Influence of heat stress on subcutaneous fat thickness and concentration of plasma in leptin in Nelore (Bos indicus) and Angus (Bos taurus) cattle submitted to thermal stress

• Grant number: 15/06933-4
• Support type: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): August 01, 2015
• Effective date (End): July 31, 2016
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Reproduction
• Principal researcher: José Fernando Garcia
• Grantee: Guilherme Andraus Bispo
• Home Institution: Faculdade de Medicina Veterinária (FMVA). Universidade Estadual Paulista (UNESP). Campus de Araçatuba. Araçatuba , SP, Brazil

Abstract

Extreme climatic conditions limitate the reproductive and productive performance due to the stress that it provokes. In bovines, it is known that heat stress is correlated with loss in feed efficiency and weight gain, reflecting in the pattern of subcutaneous fat deposition, where there is evidence of leptin action, protein produced in fat tissue with action in target organs such as the hypothalamus. Therefore, to reduce heat stress, distinct handling practices can be adopted in order to provide thermal comfort. In this context, the shading (natural or artificial) can be responsible for providing thermal comfort and increase productivity. The aim of this study is to compare the effect of levels of thermal comfort (Treated = without shading and Control = with shading) between subspecies of taurine and indicine cattle as well as its impact on fat metabolism. The analysis of plasma concentrations of leptin and fat thickness in Bos taurus (Angus n = 22) and Bos indicus (Nelore n = 22) cattle submitted or not to heat stress will be performed. Biological samples (blood) and carcass ultrasound images will be used to quantify plasma leptin and measure the thickness of subcutaneous fat, respectively. Such information will allow the analysis of the effects of heat exposure in the group of animals, with particular interest to the different response between the Treated and Control groups and between the two subspecies of bovine cattle. (AU)