Calf Birth Weight, Onset of Estrus and Postpartum Estrogen Levels of Bali Cows Raised in the Highlands and Lowlands of Gianyar Regency, Bali

This study aims to determine the calf birth weight, the onset of estrus, and estrogen levels of postpartum Bali cows raised in the highlands (Payangan District) and in the lowlands (Sukawati District), Gianyar Regency, Bali. A total of 20 Bali cows were used in this study that have given birth twice. The experimental design used was a completely randomized design (CRD) with two treatments, each consisting of 10 replications. The results showed that the average calf birth weight in the highlands was 17.29 ± 0.93 kg, while in the lowlands was 16.46 ± 0.40 kg, statistically showing a significant difference (p <0.05). The onset of postpartum estrus in less or equal to 3 months in the highlands was statistically higher (80%; p <0.05) as compared to cows in the lowlands (20%). Estrogen levels at postpartum estrus was 502.84 ± 232.20 pg/ml and 272.95 ± 184.43 pg/ml in the highlands and lowlands respectively, showed statistically significant differences (p <0.05). Increased postpartum estrogen levels that occurred every month in the two groups showed significant differences (p <0.05). From the results of the study, it can be concluded that the Bali cattle raised in the highlands show better reproductive performance than those maintained in the lowlands. Keywords: Lowlands, Highland, Calf birth weight, Estrogen, Bali cattle