Please don't worry about the children all converting to vegetarianism. We find that a very small minority of kids at Key Stages 1 and 2 will go vegetarian without parental encouragement and support. The issues surrounding vegetarianism are very lively, very current and very emotive, making them ideal to develop new and improved English skills. A belief in animal rights - that animals shouldn't be killed for food when we can eat other foods instead. Factory farming - many people think that factory farming methods where animals are kept in conditions that deny their natural instincts and behaviours and are distressing to them is wrong and should not be supported.
Food hygiene is more difficult to practise safely with meat and animal foods.
The environment - factory farms have lots of animals crammed into a small space that have nothing to do all day but eat. This produces a lot of poo. In the Netherlands - where there are six pigs to every person, they produce so much poo that it has to be shipped to Saudi Arabia and India. If all the manure were to be put into the earth it would poison the water and the land - there is simply too much of it. Excessive livestock farming in general can be bad for the environment as it uses a great deal of water, destroys the habitats of wild creatures, creates a uniform look to the countryside and necessitates logging.