Land damage due to tin mining causes a decrease in vegetation. Limited vegetation that can grow on marginal land, especially grass species, causes limited animal feed which causes slow development and body growth as well as cow reproduction. This study aims to conduct a study of the cost benefit analysis of the use of premics to meet micromineral needs in improving reproduction. The results of a cost-benefit analysis of the provision of premics in improving reproductive performance (NPV: 1,206,117,000; BCR: 4.80; IRR: 252.98%. From this value the net present value (NPV) is positive while the benefit-cost ratio (B / C ratio)> 1 thus giving premixes will provide improvements to the reproductive status in Central Bangka district.

Keywords: Benefit Cost, Premix, Reproduction