A genetic analysis of traits recorded by automatic milking systems - the possibiilty for a new method to evaluate temperament of dairy cows

Abstract

The increasing popularity of automatic milking systems beginning in Northern Europe and spreading to other parts of the world requires a re-evaluation of breeding goals for dairy cattle. Workability traits, including temperament, become more important because cows must make their own way to the milking unit and stand quietly while being milked. Fetching of cows, which increases labour requirement, should be minimalized. Besides the apparent benefits of a decrease in labour and an increase in flexibility for farmers, AMS also can record substantial amounts of data on cows. This data, when handled correctly, has the potential to be used in genetic evaluations to obtain estimates of breeding values and heritability. Records from 1674 Swedish Holstein cows from 17 commercial AMS herds were used to estimate heritabilities and variance components for 2 different teat cup kick-offs traits and milking interval. Because these traits are hypothesised to be related to temperament, genetic correlations with temperament scores were estimated. Heritability for the kick-off traits were 0.06 to 0.31 and milking interval was estimated at 0.17. Heritability for temperament score was estimated at 0.14 using scores on 1833 cows from 15 of the 17 herds. Genetic correlations between AMS data and temperament scores were moderate and significant for the two kick-off traits, r= -0.38 and -0.50 indicating that a higher temperament score (a more calm cow) could indicate less kick-offs. Results suggest that data from AMS could provide an objective method to measure temperament in dairy cows.