Mathematical modelling is an accounting tool that can be used for predicting the nutritional requirements for poultry with different genetic strains, environments and stages of meat gain or egg production, according to M.E. Reyes of Ecuador’s Universidad Nacional de Loja and co-authors at Universidad de Costa Rica in San José and the University of Arkansas in the US. In a paper published in International Journal of Poultry Science, they explain that models are also useful for describing or predicting the animal’s production process.

Modelling the daily ME requirement of broiler breeder hens requires partitioning metabolisable energy (ME) requirements into maintenance, egg mass and body weight gain. Determining the daily energy requirement for maintenance and egg production in breeders requires separating the daily energy needs for egg production from energy needs of maintenance.

The objectives of this research were:

• 1) to obtain information about body tissue changes and egg composition for breeders being fed specific intakes of ME in a set environment, and
• 2) to evaluate a technique for partitioning the ME requirement into maintenance and production for each individual breeder.

An oestrogen antagonist, Tamoxifen (Z]–1–1[p–Dimethylaminoethoxyphenyl]–1,2–diphenyhl–1butene; TAM), was used to separate the ME needs into two periods: laying and non–laying. Broiler breeder hens were provided TAM to stop egg production and their individual ME requirement for maintenance determined. Each broiler breeder resumed egg production when TAM was withdrawn and the ME requirement for egg production and bodyweight gain determined.

The researchers estimated ME required for maintenance for breeders (ME_m) housed in a constant 21°C was 98.3kcal per kilo bodyweight^0.75, ME_g for gain was 5.6kcal per gramme and ME_e for egg mass was 2.4kcal per gramme.

The energy efficiencies for protein gain (kp), fat gain (kf) and egg calories (ke) were 34 per cent, 79 per cent and 65.7 per cent, respectively.

Reyes and co-authors concluded that the use of TAM provided an opportunity to estimate breeder maintenance requirements and reduce the interdependence in estimating factorial coefficients while partitioning production energy.

Reference

Reyes M.E., C. Salas and C.N. Coon. 2011. Energy requirement for maintenance and egg production for broiler breeder hens. International Journal of Poultry Science, 10(12): 913-920.

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