The Influence of Restricted Feed Intake on the Response of Chickens to Marek’s Disease

Restriction of total feed intake accompanied by retardation of body growth rate significantly delayed the time of development as well as reduced the overall incidence of Marek’s disease in 8-week old chickens following inoculation with JM virus at day of age. When feed intake was restricted to three levels of the ad libitum intake, 80, 70 and 60 percent, the incidences of leukotic lesions in most tissues were in general proportionally reduced with the degree of feed restriction. In addition, the mortality due to Marek’s disease was significantly delayed. In the full-fed group, the mortality was seen as early as the twenty-seventh day while in the groups restricted to a 70 or 60 percent intake, no mortality was observed prior to the seventh week. These observations indicate that the amount of feed ingested influences the development of Marek’s disease neoplasia.