134. Inclusion of high levels of phytase improves feed efficiency and reduces the carbon footprint of diets fed to growing pigs

Abstract

Phytase application has evolved with greater understanding that phytate destruction improves nutrient utilization and releases inositol. Recent applications include a superdosing strategy whereby phytase is added to the diet on top of a standard level of phytase for improved performance or a maximum matrix nutrition strategy whereby greater nutrient release values are used in formulation to maintain growth and provide a cheaper diet. An experiment was conducted to evaluate these two phytase strategies on growth performance, carcass characteristics, and the carbon footprint in growing swine. Three experimental diets were formulated. The first was a control diet (CON) utilizing a standard dose of phytase (360 FTU/kg) with a Ca (0.13%) and avP (0.12%) matrix. The second treatment (superdosing; SD) used higher levels of phytase (2,000 FTU/kg) with a Ca (0.16%) and avP (0.15%) matrix. The third treatment (maximum matrix; MMN) also used 2,000 FTU/kg of phytase but utilized matrix values for energy and amino acids in addition to minerals, Ca (0.16%) and avP (0.15%). Each dietary treatment was fed over 4 phases to 15 pens containing approximately 20 pigs per pen. Pigs were assigned to treatments using a randomized block design based on BW (average initial BW = 39.8 kg). Pig weights and feed disappearance were measured and used to determine ADG, ADFI, and G:F. Data were analyzed using mean separation by T-test for growth performance. Initial BW was used as a covariate. Overall, SD increased (P < 0.05) G:F (0.366 vs. 0.360) compared to the CON and MMN was not different from the CON. There was no difference in overall ADFI or ADG. A model was implemented to test the carbon footprint of each diet. Compared to the CON, SD and MMN decreased the carbon footprint by 1% and 3.5%.