Desenvolvimento de modelo de custo e aplicação à valoração econômica de indicadores zootécnicos em um sistema de produção de caprinos leiteiros

Abstract

Bioeconomic modeling can be used to calculate marginal economic values of traits. The present work had as objectives the construction of a cost and profit calculation model for dairy goats, the modeling of the effect of zootechnical indicators and its application to the attribution of economic values to zootechnical indicators in a system. The study used data from the Goat Production Sector of the Federal University of Viçosa. A bioeconomic model was built in an electronic spreadsheet, having as inputs the quantities and prices of the inputs used in the system and their zootechnical indicators, and allocated the costs in variables, fixed operational and capital opportunity costs. Multiple Linear Regression was used to generate a prediction model of average milk production as a function of breed, litter size, weight at kidding, age at kidding, lactation order and lactation duration, using the RStudio software. The calculated profit and the milk production prediction model were applied to the calculation of the absolute and relative economic values of each zootechnical indicator. To this end, changes were simulated in each zootechnical indicator, and their effects on profit were quantified. The participation of producers in the development of the model allowed the creation of a useful tool for analysis of the production system, with the calculation of the total annual cost and per unit of each product produced, as well as the profit to the producer, which will be made available to the sector. Milk production per lactation was influenced by litter size (P=0.00325), age at calving (P=0.01886), duration of lactation (P=< 2e-16) and calving order (P=0.00575). The absolute and relative economic values were, respectively, R$ 0.446 /kid and 62.3% for litter size, -R$ 0.004 goat/month and -0.5% for age at kidding, R$ 0.011 /goat/day and 1.5% for lactation duration and R$ 0.263 /goat/kidding and 36.7% for kidding order. Litter size affects profit both because of its relationship with milk production and because of the availability of animals for sale. The duration of lactation in the flock is adequate, but it would be interesting to reduce the dry period. Elevated age at first kidding and kidding interval may account for the effect of age and kidding order. Increases in litter size and kidding order would have the biggest impact on profit. In conclusion, the cost calculation model is effective as a management tool and the economic valuation found that more than 90% of the economic value was obtained by litter size and kidding order, which are linked to the income obtained in this study. In addition, the scarcity of the theme in goat farming and the different indicators analyzed demonstrate the need to continue the research.