![]() In modern farming, pharmaceutical and nutritional developments have increased the productivity formerly controlled by selective breeding. ![]() ![]() When riding horses or using one to pull a plough, a gelding is much easier to control than a stallion and, even before the study of genetics, it was known that a nervous disposition is not entirely the fault of the environment but of heritable traits.ĭairy cows are bred according to milk yield, sows which kill their young are removed from the breeding stock, and the more muscle mass a male calf is born with, the greater its chance of passing on its genes to the next generation. Artificial selection not only concerns the appearance, productivity or muscle mass of a food source but even its behavior. ![]() Aggressive male stock has been castrated for centuries, while those males with genotypes, phenotypes ( dominant traits) of use to humans have been used as breeding stock. ![]()
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