试验旨在分析燕麦青贮替代日粮中燕麦干草和羊草对奶牛生产性能和血清生化指标的影响.选取平均胎次、体重、产奶量差异均不显著的荷斯坦泌乳奶牛32头,随机分为4组,每组8个重复,每个重复1头奶牛.对照组奶牛饲喂基础日粮,试验组分别使用等干物质含量的燕麦青贮替代基础日粮中的100％燕麦干草(Ⅰ组)、50％燕麦干草(Ⅱ组)和100％羊草(Ⅲ组).预试期14d,正式试验期35 d.结果显示,燕麦青贮的干物质(DM)、酸性洗涤纤维(ADF)、中性洗涤纤维(NDF)含量均低于燕麦干草和羊草(P＜0.05),Ca含量显著高于燕麦干草和羊草(P＜0.05).与对照组相比,Ⅰ组、Ⅱ组奶牛的乳脂率显著提高(P＜0.05),Ⅱ组乳脂量显著提高(P＜0.05),试验Ⅱ组、Ⅲ组的乳蛋白率显著提高(P＜0.05).试验Ⅱ组奶牛的养殖利润高于其他组.研究表明,使用燕麦青贮替代燕麦干草和羊草对奶牛生产性能和机体健康无不良影响,且使用燕麦青贮替代50％燕麦干草可提高奶牛的产奶量和乳品质,经济效益较好.

[Objective] This study aimed to investigate the effect of crossbred cows between Chinese Simmental beef cattle, dairy-meat dual purpose Simmental and Hebei local hybridized, and to provide reference for breeding quality beef cattle in Hebei province. [Method] In this study, the frozen semen of Chinese Simmental beef cattle and German Simmental were crossed with local Simmental crossbred cattle in Hebei Province to determine and compare the growth and development indexes of their offspring. [Result] The weight of 0, 3, 6, 12 months old of Chinese Simmental hybrid offspring were all higher than the German Simmental hybrid offspring, but the difference was not significant. The average daily weight gain（ADG） decreased with age. The ADG of Chinese Simmental hybrid offspring were greater than that of German Simmental, except the ADG of the heifers of German Simmental at 4 to 6 months were greater than the Chinese Simmental. The chest girth and abdomen circumference of beef Simmental hybrid offspring were larger than the German Simmental hybrid offspring, but the body height, hip cross height and body length were smaller than those of the German Simmental hybrid offspring. [Conclusion] In this study, the Chinese Simmental hybrid offspring had better growth and development performance than the German Simmental hybrid offspring, but the difference was not significant.

[Objective] This study aimed to estimate the genetic parameters of body weight and body size for Simmental beef cattle in Hebei province and to provide a reference for breeding programs. [Method] This study was based on the body weight and size records of 266 Simmental beef cattle in Hebei Tianhe Beef Cattle Breeding Limited Company from 2015 to 2021, which included body weight, body height, hip cross height, body length, chest girth, abdomen circumference, and cannon circumference. [Result] Genetic parameters of body weight and size traits were estimated using AI-REML and EM algorithm of DMU software combined with animal models. The results showed that the heritability estimates of body weight and body size traits were 0.41, 0.41, 0.45, 0.45, 0.48, 0.31, and 0.66, respectively. The genetic correlations between body weight and body size traits ranged from 0.20（body height） to 0.79（chest girth）, and the phenotypic correlations ranged from 0.14（hip cross height） to 0.23（chest girth）. The genetic correlations between body size traits ranged from-0.70（abdomen circumference and cannon circumference） to 0.92（body height and hip cross height）, and the phenotypic correlations ranged from-0.10（abdomen circumference and cannon circumference） to 0.94（body height and hip cross height）. [Conclusion] Body weight and body size traits were high heritability traits, and a strong positive genetic correlation was between body weight and body size traits, except for the cannon circumference. Strengthening the selection and breeding of these traits would help to improve the growth and development performance of Simmental beef cattle.

本文介绍了肉牛遗传疾病的种类、表现和遗传基础,对骡蹄症、骨硬化症、蜘蛛腿综合征、侏儒症、歪尾综合征、肌肉增生和红细胞生成性卟啉症等7种肉牛遗传病进行了概述.对我国肉牛遗传病的了解和研究具有重要意义.