Effect of thermal stress on plasma levels of IgG, leptin and IGF-1 of transition Sahiwal and Karan Fries cows

Abstract

Thermal stress is a unique and complex mechanism that causes alterations of the normal physiological mechanisms which elicits a stressful response in animals around parturition. The present study was conducted where twelve pregnant dry Sahiwal and Karan Fries cows each respectively were selected 15 days prepartum from the Livestock Research Centre of National Dairy Research Institute, Karnal. The experiment was divided into two parts. Experiment-I (thermoneutral conditions) and Experiment–II (summer season) were carried out on 6 Sahiwal and Karan Fries cows each in each season when the average maximum and minimum temperatures were (16.5˚C and 8.3˚C) and (34.2˚C and 21.4˚C), respectively. Blood samples were collected on -15, 0 and +15 days with respect to calving where day ‘0’ represents the day of calving. The plasma samples were analyzed for leptin, IGF-1 and IgG. Plasma level of IGF-1 levels were significantly (p<0.0001) lower during summer as compared to the thermoneutral condition. Also the levels were significantly (p<0.0001) lower on day of calving with respect to 15 days pre and post calving in both the breeds. Plasma level of leptin and IgG decreased significantly (p<0.01) on the day of calving with respect to 15 days pre and post calving. The study suggests that the animal requires protection during extreme climatic conditions and climate change scenario.