Data from the Swedish Beef Recording Scheme were analysed for different non-genetic factors that have an influence on body weight at different ages in beef breeds. These factors were type of birth, sex, breed group, parity, season year and age of calf at weighing. The breeds included were Hereford, Charolais, Simmental and Limousin. Twin calves had a relative weight compared to single born calves at birth of 77-80%, at weaning 86-94%, and at one year of age 91-99%. Heifers had a relative weight at birth of 93-95%, at weaning 89-92% and at one year of age 82-89% of that of bulls. Calves born at first parity had 8-14% lower weight at birth and weaning relative to those born at parities 4-8.Calves born by older cows had 2-6% lower weights. Adjustment factors for these effects were developed. By comparing the within-class standard deviations and coefficients of variation after multiplicative and additive adjustment respectively, the appropriate type of adjustment was found. Additive factors were prefered for the effects of type of birth, parity and season, whereas multiplicative factors were most appropriate for the effects of sex, breed group and age of calf when birth weight was registered. Regression equations were developed to adjust for the effect of age of calf when observing weaning and 
yearling weight.

H. Winroth

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume XV. Beef cattle, sheep and pig genetics and breeding, fibre, fur and meat quality., , 299–302, 1990
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