MARIANUS Y.M DATUR Pengarang TARSISIUS CONSIDUS TOPHIANONG Dosen Pembimbing 1 Nancy Diana F K Foeh Ketua Penguji

Bali cattle have advantages in terms of adaptation and fertilization rates, but have a growth rate that tends to be slow because the rearing system is still grazing so that livestock growth becomes uncontrolled. The purpose of this study was to determine the mating pattern and birth estimation of Bali cattle in Netemnanu Village, East Amfoang District, Kupang Regency. The number of cows used in this study were 58 Bali cattle (bos sondaicus) from smallholder farms that did not experience reproductive disorders, aged 4-7 years. The method used is observational through interviews with farmers, rectal examination and ultrasonography to determine the reproductive status of livestock. The analysis used is descriptive analysis. The results obtained showed that the days open ± 112days, the pregnancy rate was 86.20% (50/58), and the calving interval was 13 months. The oldest gestational age presentation was 8 months 18.965% (11/58). Based on pregnancy data, it is known that the peak of the mating pattern occurs in December 2021 and estimated births reach the peak in September 2022. Mating cows should be done in January - April so that births will not occur in the dry season by releasing the male only from January to March. If births occur in October – January, the availability of feed in the pasture is still very adequate, thus post-weaning calf mortality due to lack of feed can be minimized.