PSVIII-13 - Utilization of a mechanistic model to estimate the mineral deposition of females and entire males growing pigs

Abstract: Entire male (EM) production is increasing worldwide due to animal welfare regulations. The soft tissue growth and carcass composition of these animals were previously studied, but, few data are available about the minerals deposition. The objective in this study was to highlight, through modelling, potential differences in bone mineral deposition between female and EM, fed with identical diets. The data of seven nutritional trials were used to simulate the mineral deposition in bones of EM and females. All diets were tested on both sexes and growth performances were reported. The trials started at about 32 kg of bodyweight and were divided into two phases: a growing phase (between 33 and 49 days, until 60 to 69 kg) and a finishing phase (between 47 and 61 days, until 110 to 125 kg). Protein and lipid depositions were calibrated following the InraPorc model principles. The minerals deposition in soft tissues and in bones were simulated according to a recent model predicting the utilization of minerals by growing pigs. The input data were the mean of each treatment, for each sex. The simulated bone mineral content (BMC) and bodyweight of the females and EM were comparable at the beginning of the trials. The BMC at the end of growing phase was lower in EM than females (1280 vs 1298 g, P< 0.05), whereas bodyweight was equal. The BMC at the end of finishing phase tended to be lower in EM than females (P=0.10), and bodyweight was higher in EM than females (114 vs 116, P< 0.05). These results showed that during the growing phase, where the protein deposition increases quickly, the EM have less minerals in their bones than female. Therefore, with the same diet, these animals could be more sensitive to leg problems, which is reported in the field. These first results based on simulations showed that minerals requirements for EM are higher than females indicating that the minerals requirements must be adjusted according to the sex.