Study of Shearing Effect on Performance and Some Physiological and Metabolic Parameters in Dalagh Lambs under Ambient Heat Stress

The aim of the study was to investigate the effect of shearing on performance and some metabolic and physiologic parameters in fattening lambs under heat stress, 16 male, fattening Dalagh lambs3. (5±0.5 months of age) were divided into two groups and maintained individually for adaptation. One group was completely shorn and another left unshorn. Duration of the study was four consecutive weeks after the shearing. Weight changes were recorded weekly and feed intake was measured three times a week. Rectal temperature, heart rate and respiratory rate were weekly measured. Blood samples were collected and used for blood metabolites and hormone's determinations. Results showed that shearing has no significant effects on feed intake and weight gain over the study. Feed conversion ratio was improved (P<0.05) by the shearing (10.70 vs. 13.26). Shearing caused a non-significant decline in rectal temperature (P>0.05). Heart rate was not affected by the shearing, but respiratory rate was significantly decreased (P<0.05) by the shearing. Blood glucose, urea and total protein levels were not affected by the shearing. The marked decline in respiratory rate and relative decline in rectal temperature by the shearing indicate a lowered response to heat stress. Furthermore, decrease (P<0.05) in thyroxin level is due to the lower body’s heat production that generally indicating increase in energy retention in the.