Effects of Escherichia coli-specific egg yolk antibody powder on intestinal mucosal immunity and blood protein electrophoretic patterns of broiler chicks
The present study aimed at the investigation of dietary supplementation of different levels of specific egg yolk antibody (IgY) powder on intestinal mucosal immunity and serum protein electrophoretic patterns of E. coli O78:K80-challenged broiler chicks. For lyophilized antibody preparation, forty 36-week-old White Leghorn hens were hyperimmunized with E. coli O78:K80 bacteria for a 12-week-period and IgY was isolated from the eggs by the water-dilution method. Seven-day-age broiler chicks were challenged orally with 0.5 mL of E. coli O78:K80 suspension (except for the negative control). The challenge was continued for additional 7 days from day 14 to 21 with 1.0 mL of a late log phase culture (109 cfu/mL) until the level of E. coli in droppings reached to 105 cfu/g. A total of 280 broiler chicks were randomly assigned to 5 dietary treatments with 4 replicates of 14 chicks each. The four challenged-groups received a basal diet supplemented with 0 (as positive control), 0.1, 0.2, or 0.4% (wt/wt) IgY. The unchallenged-group, as negative control, fed the same unsupplemented diet. Oral infection caused increase in ileal E. coli enumeration, and induced systemic and mucosal inflammatory reactions. After three weeks of feeding, the levels of 0.2 and 0.4% IgY had the most suppressive effects (P<0.01) on the ileal E. coli enumeration and intestinal secretory IgA concentration. However, with at least 0.2% IgY, serum IgA concentration and the albumins to globulins ratio were slightly decreased (P=0.36) and increased (P=0.20), respectively. It was concluded that feeding high level of specific antibody powder, in addition to decreasing inflammatory factors, may increase the ratio of serum albumin. Therefore, the serum proteins can be directed toward metabolic pathways instead of being imposed on inflammatory pathways.