Comparative study on short-term fattening of Hu and Australian-Hu F₁ lambs

In this study, the production performance, slaughtering performance, body composition, and muscle quality of Hu and Australian-Hu F₁ lambs (Australian white sheep ♂ × Hu sheep ♀) were compared and evaluated. Equal numbers (61 each) of Hu and Australian-Hu F₁ lambs were randomly selected and kept under the same feeding conditions and diets. Their fattening and performance were measured and they were slaughtered immediately after the fattening period. The results showed that there was no significant difference in the initial body weight (0 d) and final body weight (60 d) (P > 0.05, average daily weight gain and average daily feed intake between Hu and Australian-Hu F₁ lambs over the total fattening period, although the daily weight gain of Hu lambs in the early fattening period (0～20 d) was significantly higher than that of Australian-Hu F₁ lambs (P > 0.05, while the daily weight gain of Australian-Hu F₁ lambs in the middle fattening period (20～40 d) and late fattening period (40～60 d) was significantly higher than that of Hu lambs (P < 0.05). There were no significant differences in carcass weight, dressing percentage, carcass grade (GR), and back fat thickness between Hu and Australian-Hu F₁ lambs (P > 0.05), and the differences in carcass chest circumference, carcass hip circumference and eye muscle area in Australian-Hu F₁ lambs were significantly higher than in Hu lambs (P < 0.05). Heart weight, liver weight, lung weight and its relative weight (pre-mortem weight) were all significantly (P < 0.01) higher in Australian-Hu F₁ lambs than Hu lambs, but fur weight, perirenal fat weight, mesenteric weight, tail fat weight and its relative weight (pre-mortem weight) were all significantly (P < 0.01) lower than Hu lambs. The rate of meat ripening and muscle pH₁ 45 min were significantly higher in Hu than in Australian-Hu F₁ lambs (P < 0.01), but the muscle water loss rate, meat color 24 h b*₂ value and meat color 24 h l*₂ value were significantly higher in Australian-Hu F₁ lambs (P < 0.05). In general, the early growth and development of Hu lambs were faster, but the later growth potential of Australian-Hu F₁ lambs was greater, and the carcass performance was better than Hu lambs, with less carcass fat deposition than Hu lambs and significantly improved meat performance.