Description of a growth simulation model for predicting the effect of dieton broiler composition and growth

The growth simulation program, BPHL (Bromley Park Hatcheries Limited), is a computerized, mechanistic, deterministic and dynamic approach to the evalu ation of the effects of diet on broiler carcass composition and growth. Dai ly growth is simulated with information on the initial age and live weight of the bird, number of days over which the diet is to be fed, protein and a mino acid densities of the diet, dietary metabolizable energy, and whether feed intake is to be simulated or data provided. Output provides informatio n on a daily basis with respect to daily and accumulated deposition and cur rent bird status for protein, fat, water, and ash body content. Carcass wei ght, feather weight, live weight, feed eaten, feed deprivation heat loss, l imiting amino acids, food conversion ratio, and percentage carcass fat are also provided. The approach employs empirically derived first-limiting amin o acid coefficients relating to accretion efficiency and dietary concentrat ion to define limits of protein retention, uses mathematical expressions de scribing feed intake and heat loss trajectories as datum patterns prescript ive of the strain, introduces calibration as a device for improving corresp ondence between simulated and field performance, and relies on an assumptio n that deviations to the datum patterns of food intake and heat output caus ed by strain and environmental factors can be duplicated by simple multiple rs acting on the expressions. The program may be used as a tool for exploring the predicted effect of spe cific dietary characteristics and strain parameters on growth, body composi tion, and performance.