used in the metabolic experiment,rapeseed meal from 22 different sources were selected,and the replacement ratio of rapeseed meal in experimental diet was 15%.A total of 1168 one⁃day⁃old male meat ducks were randomly allotted to 23 groups(6 replicates per group,8 ducks per replicate)and one nitrogen⁃free diet group(6 replicates per group,8 ducks per replicate).Titanium dioxide(0.5%)was added in all diets as an indigestible marker.Ducks were fed experimental diets during 16 to 18 days of age,and the experiment lasted for 3 days.The re⁃sults showed as follows:1)the Lys∶CP varied from 0.028 to 0.074 in 22 kinds of rapeseed meal,which in⁃creased with the PS of rapeseed meal increased.2)The contents of standardized ileal digestible CP,essential a⁃mino acid,nonessential amino acid and total amino acid in 22 kinds of rapeseed meal were significantly differ⁃ent(P<0.05).3)The content of standardized ileal digestible CP and Lys were 226.9 to 288.6 g/kg[mean value 254.6 g/kg;coefficient of variation(CV)17.3%]and 5.61 to 18.83 g/kg(mean value 13.97g/kg;CV 30.45%).4)The neutral detergent fiber(NDF)content(R2=0.8092,P<0.001),Lys∶CP(R2=0.9482,P<0.001)and PS(R2=0.6542,P<0.001)were suitable predictors to establish the equation of standardized ileal digestible Lys content when using univariate linear regression.5)The coefficient of determi⁃nation(R2)varied from 0.7367 to 0.9926(P<0.001)for predictive equations of standardized ileal digestible content of Lys,arginine,isoleucine,leucine,threonine,valine,phenylalanine,histidine,aspartic acid,ser⁃ine,glutamate,glycine,alanine,cysteine,tyrosine and proline based on conventional nutrient(dry matter,CP,ash,NDF,ether extract and acid detergent fiber)contents combined with PS and Lys∶CP by multiple stepwise regression,which had high fitting degrees.These results indicate that using conventional nutrient con⁃tent combined with heat processing sensitive index(PS and Lys∶CP)can successfully predict the standardized ileal digestible amino acid content in rapeseed meal for meat ducks.