Physiological responses and metabolic profile of lambs in growth phase

Growth performance and metabolic profile of native Nali (N), Chokla (C) and their crosses with Rambouillet (RC and RN) and Merino (MC) lambs maintaine d on grazing with supplementation was assessed in a study extending from bi rth to 6 months of age. Birth and weaning weights were higher in crossbred than the native lambs. Respiration rate and rectal temperature were also hi gher in crossbred than the native lambs. The RR, PR and RT were higher at b irth and gradually decreased reaching the adult values by 6 months of age. Haematocrit and haemoglobin concentrations were higher at birth compared to other age groups although similar in these genotypes. Total plasma protein was higher in lambs at birth with significant (P<0.01) fall at 14th day ag e followed by increasing trend. Blood urea nitrogen (BUN) content was highe r (P<0.01) at birth and 3 and 6 months of age than 15th day of age and gene rally higher in crossbred than that in native breeds. Concentrations of sod ium, potassium and chloride were within normal range of variation. It is co ncluded from the study that although the crossbred lambs exhibited greater physiological distress than the native breeds still their growth rate was h igher. Higher blood urea nitrogen value of these lambs indicated that their protein allowance was more than the requirement.