Modeling the effect of feeding strategy and feed prices on a population of pigs

Session 30 : Free communications: pig nutrition and managementWithin a population of pigs, variation in performance and nutritional requirements can be important.Nutritionists elaborate feeding strategies that maximize economic return at the batch scale while (in somecountries) accounting for N and P excretion. To evaluate the effect of feeding strategy and feed price onperformance, its variability, economic return and environmental impact, a simulation study was carried outusing both a virtual population of 2,000 gilts and barrows and the InraPorc® growth model. The 2,000 virtualanimal profiles were generated randomly from the average of five parameters that describe growth and feedintake, while using the covariance structure of parameters obtained in a preliminary study. The effects offactors such as feed restriction, number of diets used and amino acids level in each diet were simulated withdiets formulated using the least-cost principle. Five different contexts of feedstuff prices, corresponding toaverage prices recorded for five harvesting campaigns (2005/06 to 2009/10) were used. Calculations wereperformed for the 2,000 individual animals to obtain performance at the average final BW of 115 kg for thegroup. With reference to the French payment grid, carcass value was calculated using the final individualcarcass weights and lean meat contents. Economic return was calculated as the difference between carcassvalue and the costs of feed and labor. Results suggest that the variability of final BW was reduced withan increased supply of amino acids. Feed restriction had a greater impact on variability. The price of feedingredients influenced the optimum level of amino acids for economic return and corresponding N output.These calculations should be performed monthly to adapt nutrient supplies to the economic context