持续高温应激对肥育猪生产性能、胴体性状、背最长肌营养物质含量及肌纤维特性的影响

Effects of Constant Heat Stress on Performance,Carcass Traits,Nutrition Content and Myofiber Characteristics of Longissimus Dorsi in Finishing Pigs

本试验旨在研究持续30℃的环境高温应激对肥育猪生产性能、胴体性状、背最长肌质构分析、营养物质含量及肌纤维特性的影响。试验选取8窝共24头体重为(79.0±1.5)kg的"杜长大"三元阉公猪,其中每3头来自同一窝的猪只随机分到3组,每组8个重复,每个重复1头,3组分别为对照组(22℃适温+自由采食)、高温应激组(30℃高温+自由采食)和采食量配对组(22℃适温+采食量配对),试验期21 d。结果表明:1)持续高温应激显著降低肥育猪平均日增重(ADG)(P<0.05),极显著降低肥育猪平均日采食量(ADFI)(P<0.01)。2)3组之间的肥育猪胴体重、胴体长、平均背膘厚和皮厚均差异不显著(P>0.05),高温应激组肥育猪背最长肌大理石花纹评分在宰后24 h有低于对照组的趋势(P<0.10)。3)高温应激组肥育猪背最长肌的剪切力极显著高于对照组和采食量配对组(P<0.01)。与采食量配对组相比,高温应激组肥育猪背最长肌胶黏性和硬度有降低的趋势(P<0.10)。4)高温应激组和采食量配对组肥育猪背最长肌粗蛋白质含量显著高于对照组(P<0.05),且2组的背最长肌肌内脂肪(IMF)含量极显著低于对照组(P<0.01)。5)高温应激组肥育猪背最长肌Ⅰ型肌纤维含量有低于采食量配对组的趋势(P<0.10),采食量配对组的Ⅱx型肌纤维含量显著低于对照组(P<0.05)。由此可见,肥育后期高温应激会改变猪表观肉品质和肌肉营养物质含量。

This experiment was conducted to study the effects of constant high temperature stress on perform- ance, carcass traits, texture profile analysis, nutrition content and myofiber characteristics of longissimus dorsi in finishing pigs. Castrated 24 male Landracex Yorkshire sowsx Duroc boars （DLY） pigs were selected from 8 litters with body weight of （79.0_＋1.5） kg, and randomly divided into 3 groups with 8 replicates per group and 1 pig per replicate. Within each litter the three pigs were allocated to one of three groups： control （CR） group （constant optimal ambient temperature at 22 ~C ＋ ad libitum feeding）, heat stress （HS） group （con- stant high ambient temperature at 30 ~C ＋ ad libitum feeding） and pair-fed （PF） group （constant optimal am- bient temperature at 22 ~C ＋ pair-fed）. Each group had 8 pigs. The experiment lasted for 21 d. The results showed as follows： 1 ） the average daily gain （ADG） of HS group was significantly reduced （P〈0.05） and the average daily feed intake （ADFI） of HS group was significantly lower （ P〈0.01 ） than that of CR group. 2） No significant differences were observed on carcass weight and length, backfat thickness and skin depth a- mong three groups （P〉0.05）, while the 24 h marbling score in longissimus dorsi of HS group has a lower trend than CR group （P〈0.10）. 3） The shear force of HS group was significantly increased compared with the CR and PF groups （ P〈0.01 ）, the longissimus dorsi of HS group had the tendency of lower adhesiveness and hardness than that of PF group （P〈0.10）. 4） Compared with CR group, the intramuscular fat （IMF） content in longissimus dorsi of HS and PF groups were significantly decreased （ P〈0.01 ）, and the crude protein （CP） content was significantly increased （P〈0.05）. 5） The ratio of type 1I x in longissimus dorsi of PF group was significantly lower than that of CR group （P〈0.05）, and the ratio of type I in longissimus dorsi muscle of HS group had lower trend than that of PF group （ P〈O. 10）. In conclusion, constant high temperature stress has a significant influence on apparent pork quality and muscle nutrition content of finishing pigs.