This study was conducted in North Sulawesi, Indonesia to identify the factors affecting reproductive efficiency and to determine the contribution of each factor in reproductive efficiency of Indonesian native cows. Records of reproductive efficiency, body size (hip height, body weight, body length, heart girth) as well as age on one hundred and sixty seven Indonesian native cows (seventy six cows of the Bali breed and ninety one cows of the synthetic breed from unknown proportion of th Madura, the Sumba and the Ongole breeds) of 58 farmers were available in this research. The data were analyzed by covariance analysis using SAS package including reproductive efficiency as a dependent variable and breed, body size (hip height, body weight, body length, heart girth) and age of cows as independent variables. The contribution of each independent factor to dependent variable was estimated as the percentage of the sum of square in the corrected total sum of squares. The results showed that body weight and body size of cows would be considered as th most important factors affecting reproductive efficiency of Indonesian native cows. Therefore, the reproductive efficiency could be increased by 1) using cows that reached a target weight of at least 250 kg, 2) using cows with relatively well developed height at hip of at least 117 cm, heart girth of at least 150 cm, and body length of at least 125 cm, 3) keeping breeding cows that reach a target age of 24 months old with the maximum interval between postpartum and next breeding season of 90 days for each year, and 4) using good nutritional feeding to reach the optimum weight and body condition. |