摘要
本试验旨在研究低蛋白质饲粮对滩羊生长性能、消化代谢、屠宰性能及肉品质的影响.选择3月龄健康、体况相似、平均体重在(21.58±7.94)kg的滩羊36只,随机分为4组,每组3个重复,每个重复3只.对照组饲喂蛋白质水平为13％的饲粮,3个试验组分别饲喂比对照组饲粮蛋白质水平降低1％(试验Ⅰ组)、2％(试验Ⅱ组)和3％(试验Ⅲ组)的能氮平衡的饲粮.预试期10 d,正试期60 d.结果显示:1)滩羊的初始体重、终末体重以及干物质采食量各组间均无显著差异(P＞0.05);对照组与试验Ⅰ组的平均日增重显著高于试验Ⅱ组与试验Ⅲ组(P＜0.05);料重比以试验Ⅰ组最低,与对照组差异不显著(P＞0.05),但显著低于试验Ⅱ组与试验Ⅲ组(P＜0.05).2)干物质、中性洗涤纤维和酸性洗涤纤维的表观消化率各组之间均无显著差异(P＞0.05).3)对照组的进食氮显著高于试验Ⅱ组和试验Ⅲ组(P＜0.05),粪氮、尿氮显著高于试验Ⅰ组、试验Ⅱ组和试验Ⅲ组(P＜0.05);然而,各组在沉积氮、氮消化率、氮利用率上的差异均不显著(P＞0.05);相比之下,试验Ⅰ组、试验Ⅱ组和试验Ⅲ组的氮生物学价值分别较对照组提高2.13％(P＜0.05)、1.54％(P＞0.05)和0.54％(P＞0.05).4)饲喂低蛋白质饲粮对滩羊的宰前活重、头重、蹄重、骨重、骨肉比无显著影响(P＞0.05),对GR值、眼肌面积、尾部脂肪重、胴体脂肪重也均无显著影响(P＞0.05);胴体脂肪重随着饲粮蛋白质水平的降低而降低;此外,试验Ⅰ组的屠宰率相较对照组、试验Ⅱ组、试验Ⅲ组分别提高5.12％、10.32％、4.65％,但各组之间差异不显著(P＞0.05).5)饲喂低蛋白质饲粮对滩羊肉的pH45min、失水率、剪切力、熟肉率、肉色的红度和黄度值、脂肪颜色以及大理石纹评分均没有显著影响(P＞0.05);对照组的滴水损失率显著高于试验Ⅲ组(P＜0.05);试验Ⅲ组的肉色亮度值显著高于对照组与试验Ⅰ组P＜0.05).6)各组滩羊肉中水分、粗灰分及粗脂肪含量均差异不显著(P＞0.05);对照组与试验Ⅰ组滩羊肉中粗蛋白质含量显著高于试验Ⅲ组(P＜0.05).综上所述,在能氮平衡的基础上将饲粮蛋白质水平由13％降至12％,不仅可减少氮排放,且不会对滩羊的生长性能、消化代谢、屠宰性能及肉品质产生负面影响.
Abstract
The objective of this experiment was to study the effects of low protein diet on the growth perform-ance,digestion and metabolism,slaughter performance and meat quality of Tan sheep.Thirty-six healthy 3-month-old Tan sheep,with similar body condition and average body weight of(21.58±7.94)kg,were selected and randomly split into four groups with three replicates and each replicate with three sheep.Sheep in control group were fed a diet with 13％protein,while those in trial groups Ⅰ,Ⅱ and Ⅲ were fed diets with protein levels that were 1％,2％and 3％lower than that of control group diet based on the energy-nitrogen balance.The pre-feeding period was 10 d and the formal period was 60 d.The results were as follows:1)there were no significant differences in the initial body weight,final body weight and dry matter intake of Tan sheep among the four groups(P＞0.05).The average daily gain of the control group and trial group Ⅰ was significantly higher than that of trial groups Ⅱ and Ⅲ(P＜0.05).The lowest feed to gain ratio was observed in the trial group Ⅰ,which was not significantly different from that of control group(P＞0.05),but significantly lower than that of trial groups Ⅱ andⅢ(P＜0.05).2)There were no significant differences in the apparent digestibility of dry matter,neutral deter-gent fiber and acid detergent fiber of Tan sheep among the four groups(P＞0.05).3)The nitrogen intake of the control group was significantly higher than that of the trial groups Ⅱ and Ⅲ(P＜0.05),and the fecal nitrogen and urine nitrogen were significantly higher than those of the trial groups Ⅰ,Ⅱ and Ⅲ(P＜0.05),but no significant differences in the retention nitrogen,nitrogen digestibility and nitrogen utilization efficiency were observed a-mong four groups(P＞0.05).In contrast,the biological value of nitrogen of the trial groups Ⅰ,Ⅱ and Ⅲ was higher than that of control group,with an increase of 2.13％(P＜0.05),1.54％(P＞0.05)and 0.58％(P＞0.05),respectively.4)Feeding low protein diets had no significant effects on live weight before slaughter,head weight,hoof weight,bone weight and bone/meat ratio(P＞0.05),and had no significant effects on the GR val-ue,loin eye area,tail fat weight and carcass fat weight of Tan sheep(P＞0.05).However,the carcass fat weight decreased correspondingly with the reduction of dietary protein level.The trial group Ⅰ had a 5.12％,10.32％and 4.65％increase in slaughter rate compared with the control group and trial groups Ⅱ and Ⅲ,respectively,but the difference among groups was not significant(P＞0.05).5)Feeding low protein diet had no significant effects on pH45 min,water loss rate,shear force,cooked meat rate,meat color redness and yellowness values,fat color and marbling score of Tan sheep(P＞0.05).The drip loss of the control group was significantly higher than that of the trial group Ⅲ(P＜0.05).The meat color brightness value of trial group Ⅲ was significantly higher than that of control group and trial group Ⅰ(P＜0.05).6)There were no significant differences among the groups in mois-ture,ash and ether extract contents of mutton for Tan sheep(P＞0.05).The crude protein content of mutton for Tan sheep of the control group and the trial group Ⅰ was significantly higher than that of the trial group Ⅲ(P＜0.05).In conclusion,based on the energy-nitrogen balance,dietary protein level is decreased from 13％to 12％,it can not only reduce nitrogen emission,but also have no negative effects on the growth performance,di-gestive and metabolism,slaughter performance and meat quality of Tan sheep.[Chinese Journal of Animal Nu-trition,2024,36(5):3117-3130]
基金项目
宁夏回族自治区自然科学基金(2022AAC03125)
维普
万方数据