Factores que influenciam o peso ao nascimento de vitelos Holstein Friesian

The aim of this study was to determine the effect of some factors on Holstein-Friesian calves birth weight (n=349) born between 1985 and 2001 in a cowshed located on Castelo Branco, Beira Interior Region, Portugal. The results were: calves birth weight from first calving (38,05 kg ±5,93) was less (P<0,05) than calves birth weight from other calving; the heavier birth weight has been found on 3o- 4o calving with 43,23 kg (±5,74) and 43,12 kg (±5,30) respectively; male calves were always heavier (43,00 kg ±5,89) (P<0,05) than females (38,93 kg ±5,85); calves from HFH cows were heavier (44,47 kg ±5,92) (P<0,05) than calves from others provenience cows (BF 38,72 kg ±5,38) (HFA 39,98 kg ±6,92) (EZN 39,18 kg ±4,95); the birth weight was positively correlated with gestation length (r=0,501; P<0,01); the birth weight was negatively correlated with ambient temperature (r=-0,289; P<0,01); calves birth weight from Winter calving were heavier (42,98 kg ±5,88) (P<0,05) then birth weight from Summer calving (39,41 kg ±6,42). The results allowed us to conclude that those factors like calving number, sex of calf, dams provenience, gestation length and ambient temperature can influence Holstein-Friesian calves birth weight.