Effects of cow families on type traits in dairy cattle

The component of variance attributable to maternal lineage for type traits in the UK Holstein Friesian dairy population was estimated. First lactation type classification records of 33 325 contemporary cows, classified betwee n 1996 and 1998 were used in the analysis. Maternal pedigree records were t raced back to 1960 to establish maternal lineages. The tracing resulted in cows being assigned to 10 332 cow families with more than one cow per famil y. Sixty-six percent of the cows were in families of less than five. The tr aits comprised 16 linens type traits, a total score trait, four composite s cores and measures of temperament and ease of milking. Univariate analysis of each trait was performed using residual maximum likelihood, with and wit hout a maternal lineage component. A principal component analysis used a sc ree test to determine the number of independent traits being considered in order to establish a level of significance for the test statistic. It was f ound that eight principal components were responsible for the variation in type. The composite body score trait was found to have a 1.5% component of maternal lineage variance, significant at the 5% level. No other traits sho wed a significant maternal lineage variance component.