Incidence of unabsorbed yolk sacs in broilers, broiler breeder roosters, white Leghorn hens, and Athens-Canadian randombred control broilers.

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 that 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 their abdominal cavities were opened for determination of the presence of unabsorbed yolk sacs. Carcasses with obliterated yolk stalks or stalks with no detectable yolk material were categorized as normal. Those with unabsorbed yolk sacs were further separated into 2 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 to 10 mm, and 3) large was >10 mm. From the 300 commercial broiler carcasses that were 6 wk old, 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 commercial broiler carcasses that were 8 wk old, 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 ACRBC broilers.