Effect of morphological changes in feather follicles of chicken carcasses after defeathering and chilling on the degree of skin contamination by Campylobacter species

Campylobacter jejuni and C. coli are the leading causes of enteric infections in many developed countries. Healthy chickens are considered to act as reservoirs of campylobacters, as the organisms colonize the intestinal tract. Once infected birds enter a processing plant, contamination of chicken carcasses with campylobacters occurs over the entire skin during defeathering and evisceration due to leakage of crop and/or intestinal contents. Although the role of feather follicles in the contamination of chicken carcasses by campylobacters during processing is still debatable, it has been considered that the microorganisms would be entrapped and retained in the follicles due to the morphological changes resulting from defeathering and chilling. In the present study, we observed the morphology of feather follicles in chicken carcasses after defeathering and chilling. A total of 3,133 feather follicles were examined for morphological changes before and after chilling. Shortly after defeathering, most (91.5%) of the follicles were closed, whereas after chilling they were either closed (85.5%) or open (6%), although a small proportion of enlarged follicles became smaller or closed (2.6%). Moreover, 5.9% of the follicles that were slightly open became further enlarged after chilling. Furthermore, the proportion of enlarged feather follicles that became closed after chilling showed no discernible relationship with the degree of campylobacter contamination in different areas of the carcass skin, suggesting that campylobacters may not be confined to feather follicles as a result of the morphological changes attributable to defeathering and chilling.