Fisiologia, comportamento e produção de leite em genótipos caprinos sob pastejo em modelos de produção irrigados no semiárido brasileiro

Abstract

This study aimed to assess the impact of genotype (Anglo-nubian and Saanen), type of grass (tanzania grass and tifton-85), the same management (intensive, moderate and mild) and time of year (dry, transition and wet) on physiological parameters, behavior, production and physico-chemical characteristics of goat milk kept in pasture in the semiarid region of Northeast Brazil. We used thirty-six goats than twice a week (morning or afternoon) had collected their physiological data (temperature fur, rectal temperature, respiratory rate, heart rate and sweat rate). Three collections were made of animal fur (the fur coat thickness, length, diameter and density of the hair). Environmental variables were recorded to calculate the Enthalpy of Comfort Index Animal. Analyses of the blood count, as well as measurements of cortisol, thyroxine and triiodothyronine. These goats yet had their behavior evaluated twice during the season and were also collected data their production and physicochemical characteristics for milk three times a week. Data were expressed as mean and standard error and evaluated by ANOVA and the means were compared by Tukey test (P>0.05). Milk production was analyzed by regression over the lactation. It was observed that in the transition period (morning and afternoon) and rainy (late) values of temperature and humidity were crucial to keep the goats out of the thermal comfort zone. The temperature was higher pelt for Anglo-nubian (36.7 °C), while respiratory rate (73.6 breaths.min-1) and heart (93.0 beats.min-1), length (1,85 cm) and diameter of the hair (0.048 μM) were higher for the Saanen and may indicate a condition of acclimatization or adaptation. Feeding behavior has changed with the season. As for milk production, Anglo-nubian goats produces better grazing tifton-85 or under intensive management in tanzânia grass under management moderate or mild. Already Saanen produces better grazing tanzânia grass under intensive management or tifton-85 moderate or mild under management. Other evaluations remained within the normal range. We conclude that dairy goats in semiarid environment homeothermy and maintain their milk supply with adequate physicochemical characteristics.