Rearing system affects the efficiency of oleic acid deposition in Duroc x Iberian pigs
The aim of the study was to evaluate the impact of the rearing system (intensive 2.5 m2/pig vs. semi-extensive 30 m2/pig) used during the growing-finishing period on PUFA deposition by using an oleic enriched diet during the finishing period. The Iberian pig regulations require a minimum of 51% of oleic acid in fat (10 cm from the caudal basis) at slaughter to be considered for cured ham. Therefore, the effect of the rearing system on the time spend to reach the oleic acid proportion was also evaluated. A total of 16 barrows (Duroc x Iberian) were selected at 90 kg of BW (n = 8 per system) and offered the same growing and finishing diets. A diet based on barley- wheat-oats and soybean-sunflower meal to contain 14.7 MJ/kg ME; 5.7 g/kg Lys; 60.9 g/kg ether extract and 34.3 g/kg oleic acid was fed for the finishing period. Back fat samples were collected from each pig on days 0, 14, 28, 62 and 85 (slaughter) of the finishing period. Back fat samples were collected by an automatic cut/extraction system with a needle (8 mm Ø) and fatty acid profile was analyzed by the direct transesterification method and the percentage of oleic acid content calculated. The deposition response of the oleic acid was fitted by linear regression using the REG procedure of SAS. The comparison of slopes and times were analyzed with ANOVA by using the GLM procedure of SAS. The oleic acid deposition response for the semi-extensive reared pigs was y= 46.6 + 0.054(t) (R2 = 0.84) while for the intensive reared pigs was y = 47.5 + 0.071(t) (R2 = 0.83). Higher efficiency for oleic acid deposition was observed for the animals reared in the intensive system (P = 0.013). Therefore, a reduction of the days spent to reach the required level of oleic acid (51%) was observed for the animals reared in the intensive system than those reared in a semi-extensive system (49.0 vs. 80.4 d SEM = 5.24; P = 0.003). However, although higher efficiency on oleic acid and PUFA deposition was observed for the animals reared in the intensive system, the higher subcutaneous and inter-muscular but not intramuscular (marbling) fat content of the semi-extensive reared pigs has to be taken into account. It is concluded that the rearing system has a high impact on the efficiency of oleic acid deposition.
iberian, oleic acid, rearing system