beta-carotene's crucial role in dairy herd reproductive performance

摘要

Cow numbers have decreased in many countries over the past 30 years whilst average milk yields have tended to rise. But this increased productivity has brought with it the negative trend of higher culling rates. USDA results from 2007 (Fig. 1) show 26% of cows leaving herds too early in their life are culled because of reproductive problems. One of the most important of these problems with the modern dairy cow is the inability to rebreed after conception. This leads to long calving intervals and high herd replacement rates: major economic threats reducing the farmer's monthly bottom line.