Assessing the Ability of Maternal Antibodies to Protect Broiler Chicks Against Colonization by Salmonella Heidelberg

Vaccine regimes and maternal antibody protection are important in ensuring the health of poultry and critically important in decreasing contamination of poultry products with foodborne pathogens that threaten human health. Here, we assessed the role of passive immunity on the resistance of progeny to early colonization when challenged with Salmonella Heidelberg. Two broiler breeder hen flocks which had received a Salmonella vaccine regime consisting of two live attenuated and two killed vaccines during rearing were selected for study. ELISA titers were used to assess antibody levels in the parent flocks, with one low- and one high- titer flock selected for study. Progeny chicks (1 day of age) were taken from each flock and challenged with Salmonella Heidelberg at low (10^{3}) or high doses (10^{5}) at 3 days of age. At 14 days postinoculation, all birds were euthanatized and their liver, spleen, and ceca collected for culture. ELISA analysis found Flock A (30-wk flock) demonstrated higher Salmonella antibody titers in the parents as well as yolk titers in the progeny, resulting in greater early protection from colonization by Salmonella Heidelberg while Salmonella colonization rates were higher in the progeny of the older parent Flock (B) that demonstrated lower antibody titers in the parents and the yolks of the progeny. These results suggest that as the breeder hens’ protective antibodies wane with age; the maternal antibody protection in their progeny also becomes less effective in preventing cecal colonization by Salmonella early in life, which has the potential for affecting the health of the bird and contamination of meat products destined for the consumer.