Genetic parameters, maternal ability and related selection criteria for unsupplemented Hereford range cows.

Data on 5,130 unsupplemented Hereford range cattle were used to evaluate genetic and phenotypic parameters of growth to 2 yr of age under extensive range conditions. From those data, records on 769 heifers saved as replacements were used to evaluate the relationship between growth and subsequent productivity expressed as most probable producing ability (MPPA). Variation in weight largely was due to the year effect.

Maternal influence on growth of laboratory rats.

Data from 2,089 laboratory rats utilized in selection experiments were used to estimate maternal influence on growth from weaning (21 d) to 16 wk of age. Adjustment factors were calculated for the effects of sex, generation, litter size, inbreeding of the dam and inbreeding of the offspring on the body weights. The effect of line of sire was included in the analysis of variance models.