Effects of heat stress on production traits of the Girolando breed and selection for tolerance to heat stress

• Grant number: 24/08528-9
• Support Opportunities: Regular Research Grants
• Start date: October 01, 2024
• End date: September 30, 2026
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Genetics and Improvement of Domestic Animals
• Principal Investigator: Renata Negri dos Santos
• Grantee: Renata Negri dos Santos
• Host Institution: Faculdade de Engenharia (FEIS). Universidade Estadual Paulista (UNESP). Campus de Ilha Solteira. Ilha Solteira , SP, Brazil
• Associated researchers: Ariany Faria De Toledo ; Daniel Montanher Polizel ; Hinayah Rojas de Oliveira ; Marcos Vinicius Gualberto Barbosa da Silva
• Associated scholarship(s): 24/18006-0 - Impact of heat stress on the productive traits of Girolando cattle, BP.IC

Abstract

Several environmental factors affect animal performance, making it difficult to identify those genetically superior for the traits of interest. Despite the myriad of research in dairy farming, there is a gap regarding the implications of the genotype-environment interaction in the selection of sires for production and heat tolerance. The aim of this proposal is to investigate the effect of heat stress on production and reproduction traits of dairy cattle raised in a tropical environment and to identify the most appropriate statistical approach for evaluation and selection for heat tolerance in different breed compositions. The data used (phenotypes, genotypes and pedigree) will be collected by Breed Association and made available by Embrapa Dairy Cattle. Data of test-day milk yield, protein, fat and somatic cell score, age at first calving and interval of calving of different breed compositions, of first order of calving, collected between 2000 and 2024. The optimal temperature and humidity index will be evaluated to be used in the preliminary and final analyses. Identification of the heat comfort threshold and quantification of production losses will be carried out for each breed composition. For genetic evaluation, numerous models will be tested. After choosing the best genetic evaluation model, genomic prediction will be performed. To legitimize the methodology, a cross-validation will be carried out. The classification of sires in terms of environmental sensitivity will be given by graphical analysis of the predicted transmission capacity (GPTA), which represents half of the sire's genetic value. The GPTA will represent the expected average performance for the daughters of each sire in the different combinations of temperature and humidity. For the analyzes the software R, REMLF90, BLUPF90 will be used mainly (AU)