Growth curves for body weight and major component parts, feed consumption, and mortality of male broiler chickens raised to maturity

Body weight; yield of the major carcass component parts of breast, leg, thigh, drumstick, breast meat, thigh meat, and drumstick meat; feed consumption; feed conversion; and mortality of male broiler chickens from two commercial strains were measured from hatching to 154 d of age. As no differences were observed between the two strains, for any of the traits measured, the statistical analysis was made using pooled data. Growth curves for BW, breast weight, and leg weight were calculated. The Richards function was chosen to fit the data. The type of the curves predicted was typically sigmoid. Asymptotic weights for BW, breast weight, and leg weight were estimated at 6,870.2, 1,744.2, and 851.5 g, respectively. Age at point of inflection, at which maximum growth rate is attained, was predicted at 44.4, 47, and 49.1 d, respectively. The percentage of breast and breast meat increased with age, whereas percentages of leg, thigh, and drumstick remained roughly constant. Weekly feed conversion was determined, and polynomial functions were applied to relate feed consumption and feed conversion to the age of the birds. Cumulative mortality increased with age, especially beyond 70 d of age, rising to 50% by the end of the experiment. Mortality was related to high incidence of leg weakness observed in the same period. The results of the current study provide information on the growth potential of contemporary, genetically improved broiler chickens by means of a mathematical model.