Effects of maize conservation techniques on the apparent total tract nutrient and mineral digestibility and microbial metabolites in the faeces of growing pigs

A digestibility trial was conducted to investigate the effects of different maize conservation techniques on the nutrient digestibility of a commercial maize-soybean meal diet fed to growing pigs. The influence on the content of biogenic amines, volatile fatty acids (VFAs) and ammonia in the faeces was also determined. Maize was either dried (dried maize), ensiled after milling (maize silage) or tight-closed-stored (TCS-maize) as a whole grain. Nine growing pigs (35.1 ± 0.8 kg) were used in a 3 × 3 Latin square experiment. They were fed diets based on the different maize conserves, barley and soybean meal to ensure the same content of N, energy and digestible phosphorus (P) in the diet. The apparent total tract digestibility (ATTD) of the DM, ash and starch was improved (P<0.05), and the ATTD of the ether extract tended to be improved (P<0.10) when the maize was fermented. Moreover, based on the results related to the ATTD of P in the different maize conserves of a previous study, less P was added to diets that were based on fermented maize. Nevertheless, the P excretion was reduced without compromising P utilisation. The metabolic products of the gut microorganisms, biogenic amines and most VFAs in the faeces were reduced when the animals were fed fermented maize (P<0.05). The observed effects were more pronounced in the maize silage treatment. In conclusion, the current data suggest that the air-proofed storage of wet maize can be a strategy to improve the feeding value of maize-based diets fed to pigs.