PSI-A-2 Effects of Microencapsulated Zinc Oxide on Nursery Pig Growth Performance and Intestinal Morphology

Abstract

Abstract The inclusion of pharmacological levels of zinc oxide (ZnO) has been used to enhance the health and performance of piglets immediately post-weaning for decades, but there is consumer and regulatory pressure to limit this practice. Microencapsulation can allow for a more targeted release and better utilization of zinc oxide, thus making it a viable alternative to conventional ZnO. The objective of this experiment was to evaluate the impact of a microencapsulated ZnO on growth performance and intestinal morphology in newly weaned pigs. A total of 300 nursery pigs (DNA 200 x 400; initially 6.03 ± 0.08 kg BW) were allotted in a completely randomized design to one of five dietary treatments: 1) Negative control (basal diet with no added ZnO); 2) basal diet + 3,000 ppm added Zn from ZnO in phase 1 and 2,000 ppm added Zn from ZnO in phase 2; 3) basal diet + 400 ppm added Zn from ZnO; 4) 3,000 ppm added Zn from microencapsulated ZnO in phase 1 and 2,000 ppm added Zn from microencapsulated ZnO in phase 2; and 5) 400 ppm added Zn from microencapsulated ZnO in phases 1 and 2. Pigs were fed treatment diets from d 0 to 28, and a common diet was fed to all pigs from d 29 to 42. To determine average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency (G:F), pigs and feeders were weighed weekly. On d 28, 6 piglets per treatment were euthanized to collect small intestinal samples. Tissue samples were fixed in formalin, stained with hematoxylin and eosin, and slides were then evaluated for villi height (VH) and crypt depth (CD) on 10 villi per sample. Data were analyzed using the GLIMMIX procedure of SAS. There was no evidence of differences (P > 0.05) in ADG, ADFI or G:F for the entire treatment period (d 0 to 28); however, pigs fed the negative control or a diet with microencapsulated ZnO had improved (P < 0.0001) ADG and ADFI during the common period compared with pigs fed conventional ZnO. There was no evidence of differences (P > 0.05) in the VH and CD of both proximal and distal ileum samples. Results indicate the need for further investigation of the use of M-ZnO in post weaned nursery pigs.