Submitted to: Journal of Applied Poultry Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 4, 2001
Publication Date: January 1, 2002
Citation: BUHR, R.J., DICKENS, J.A. EXTRACTION LOAD AND INTACT CROP REMOVAL DURING MANUAL EVISCERATION OF BROILERS: 2. INFLUENCE OF AGE, GENDER, AND DIRECTION OF EXTRACTION. JOURNAL OF APPLIED POULTRY RESEARCH. 2002. Interpretive Summary: Processing experiments were conducted to evaluated the influences of bird sex, age, and direction on the maximum force required for removal of the crop and the resulting incidence of intact crops. Incomplete removal or rupture of the crop during evisceration can potentially lead to bacterial contamination (Salmonella and Campylobacter) from ingesta onto the internal and external surfaces of the carcass. Male and female broiler chickens at 5-8 wk of age were defeathered and the crop was either pulled through the thoracic inlet into the breast cavity toward the vent or pulled toward the head thereby avoiding the thoracic inlet. The force required to remove the crop increased with age and weight. Force values for males were 21% higher than those for females. When maximum force was adjusted by body weight, the sex difference was no longer significant. The maximum force required to pull the crop toward the head was 16% less than through the thoracic inlet. Over the 5-8 wk period the incidence of crops removed intact that were pulled through the thoracic inlet was 69% for females and 59% for males, compared to significantly higher incidences of intact crop removal obtained for crops removed toward the head, 92% for females and 98% for males. This extremely high incidence of crops extracted intact (95%) when pulled toward the head indicates that alternative methodology for crop removal during automated commercial evisceration should be considered.
Technical Abstract: A series of experiments evaluated the influences of gender, age, and the direction of crop extraction on the maximum load required for manual removal of the crop and the resulting incidence of crops removed intact. Male and female broilers at 5, 6, 7 and 8 wk of age were electrically stunned, bled, scalded, and defeathered prior to removal of the crop either through the thoracic inlet toward the vent or avoided the thoracic inlet by removal toward the head (n = 16 per gender, age, and direction). The maximum load required to remove the crop increased with age and body weight, but at a slower rate than body weight. Values for males were 21% higher than those for females over the 4-wk period. When maximum load was adjusted by weight at slaughter, the gender difference was no longer significant. The maximum load required to extract the crop toward the head was 16% less than through the thoracic inlet. This difference was present for male and female broilers at each age sampled. Correlations between live weight and maximum load were higher for crops pulled through the thoracic inlet (r = 0.78) than for those removed toward the head (r = 0.57); and also higher for crops removed intact (r = 0.84) than for those crops that broke (r = 0.66). Over the 5 to 8 wk period the incidence of crops removed intact that were pulled through the thoracic inlet was 69% for females and 59% for males, compared to significantly higher incidences of intact crop removal obtained for crops removed toward the head, 92% for females and 98% for males. These results suggest that the maximum load to extract the crop increases at a slower rate than live weight for both female and male broilers from 5 to 8 wk of age.