Effect of the temperature-humidity index on milk production, milking frequency and behavior of cows in pasture-based automatic milking systems

Abstract

In this work, it was hypothesized that milking frequency and behavior are negatively affected by conditions of temperature and humidity index high or above the threshold on the same day and that milk production is negatively associated with a higher rate of milking. temperature and humidity in the previous days. Therefore, the objective of this work was to evaluate the impact of thermal stress on milk production, ordering frequency and animal behavior in an automatic ordering system with voluntary traffic based on pastures, through environmental and physiological indicators. During six consecutive summers since 2016, in a voluntary order system, 65 high-producing Holando Argentino cows were evaluated. For data analysis, a mixed linear model was obtained. The average temperature and humidity index had the greatest effect on milk production (average decrease of 0.18 L for each index unit increase) during all test days (days 0, −1, −2 and −3). ), followed by the maximum temperature and humidity index (average decrease of 0.14 l), where day −3 had the least effect. On the other hand, the minimum temperature and humidity index during all the test days did not affect milk production per cow per day (P>0.05). The average request frequency per cow per day was negatively associated with the average temperature and humidity index on days 0, -1 and -2 (P<0.002). The behaviors standing, lying down, and lying down ruminating were associated with the mean temperature and humidity index on day 0 (p<0.05).