AbstractDisease incidence in dairy cattle is to be reduced for animal welfare and economical reasons. This should be achieved not only by improvement of management but preferably also by genetic means. This study looks at the possibility of decreasing disease incidence in first lactation cows by increasing food intake. The latter is not measured on the cows directly but on young bulls during their performance test. Data consisted of 2203 Danish Red, 4527 Danish Black and White and 1022 Danish Jersey potential AI-bulls and 56 494 Danish Red, 264107 Danish Black and White and 57 661 Danish Jersey first lactation cows. Measures of food intake were provided by two Danish performance test stations. Information on incidence of mastitis, retained placenta, metritis, sole ulcer and ketosis as well as calving interval and energy corrected milk yield of first lactation cows was based on data extracted from the national data base in Denmark. Genetic (co)variances were estimated using restricted maximum likelihood. Heritability estimates of disease incidence and calving interval were low, ranging from <0.01 to 0.13 depending on breed. Heritability estimates of energy corrected milk yield were in the range of 0.28 to 0.33. In all breeds, an unfavourable genetic relationship between milk yield and disease incidence was found, while genetic correlations between food intake and ketosis were favourable, ranging between -0.03 and -0.25. Fertility disorders had an inconsistent correlation with food intake traits across breeds. Food intake of bulls could be included in the selection process in order to avoid nutrition-related disorders like ketosis.
A stochastic model for the simulation of management decisions in dairy herds, with special reference to reproductive performance.
