Body minerals content of reproductive sows
Contenu corporel en minéraux des truies reproductrices
Résumé
Minerals are essential for development and maintenance of the skeletal system and for many essential physiological functions. Factorial determination of mineral requirements is generally based on potential retention of total body minerals as a driving force. Since little information is available for breeding sows, data for fattening pigs is often used, which makes predictions inaccurate. Complete dissection (lean, fat, bones, skin, organs) of 189 sows was performed, and 23 of them were also chemically analyzed. Body minerals and protein contents were determined from these data using the double-regression technique. Sows were from different parities and had different physiological status: 42 and 66 primiparous sows at farrowing and at weaning, and 25 and 56 multiparous sows at mating and at farrowing, respectively. Body minerals weight (BM) differed according to parity and physiological status of
sows. The prediction equation of BM (kg) was more accurate with body protein (BP, kg) as a predictor [BM = -0.327 + 0.22719 BP - 0.000656 BP2; R2 = 0.98] than with empty body weight (EBW, kg) as a predictor [BM = -4.262 + 0.07527 EBW – 0.000116 EBW2; R2 = 0.81]. This was partly related to body fat content, which varied according to the physiological status of sows (17-23% of carcass weight). Indeed, when backfat thickness (P2, mm) was considered, the accuracy of the prediction equation based on EBW increased: [BM = -1.284 + 0.05981 EBW – 0.0000672 EBW2 – 0.10414 P2, R2 = 0.91]. It was concluded that body protein mass predicts body minerals of reproductive sow mass better than EBW. However, although less accurate, using EBW and P2 as predictors could to be an interesting alternative that is easier to apply in practice.