258 Nutritional strategies allowing inorganic phosphates reduction in maintaining maximum growth performance and bone mineralization in piglets

Abstract Phosphorus (P) is an essential component for optimal maintenance of growth and bone mineralization but its inclusion in animal feed is a core concern for economic and environmental concerns in ensuring sustainability of this resource. This study aimed to test impacts of different nutritional strategies such as dietary calcium (Ca) reduction and phytase superdosing for piglets fed without inorganic phosphate. A total of 147 piglets Piétrain*(Large White*Landrace) were divided among 5 experimental diets. Three levels of digestible P were tested (0.21%, 0.27%, 0.33%) by adding monocalcium phosphate (MCP) from 1) a negative control diet (NC) without MCP, 2) a diet with 0.3 % MCP (NC+0.3 % MCP), or 3) a diet with 0.6 % MCP (NC+0.6 % MCP). Those three diets contained 250 FTU/kg of phytase and a minimum amount of phytate set at 0.27%. All dietary treatments were formulated following a constant Ca:digestible P ratio at 2.1. The other two diets were formulated with two phytase’ doses added on top of the NC diet 4) 2,000 FTU/kg (NC+2000 phy) or 5) 3,000 FTU/kg (NC+3000 phy). Piglets were weighed individually at 42, 55 and 69 d of age, and feed intake per phase was recorded per pen. Average daily gain (ADG), daily feed intake (ADFI) and feed conversion ratio (FCR) were calculated. At the end of the experiment, right metacarpal was removed from 12 animals per treatment to analyze bone mineralization. Data were submitted to an ANOVA including effects of dietary treatments and body weight at start of the trial using JMP 16.2.0. Differences among means were separated by a Student’s test and significance accepted at P 0.05. Liveability % was not different between treatments. The reduction of Ca and digestible P in NC did not affect growth performance (P 0.05) but reduced bone ash % compared with PC (P 0.05, 30.4 % vs 34.6 %, respectively). Phytase supplementation at 2,000 and 3,000 FTU/kg improved body weight gain (28.8 kg for animals fed NC vs 30.0 kg for NC+2000 phy vs 30.2k g for NC+3000 phy, P 0.05), feed efficiency (1.60 vs 1.50 for NC and NC + 3000 phy, respectively; P 0.05) and bone mineralization (P 0.05). This experiment confirms the benefit of reducing the Ca and concomitantly P levels in piglet feed without impairing growth performance by optimal use of phytase that also provides the ability to overcome dependence on inorganic phosphates.