Biological rhythmicity of the plasma antioxidant defence in lambs following supplementation of micronutrients or providing shelter in temperature-controlled microenvironment in summer

摘要

Antioxidant defence is one of the important biological adaptations to thermal stress in animals. Micronutrients play crucial roles in the bioactivity of several antioxidant systems. Shelter management by providing a thermo-comfort micro-environment to animals may also combat the heat stress during summer. Hence, the aim of the present study was to assess the biological ability of Malpura lambs to counter thermal stress following supplementation of micronutrients and providing shelter in a temperature-controlled climatic chamber during the hot day-hours in summer. Twenty-one lambs of 3 - 5 months age were equally divided in to three group viz. Group1: control, Group2: micronutrient- supplemented and Group3: housing in thermo-neutral climatic chamber. Lambs in group1 and 2 were maintained in a shed having free access to hot wind while the lambs in group 3 were kept inside a climatic chamber (temperature and relative humidity about 30 degrees C and 40%, respectively) between 10 am to 4:30 pm. All the lambs were provided identical diet consisting of 2.5 kg concentrate and ad libitum quantities of Cenchrus ciliaris hay and clean water. Group3 lambs were additionally supplemented with 0.150 g micronutrient pellet per animal per day for a period of 30 days. Blood samples were collected at 0, 15, 30 days and plasma antioxidants activity were estimated. The catalase activity in the micronutrient-pellet supplemented group was significantly (p < 0.05) higher than the control both at day15 and day30. The superoxide dismutase activity was increased significantly (p < 0.05) at day30 than the day0 in both the micronutrient-supplemented and climatic chamber groups. In conclusion, both the micronutrient supplementation and housing in a thermo-comfort environment enhance the antioxidant defence and biological adaptation in lambs during thermal stress in summer.