Effects of dietary narasin inclusion level on the growth performance, incidence and severity of diarrhea, and viral shedding in nursery pigs infected with Porcine Epidemic Diarrhea Virus (PEDV)

Abstract Text: This study was conducted to determine the effects of narasin on the growth performance, incidence and severity of diarrhea, and viral shedding in nursery pigs infected with Porcine Epidemic Diarrhea Virus (PEDV).  The study was carried out over a fixed-time period of 14 d from 29 to 43 d of age (7.6 ± 0.64 to 12.1 ± 0.96 kg BW, respectively).  A RCBD (blocking factor = weight) was used with 3 narasin inclusion levels (0, 30, and 60 mg/kg).  Diets were formulated to meet or exceed NRC (2012) recommendations for nursery pigs.  A total of 75 barrows (n=36) and gilts (n=39) were used and were housed in mixed-gender pens of 5 pigs (5 groups/treatment).  Pigs were allocated to pens and treatments at weaning (22 d age) and started on dietary treatments 7-d prior to being challenged with PEDV.  Pigs were weighed on day -7, 0 (start; challenge), 5, and 14 (end) of the study; all feed additions to the feeders were recorded.  Diarrhea scores (1 = Normal, 2 = Pasty, 3 = Semi-solid, 4 = Loose) were recorded and fecal swab samples were taken each d following the challenge to determine viral shedding values.  No pigs died or were removed while on study.  Compared to the control, feeding narasin from d 0 to d 5 increased (P ≤ 0.05) ADG (0.11, 0.17, and 0.22 kg for 0, 30, and 60 mg/kg, respectively; SEM = 0.025) and G:F (0.375, 0.551, and 0.670; SEM = 0.0767, respectively), but there was no effect (P > 0.10) on overall growth performance from d 0 to d 14.  Diarrhea scores decreased with increasing narasin level (1.49, 1.45, and 1.37, respectively), although these differences were not statistically significant (P > 0.10).  Compared to the control (0 mg/kg), pigs fed 30 mg/kg narasin had lower (P < 0.10) viral shedding on d 2 and 3 of study; pigs fed 60 mg/kg narasin had lower (P < 0.10) viral shedding on d 2, 3, 4, 5, and 6 of study compared to the control.  The results of this study suggest that feeding narasin lowers viral shedding levels of PEDV in nursery pigs, but further research is needed to understand the impacts of narasin on growth performance and incidence of morbidity and mortality in pigs infected with PEDV.

Keywords: Growth, Pigs, PEDV, Viral shedding