Abstract
An experiment was conducted to study the response of a slow growing chickens breed "Sinai" to feed restriction (FR) and the effects on growth performance, blood constituents and immune markers using a total number of 60 unsexed 7-d-old chicks. Chickens were housed in battery brooders during d 1 to 35 of age and randomly distributed keeping similar initial body weight, in two FR treatment groups. During 0-6 d of age, chickens were fed ad libitum, a mash commercial diet. During d 7-14 of age, chickens were fed either 100 or 80 % of the daily amount of feed consumed by the control group during the previous day. From d 15 to d 35, chickens were fed ad libitum diets a mash commercial diet. At the end of the experiment, body weight gain on the FR regimen was significantly lower than that of the control group, but feed intake and feed conversion ratio (FCR) were not affected. In addition, red blood cells parameters and white blood cells traits were not negatively affected. However, hemagglutination inhibition titter for New castle disease virus, monocyte and total cholesterol were significantly decreased by FR regimen, but blood plasma albumin and immunoglobulin A significantly increased. In conclusion, slow growing chickens could tolerate 27.2 % FR during the 2(nd) week of age without significant differences in feed intake and FCR for the whole period, and general health status and metabolic profiles indicating a compensatory growth during 15-35 d of age although growth was in favour to the unrestricted group.