Endocrine and hematobiochemical profile of lambs raised in a semiarid region with different growth potentials during the postweaning period

This study was conducted for establishment of the relationship of blood variables with growth rate of postweaned lambs. Eight lambs each of fast growth (FG; 11.6 ± 0.5 kg live wt. at weaning) and slow growth (SG; 7.7 ± 0.5 kg live wt. at weaning) were monitored fortnightly for endocrine and hematobiochemical variables along with parasitic load and growth performance. Recording of body weight (BW) and average daily gain (ADG) was performed monthly from birth to 180 days. Triiodothyronine (T3) and thyroxine (T4) were significantly (P < 0.05) higher while thyroid-stimulating hormone (TSH) and insulin-like growth factor-1 (IGF-1) were significantly (P < 0.05) lower in FG lambs compared to SG lambs. Blood cell counts, hematocrit, hemoglobin, mean corpuscular volume, and mean corpuscular hemoglobin were significantly (P < 0.05) higher in FG lambs compared to SG lambs. Except for the birth wt., the BW and ADG of FG lambs were significantly (P < 0.05) higher at all time points. Liver enzymes (alkaline phosphatase and alanine aminotransferase) and triglyceride were significantly (P < 0.05) higher in SG lambs compared to FG lambs. These findings indicate a significant influence of growth rate on peripheral concentrations of endocrine and some hematobiochemical variables in lambs. These selected variables can be used for early identification and culling of slow-growing lambs for better economic return to lamb producers.