If no AGP are used, dietary crude protein concentrations should be reduced to less than 18% in diets fed to pigs during the immediate post-weaning period. Diets should be fed in a liquid form if possible, preferably as fermented liquid feed. Feed intake should be restricted to 75% of ad libitum intake during the initial 2 wk post-weaning to reduce the amount of substrates available to pathogens in the hind gut. The profit from pig production will be maximized if pigs are weaned between 21 and 28 d of age. All-in all-out production should be practiced and pigs should always be weaned into an empty, clean, and disinfected room, preferably at a location separated from the sow farm. Disease pressure and mortality do not necessarily have to increase if no AGP are used, but profits will likely be reduced because costs of preventing diseases in pigs fed diets containing no AGP often are greater than the cost of AGP.
D.Y. Kil and H.H. Stein. Invited Review: Management and feeding strategies to ameliorate the impact of removing antibiotic growth promoters from diets fed to weanling pigs. Canadian Journal of Animal Science. 2010. Vol. 90 (4): 447-460.