Modelling of Body Mass Increase and Feed Conversion Ratio in Chickens ROSS 208

Abstract

The fattening efficiency evaluation in broilers, expressed in the European Efficiency Factor (EEF index) requires the information on mortality rate, body mass and feed conversion ratio reached at the age of their delivery to slaughter. This requirement is met by the use of the deterministic simulation model BIOM N 2001. In contrast to the contemporary widely used models of growth that describe the body mass growth as a function of time, the BIOM N 2001 model is based on the conversion of metabolizable feed energy into the gross energy deposited in the tissues of a growing warm-blooded animal. The results, obtained in an experiment with broiler chickens ROSS 208, demonstrate the formal compatibility of this new methodical approach with the classical growth function of Gompertz. The advantage of this new method is its compatibility with variables, generally used at well performing farms in the course of the fattening period, i.e. good agreement between the calculated values and those measured in an experiment, namely the amount of feed consumed under the measured climatic conditions of the breeding hall, the body mass of broilers (females-2 374 g, males-2 696 g), their age at slaughter maturity, and the feed conversion ratio. Taking into account the actual mortality of the flock it is easy to calculate the EEF index and to use the BIOM N 2001 model for the solution of prognostic or diagnostic tasks. Broiler chickens, deterministic model, body mass, feeding The classical approach to simulation of body mass growth by means of the Gompertz's function frequently used in the growth evaluation of broiler chickens (e.g. Rogers et al. 1987; Hurwitz and Talpaz 1997) describes the experimental growth curve as a function of time. Likewise Emmans (1997) derives the expected feed consumption in the growing organism from the time course of the Gompertz function. The new approach in a simulation of body mass growth based on the conversion of metabolizable energy consumed in the feed, into mass and gross energy of proteins, lipids and carbohydrates deposited in the growing body was published by Novák L. (1996), Novák L. and Zeman (1997). The influence of air temperature, humidity and ventilation rate in the stable on the available net energy for production, compatible with parameters currently found in well performing farms was presented recently (Novák, P. et al. 2000). This knowledge was now incorporated into the series of the growth models BIOM and BIOM N 2001, published by Novák L. (2000, 2003). The aim of this paper is to demonstrate the validity of the BIOM N 2001 model in simulation of body mass growth and feed conversion ratio data, with results of the carefully carried experiment on broiler chickens. Materials and Methods The growth experiment with broiler chickens ROSS 208 was carried out at the Research Institute for Animal Production Praha-Uhfiínûves. The experimental groups were kept separated by sex in pens (1.5•× 3 m) of 50

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