Verification and calibration of a simulation model for reproductive performance of beef cows based on body condition score internal evaluation

[摘要] This work was carried out with the goal of demonstrating and performing internal evaluation of the mathematical model developed to describe the reproductive performance in production systems and to simulate reproductive performance of beef cows from the body condition score at calving (BCSAC). This model is based on the relationship between BCSAC and the interval between calving and conception (ICC) for lactating cows; for heifers and empty cows at conception, it was based on the probability of occurrence. For internal evaluation of the model, it was used the methodologies of verification and calibration. The use of technique of variation of input data was done based through the construction of scenarios by changing BCSAC, starting date of the reproductive season (SDRS), average date of calving (ADC), and average daily weight gain from birth to weaning (ADWGBW). These scenaries also served for demonstration of the model. Through calibration, it was chosen new standard deviations for the following variables: gestation period, ADWGBW and average birth date (ABD). Tests for degenerescence and independence of seeds generating random numbers, after calibration, showed coherence of the model in generating randomness for the variables being studied. Variation on the input data showed effectiveness of the model to simulate the dynamics of reproduction systems. Nevertheless, adjustments in conception rate of primiparous females are needed for the model to generate values that are compatible with reality.

[学科分类] 兽医学

[关键词] beef cattle;mathematical models;modeling;reproduction    IntroduçãoA modelagem;processo de construção de um modelo;é;sobretudo;uma tentativa de integração de diferentes fenômenos;limitada pelos recursos humanos e materiais utilizados na sua construção (Lovatto & Sauvant;2001) e baseada principalmente na sistematização;o que permite o posicionamento do modelador frente ao estado de conhecimento (Lovatto;2003)