RESUMO
A two-way selection procedure was performed on a Landrace pig line. First the cardiac output (CO) values (6.89 +/- 1.27 L/min) were estimated by ECG-gated magnetic resonance imaging (MRI) to quantify the heart performance of the boars (n = 30), then total body skeletal muscle volume (MVTB; 48.7 +/- 5.17 dm3) was determined applying spiral computerised tomography (CT). The relative cardiac output value (RCO) was developed, expressing the relationship between CO and MVTB. Four superior [RCO value below 6.7 dm3 / (L x min(-1))] and one minus variant [(8.97 dm3 / (L x min(-1))] boars were taken into breeding. The best fifteen percentage of the first generation males (n = 30) was characterised according to their RCO values. Significant difference was found between the developed performance measure of the progenies of minus and plus variant boars [8.2 +/- 0.65 and 5.63 +/- 0.70 dm3 / (L x min(-1)), n = 7 and 23], respectively. Comparing the existing five progeny groups, all of the 'HP+' groups differed significantly from the 'HP-' one, where the largest heart performance contrast found was 3.2 dm3 / (L x min(-1)). Based upon the results, the selection is being continued on a larger population.
