Response of Broilers to Early Stage Feeding of Spray Dried Porcine Plasma in Presence of Necrotic Enteritis Challenge

Necrotic enteritis (NE) is an enteric disease of poultry caused mainly by a spore-forming grampositive bacterium, Clostridium perfringens, resulting in decreased growth, high mortality, and increased veterinary costs (Wade and Keyburn, 2015). While supplementing poultry diets with antibiotics can control NE, emerging antibiotic-resistant microbes and transfer of such resistance factors into human medicine have resulted in restriction or ban of antibiotic usage across the world. Inclusion of plasma proteins in feed may show potential for poultry health in a post-antibiotic era. Plasma proteins contain immunoglobulins and other components that may benefit both healthy and NE affected birds. The current study was carried out to examine the effects of spray-dried porcine plasma (SDPP) on growth performance and immunological parameters in broilers under NE challenge.

A total of 720 day-old Ross 308 male parental line were randomly assigned to four treatments with 12 replications in a 2 × 2 factorial arrangement. The factors included NE challenge (no, yes) and SDPP (0 or 20 g/kg in starter phase, 0 to 10 d). Challenged birds were gavaged with 1 ml Eimeria vaccine (E. acervulina, E. brunetti and E. maxima) on d 9 and C. perfringens strain NE-18 on d 14. Feed intake, body weight gain (BWG), and FCR were determined on d 8 and 29. Eimeria oocysts were counted in the excreta on d 14 and 16. On day 16, three birds from each pen were sampled to examine lesion scores, organ weights, and gut leakage by determining passage of gavaged FITC-d into blood. Jejunal tissues were collected for histological examinations. Serum samples were collected to measure immunoglobulins (IgA, IgM, IgG), α-1 acid glycoprotein (αAGP), ovotransferrin and interleukin-6 (IL-6).

The NE challenge was successful as shown by a lower feed intake, reduced body weight gain, higher FCR (P < 0.001) and higher lesion scores (P < 0.01) in duodenum, jejunum and ileum than the unchallenged birds. Challenged birds had lower villus height to crypt depth ratio, and higher FITC-d concentrations in blood serum than the unchallenged birds(P < 0.001). Early feeding of SDPP (0 to 10 d) decreased FCR by 4.5 points before NE challenge (i.e. from d 0 to 8, P < 0.001). During the overall period of 0 to 29 d, dietary SDPP decreased (P < 0.01) FCR by 1.5 points and tended (P = 0.07) to increase BWG. Dietary SDPP did not affect lesion scores in the gut, oocyst counts in the excreta, and villus height to crypt depth ratio (P > 0.05). An interaction was observed (P < 0.05) that SDPP lowered (P < 0.01) serum FITC-d concentration only in the challenged birds compared to those without SDPP, but not in nonchallenged birds. Dietary SDPP increased (P < 0.05) the relative weight of bursa on d 16. There was no interaction between SDPP and NE challenge on performance parameters, lesion scores, and oocyst counts in the excreta. Challenge increased the levels of IgA, IgM and αAGP levels in the serum on day 16. Dietary SDPP decreased (P < 0.05) the level of αAGP and IL-6 in serum on d 16. These results indicate that early inclusion of SDPP enhances performance possibly through reduced inflammation in the NE infected or uninfected birds. Further work should examine shorter periods of SDPP inclusion at higher doses.