Physiological Responses of Lambs Maintained on Varying Levels of Energy Under Heat Exposure

Abstract

An experiment was conducted to assess relationship between dietary energy and heat tolerance in lambs fed to gain @ 100 AOG as per standard during summer in animal shed (G₁) or in sun (G₂) or fed 115% (G₄) and 130% (Got) of their requirement under sun. Same OM) was maintained in all the groups. Water intake was higher in sun-exposed G₂. G₃, and G₄ compared to that of animals in shade (GJ). During summer. the respiration rate (RR) of lambs was 51 beats min-) in the morning. which increased by 129% to 116 beats min-) in the afternoon. The RR was higher in sun-exposed groups compared to animals in the shed. Among the sun-exposed groups. it was higher in G₃ and G₄. The pulse rate increased from 88 to 108 counts minot from morning to peak hot period. hut was lower in G₁ and G₂ than in high-energy-fed G₃ and G₄. Sweating rate was higher in sun-exposed animals. compared to those in the shed. It was higher when RH and ambient temperature were high. Blood sugar content was also higher in G₁, and G₂ than in G₁ and G₂. The results indicated that water consumption and physiological responses of sun-exposed groups were higher compared to animals in shade. Among the sun-exposed groups. the responses were less pronounced in high-energy-fed groups than in the lambs fed as per requirement.