The aim of this study was to evaluate the influence of body weight on the efficiency of dairy cows. Data were derived from 161 commercial Austrian dairy farms. An optimum body weight range for efficiency does exist as the relationship of milk yield and body weight is nonlinear. Specialized dairy breeds seem to respond more intensively to body weight range than dual-purpose breeds. Cows with medium weights are the most efficient. A further increase in dairy cows’ body weights should be avoided.

The lactation curve and lactation survival are important in dairy cattle breeding. Their simultaneous improvement results in economic benefits. The genetic relationship between the lactation survival and the lactation curve shape traits of milk yield and fat and protein percentages using information from of 25 981 primiparous Tunisian Holsteins was investigated. Cows that had higher persistencies for fat and protein percentages were more likely not to survive.

The aims of the study were to estimate allele and genotype frequencies at g.-274C > G locus in the promoter region of the SIRT1 gene and to investigate, for the first time, the relationship among different genotypes and milk and reproduction traits in the Agerolese cattle breed. The investigated population was found to be polymorphic at the investigated locus. Concerning milk production performance, significant differences between genotypes were found.

The objective of this study was to predict dairy cows' body weight from body size measurements. Body weight is an important trait for both management and breeding. Data were derived from 167 commercial Austrian dairy farms. To ensure high prediction accuracy, the use of a combination of both heart girth and belly girth is recommended if the use of scales is impossible. The large and heterogeneous data set supported a valid prediction.

The impact of the milking technique on the individual animal and the reaction of the animal on the technique were investigated. With the use of objectively recorded data from automatic milking systems (AMSs), auxiliary traits that reflect animal behavior in the milking system were defined, free from subjective impressions of classifiers. There is an apparent possibility to breed cows for AMS systems based on AMS data, though it is imperative to have further validation based on larger datasets.