The aim of this research is to discover how several factors – namely feed, age, and parity might contribute toward cases of reproduction disorder in beef cattle of Modo District, Lamongan in 2015. Materials used in this research are data obtained from five villages, showing 340 out of 3.331 animals exhibiting reproduction disorder symptoms. The method used for this research is the survey method, and primary and secondary data were obtained. Primary data were obtained from field surveys of interviewing farmers, local animal health officials and artificial inseminators. Secondary data were obtained from examination for reproduction disorder in beef cattle by the Livestock and Animal Health Service of Lamongan. The data obtained were then tabulated and analyzed with the regression tree method using Windows Statistical Product and Service (SPSS) to determine the main cause of reproduction disorder in beef cattle of Modo District, Lamongan in 2015. The results show that feed is the main factor contributing to reproduction disorder in beef cattle of Modo District, Lamongan, while age and parity showed a less significant role.
Key words: Beef cattle, feed, age, parity, reproductive disorders