Alfalfa as a nutritive modulator in maintaining the innate immune response during the molting process

Abstract

Forced molting of laying hens increases enteric foodborne pathogens in the reproductive tract, leading to contaminated eggs and progeny of infected hens. Currently, we lack a complete understanding of how conditions such as molting affect the immune system. Previous reports have shown that alfalfa is effective in inducing a molt as well as in producing protection against Salmonella Enteritidis organ invasion. Our laboratory has also shown that immune functions are significantly reduced during molting. The present investigation evaluates a specific parameter of immune function, heterophil function, during an induced molt in hens fed alfalfa. Three replicate experiments used hens older than 65 wk of age that were divided into 6 groups of 12 hens each and placed in individual laying cages. Two weeks before dietary changes, hens were placed on an 8L:16D photoperiod that continued for the 12-d experiment. Peripheral blood samples were taken from hens on d 0, 2, 6, and 12 of molt. Hens were randomly placed into 3 treatment groups: nonfed hens, fully fed hens, and alfalfa-fed hens. To evaluate heterophil functions, the production of an oxidative burst as well as cellular degranulation assays were performed. In addition, total and differential peripheral blood leukocyte counts were performed. When compared with the nonfed control, alfalfa-fed birds showed significantly (P < 0.05) higher oxidative burst and degranulation activities. The data confirm previous observations that heterophil functions are significantly decreased in nonfed birds and the data show that birds fed alfalfa had numerically increased heterophil functions over a 12-d molting period when compared with heterophils of nonfed controls. Commercial integrators should consider using alfalfa when developing new molting programs.