Egg yolk and serum antibody titers of broiler breeder hens immunized with uricase and or urease

This study evaluated whether broiler breeder hens immunized with uricase (UC), urease (UE), or UC + UE would develop antibody (IgY) titers against these enzymes to prevent manure-N degradation and NH₃ release. Ross × Arbor Acres hens were assigned to PBS (control), UC, UE, or UC + UE injection treatments. Each group had 19 hens per treatment. On d 0, each of the enzymes or PBS was emulsified with complete Freund's adjuvant and administered intramuscularly, whereas on d 7 and 14, a booster injection of PBS or enzymes was administered as an incomplete adjuvant. Blood samples were taken on d 0, 4, 9, 12, 17, 21, and 24 for serum-specific IgY titer analysis. Eggs were collected for yolk-specific IgY titer analysis. Manure samples were taken for nutrient, pH, and NH3 measurements. Elevated egg yolk anti-UC-IgY titers were observed from UC-immunized hens after the second immunization (P ≤ 0.0001), and they remained higher than those of the PBS- or UEimmunized hens from d 9 to 24. After the first injection, egg yolk anti-UE-IgY titers from hens immunized with UE or the combined antigen were greater than those of birds injected with PBS or UC (P ≤ 0.01). The serum anti-UC-IgY response to UC immunization was observed after the first injection (P ≤ 0.01) and on d 9 (P ≤ 0.0001), and titers remained greater than those of hens immunized with PBS or UE until d 28. The serum anti-UE-IgY titers remained low until much later compared with the anti-UC-IgY titers. Only at 24 and 28 d were anti-UE-IgY titers significantly greater in the UEimmunized hens than in hens immunized with PBS or UC. Hens immunized with UC or UE responded with both egg yolk and serum IgY titers. The combined antigens were significantly greater than the PBS control but had less effect than the individual UC or UE in both the egg yolk and serum. These findings indicate that despite measurable egg yolk and serum IgY titers, immunizing hens with UC, UE, or the combined antigens did not affect the manure nutrients or NH₃ emissions of the treated hens.