低蛋白质水平饲粮添加过瘤胃蛋氨酸对黔北麻羊生长性能、养分消化率、血浆生化和抗氧化指标及瘤胃发酵参数的影响

Effects of Rumen-Protected Methionine Supplementation in Low Protein Level Diet on Growth Performance,Nutrient Digestibilities,Plasma Biochemical and Antioxidant Indexes and Rumen Fermentation Parameters of Qianbei Brown Goats

本试验旨在研究低蛋白质水平饲粮添加过瘤胃蛋氨酸(RPMet)对黔北麻羊生长性能、养分消化率、血浆生化和抗氧化指标及瘤胃发酵参数的影响。选择体况良好,年龄、体重[(32.43±1.84)kg]相近的黔北麻羊18只,随机分为3组,每组6个重复,每个重复1只羊。对照组饲喂基础饲粮(粗蛋白质含量为12.42%),且不添加RPMet;Ⅰ组、Ⅱ组的饲粮蛋白质水平均较基础饲粮低2个百分点(粗蛋白质含量为10.21%),且分别添加0.2%、0.4%的RPMet。预试期14 d,正试期7 d。结果表明:1)各组试验羊的末重、干物质采食量(DMI)、平均净增重(ANG)、平均日增重(ADG)、料重比(F/G)差异不显著(P>0.05)。2)Ⅱ组粗蛋白质、粗脂肪消化率显著高于对照组和Ⅰ组(P<0.05)。3)各组血浆生化(总蛋白、白蛋白、总氨基酸、尿素氮、尿酸、肌酐含量及碱性磷酸酶、谷草转氨酶、谷丙转氨酶活性)和抗氧化指标(超氧化物歧化酶、谷胱甘肽过氧化物酶、过氧化氢酶活性及丙二醛含量)差异不显著(P>0.05)。4)各组瘤胃pH、氨态氮浓度、挥发性脂肪酸比例和纤维素酶(微晶纤维素酶、羧甲基纤维素酶、纤维二糖酶与木聚糖酶)活性差异不显著(P>0.05)。由此可见,低蛋白质水平饲粮添加RPMet对黔北麻羊生长性能、血浆生化和抗氧化指标及瘤胃发酵参数没有产生负面影响,且添加0.4%的RPMet还可提高饲粮粗蛋白质和粗脂肪消化率。

This study was conducted to investigate the effects of rumen-protected methionine(RPMet)supplementation in low protein level diet on growth performance,nutrient digestibilities,plasma biochemical and antioxidant indexes and rumen fermentation parameters of Qianbei brown goats.Eighteen Qianbei brown goats with good physical condition and similar age and body weight[(32.43±1.84)kg]were randomly divided into 3 groups with 6 replicates in each group and 1 goat in each replicate.Goats in the control was fed a basal diet(crude protein content was 12.42%)without RPMet supplementation;others in group Ⅰ and group Ⅱ were fed diets(crude protein content was 10.21%)which dietary protein level was decreased by 2% than the basal diet,and supplemented with 0.2% and 0.4% RPMet,respectively.The pre-experimental period lasted for 14 days,and the experimental period lasted for 7 days.The results showed as follows:1)there was no significant difference in the final weight,dry matter intake(DMI),average net gain(ANG),average daily gain(ADG)and feed to gain ratio(F/G)of goats among all groups(P>0.05).2)The digestibilities of crude protein and ether extract of group Ⅱ was significantly higher than those in control group and group Ⅰ(P<0.05).3)There was no significant difference in plasma biochemical(total protein,albumin,total amino acid,urea nitrogen,uric acid,creatinine contents and alkaline phosphatase,aspartate transaminase,alanine aminotransferase activities)and antioxidant indexes(superoxide dismutase,glutathione peroxidase,catalase activities and malondialdehyde content)among all groups(P>0.05).4)There was no significant difference in rumen pH,ammoniacal nitrogen concentration,volatile fatty acid proportion and cellulase(microcrystalline cellulose,xylanase,cellobiase and carboxymethyl cellulose)activities among all groups(P>0.05).It is suggested that RPMet supplementation in low protein level diet has not effect on growth performance,plasma biochemical and antioxidant indexes and rumen fermentation parameters of Qianbei brown goats,and adding 0.4% RPMet can improve the digestibilities of crude protein and ether extract.