PSIV-A-3 - Assessing the impact of zinc oxide supplementation vs no zinc oxide supplementation in nursery pigs two weeks post-weaning

Abstract: Zinc oxide (ZnO) is frequently incorporated into diets for post-weaning pigs as a growth promoter and an alternative to antibiotics to help prevent diarrhea. The growth-promoting benefits of additives are thought to depend on health status and growth rate with high-health pigs requiring lower levels of additives than health challenged pigs. This study aimed to assess the effects of ZnO supplementation on post-weaning outcomes in high-health nursery pigs fed complex nursery diets designed for high growth rate (20% whey permeate, 7.5% spray-dried plasma). A total of 240 weaned pigs from 17 litters (weaning age: 19 ± 2 days; weaning body weight (BW): 5.4 ± 1.1 kg) were included in this study. Pigs were allocated weaning BW to one of two dietary treatments, both meeting or exceeding NRC requirements for their respective phases: treatment one with no zinc oxide supplementation (CON), and treatment two with 2000 ppm zinc oxide supplementation (ZnO). Individual BW and feed consumption were measured on days 0, 7, and 14 to calculate average daily gain (ADG), average daily feed intake (ADFI), and gain-to-feed ratio (G: F). Blood and fecal samples were collected from three pigs per litter on days 0 and 14 to analyze IgG, serum antibodies (PCV2), and changes in the fecal microbiome (analysis pending). Fecal scores were assigned daily on a pen basis throughout the study using the following scoring system: 1 = firm feces, 2 = soft feces, 3 = mild diarrhea, and 4 = severe or watery diarrhea. Data were analyzed using the PROC MIXED procedure in SAS to evaluate the fixed effect of treatment on growth performance. No mortality was observed. On d14, pigs fed weighed 7.7 kg and 8.3 kg for CON and ZnO treatments, respectively. The ZnO group had greater ADG than the CON group in the second week post-weaning (294 vs. 206 g/d; SEM: 21.1; P = 0.008), as well as greater overall ADG across the experimental period (217 vs. 166 g/d; SEM: 16.4;P = 0.007). The ZnO group also tended to have greater ADFI than the CON group in the first week post-weaning (P < 0.10) and had greater ADFI in the second week post-weaning (338 vs. 280 g/d; SEM: 13.7; P = 0.007), with an overall greater ADFI (258 vs. 227 g/d; SEM: 7.3; P = 0.006). In conclusion, ZnO supplementation at 2000 ppm effectively improves feed intake and growth performance. The use of ZnO is a valuable strategy in swine nutrition to support the growth of healthy, newly weaned pigs.