青稞替代玉米对育肥牦牛生产性能和肉品质的影响

本试验旨在研究青稞替代玉米对育肥牦牛生产性能、屠宰性能、养分表观消化率及肉品质的影响。采用2×3交叉设计,以日粮类型(玉米、60%青稞+40%玉米)和不同精粗比(30∶70、40∶60和50∶50)为两因素,选取36头年龄4周岁左右、体重为(144±21.0)kg的麦洼公牦牛,随机分为6组,每组6个重复,每个重复1头牛。预饲期15d,正试期180d。结果表明:1)日粮类型及精粗比对牦牛生产性能无显著影响(P>0.05)。2)青稞-玉米组的净肉率显著高于玉米组(P<0.05),但屠宰率和眼肌面积无显著差异(P>0.05);精粗比对屠宰性能无显著影响(P>0.05);日粮类型和精粗比二因素对眼肌面积的互作影响显著(P<0.05),以青稞-玉米(40∶60)组效果最优。3)日粮类型对养分表观消化率无显著影响(P>0.05);与30∶70相比,40∶60和50∶50极显著提高了有机物(OM)和总能(GE)的表观消化率(P<0.01)、显著提高了粗蛋白(CP)的表观消化率(P<0.05);日粮类型和精粗比二因素对GE、OM和粗脂肪(EE)的表观消化率有显著的互作影响(P<0.05),以玉米(40∶60)组效果最佳。4)青稞-玉米组和玉米组背最长肌亮度值(L*)、红度值(a*)、pH值均无显著差异(P>0.05),但青稞-玉米组的黄度值(b*)和滴水损失显著低于玉米组(P<0.05)、蒸煮损失极显著低于玉米组(P<0.01);随着精粗比的升高,蒸煮损失有逐渐降低的趋势(P=0.075)。5)日粮类型对背最长肌的嫩度无显著影响(P>0.05);随着精粗比的升高,剪切力逐渐减小(P>0.05),肌纤维直径有减小的趋势(P=0.059),肌纤维密度显著增加(P<0.05),肌纤维面积显著减小(P<0.05)。综上所述,以青稞替代日粮中60%的玉米能够提高育肥牦牛的屠宰性能,改善牦牛肉的品质;日粮精粗比为40∶60时饲喂效果最佳。

Effects on production performance,slaughter performance,apparent digestibility of nutrients and meat quality of partial substitution of corn concentrate with highland barley in a yak fattening system

This study was conducted to investigate the effects of partial substitution of corn concentrate by highland barley in a yak fattening system. The experiment comprised a factorial combination of two levels of diet type (100% corn; 60% highland barley+40% corn) and three different concentrate∶forage ratios (CFR, 30∶70, 40∶60, 50∶50). Healthy Maiwa male yaks n=36; 4 years of age; (144±21.0) kg body weight] were randomly divided into 6 groups, of 6 animals. Hence, the individual animals in each group were taken as experimental replicates. There was a pre-experimental period of 15 days, followed by a trial period of 180 days. Data collected included: production performance, slaughter performance, apparent digestibility of nutrients, muscle physical and chemical indexes, muscle tenderness and fiber characteristics of the yaks. It was found that: 1) Diet type and concentrate∶forage ratio had no significant effect on production performance (P>0.05). 2) The net meat percentage of the 60%-40% barley-corn group was significantly higher than that of the 100% corn group (P<0.05), but no significant differences between the two diet-type groups in dressing percentage and eye muscle area were observed (P>0.05). CFR had no significant effect on slaughter performance (P>0.05). There were significant interaction effects between the dietary types and concentrate∶forage ratios on the eye muscle area (P<0.05), and the best group was 60%-40% barley-corn with 40∶60 CFR. 3) Diet type had no significant impact on apparent digestibility of nutrients. However, compared with the 30∶70 CFR, the apparent digestibilities of organic matter (OM), gross energy (GE) and crude protein (CP) were significantly improved in the 40∶60 and 50∶50 CFR groups (P=0.002, 0.003 and 0.018, respectively). Significant interactions were observed between diet type and CFR, for the apparent digestibility of gross energy (GE), organic matter(OM), and ether extract (EE) (P<0.05), with the best group being 100% corn with 40∶60 CFR. 4) No significant difference was found between diet types for lightness value (L^*), redness value (a^*) and pH in the longissimus dorsi muscle (P>0.05), but the yellowness value (b^*), drip loss and cooking loss of the 60%-40% barley-corn group were significantly lower than those of the 100% corn group (P=0.044, 0.048 and 0.003, respectively). With increasing CFR, cooking loss decreased (P=0.075). 5) Diet type had no significant effect on muscle tenderness (P>0.05). However, with increased CFR, shear force was decreased (P>0.05), muscle fiber diameter was decreased (P=0.059), muscle fiber density was significantly increased (P<0.05), and muscle fiber area was significantly decreased (P<0.05). In conclusion, a 60% substitution of highland barley in a corn concentrate diet in a yak fattening system, improved the slaughter performance, and meat quality. Considering all the data, the optimal dietary concentrate∶forage ratio for yaks in this study was 40∶60.