Avaliação da produção leiteira e tolerância ao calor de vacas da raça girolando

Abstract

The Brazil has tropical climate with high temperatures during most the year, it contributes to limit milk yield of cow races from temperate regions. As the cows more productive are from europeans countries, which has different climate conditions compared with Brazil climate, there was necessity search animals more tolerant to the rigors of tropics. One of strategies utilized was the adoption of schemes of crossing between europeans and zebuines breeds, highlighting Holstein (HOL) and Gir (G), looking for obtain in halfbreed progenity, rusticity ally high milk production. Thus, was objective collect technical support, via review of literature, about principal aspects related of termical stress of bovine by heat and conduce a search with objective of evaluate the tolerance of heat of three differents genetical groups of Girolando cows. All animals have a Thermal Comfort Zone (TCZ), that undergoes variation according the breed, this is important to maintenance normal functionality of organism consequently the life. Some physiological parameters are commonly utilized to evaluate the heat tolerance of dairy cows, between them stand out Respiratory Rate (RR), temperature of the body surface (TBS), temperature of the udder surface (TUS), rectal temperature (RT), sweating rate (SR) and score of panting (SP). These parameters should be analysed together with bioclimatologicals variables, providing important info about physiological facing the stress by heat challenges. The Girolando dairy yield can be influenced by your genetic composition.