Comportamento ingestivo e termografia infravermelha de vacas F1 Holandês x Zebu no terço final de gestação em diferentes ambientes pastoris

Abstract

The climatic and growth conditions of the pasture influence the ingestive behavior, besides causing changes in the body surface temperature of the animal. In view of the above, the objective was to evaluate the ingestive behavior and body surface temperature of non-lactating Holstein x Zebu F1 cows in the final third of gestation, managed in two pastoral environments. The experimental design was a completely randomized design with two treatments: deferred brachiaria grass at the beginning of regrowth and xaraes grass in full vegetative growth, with 40 replications. The climatic characteristics of pastoral environments were monitored with the use of continuous reading dataloggers. Ingestive behavior was observed during 24 hours and divided into four periods (morning, afternoon, night and dawn). The bit rate was obtained based on the time spent to complete 20 bits of apprehension. The body surface temperature was collected using thermographic camera every 4 hours in all animals in the pasture. The Black Globe Temperature and Humidity Index (BGHI) presented high volatiles in the morning and afternoon, reaching approximately 92. The time spent on grazing of the animals in both treatments was not influenced by the environment, which occurred in periods of greater BGHI, but the pasture condition influenced the grazing time and was higher in the delayed grazing of rearing grass (707.5 minutes), where the lowest bit rates (35.7 boc.min-1) were also observed. Due to the better grazing condition, the animals in the vegetative growing grass-grass pasture showed a shorter grazing time (479.5 min) and higher bit rates (43.5 boc.min-1). The rumination and leisure activities occurred during the night in both treatments. In both pastoral environments, surface temperature fluctuations occurred, but the effect of ruminal activity was verified at 08:00 in the animals accommodated in the brachiaria grass. At other times in both treatments, TSC was influenced by the climatic environment. However, it is concluded that the grazing time of F1 HxZ cows at the end of gestation is influenced by the vegetative condition of the pasture and not by the climate since they graze in an environment with BGHI equal to 92.