Management of breeding bulls of Busha cattle in Croatia - a bull:cow ratio trends

The Busha cattle breed contributes to a genetic diversity for centuries in Croatia, with the number of breeding cows significantly increasing in the last decades. Successful reproduction of native breeds in outdoor breeding conditions is a multifactorial phenomenon influenced by genetic and non-genetic factors. Improving fertility and conception in native outdoor breeding units with optimal bull:cow ratio is important to reduce costs of production and avoid negative effects of reproductive management in the herd. Herds of the Busha cattle across Croatia were included in the study to calculate the variability and trends in the bull:cow ratio among the herds. The data on 204 active breeding bulls born in the 2007-2020 period were obtained from the Veterinary Information System of the Ministry of Agriculture, Directorate for Veterinary Administration. Observed vs. expected frequencies were tested with Chi-sqaured test using the three model approach according to the expected number of bulls per cows in the herd ; model 1 as 1:10, model 2 as 1:15, and model 3 as 1:20. Analyzing the proportions of the expected bull:cow ratios significant differences were recorded for model 1 (herds with >31 cows, P61 cows, P81 cows, P