The dynamic adaptation of Brazilian Brahman bulls

Publication date: April 2019Source: Journal of Thermal Biology, Volume 81Author(s): Débora Andréa E. Façanha, Josiel B. Ferreira, Jacinara Hody G. Morais Leite, José Ernandes R. de Sousa, Magda M. Guilhermino, Wirton P. Costa, Luis A. Bermejo Asensio, Angela Maria de Vasconcelos, Robson Mateus F. SilveiraAbstractHeat stress is one of the most important factors that affect the performance of some Bos taurus breeds and crosses in tropical regions. The Brahman breed was developed in hot regions of the world and often has genes that confer resistance to heat stress compared to other breeds of beef cattle. The goal of this work was to evaluate the adaptive responses of Brahman bulls, based on physiological, hormonal and hair characteristics according to season. The physiological, hormonal and hair characteristics were rectal temperature (RT), respiratory rate (RR), sweating rate (SR), triiodothyronine (T3), thyroxine (T4), cortisol concentrations (CO), coat thickness (CT), hair length (HL), hair diameter (HD) and hair density (ND). These were recorded in Brahman bulls from a Cerrado biome during four seasons: spring (21 September to 20 December), summer (21 December to 17 March), autumn (18 March to 20 June) and winter (21 June to 20 September). Data was analyzed using a general linear model that included season as a fixed effect; in addition, multivariate tests and logistic regression were also used to characterize the animals within each season. The meteorological variables ...
Source: Journal of Thermal Biology - Category: Biology Source Type: research