Skip to main content
ARS Home » Research » Publications at this Location » Publication #194125


item Cox, Nelson - Nac
item Richardson, Larry
item Buhr, Richard - Jeff
item Northcutt, Julie
item Cray, Paula
item Bailey, Joseph

Submitted to: Journal of Applied Poultry Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/16/2006
Publication Date: 12/1/2006
Citation: Cox Jr, N.A., Richardson, L.J., Buhr, R.J., Northcutt, J.K., Cray, P.J., Bailey, J.S., Fairchild, B.D., Mauldin, J.M. 2006. Natural occurrence of campylobacter spp., salmonella serovars and other bacteria in unabsorbed yolks of market age commercial broilers. Journal of Applied Poultry Research. 15(4):551-557.

Interpretive Summary: In the developing avian embryo, the main energy source is the yolk. After hatch, the chick rapidly initiates the transition from yolk dependence to utilization of exogenous feed and at the same time the unabsorbed yolk is internalized into the avian digestive system. Little is known about the bacteriology of these unabsorbed yolk sacs. However, recently a number of carcasses at processing plants have been observed to have unabsorbed yolk sacs and this could be a possible critical control point of contamination in the processing plant. In this study, we found that Campylobacter, Salmonella, and other bacteria are naturally present in these unabsorbed yolk sacs at a fairly high incidence rate. However, the significance of these bacterial reservoirs and carcass contamination is yet to be determined.

Technical Abstract: In the developing avian embryo, the main energy source is the yolk. Towards the end of the incubation period, the remaining yolk sac is internalized into the abdominal cavity. At hatch, the remaining yolk comprises 20% of the chick’s body weight and provides the nutrients needed for maintenance. Post hatch, chicks rapidly initiate the transition from yolk dependence to the utilization of exogenous feed. However at present, it is not known what types of bacteria are found to be associated with unabsorbed yolk sacs from market age broilers. For experiment 1, 100 6-wk old defeathered broiler carcasses were obtained from a commercial processing facility during each of three visits. In the second experiment, 100 8-wk old defeathered broiler carcasses were obtained from a different commercial processing plant on four separate occasions. For both experiments, each carcass was aseptically opened and inspected for the presence of an unabsorbed yolk sac. Three to five carcasses containing a free floating yolk sac (within the abdominal cavity) and the yolk stalk (without a yolk sac) and three to five carcasses containing an attached yolk/yolk stalk from each repetition were randomly selected and analyzed for levels and types of total aerobic bacteria (APC), Enterobacteriaceae (ENT) and for the presence of Campylobacter spp. and Salmonella serovars. The APC ranged from log 3.3 to greater than log 6.0 and the ENT from log 2.8 to greater than log 6.0. Staphylococcus spp. and Streptococcus spp. were the predominant organisms in APC while Escherichia coli and Hafnia alvei were found to comprise the ENT. Campylobacter spp. were found in 29% of the yolk stalks, 32% of the attached and 13% of the free floating yolk sacs. All Campylobacter isolates were determined to be C. jejuni except for one attached yolk/yolk stalk which was C. coli. Salmonella serovars were found in 26% of the yolk stalks, 48% of the attached and 23% of the free floating yolk sacs and the majority of Salmonella isolates were S. Typhimurium. The significance of these bacterial reservoirs and carcass contamination during processing is yet to be determined.