By 2050 livestock population is expected to double. Nowadays practices are not sustainable because they generate far too much pollution, so new practices and technologies are needed to produce better food, in bigger quantities with less impact on the environment.
Cows emit methane, which is really bad in the atmosphere since it is a gas with high green house effect potential, and therefore contributes to global warming and climate changes.
Some researchers report however that adding garlic to cows diet leads to a significant decrease of methane emissions (initial report says 50%).
Anyway garlic is highly recommended for humans too.