Abstract
An overview of the literature indicates that lower rather than higher dietary concentrations of black cumin seed may have a positive influence on feed efficiency in broiler chickens. In this study, 4 day old broiler chickens were fed either a diet without or with black cumin seed at inclusion levels of 0.25, 0.50 or 0.75% for a period of 7 weeks. Body weight gain during the 1st, 4th and 7th week of the experiment was significantly decreased by each level of dietary black cumin. The diets containing black cumin seed did not significantly influence weight gain and feed efficiency as measured for the entire experimental period. However, the diets with either 0.25, 0.50 or 0.75% black cumin lowered group-mean weight gain by 4.7, 3.3 and 6.5%, respectively and raised the group-mean feed conversion ratio (g feed/g weight gain) by 3.7, 4.8 and 7.0%. The final weights of breast, thigh and drumstick were not affected by the composition of the diet. It is concluded that dietary black cumin seed may deteriorate feed efficiency in broiler chickens in a dose-dependent relationship. It is unclear why the present observation is opposite to the outcome of various earlier studies of other investigators.