PSII-19 - Enzymatically Treated Yeast: An Alternative to Therapeutic Levels of Zinc Oxide in Nursery Pig Diets

Abstract: At weaning 144 pigs (21 d old, BW 7.32±0.55 kg), were used to determine the efficacy of replacing therapeutic levels of Zinc Oxide with enzymatically treated yeast in nursery diets on growth performance, and nutrient and energy digestibility. Four pigs were placed in a pen and allocated to one of four dietary treatments (n=9). A control (CON) Corn, wheat, and soybean meal based pelleted diet, supplemented with either enzymatically treated yeast (HY40), Zinc Oxide (ZnO) or both (HY40+ZnO). Diets were provided in two phases, phase I from 0 to 14 and phase II from 15 to 42 days post-weaning. Inclusions of HY40 and ZnO were 0.5% and 3,000ppm, respectively, in phase I and were halved in phase II. All diets contained 0.2% TiO₂ to measure apparent total tract digestibility (ATTD) of nutrients and energy on days 7, 14 and 28. Aside from average daily feed intake (ADFI) during phase II, no interactive effects of HY40×ZnO were found for growth performance parameters (i.e., body weight, BW; average daily gain, ADG; and gain:feed, G:F). Pigs provided ZnO and HY40 had increased overall ADG by 57 and 21g/day, resulting in heavier pigs at the end of the nursery period (2 and 1 kg, respectively; P < 0.05). Only ZnO improved G:F during phase I compared to CON and HY40 pigs (0.843 vs. 0.773; P < 0.05). The ATTD of dry matter (DM), crude protein (CP) and gross energy (GE) was unaffected by any treatment on day 7, but on day 14, ATTD of pigs fed HY40, ZnO and HY40+ZnO had greater (P<0.05) DM, CP, and GE than CON. On day 28, pigs fed HY40, HY40+ZnO and CON had greater (P<0.05) ATTD of DM and GE than those fed ZnO. Therefore, enzymatically treated yeast is an effective alternative to therapeutic levels of ZnO supplementation in nursery diets