Effect of diflubenzuron (Dimilin; TH--6040) on the hyaluronic acid concentration in chicken combs

The addition of N-[[(4-chlorphenyl)amino]carbonyl]-2,6-difluorobenzamide(diflubenzuron; Dimilin; TH-6040) up to levels of 250 ppm of the total diet of both male broilers and layers for 98 days did not affect the hyaluronic acid (HA) concentration (microgram/g tissue) in the combs. The concentration was measured at 21, 28, 42, 56, and 98 days on feed. The concentration in the combs of the layers were not significantly different at any sampling period regardless of diet. At the end of 56 days on feed, the combs of the broiler controls had a significantly (P less than .025) higher concentration than did any of the groups fed diflubenzuron. There were no differences observed at 21, 28, 42, or 98 days in the broilers. The HA concentration increased as the chickens matured and became larger; however, large variations were observed within the various groups at a given sample period.