Parâmetros fisiológicos e consumo voluntário de ovinos alimentados com fontes de lipídios associados à palma forrageira

Abstract

The objective was to evaluate the effect of different sources of lipids associated with forage cactus in the diet of sheep on the thermal comfort of the animals through physiological indicators and dry matter consumption. The maximum and minimum temperatures, relative air humidity, ambient air temperature of the experimental shed were monitored, whose data were used to calculate the temperature-humidity index (THI) and the Black Globe-Humidity Index (BGHI) aiming at estimate the thermal comfort of animals. The experiment was carried out at the Departamento de Zootecnia (DZ) of the Universidade Federal Rural de Pernambuco (UFRPE), located in Recife-PE. Twenty-four male lambs were used, with a mean age of six months and mean initial body weight of 22.0 ± 1.11 kg. The experimental period was 8 weeks, with isonitrogenous diets, based on forage cactus, tifton hay, maize corn, soybean meal, mineral mixture, with 3 treatments, T1 being composed of cottonseed, T2 of extra fat corn germ and T3 of dry coconut film. In order to evaluate the physiological parameters, respiratory frequency (RF), heart rate (HR), rectal temperature (RT) and body temperature (BT) were measured, the latter being measured at 4 points on the animal's body, forehead, neck, loin and shin. Data were collected every 2 experimental weeks at 8:00 am and 3:00 pm. The temperature and relative humidity of the air were measured throughout the experiment. The design used was a completely randomized design in a split-plot scheme, allocating the effect of the treatment (diets containing different varieties of lipids) in the plots and in the sub-plots the effect of the evaluation shift (morning and afternoon). The obtained data were submitted to analysis of variance and average grade comparison by Tukey test and Pearson correlation analysis between variables. There was no significant interaction between the factors (diet and shift), and there was no dietary effect on the respiratory frequency and body temperature variables, however, the heart rate and rectal temperature variables showed a difference (p ≤ 0.05) on the shift, being higher in the afternoon. Despite being susceptible to heat stress according to the high THI and BGHI, thanks to the adaptability and metabolic strategies of sheep to dissipate heat, the animals were able to maintain body temperature within the normal range for ruminants. It is concluded that the experimental diets did not cause damages to the physiological parameters, and the climatic conditions are responsible for increasing the physiological variables.