Protease Supplementation in the Diet of Finishing Pigs: Implications on the Quality of Organic Fertilizers for Forage Production and Soil Chemical Composition

The study evaluated the inclusion of protease in the diet of pigs in the final phase, analyzing its effects on residues used as organic fertilizer (OF) for corn silage cultivation. Conducted at the Federal Institute of Education, Science and Technology of Goiano, Rio Verde Campus, the experiment had three phases: the use of protease in intensive pig production, production of OF—pig slurry (PS), and its application in corn silage cultivation. The inclusion of protease in the diet did not affect the final weight of the pigs, with a mean of 89.75 kg. The use of PS from this production system did not affect the forage mass (23.64 Mg ha−1). On the other hand, in the short term, PS without enzyme both at sowing and covering, biofertilizer with enzyme at sowing and urea at covering, and PS with enzyme both at sowing and covering increased magnesium levels in the soil, with values ranging from 1.40 to 1.44 cmolc dm−3. Although protease did not affect animal performance in the finishing phase, the waste produced by this production system influenced the soil’s chemical composition; furthermore, the use of PS from systems with or without enzymes could partially replace chemical fertilization.