Comparison of total immunoglobulin A levels in different samples in Leghorn and broiler chickens

Objective: To standardize an ELISA protocol to quantify total immunoglobulin A(IgA)from different biological samples.Methods: Two independent experiments were conducted. In Experiment 1, total IgA levels were quantified from the lachrymal fluid, tracheal swab, and cloacal swab at various time points from Days 30 to 89 in white Leghorn chickens. Experiment 2 was conducted to evaluate the effect of 50 or 500 ppb of aflatoxin B1(AFB1) on total IgA quantified in samples from the lachrymal fluid, tracheal swab, gut content and cloacal swab in broiler chickens at 21 days of age.Results: Lachrymal fluid contained the highest level of IgA; however, the sampling procedure was time consuming and stressful to the bird, and the sample volume depends largely on the size of the chicken. Cloacal swabs also contained a high concentration of IgA; this sampling procedure was faster than lachrymal fluid sampling and was not affected by the age of the bird. Tracheal sampling was more difficult than cloacal sampling; the age of the bird limited the sampling, and the IgA concentration was the lowest detected at all sampling ages. 500 ppb of AFB1 significantly reduced total IgA concentration in the gut content compared with control or 50 ppb of AFB1 treated groups.Interestingly, a significant reduction in total IgA was also observed in those chickens that received 50 ppb of AFB1 in gut rinse when compared with cloacal swabs.Conclusions: The results of this study suggest that cloacal swab is an easy and reliable way to evaluate mucosal IgA concentration in both Leghorn and broiler chickens.