不同营养水平日粮对奶公牛直线育肥性能的影响

Nutrition effects on growth of Holstein bulls

为了研究不同能量和蛋白质水平日粮对奶公牛直线育肥性能的影响.选择4～5月龄左右、平均体重为121kg的奶公犊36头,随机分成两组,试验Ⅰ组（饲喂低营养水平日粮）、试验Ⅱ组（饲喂高营养水平日粮）,每组18头.试验期440d.整个育肥试验以12月龄划分为前期和后期2个阶段.结果表明,整个育肥期,试验Ⅱ 组的平均日增重比试验Ⅰ组提高了5.83%（P〉0.05）,料重比降低了3.11%（P〉0.05）.试验Ⅱ组的粗蛋白质、粗脂肪、中性洗涤纤维、酸性洗涤纤维、钙和磷的表观消化率较高,但是与试验Ⅰ组差异不显著（P〉0.05）.试验Ⅱ 组的谷草转氨酶、谷丙转氨酶、生长激素、甲状腺素含量比试验Ⅰ组显著提高了8.27%,13.85%,6.70% 和1.26%（P〈0.05）.血清尿素氮含量降低了12.22%（P〈0.01）.两个营养水平日粮对屠宰率、胴体产肉率和净肉率没有影响.随着营养水平的提高,pH、剪切力、蒸煮损失、失水率有下降的趋势,牛肉中的蛋白质和脂肪含量有上升的趋势,但差异不显著（P〉0.05）.与试验Ⅰ 组相比,试验Ⅱ 组的pH、剪切力、蒸煮损失和失水率分别降低了2.34%,12.97%,18.30%和3.38%,牛肉中粗蛋白和粗脂肪含量分别提高了4.95%和8.55%.养殖效益试验Ⅱ组比试验Ⅰ组多收入0.98元/（日·头）,全期效益试验Ⅱ组比试验Ⅰ组多收入431.20元/头.因此,提高日粮的营养水平,可以促进奶公牛的生长、改善肉品质和增加经济效益.

The objective of this trial was to evaluate the effects of different dietary energy and protein levels on linear-fattening performance of Holstein bulls.Thirty six Holstein bulls(mean live weight 121kg)aged 4-5months were allocated into two equal groups;group I(low nutrition diet)and groupⅡ(high nutrition diet).The experimental period continued for 440 days.The average daily gain(ADG)of groupⅡ was 5.83% higher(P>0.05)than that of group I,but the feed/gain ratio of group Ⅱ was 3.11%lower than that of group Ⅰ(P>0.05).There was no difference between groupⅠ andⅡin the apparent digestibility of crude protein,ether extract,neutral detergent fiber,acid detergent fiber,calcium and phosphorus.Glutamic-oxalacetic transaminase,glutamic-pyruvic transaminase,growth hormone and tetraiodothyronine in the blood of groupⅡbulls were increased by 8.27%,13.85%,6.70%and 1.26%(P<0.05)compared with group I bulls,respectively.The amount of blood urea nitrogen was significantly decreased 12.22%(P<0.01).Nutrition level had no effect on the dressing percentage,carcass weight and net meat percentage.Compared with group I,pH,drop loss,shear force and dehydration rate of groupⅡ were decreased by 2.34%,12.97%,18.30% and 3.38% at72 h,respectively.The amount of crude protein and ether extract were increased by 4.95%and 8.55%.The economic advantage of groupⅡ bulls was 0.98yuan/(head·day)compared to groupⅠ.The total benefit from groupⅡbulls was 431.20yuan/head.Increasing energy and protein levels in diets of young Holstien bulls promoted growth and meat quality and the economic outcomes.