Phytase Overdose in Diets for Pigs from Weaning to Slaughter: Effects on Performance, Carcass and Meat Quality

This study aimed to evaluate the extra-phosphoric effect of increasing doses of bacterial phytase (RONOZYME HiPhos) in corn- and soybean meal-based diets on performance, carcass yield, and meat quality in pigs during the nursery, growing, and finishing phases (GT). Two hundred and fifty pigs, castrated males and females, with an initial weight of 6.08 ± 0.748 kg and 21 days of age, were allocated to a randomized complete block design based on initial body weight, with five treatments and ten replicates per treatment: PC: positive control diets, supplemented with inorganic phosphorus (P) and calcium (Ca), meeting their full nutritional requirements; NC: negative control diets, with reduced available phosphorus (-0.18%) and calcium (-0.16%); 1000 FYT: NC + 1000 phytase units (FYT)/kg of feed; 2000 FYT: NC + 2000 FYT/kg of feed; 3000 FYT: NC + 3000 FYT/kg of feed. Average daily gain (ADG) in the nursery phase did not differ between the groups supplemented with 1000, 2000 and 3000 FYT/kg and PC, but was higher (p < 0.05) than NC. Feed conversion ratio (FCR) in the same phase was similar between PC and the groups supplemented with phytase, all being better (p < 0.05) than NC. The quadratic effect for phytase was verified for FCR in the phase, with the best inclusion of 2320 FYT/kg of feed. In the GF phases and in the overall experimental period (21 to 156 days), the results for average daily feed intake (ADFI), ADG and FCR favored PC and the groups supplemented with phytase compared to the NC (p < 0.05). A quadratic effect was observed for FCR considering the entire GF phase, with the best inclusion of 1923 FYT/kg of feed. Groups supplemented with phytase and PC obtained better carcass results compared to NC (p < 0.05). Linear effects were observed to percentage and quantity of lean meat in the carcass. There was no difference between treatments for meat quality. Supplementation with phytase in corn- and soybean meal-based diets with severely reduced inorganic P and Ca improved pig performance at all stages, with optimized inclusion values of approximately 2200 FYT/kg of feed, and dose-dependent benefits on carcass characteristics.