In developed countries, on the other hand, intakes of food from animals are higher than justified by nutritional grounds alone. Opinions differ as to whether a decrease in intake of these foods would benefit the health of the general population. In all countries, the palatability and dietary diversity contributed by meat, milk, and eggs are undoubtedly important factors, in addition to nutritional content, in determining intake levels. Conversion rates of the energy and protein in feeds consumed by animals to human food energy and protein vary, depending on species, production system, feed type, and product. This fact has been overlooked in some assessments of the role of animals in food production.
Less grain is fed to livestock in developing than in developed countries.
It has been estimated that, on a global basis, animals produce a kg of human food protein for each 1.4 kg of human-edible protein consumed. The biological value of protein in foods from animals is about 1.4 times that of foods from plants. Thus, diverting grains from animal production to direct human consumption would, in the long term, result in little increase in total food protein and would decrease average dietary quality and diversity. Also, feed grains can be and are diverted to direct human use during periods of temporary food grain shortage. An additional consideration is that maize, the principal feed grain, yields much more per hectare than wheat, the number one food grain.