Physiological responses and metabolic profile of lambs in growth phase

Abstract

Growth performance and metabolic profile of native Nali (N), Chokla (C) and their crosses with Rambouillet (RC and RN) and Merino (MC) lambs maintained on grazing with supplementation was assessed in a study extending from birth to 6 months of age. Birth and weaning weights were higher in crossbred than the native lambs. Respiration rate and rectal temperature were also higher in crossbred than the native lambs. The RR, PR and RT were higher at birth 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 age followed by increasing trend. Blood urea nitrogen (BUN) content was higher (P<0.01) at birth and 3 and 6 months of age than 15th day of age and generally higher in crossbred than that in native breeds. Concentrations of sodium, potassium and cbloride were within normal range of variation. It is concluded from the study that although the crossbred lambs exhibited greater physiological distress than the native breeds still their growth rate was higber. Higher blood urea nitrogen value of these lambs indicated that their protein allowance was more than the requirement.