添加过瘤胃蛋氨酸、赖氨酸对荷斯坦奶公牛生长性能和胴体化学成分的影响

本文旨在研究在基础饲粮中添加过瘤胃蛋氨酸(RPMet)、过瘤胃赖氨酸(RPLys)对荷斯坦奶公牛生长性能和胴体化学成分的影响,探讨用RPMet和RPLys替代部分饲粮粗蛋白质的可行性。试验采用完全随机设计,选择12月龄左右,体重、体尺相近的健康奶公牛25头,随机分为5组,每组5头。对照组饲喂基础饲粮,4个试验组M15、L30、M15+L30、LCP组分别在基础饲粮中添加RPMet 15 g/d、RPLys 30 g/d、RPMet 15 g/d+RPLys 30 g/d、RPMet 15 g/d+RPLys 30 g/d(同时降低饲粮粗蛋白质2.20%)。预试期10 d,正试期150 d。结果表明,与对照组相比:1)基础饲粮中添加RPMet和RPLys对奶公牛干物质采食量无显著影响(P0.05);L30、M 15+L30、LCP组末重和平均日增重显著增加(P0.05),且均以M 15+L30组最高,但M 15+L30组与LCP组无显著差异(P0.05);M 15+L30和LCP组料重比显著降低(P0.05),以M 15+L30组最低,这2组间差异不显著(P0.05)。2)M 15+L30和LCP组奶公牛胸围和胴体中粗蛋白质含量显著提高(P0.05),这2组间差异不显著(P0.05)。3)M15+L30和LCP组奶公牛胴体中必需氨基酸苏氨酸、亮氨酸、精氨酸的含量显著提高(P0.05),这2组间差异不显著(P0.05),M15+L30组异亮氨酸含量显著提高(P0.05);M15+L30和LCP组奶公牛胴体中非必需氨基酸中天冬氨酸、丝氨酸、谷氨酸、甘氨酸、丙氨酸、半胱氨酸、脯氨酸以及总氨基酸含量显著提高(P0.05),L30和M15+L30组酪氨酸含量显著提高(P0.05),这2组间均无显著差异(P0.05)。由此可见,饲粮中添加RPMet和RPLys在一定程度上提高了奶公牛的生长性能,增加了胴体中蛋白质的合成和氨基酸沉积,且添加RPMet 15 g/d+RPLys30 g/d能够在一定程度上替代部分饲粮粗蛋白质(2.20%)。

Effects of Rumen-Protected Methionine and Lysine Supplementations on Growth Performance and Carcass Chemical Composition of Holstein Bulls

This experiment was conducted to investigate the effects of rumen-protected methionine ( RPMet) and lysine ( RPLys) supplementations on growth performance and carcass chemical composition of Holstein bulls, and to discuss the feasibility that RPMet and RPLys instead of part protein of diet.Twenty five Holstein bulls aged about 12 months with similar body weight and body measurements were selected and divided into 5 groups with randomized experiment design, and each group included 5 Holstein bulls.The control group was fed a basal diet, the experimental groups were fed the basal diet added with RPMet 15 g/d ( M15 group) , RPLys 30 g/d ( L30 group) , RPMet 15 g/d+RPLys 30 g/d ( M15+L30 group) and RPMet 15 g/d+RPLys 30 g/d ( meanwhile dietary crude protein content was lowered by 2.20%) ( LCP group) , respectively.Adap-tation and experimental periods lasted for 10 and 150 d, respectively.The results showed that compared with control group:1) dry matter intake was not affected by RPMet and RPLys supplementations ( P>0.05);L30, M15+L30, LCP groups significantly increased final weight and average daily gain ( P<0.05) , and the values reached the highest in M15+L30 group, but they were not significantly different from those in LCP group ( P>0.05); M15+L30 and LCP groups significantly decreased feed to gain ratio ( P<0.05) , and M15+L30 group had the minimum value, but the difference between M15+L30 and LCP groups was not significant ( P>0.05) . 2) Chest girth and carcass crude protein content in M15+L30 and LCP groups were significantly increased ( P<0.05) , while there was no significant difference between the two groups ( P>0.05) .3) M15+L30 and LCP groups significantly increased carcass essential amino acid contents including threonine, leucine and arginine ( P<0.05) , and the differences between the two groups were not significant ( P>0.05);M15+L30 group sig-nificantly increased isoleucine content ( P<0.05); M15+L30 and LCP groups had significantly higher non-es-sential amino acid contents including aspartate, serine, glutamic acid, glycine, alanine, cystine and proline and total amino acid content ( P<0.05); L30 and M15+L30 groups had significantly higher tyrosine content ( P<0.05) , but there was no significantly difference between the two groups ( P>0.05) .It is concluded that dietary supplementations of RPMet and RPLys can improve growth performance and increase carcass protein and amino acid contents of Holstein bulls, and the supplementation of RPMet 15 g/d+RPLys 30 g/d can in-stead part of dietary crude protein (2.20%).