饲粮蛋白质水平和棉籽粕取代豆粕对肉牛育肥的影响

本试验在满足肉牛营养需要的基础上,采用棉籽粕替代饲粮中的豆粕,形成不同蛋白质水平和成本的饲粮,旨在探讨饲粮蛋白质水平和棉籽粕替代豆粕对肉牛育肥的影响,同时为降低肉牛育肥成本和提高育肥效果提供依据.试验选用年龄(平均年龄为28月龄)、体重[初始均重为(678±122)kg]相近的健康杂交一代阉牛(日本和牛♂×鲁西黄牛♀)40头,随机分成4个试验组,每组10头牛.预试期为15 d,正试期240 d.结果表明:蛋白质水平为14.8％的饲粮组试验牛的日增重比蛋白质水平为12.8％的饲粮组提高18.57％(P ＞0.05).与饲喂蛋白质水平为12.8％的饲粮相比,饲喂蛋白质水平为14.8％的饲粮可以显著或极显著提高肉牛的屠宰率、净肉率、肋部脂肪厚、背膘厚(P＜0.05或P＜0.01),而对肉牛的胴体产肉率、眼肌面积、高档肉块占活重比例、肉骨比影响不显著(P＞0.05).同等蛋白质水平下,用棉籽粕全部或部分替代豆粕对肉牛日增重及各项屠宰性能指标的影响均不显著(P＞0.05),但棉籽粕组饲粮单价、肉牛每千克增重成本都低于豆粕组.由此得出,在肉牛育肥后期可以用棉籽粕替代豆粕,以降低成本.目前我国《肉牛饲养标准》(2004)推荐的肉牛育肥所需的蛋白质水平低于本试验用杂交一代阉牛(日本和牛♂×鲁西黄牛♀)的需要.

Effects of Dietary Protein Level and Replacing Soybean Meal with Cottonseed Meal on Fattening of Beef Cattle

In order to study the effects of protein level and replacing soybean meal with cottonseed meal on fattening of beef cattle,diets with different protein levels and costs were prepared by replacing soybean meal with cottonseed meal based on meeting nutrient requirement of beef cattle.Forty healthy first-filial generation beef cattle(Japanese black cattle ×Luxi yellow cattle ♀) with similar age(average age was 28-month-old) and body weight [average body weight was(678±122) kg] were randomly divided into 4 experimental groups with 10 beef steers per group.The adjustment period lasted for 15 days,and the experimental period lasted for 240 days.The results showed as follows: compared with the group with the diet containing 12.8% protein,the daily gain of beef cattle in the group with the diet containing 14.8% protein was increased by 18.57%(P>0.05).The dressing percentage,meat percentage,rib fat thickness and backfat thickness of beef cattle fed 14.8% protein diet were significantly increased than those of beef cattle fed 12.8% protein diet(P<0.05 or P<0.01),but feeding 14.8% protein diet had no significant effect on the carcass meat percentage,eye muscle area,percentage of high-value cuts to live weight and meat-bone ratio(P>0.05).Under the same protein level,partial or whole replacing soybean meal with cottonseed meal had no effect on the daily gain and carcass traits of beef cattle(P>0.05),but the unit price of diets and costs of per kilogram of weight gain in cottonseed meal group were lower than those in soybean meal group.In conclusion,using cottonseed meal instead of soybean meal in the later stage of fattening of beef cattle is viable to reduce feeding costs.The demand of protein level for beef cattle recommend by current Feeding Standard of Fattening of Beef Cattle(2004) is lower than that for first-filial generation cattle(Japanese black cattle ×Luxi yellow cattle ♀) in this experiment.