Avaliação da plasticidade fenotípica para produção leiteira em um rebanho holandês na região de São Bento do Una (PE)

Abstract

The climate acts directly on animals, which when exposed to bad weather for several hours of the day, become extremely susceptible to a permanent state of stress, which trigger physiological changes in adaptation, compromising the productive performance of the animal. Most animals raised for milk production are sensitive to the high temperatures found in tropical areas, and the climate elements are often so intense that they cause an imbalance between the animal and the environment. The present study evaluated the phenotypic plasticity for dairy production in a Holstein herd in the region of São Bento do Una (PE), as well as evaluated the different genotypic composition of the animals for the HSP-70 gene, influences their climate adaptation and consequently milk production. With the help of the Pernambuco Agronomic Institute (PAI) - São Bento do Una Experimental Station it was possible to acquire 117,323 daily milk production data from 271 animals from 2008 to 2018. Information on daily rainfall from 2008 to 2014 were obtained on the website of the Pernambuco Water and Climate Agency (PWCA), the materials of solar radiation, relative humidity, average, maximum and minimum temperature, referring to the years 2008 to mid 2012, were purchased from Integrated Data Center (IDC) from the National Institute for Space Research (NISR) and climate data from the end of the year 2012 to 2014 were received by IPA Experimental Station of São Bento do Una. Molecular genetics analyzes were obtained from Maria das Dores Silva Araújo's master's thesis, entitled “Genetic diversity and association of the heat shock gene (HSP-70) with the productive performance in dairy cows in the semiarid”. The study was conducted on the basis of ITU, as they better indicate the quality of the animals' thermal comfort than simply the climatic variables alone. After the acquisition and correction of data related to milk production, climatic variables, HSP-70 gene polymorphisms and ITU was created a single database with 24,196 observations of six polymorphisms. Correlation, variance, regression and descriptive analyzes, performed with the information present in the database, were performed with the aid of SAS version 9.4 software. By evaluating the HSP-70 gene, the phenotypic plasticity for milk production in the Dutch herd was confirmed, and the influence of different animal genotypic compositions for the same gene. Through the collected data, the G polymorphism was the one with the highest productive average and the lowest average productivity loss under thermal stress conditions, and can be used as a basis for the improvement of animals for tropical region.