Female Bali Cattle Body Size Clusterization and its Impact on their Reproductive Status

Background of the Study: Bali cattle standardization stipulates quality requirements and measurement methods for Bali cattle breeds. Bali cattle breed are cattle that have superior characteristics and pass these traits to their offspring and meet certain requirements to be bred. This standard stipulates the quality requirements and method of measuring Bali cattle breeds. Quantitative requirements are determined based on the application of the Indonesian National Standard (SNI) for Bali cattle. Quantitative parameters based on SNI for female Bali cattle include chest circumference, shoulder height, and body length. However, the impact of the classification of Bali cattle based on SNI on their reproductive status has not been reported. The reproductive status can be observed from the age at first estrus, age at first breeding, gestation period, age at first calving, postpartumestrus, and postpartumbreeding. Aim: This study aims to investigate the clustering of female Bali cattle based on SNI and its impact on their reproductive status. Moreover, this study also aims to determine the diversity of reproductive status and the correlation between reproductive status. Thus, in making a selection of reproductive status, it can be determined which one is done first and which can be done simultaneously. Method: Data were obtained from 25 female Bali cattle intensively reared at the Center for Superior Bali Cattle Breeding (Pusat Pembibitan Sapi Bali Unggul, abbreviated as PPSBU) in Gerogak, Buleleng Regency, Bali. The data obtained were analyzed by hierarchical cluster analysis with SNI characteristics of Bali cattle as variables, such as chest circumference, shoulder height, body length, and cattle that had been clustered as objects (cluster cases). The results obtained were in the form of cluster membership tables and a dendrogram graph. To find out its impact on reproductive diversity, the obtained data were analyzed by biplot analysis. The analysis procedure was conducted using IBM SPSS (Statistical Product and Service Solutions) version 26. Results: The results showed that intensively reared female Bali cattle clustered using hierarchical cluster analysis with SNI characteristics for Bali cattle. The most uniform reproductive status was the gestation period, followed by the age at first calving, the age at first breeding, and the age at first estrus, while the most varied was postpartumestrus. There was a very significant correlation between the age at first estrus with the age at first breeding and the age at first calving, as well as between the age at first breeding and the age at first calving. This result indicates that the earlier the age at first estrus, the faster the breeding, which means that the age at first calving is also faster. Meanwhile, the gestation period and postpartumestrus had no significant correlation with the age at first estrus, the age at first breeding, and the age at first calving. The reproductive status of Bali cattle obtained was not influenced by body size which had been clustered into 3 classes, namely class I, class I, and class III based on SNI Bali cattle. Conclusion: Intensively reared female Bali cattle can be clustered using hierarchical cluster analysis with the SNI characteristics for Bali cattle, the most uniform reproductive status was gestation period, followed by the age at first calving, the age at first breeding, and the age at first estrus, while the most varied was the postpartumestrus. There was a positive correlation between the age at first estrus, the age at first breeding, and the age at first calving, but these three reproductive statuses were not correlated with gestation period and postpartumestrus. Hence, female Bali cattle clustering have no impact on the reproductive status of intensively reared Bali cattle.