Factors accounting for these changes have been recently reviewed by Australian researchers. Briefly they include the health state of the herd, the form of feeding (dry vs. liquid feeding), and the withdrawal of milk and hence of milkderived growth factors, and glutamine, a major fuel for the developing intestine. However, the most important factors are likely to be a transient hypersensitivity to antigenic components present in the diet and a low energy intake in the immediate post-weaning period.