不同蛋白能量水平日粮对肉牛生产性能和肉品质的影响

Effects of different energy and protein levels on growth performance and beef quality in the bull

采用单因素随机区组设计,选择体重相近的健康肉牛40头,随机分成4组,分别饲喂低（Ⅰ）、中（Ⅱ）、较高（Ⅲ）和高（Ⅳ）能量蛋白水平日粮,研究不同能量蛋白水平对肉牛生长性能、屠宰性能、肉品质和血液指标的影响.结果表明：随着日粮能量蛋白水平的增加,试验牛的日增重不断提高,由959 g/d提高到1 181 g/d,提高21.88％ （P＜0.05）;各试验组屠宰率和净肉率差异显著（P＜0.05）,Ⅳ组最高,分别为60.84％和49.21％;背膘厚度试验各组差异显著（P＜0.05）,Ⅲ组最高,达到106.5 mm;各组间肉的剪切力无显著差异（P＞0.05）;各试验组牛肉中饱和脂肪酸和单不饱和脂肪酸含量无显著差异（P＞0.05）,但多不饱和脂肪酸存在显著差异（P＜0.05）,其中Ⅲ组多不饱和脂肪酸含量最高,为6.7％,Ⅰ组最低为5.31％,相对提高26.18％ （P＜0.05）;每日每头经济效益最高达6.91元,最低为3.14元,相对多收入3.77元.因此,本试验条件下,在BMY育肥过程中,200～ 350 kg体重阶段以Ⅲ组能量和蛋白质水平较为适宜,经济效益最高。

The experiment was conducted to study the effect of different levels of energy and protein on growth performance and blood bio- chemical index by using a single factorial design and 40 heads of bulls with similar weight and health were selected. These bulls were ran- domly divided into four groups that were relatively fed low, medium and high energy-protein levels dairy ration. The results showed that the daily gain of cows was improved as increases of diet energy-protein levels. The average day gain （ADG） was relatively increased about 21.88% （ P〈0.05 ） from 959 g/d to 1 181 g/d. The slaughter rate and pure meat percentage were found significantly different among groups （P〈0. 05） , and the highest was in group Ⅳ, their value were 60. 84% and 49. 21%. Back fat thickness were highest in group Ⅲ and reached to 106. 5 mm （P〈0.05）. The shear force has no significantly different （ P〉0.05 ）. The saturated fatty acid and monounsaturated fatty acid contents of beef in four groups were not significantly different （ P〉0. 05 ）, but the polyunsaturated fatty acid was different signifi- cantly （P〈0. 05）. The lowest monounsaturated fatty acid contents were in group Ⅰ of 5.31% and the highest were in group Ⅳ of 6. 70% , relative reduced by 26. 18% （P〈0. 05）. The highest income of everyday each cow was 6. 91 RMB but the lowest was 3.14 RMB, increased 3.77 RMB. Together, our finding suggested that the energy and protein level in group Ⅲ was appropriate and economic benefit was the high- est in the BMY finishing process during 200 -350 kg weight under this experimental condition.