INTERAÇÃO ENTRE FATORES AMBIENTAIS, SAÚDE, EFICIÊNCIA PRODUTIVA E REPRODUTIVA DE VACAS HOLANDESAS EM FREE STALL

Abstract

The major dairy breed used in the intensive production system is the Holstein-Frísia, which is a temperate climate race and needs a controlled microclimate. In the free stall system, the use of fans associated with water sprinkler helps control heat stress (HS) during warmer days. Given the problem, the objective was to evaluate the environmental factors interaction in calving and first artificial insemination (AI), the health of uterus, hoof and udder, productive and reproductive efficiency of lactating Holstein cows in the free stall. From software Ideagri® (Belo Horizonte, Brazil) and Dairy Plan® (GEA, Düsseldorf, Germany), production, breeding and health data were collected from 321 cows, with 392 records of first postpartum AI and 451calving records in March 2016 to June 2018 of a dairy farm located in the county of Santa Helena de Goiás/Goiás. The temperature and humidity index (THI) were calculated from the meteorological temperature and relative air humidity, from data provided by the farm's weather station software (ADAMA Clima®, Adama Brazil, Londrina, Brazil). The environmental variables were evaluated for season by analysis of variance (ANOVA) and the means compared by the Kruskal-Wallis test. The effects of the birth season and AI on pregnancy rate at 60 days after the first AI were evaluated by logistic regression contained in the “aod” package from R software, and the differences between the average pregnancy rates of each season were set by the chi-square test. Correlation analysis was performed by the “polycor” package. The correlation matrix was decomposed into eigenvalues and eigenvectors, and used for Principal Component analysis (PC) using the package “PCAmixdata”. PC results were used for cluster analysis with the cluster package. The pregnancy rate at 60 days after the first postpartum AI was positively influenced on the fourth lactation, and negatively by the occurrence of placental retention (PR) and warm seasons in which the AI was performed. In conclusion, the PR and the AI station with a maximum UTI above 80 interfered in the reproductive efficiency of lactating Holstein cows, which could generate economic losses.