Effects of collagen casing manufacturing residue on the productivity and gastrointestinal function of meat-type chickens

The main component of artificial sausage casing is collagen. In this study, we added the manufacturing residue from this casing to broiler feed as an eco-feed material, and analyzed the productivity, intestinal mucosa, immune function, and intestinal flora of the chickens. Fifty-two 1-day-old male broiler chicks (ROSS 308) were used for the 22-day study after their random allocation to two groups. Both groups were fed experimental feed for broilers without antibiotics. The casing group feed was supplemented with 1.0% manufacturing residue from casing production. This experiment was repeated twice (104 birds). From day 4 to the end of feeding period, the chickens’ bodyweights were significantly higher in the casing group than in the control group. The heights of the duodenal and ileal villi and the thickness of the cecal mucosa were significantly greater in the casing group than in the control. These findings suggest that the efficiency of nutrient absorption was greater in the casing group. The expression of inflammatory cytokine genes associated with general immunity (spleen) and local immunity (cecum tonsils) was significantly reduced in the casing group. A comparison of the numbers of bacteria in the duodenum, ileum, and cecum using selective quantitative culture indicated that the numbers of lactic acid bacteria and Escherichia coli differed between the individuals in each group. No correlation between bacterial counts and bodyweight was observed. In this study, we have demonstrated that chronic inflammation in the intestinal tract was partly suppressed by the administration of the residue from the manufacture of collagen casing. This fact is supported by the increased nutritional absorption efficiency and the improved intestinal mucosae in the experimental chickens. Our results also suggest that improving the efficiency of energy distribution by feeding the manufacturing residue from collagen casing improved the weight gain in the chickens. In conclusion, we suggest that the residue from the manufacture of collagen casing is a useful feed supplement for breeding meat-type chickens.