147 The Impact of Salinomycin and Crude Protein Level on Endemically Enterically Challenged Nursery Pigs

Abstract

Abstract Endemic enteric challenges antagonize nursery pig livability and performance. Recent limitations in the therapeutic control of Coccidia have increased the prevalence of coccidiosis in suckling and nursery piglets. Together with diet structure, intestinal inflammation and function may be compromised. Therefore, our objective was to evaluate the use of the coccidiostat, salinomycin, in conjunction with high (HCP) and low (LCP) dietary crude protein (CP) on performance, survivability, and cocci shedding of nursery pigs. Mixed sex pigs (n = 120; initial body weight = 5.63 ± 1.4) were sourced from a coccidia, rotavirus, and hemolytic Escherichia coli positive sow farm and randomly allotted to single sex pens in a 2x2 factorial design (10 pens/treatment). Pigs were fed either HCP (24%) or LCP (18%) diet with or without salinomycin. All pigs were fed in three phases lasting 9, 12, and 21 days, respectively. Salinomycin was fed in phases 1 and 2 at 90 ppm and in phase 3 at 60 ppm. Pen body weights and feed disappearance were collected at the start and end of each phase to calculate average daily gain (ADG), average daily feed intake (ADFI), and gain to feed ratio (G:F). Fecal consistency was scored for diarrhea presence daily. Within pen, pooled fecal samples were collected on days 9 and 20 for fecal float analysis of Coccidia oocyst counts. On day 9, one pig per pen selected based on median ADG within each pen was euthanized for tissue collection and histopathology assessment. Performance data, mortality/removals, and fecal cocci presence were analyzed for the effects of CP, salinomycin, and their interaction. Pen was the experimental unit and significance was set at P ≤ 0.05. Fecal coccidia oocysts counts were reduced by 85% (P < 0.05) and 80% (P = 0.066) at day 9 and 20, respectively in salinomycin verses control fed pigs. Salinomycin and LCP both decreased diarrhea incidence during phase 2 (P < 0.05). A CP and salinomycin interaction was observed during phase 2 and a tendency was observed overall as salinomycin seemed to mitigate diarrhea presence in HCP pigs (P < 0.05 and P = 0.090). Pigs fed salinomycin had reduced removal rates of 10 and 0%, compared with 15 and 30% for unmedicated LCP and HCP pigs (P < 0.05). No CP by salinomycin interactions for performance metrics were observed. In phase 1, no main effects were observed. During phase 2, LCP tended to increase ADFI for HCP (0.52 vs. 0.44 kg/d, respectively, P = 0.064). During phase 3, salinomycin increased G:F (P < 0.05) and tended to increase ADG (P = 0.080) compared with the control. Overall, 42 day nursery performance was not different between treatments. In conclusion, crude protein did not influence nursery pig performance. However, salinomycin reduced coccidiosis shedding and increased survivability in naturally enterically challenged nursery pigs.