Natural antibody isotypes as predictors of survival in laying hens

To identify possible relationships between survival and titers of natural antibody (NAb) isotypes in serum of laying hens, birds from 12 purebred layer lines of 2 commercial breeds, Rhode Island Red (n = 524) and White Leghorn (n = 538), were monitored for survival during one laying period (from 20 until 70 wk of age). Titers of NAb isotype IgM- and IgG-binding keyhole limpet hemocyanin (KLH) in serum were measured at 20, 40, and 65 wk of age, respectively. Overall, the titers of IgM and IgG binding KLH decreased with aging. At the same age, lines within breed showed significantly different titers of isotypes (P < 0.0001). Multivariable logistic regression analysis showed that NAb isotype IgM and IgG titers at 20 wk of age were associated with survival at 20 to 40 wk of age. In the R breed, odds ratios of 0.56 (P < 0.0001) for IgM and 0.72 (P = 0.02) for IgG were estimated; in the W breed, these were 0.74 (P < 0.01) and 0.99 (P = 0.95) for IgM and IgG, respectively. We conclude that titers of Nab isotypes, especially the IgM-binding KLH at 20 wk of age, are indicative for survival during the laying period. The higher the titers of NAb isotypes, the higher the probability of layers to survive.