Effect of different diet level on the physiological adaptability, biochemical and endocrine responses and relative hepatic HSP70 and HSP90 genes expression during summer season in Osmanabadi kids

Abstract

The study was conducted to investigate the impact of different levels of feed on the adaptive capability based on physiological, blood biochemical, endocrine and molecular mechanisms in growing Osmanabadi kids. The primary objective of the study was to identify if HSP70 and HSP90 can be a nutritional stress marker for goat. The study was conducted for a period of two months. The animals were randomly divided into three groups as GI (n = 6; ad libitum feeding), GII (n = 6; 20% less than ad libitum) and GIII (n = 6; 40% less than ad libitum). The animals were fed with feed consisting of 50% roughage and 50% concentrate. Blood collection was carried out at fortnightly intervals. Body weights were recorded at weekly interval. Physiological responses, biochemical responses, plasma tri-iodo-thyronine (T3), thyroxin (T4) and cortisol were recorded at fortnightly interval. At the end of study period, only GI and GIII animals were slaughtered and different organs were collected for histopathological studies as well as for hepatic HSP70 and HSP90 mRNA transcript expression. Body weight recorded showed significant (P < 0.01) differences between the groups. Physiological responses showed significant (P < 0.01) variation among the groups. Among the biochemical parameters, plasma glucose and total plasma protein and globulin showed significant (P < 0.01) differences between the groups. Plasma T3 (P < 0.01), T4 (P < 0.01) and cortisol (P < 0.05) also differed significantly between the groups. The relative hepatic HSP70 mRNA transcript expression was significantly (P < 0.05) higher in GIII (2.8 fold) as compared to GI (1 fold) kids. Similar result was obtained for hepatic HSP90 mRNA transcript expression. From the results, it can be concluded that Osmanabadi kids possessed the ability to alter their adaptive mechanisms to maintain homeostasis. Further, the study revealed the significance of providing the optimum nutrition for these animals to adapt to existing environmental conditions. The study also established that respiration rate (RR), rectal temperature (RT), T3, T4 and cortisol are considered as nutritional stress markers for goat. Further, the results revealed that probably this is the first study to establish the nutritional stress impact on heat shock protein (HSP) expression in goats. The study identified both HSP70 and HSP90 to be the ideal molecular markers for feed deficit in goat