Rey A I, Daza A, López-Carrasco C, López-Bote C J
Departamento de Producción Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, 28040 Madrid, Spain.
Meat Sci. 2006 May;73(1):66-74. doi: 10.1016/j.meatsci.2005.10.018. Epub 2005 Dec 22.
The experiment was undertaken to provide information on the influence of grass intake in a high fat diet based on acorns, in either free-range or confinement, on the carcass yield and characteristics, and on the accumulation of fatty acids and tocopherols. Groups raised free-range or with acorns and grass in confinement had the highest total backfat. Grass addition to the feed did not significantly modify the carcass weight and cut yield. However, outdoor raising produced lower carcass weights and yield, Longissimus dorsi muscle and ham weights than those fed the formulated diet or acorns and grass in confinement. Neither grass intake nor outdoor rearing did modify significantly the proportion of saturated fatty acids of the backfat. However, a lower proportion of saturated fatty acids was found in the intramuscular neutral lipids from pigs fed outdoors. Pigs reared free-range had significantly (P=0.0001) higher proportions of C18:1n-9 in the inner layer and in the intramuscular neutral lipids than the other groups. The grass intake significantly (P=0.0001) increased the proportion of C18:3n-3 in the inner and outer fat layers and intramuscular neutral lipids, while the outdoor rearing system not only affected on the proportion of linolenic acid but also C22:5 and C22:6 of the inner backfat layer and intramuscular polar lipids. These results suggest that the outdoor rearing allows a higher accumulation of n-3 fatty acids maybe due to an increased activity of the desaturase and elongase enzymes. On the other hand, the accumulation of tocopherols was not significantly modified neither by the grass intake nor the outdoor rearing, while differences were detected by the type of feeding (diet vs. acorns/acorns and grass). It is concluded, that the outdoor rearing system affects the nutritional value of meat, mainly by improving the fatty acid composition.
本实验旨在提供信息，研究在以橡子为基础的高脂日粮中，自由放养或圈养条件下，青草摄入量对胴体产量和特性、脂肪酸及生育酚积累的影响。自由放养或圈养且日粮中添加橡子和青草的组，总背膘最厚。在饲料中添加青草对胴体重和分割肉产量没有显著影响。然而，户外饲养的猪胴体重和产量、背最长肌和火腿重量均低于饲喂配方日粮或圈养且日粮中添加橡子和青草的猪。青草摄入量和户外饲养均未显著改变背膘中饱和脂肪酸的比例。然而，户外饲养的猪肌肉内中性脂质中的饱和脂肪酸比例较低。自由放养的猪在内层和肌肉内中性脂质中C18:1n-9的比例显著高于其他组（P=0.0001）。青草摄入量显著增加了内外脂肪层和肌肉内中性脂质中C18:3n-3的比例（P=0.0001），而户外饲养系统不仅影响内层背膘和肌肉内极性脂质中亚麻酸的比例，还影响C22:5和C22:6的比例。这些结果表明，户外饲养可能由于去饱和酶和延长酶活性增加，使n-3脂肪酸积累量更高。另一方面，青草摄入量和户外饲养对生育酚的积累均无显著影响，而不同饲养方式（日粮与橡子/橡子和青草）之间存在差异。得出的结论是，户外饲养系统主要通过改善脂肪酸组成来影响肉的营养价值。
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