Resumo

MARTINEZ-GONZALEZ, Juan Carlos et al. Non-genetic factors affecting birth and weaning weight in Angus calves. Zootecnia Trop. [online]. 2011, vol.29, n.2, pp.151-160. ISSN 0798-7269.

To determine the influence of some non-genetic factors on birth (BW) and weaning weight corrected to 205 d (WWA) of Angus calves, 1,999 and 1,574 weights were analyzed. All the animals were grazing and they were vaccinated against enzootic every six months. The data was analyzed using an analysis of variance under least squares methodology and the statistical model included: year of birth (YB = 1991-2007), season of birth (SB = Cold, Dry and Rainy), parity number (PN = 1, 2, 3,… ≥9 calving) and sex (SX = Males and Females) and the interactions YB*SB, YB*PN and YB*SX. All effects and the interactions affected BW and WWA (P<0,01). The means and standard deviation were 36.2 ± 2.6 and 186.8 ± 30.0 kg, respectively. The differences between the best years (2007) and worse year (1991) to BW was 1.1 kg. Cows of 1, 2 and ≥9 calving had calves less heavy. Male calves weighted more than female to birth and weaning. The interactions that involved YB indicate that the direction and magnitude of the effects are not constant within every year. The interaction YB*SB, YB*PN and YB*SX were important on WWA without being possible to define some tendency or magnitude. All the environmental effect studied was important.

Palavras-chave : Angus cattle; environmental factors; birth and weaning weight.