PROVISION OF LACTOSE TO MOLTING HENS ENHANCES RESISTANCE TO SALMONELLA-ENTERITIDIS COLONIZATION

Older leghorn hens, more than 50 weeks of age, were divided into three groups designated 1, unmolted controls; 2, molted; or 3, molted treat ed with lactose. Forced molt was induced by 14 days of feed removal. L actose was provided to the hens in group 3 as 2.5% (wt/vol) of the dai ly drinking water. Each hen in all groups was challenged orally with 1 0(5) Salmonella enteritidis (SE) cells on day 7 of feed removal The st udy was repeated in three replicated trials. The concentrations of ace tic, propionic, and total volatile fatty acids (VFA) in the cecal cont ents of the molted hens in groups 2 and 3 decreased significantly (P < 0.05) on days 6 and 14 of molt compared with the unmolted controls. Fo rced molt had no apparent effect on pH or on the oxidation-reduction p otential of the ceca Compared to the unmolted I controls, SE cecal and spleen and liver colonization was significantly increased (P <0.05) i n the malted hens in group 2. Compared to the molted hens in group 2, SE cecal and spleen and liver colonization was significantly decreased (P <0.05) in two of three trials in the hens in group 3 provided with lactase. The results suggested that the increased susceptibility of m olting hens to SE colonization may be associated with decreased fermen tation and production of VFA by cecal bacteria or by a depletion of th e number of VFA-producing bacteria present in the ceca The results fur ther suggest that providing lactose in the drinking water during molti ng may significantly enhance resistance to SE colonization.