Browsing by Author "Laakkonen, Anna-Katri"

In beef production, the successful reproduction of animals plays a significant role. The gestation length in cattle is about 9 months, but there is variability between breeds. Gestation length in beef breeds is longer than in dairy breeds. Gestation length is correlated with calving difficulties. The objective of this study was to investigate factors affecting gestation length in beef cattle. Data was received from Faba co-op. The aim was to calculate the phenotypic gestation lengths for Charolais and Hereford, as well as for their crossbreeds with the most common beef breeds used in Finland. One of the objectives of this study was to calculate heritability estimates for gestation length for pure Charolais and Hereford breeds. Data from Charolais and Hereford calves born in 2009-2018 were used in the analysis. There were 2883 Hereford calves and 3370 Charolais calves in the data. Finally, only pregnancies that had resulted from artificial insemination with the minimum length of 165 and maximum length of 305 days long were included in the analysis. Two different models were used to estimate the variance components, one involving only the direct genetic effect of the calf and the other also considering the maternal effect. Fixed factors in both models included sex of calf, number of calves born, calving season, herd-year, and parity-age. All fixed factors were statistically significant. Based on the results, there were phenotypic differences in gestational lengths between breeds, heavier beef breeds having longer gestations. In the model including only the direct genetic effect of the calf, relatively high heritability estimates were obtained, but in the maternal model the direct heritability was lower, and the maternal heritability was very high. The current data was not well suited for the evaluation of the key figures of the maternal model, so the results should be treated as preliminary.