Phytase is the most widely used enzyme in swine nutrition, but the effects of overdosing remain variable and underexplored.
Objective: This study aimed to evaluate the extra-phosphoric effects of increasing doses of bacterial phytase in corn- and soybean meal-based diets on performance, carcass traits, and meat quality in pigs during the nursery, growing, and finishing phases.
Method: Two hundred and fifty pigs (castrated males and females; initial BW: 6.1 ± 0.75 kg; 21 days old) were assigned to a randomized complete block design with five treatments and ten replicates each: PC, positive control diets supplemented with inorganic phosphorus (P) and calcium (Ca) to meet complete 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; and 3000 FYT, NC + 3000 FYT/kg of feed.
Results: The results showed that average daily gain (ADG) during the nursery phase in pigs supplemented with 1000, 2000, and 3000 FYT/kg was comparable to the PC group and higher than the NC group. Feed conversion ratio (FCR) during the same phase was similar between the PC and phytase-supplemented groups, with improved values compared with NC. A quadratic response to phytase supplementation was observed for FCR during the nursery phase, with an optimal inclusion level of 2320 FYT/kg of feed. During the growing and finishing phases and throughout the overall experimental period (21 to 156 days), average daily feed intake (ADFI), ADG, and FCR values were improved in the PC and phytase-supplemented groups compared with NC. A quadratic response for FCR was observed during the complete growing-finishing period, with an optimal inclusion level of 1923 FYT/kg of feed. Phytase-supplemented groups and PC showed improved carcass traits compared with NC, with linear effects observed on carcass lean meat percentage and quantity.
Conclusion: In conclusion, the results indicate that phytase supplementation in corn- and soybean meal-based diets with substantially reduced inorganic P and Ca levels improves pig performance throughout all production stages, with an optimized inclusion level of approximately 2200 FYT/kg of feed and dose-dependent benefits on carcass characteristics.
Marques CSH, Callegari MA, Dias CP, Souza KL, Martins CCS, Fascina VB, Oba A, Carvalho RH, da Silva CA. Phytase Overdose in Diets for Pigs from Weaning to Slaughter: Effects on Performance, Carcass and Meat Quality. Veterinary Sciences. 2026; 13(6): 516. https://doi.org/10.3390/vetsci13060516