Effects of sire breed-grazing system and environmental parameters on the behaviour of beef calves just after birth☆

Abstract Effects of sire breed-grazing system and environmental factors on the first activities of high grade Nellore and crossbred Canchim × Nellore, Angus × Nellore, and Simmental × Nellore calves raised in intensive production systems and high grade Nellore calves raised in an extensive production system, after birth, were studied. During 2 years, 185 calves were observed from birth until the end of first suckling, and the following variables were estimated: duration of maternal attention (cow to calf) during the first 15 min after calving, latency to first attempt to stand up, latency to stand up, latency to first suckling, duration of first suckling and the interval from standing to suckling. Data were analyzed by least squares methods, with models that included fixed effects of year and time of the year of birth (March–April (early autumn) and May–June (late autumn)), sire breed-grazing system (Sy), sex of calf (Se), category of cow (primiparous and pluriparous), time of birth, Sy × Se, year × Sy and year × time of the year interactions and the covariates weight of calf, rainfall, air temperature and relative humidity in the day of birth. Calves born from 6:00 to 8:00 h presented the longest latencies to first stand up (40.3 ± 5.1 min) and the shortest occur from 14:00 to 16:00 h (15.8 ± 2.7 min) ( P P P P P  > 0.05) any behaviour variable studied. As regard to sex differences, female calves did take less ( P Bos indicus calves in subtropical environmental need extra care when born on rainy days, especially during the first hours of the day.