Mortality in Austrian dual purpose Fleckvieh calves and heifers

Most countries worldwide already include functional traits in the breeding goals for cattle. Among those are e.g. reproductive traits or longevity while traits regarding calves or heifers are hardly considered. Mortality, but also culling of heifers before first calving may result in higher replacement costs but also in reduced possibility for selection and is thus of importance in cattle breeding. Thus, the aim of this investigation was to explore the genetic background of postnatal mortality and involuntary culling in Austrian Fleckvieh (dual purpose Simmental) calves and replacement heifers. The following periods were defined for analyses: P1 = 48 h to 30 days, P2 = 31 to 180 days, P3 = 181 to 365 days, P4 = 366 days to first calving or a maximum age of 1200 days if no calving was reported, P5 = birth to age at first calving or a maximum age of 1200 days if no calving was reported, P4S = heifers having at least one insemination slaughtered in P4, defined as involuntarily culled. After data editing records of more than 86,000 calves and heifers were investigated. Mortality rates were 1.85, 1.39, 0.36, 0.70, and 5.61% for the defined periods P1–P5, respectively; 7.78% of heifers were involuntarily culled (P4S). For the estimation of genetic parameters a linear and threshold sire model and a linear animal model with the random effects herd ⁎ year and sire as well as the fixed effects year ⁎ month, number of dam's parity, and calving ease were applied. In total, the pedigree consisted of 11,609 animals (sire model, sire–dam relationship) and 237,113 animals (animal model). For mortality traits, heritabilities ranged from < 0.0001 (P3) to 0.018 (P5) for the linear models, and 0.001 (P3) to 0.072 (P1) for the threshold model, respectively. Heritabilities for involuntary culling (P4S) were 0.024, 0.021 and 0.067 for the linear animal, linear sire and threshold sire model, respectively. The rank correlations were > 0.99 between random effects of sires obtained with linear sire and threshold sire models and were lower (r = 0.77 to 0.90) for animal and sire models, respectively. Total calf and heifer mortality is higher than stillbirth. Consequently, its economic impact on cattle breeding should not be neglected. Based on the results obtained in this study selection against higher postnatal mortality and involuntary culling of heifers should be possible. Furthermore, monitoring of the population and of extreme bulls might be very useful for breeding organisations to avoid deterioration in these traits.