# Evaluating the Effects of Strategic Use of High Phytase Levels on Growth Performance and Carcass Characteristics of Late-Finishing Pigs Exposed to Limited Floor Space

## TL;DR

This study found that adding high levels of phytase to pig feed did not improve growth performance in pigs housed under limited floor space.

## Contribution

The study evaluates the impact of hyper-dosing phytase on late-finishing pigs under space restriction, a novel approach in swine nutrition and housing research.

## Key findings

- Space restriction reduced growth rate, final body weight, and feed intake in pigs.
- Hyper-dosing phytase increased inositol and serum glucose but did not improve growth performance.
- Phytase supplementation had no effect on feed efficiency or carcass characteristics.

## Abstract

The reduction in available floor space per unit of pig body weight reduces growth performance during the late-finishing stage of pig production. Feeding elevated levels of phytase has the potential to destroy the anti-nutrient phytate present in grains and oilseeds, thereby increasing nutrient availability. Applying high doses of phytase in swine diets is a strategy to reduce feed costs and environmental phosphorus pollution, while promoting increased growth performance of pigs. In addition, the associated increase in inositol and other nutrients may improve growth performance and become an important strategy to reduce the stress of heavy weight pigs housed under restricted space. Therefore, this study evaluated the impacts of hyper-dosing dietary phytase (5000 FTU/kg of feed) on the growth performance, carcass characteristics, inositol concentrations, and serum chemistry of late-finishing pigs when housed under adequate or restricted space. Space restriction reduced growth rate, final body weight at marketing, and feed intake, without affecting feed efficiency. Hyper-dosing phytase did not impact growth performance, regardless of space restriction, but it increased inositol concentrations, increased serum glucose concentrations, reduced aspartate aminotransferase, and tended to reduce alanine aminotransferase compared to super-dosing (2500 FTU/kg). Feeding extra phytase did not improve the growth performance of pigs regardless of space restriction.

This study evaluated the effects of high doses of phytase on the growth performance, carcass characteristics, and serum chemistry of late-finishing pigs housed under space-restricted conditions. Pigs (n = 375; 94.63 ± 0.61 kg) were randomly assigned to 48 pens, with 7 to 8 pigs per pen, balanced for gilts and barrows. Two phytase doses (control of 2500 FTU/kg or hyper-dose of 5000 FTU/kg) and two space allocation dimensions (adequate with 0.85 m2/pig or restricted with 0.66 m2/pig) were combined to create a 2 × 2 factorial arrangement (12 replicates per treatment). The three heaviest pigs per pen were marketed on day 28, and the remaining pigs were marketed on day 42. No interactions (p > 0.10) were observed between the floor space allowance and phytase supplementation. The body weight, daily gain, and feed intake at the first marketing and for all pigs marketed were reduced (p ≤ 0.009) by space restriction, without affecting the gain-to-feed ratio. Space restriction increased serum protein and decreased urea N, and hyper-dosing phytase increased plasma inositol and serum glucose and decreased serum aspartate aminotransferase (p < 0.05). The results indicate that space restriction reduced the growth rate, feed intake, and body weight of late-finishing pigs, and that hyper-dosing phytase was not beneficial in improving growth performance regardless of space allowance.