Title: INCIDENCE OF UNABSORBED YOLK SACS IN BROILERS, BROILER BREEDER ROOSTERS, WHITE LEGHORN HENS, AND ATHENS-CANADIAN RANDOMBRED CONTROL BROILERS
Submitted to: Poultry Science
Publication Acceptance Date: 3/9/2006
Citation: Buhr, R.J., Northcutt, J.K., Richardson, L.J., Cox Jr, N.A., Fairchild, B.D. 2006. Incidence of unabsorbed yolk sacs in broilers, broiler breeder roosters, white leghorn hens, and athens-canadian randombred control broilers. Poultry Science. 85:1294-1297.
Interpretive Summary: The importance of the unabsorbed yolk material that remains in the yolk sac after hatching as a possible reservoir for bacteria contamination of processed poultry carcasses is presently being investigated. However, it is unknown at what frequency unabsorbed yolk sacs persist at the time of processing of broilers and spent breeders. Therefore, commercial broilers (at 6 or 8 weeks of age), broiler breeder males at 52 weeks of age, laying hens at 102 weeks of age, and Athens-Canadian Randombred Control (ACRBC, 1950's style broiler) broilers at 8 weeks of age were obtained, euthanized, and the abdominal cavity opened for determination of the presence of an unabsorbed yolk sac. Carcasses with obliterated yolk stalks and/or stalks with no detectable yolk material were categorized as normal. Those with unabsorbed yolk sacs were further separated into two groups: 1) attached by the yolk stalk to the small intestine; or 2) unattached within the abdominal cavity. From the 6 week old commercial broiler carcasses, 54% were categorized as normal with no detectable yolk sac, 35% had an unabsorbed yolk sac attached to the yolk stalk, and 12% had unattached yolk sacs. From the 8 week old commercial broiler carcasses, 49% of the carcasses were normal, 31% had attached unabsorbed yolk sacs, and 20% had unattached yolk sacs. From the rooster carcasses, 73% were normal, 8% had attached unabsorbed yolk sacs, and 19% had unattached yolk sacs. From the laying hen carcasses, 88% were normal, 8% had attached unabsorbed yolk sacs, and 4% were unattached yolk sacs. From the ACRBC carcasses sampled, 76% were normal, 4% had attached unabsorbed yolk sacs, and 20% were unattached yolk sacs. The incidence of unabsorbed yolk sacs in present day commercial broilers appears twice as high as for mature roosters, hens, or ACRBCs, and therefore may serve as a reservoir for bacteria contamination of processed broiler carcasses. The restrictive feeding and lighting programs that breeders and laying hens are subjected to during rearing may influence yolk sac utilization by chicks after hatching.
Technical Abstract: Unabsorbed yolk sacs are being investigated as a possible reservoir for internal Campylobacter and salmonellae contamination of processed poultry carcasses. However, it is unknown at what frequency unabsorbed yolk sacs persist at the time of processing of broilers and spent breeders. Seven sets of 100 broiler carcasses (at 6 or 8 wk of age) were obtained from commercial processing plants. In addition, 100 52-wk-old broiler breeder males, 100 102-wk-old Leghorn hens, and 300 8-wk-old Athens-Canadian Randombred Control (ACRBC) broilers were euthanized and the abdominal cavity opened for determination of the presence of an unabsorbed yolk sac. Carcasses with obliterated yolk stalks and/or stalks with no detectable yolk material were categorized as normal. Those with unabsorbed yolk sacs were further separated into two groups: 1) attached by the yolk stalk to the small intestine; or 2) unattached within the abdominal cavity. Yolk sacs were further classified by size: 1) small was< 2 mm in diameter; 2) medium was 2 mm to 10 mm; and 3) large were greater than 10 mm. From the 300, 6-wk-old commercial broiler carcasses, 54% were categorized as normal with no detectable yolk sac, 35% had an unabsorbed yolk sac attached to the yolk stalk, and 12% had unattached yolk sacs. From the 400, 8-wk-old commercial broiler carcasses, 49% of the carcasses were normal, 31% had attached unabsorbed yolk sacs, and 20% had unattached yolk sacs. From the 100 rooster carcasses sampled, 73% were normal, 8% had attached unabsorbed yolk sacs, and 19% had unattached yolk sacs. From the 100 White Leghorn hen carcasses sampled, 88% were normal, 8% had attached unabsorbed yolk sacs, and 4% were unattached yolk sacs. From the 300 ACRBC carcasses sampled, 76% were normal, 4% had attached unabsorbed yolk sacs, and 20% were unattached yolk sacs. The incidence of unabsorbed yolk sacs in present day commercial broilers appears twice as high as for mature roosters, hens, or ACRBCs.