Multiple Regression and Principal Components Analysis of Puberty and Growth in Cattle

Abstract

Multiple regression and principal components analyses were employed to examine relationships among pubertal and growth characters. Records used were from 424 bulls and 475 heifers produced by a diallel mating of Angus, Brahman, Hereford, Holstein and Jersey breeds. Characters studied were age, weight and height at puberty and measurements of weight and hip height from 9 to 21 mo of age; pelvic measurements of heifers also were included. Measurements of weight and height near 1 yr of age were related most highly to pubertal age, weight adn height. Larger size near 1 yr of age was associated with younger, larger animals at puberty. Growth rate was associated with pubertal characters before, but not after, adjustment for effects of breed-type. Principal components of the variation of pubertal and growth characters among animals were strongly related to both weight and height. The majority of the variation among breed-types was due to height. Characteristic vectors of principal components describing the variation of bulls and heifers were strikingly similar. The variance-covariance structure of pubertal characters was essentially the same for both sexes even though the mean values of the characters differed.

Análise de componentes principais em características de produção de aves de postura

“…Segundo Baker et al (1988), a análise dos componentes principais pode revelar relações não-identificadas previamente, contribuindo para melhor interpretação dos dados.…”

“…Nesse contexto, a análise de componentes principais deve contribuir na interpretação das relações entre as variáveis e consequentemente nas decisões (Baker et al, 1988;Roso & Fries, 1995).…”

Estimativas de parâmetros genéticos para altura do posterior, peso e circunferência escrotal em bovinos da raça Nelore

“…Essa prática pode não ser a mais apropriada em um sistema de criação extensivo, haja vista a inclusão da altura do posterior (ALT) nos critérios de seleção, como boa alternativa para controlar o tamanho dos animais. A característica ALT é de fácil mensuração e menos susceptível às variações de meio ambiente e reflete melhor o tamanho corporal quando comparada à medida de peso vivo do animal (Baker et al 1998). Alguns autores (Vargas et al, 1998(Vargas et al, , 2000Riley et al, 2002;Silva et al, 2003) estimaram herdabilidades de magnitude moderada à alta para a ALT, em animais zebuínos, variando de 0,30 a 0,87.…”

Development and reproductive performance of Hereford heifers of different frame sizes up to mating at 14-15 months of age

“…Baker et al (1988) considered that hip height is the most convenient way to describe the skeleton size in beef cattle. Although Pereira et al (2010) found high positive correlations between growth traits and hip height, the authors concluded it had little influence on the reproductive performance of Nelore heifers.…”