Study on growth performance, slaughter performance, and musclequality of Hu sheep with different daily gain

The growth performance indices of Hu sheep male lambs during the fattening period such as feed intake, body size, and body weight in 80～180 days were measured by single pen feeding for 20 days as a test cycle, with the aim of studying the effect of average daily gain (ADG) on growth performance, slaughter performance, and muscle quality of Hu sheep. Slaughter performance and muscle quality were measured immediately after the measurement of growth performance. According to the ADG from 80 to 180 days, the test group was divided into high (H), medium (M), and low (L) groups, with 76, 110, and 66 Hu sheep, respectively. The results showed that: 1) The increases in body height, body length, and chest circumference of Hu sheep in group H were significantly higher than those in group L (P < 0.05), and better than those in group M (P > 0.05). 2) The pre-slaughter live weight, carcass weight, and carcass length of Hu sheep in group H were significantly higher than those in group L (P < 0.05), and the proportion of head and hoof weight and organ weight (except liver weight) to pre-slaughter live weight of Hu sheep in group L was significantly higher than those in the other two groups (P < 0.05), and the proportion of liver weight and its proportion to pre-slaughter live weight in group H were significantly higher than those in groups L and M (P < 0.05); the GR value, backfat thickness, tail fat weight, perirenal fat weight, and mesenteric fat weight in group H were significantly higher than those in the other two groups (P < 0.05), and the proportion of mesenteric fat weight to pre-slaughter live weight was significantly higher than that in group L (P < 0.05). 3) There were no significant differences (P > 0.05) between the three groups of Hu sheep in terms of cooked meat percentage, water loss, drip loss, shear force, pH₁, and 24 h meat color. Furthermore, 45 min a* (redness) and 45 min b* (yellowness) were significantly higher in group L than in the other two groups (P < 0.05), and pH₂₄ and 45 min L* (brightness) were significantly lower in group H than in the other two groups (P < 0.05). The production performance of Hu sheep in group H was the best, with higher body weight and meat production absolute value, and there was no significant difference in muscle quality among the three groups. The relative weight of the liver had a significant effect on the growth rate of Hu sheep, which may be related to the metabolic capacity of the liver, but the exact mechanism needs to be confirmed by further studies.