Efficacy of lincomycin feed medication for the control of necrotic enteritis in broiler-type chickens.

Necrotic enteritis was reproduced in two trials, conducted in a penned research-type broiler facility, by growing broiler-type chickens on litter obtained from a commercial poultry house which had experienced a chronic necrotic enteritis mortality problem. In each trial, various concentrations of lincomycin in feed were evaluated for effectiveness in controlling necrotic enteritis. Lincomycin was evaluated at concentrations of 2 to 100 g./ton in Trial 1 and at concentrations of 2 and 4 g./ton in Trial 2. In each trial, non-lincomycin medicated control groups were also included. Each trial included six treatment groups each consisting of four 60-bird replicates. The coccidiostat used in all groups in Trial 1 and in four of the six treatment groups of Trial 2 was the same as had been used on the farm which the litter had been obtained. No other medications were used in any groups. Clinical coccidiosis due to Eimeria brunetti and E. maxima was prevalent in both trials. Birds receiving lincomycin at a concentration of 2 g./ton, or higher, showed a significant reduction in mortality from necrotic enteritis when compared to birds in coccidiostat-control pens not receiving lincomycin medication. Clostridium perfringens was isolated from the litter in all pens and from the livers of birds dying from necrotic enteritis.