Efeito do Sombreamento sobre a Produção e Qualidade do Leite em Vacas Girolando

Abstract

The aim of this study was to evaluate the effect of shading on milk production and milk quality in girolando cows. Sixteen Girolando cows were used, divided into two groups, with two treatments, the first group remained in paddock without shade and the second in paddock with shade. Every 15 days, each group of animals underwent one of the treatments, totaling 120 days of experiment. The 15 days of permanence in each treatment were divided into two periods, seven days for adaptation and eight days for sample collection. During the period of data collection were measured: the temperature and relative humidity of the air in the paddocks and the milking room; evaluation of the temperature and humidity index; respiratory rate and rectal and superficial temperature of the skin and udder of the animals and thermographic digital infrared. Also, milk samples for physical-chemical evaluation were collected and the milk was weighed to evaluate the daily production of the animals. Descriptive evaluations of the behavior of the animals were carried out, aiming to evaluate the thermal comfort. A cross-over experimental design was used, with an interval between two treatments. Subsequently, analysis of variance, Pearson correlation and principal component analysis were performed, the thermographic images were processed in a FLIR Tools software to ensure greater precision in relation to surface temperatures. The period of the year during which the animals are kept in sun and shade can affect the average, maximum and minimum temperatures, the surface temperature of the skin as well as the THI. It is concluded that the animals that were subjected to areas with and without shading there was a correlation between the constituents of milk among themselves, and between physiological and environmental variables, but did not affect milk production.