Plasma leptin as a predictor for carcass composition in growing lambs

The experiment was conducted on 30 single born Polish Merino ram lambs. At the age of 112 d, 10 ram lambs were slaughtered at 20 kg (group 1), 25 kg (group 2), and 30 kg (group 3) live weight. Plasma leptin increased between 20 and 25 kg, as well as 25 and 30 kg live weight. The differences between group 1 vs. group 3 and group 2 vs. group 3 were statistically important (P < 0.001). The lack of differences in meat content of the pelvic limb between the groups and, at the same time, the lower fat content (P < 0.001) in group 1, plus the higher fat content of the two remaining groups, are evidence of the higher fatness of carcasses in groups 2 and 3. The fat tissues except the subcutaneous fat were significantly related with the leptin concentrations at slaughter. The leptin concentration of lambs slaughtered at 30 kg live weight surpassed significantly the values noted in groups 1 and 2 (P < 0.001). The correlations between leptin and body composition indicate that plasma leptin concentration at 30 kg live weight can be a predictor of body fat. The correlation of meat weight with leptin concentration has shown no statistical differences.