The problem is that animals are inefficient at converting plants to edible flesh. It takes, for example, grain to produce kilogram of the U.S. Government estimates. After putting so resources into animals, what do we get out? Manure at a rate of over 10,000 kilograms per second in Canada alone, according to the government. Environment Canada says cattle excrete 40 kilograms of manure for every kilogram of edible beef. A large egg factory can produce 50 to 100 tonnes of waste per week, the Ontario Ministry of Agriculture estimates.