Epsilon Open Archive

Abstract

Slow-milking cows lead to less efficient use of automatic milking systems (AMS) or may hold up the milking process when many cows are milked together in conventional milking parlours (CMP). Traditionally, genetic evaluations for milkability have been based on subjective observations, where the herdsmen have scored the animals once on a scale from slow to fast milking. This thesis aims at providing information useful for a genetic evaluation system based on in-line measured milkability traits. The aim was also to advance our understanding of the genetic relationships between milkability, udder conformation and udder health in order to evaluate opportunities of improving both milkability and udder health.

Milkability data from two different sources were used in the analyses: AMS and CMP data from commercial herds with Swedish Holstein and Swedish Red cows. Average flow rate (AFR), milking time (MT), box time (BT), handling time and proportion Attachment failures were used as most promising measures of milkability. The results showed that it is possible to use in-line measured information about milkability for genetic evaluation purposes. Moderate to high heritabilities and generally high repeatabilities were found for AFR, MT and BT in both breeds. High genetic correlations were obtained between AFR and the time traits. High genetic correlations between traits measured in the two systems showed that it should be possible to jointly use them in the genetic evaluation.

Shallow udders with short and thin teats were genetically associated to higher milking speed. High correlations of udder and teat conformation from in-line measured teat coordinates to corresponding traits scored by classifiers show the potential for future use of information from teat coordinates as a complement to classifications.

High milking speed was generally shown to be genetically correlated to worse udder health even though the results were somewhat inconsistent between the breeds. In the future, emphasis should be put on an udder health and milkability index aiming at improving both milkability and udder health.