The Effects Of Grazing On Meat Quality And Its Mechanism In Songliao Black Swine

T aking Songliao Black Swine as re search object, the growt h performance, body inde x, slaughter traits, meat quality and blood bi ochemical indexes were compared between barn feeding group and grazing group, and the mRNA levels of four specific MyHC(Myosin heavy chain) isoforms,CAST(caplastatin),LPL(Lipoprotein lipase)were analyzed by fl uorescent quantitative PCR. The results are as follows:G rowth performance: The daily gain(452.17±17.85g) and feed- weight radio(2.23±0.22) in grazing group were significantly lower than those in barn feeding group(699.54±18.56 g and 3.12±0.19)(P﹤0.05).Body index:In grazing group,the length index was lower than that in barn f eeding group,but there was no significant difference between the two group(P﹥0.05).The bust index was extremely significant higher(P﹤0.01)and body index wa s significantly lower(P﹤0.05)than those compared to barn feeding group.Slaughter traits:In grazing group, lung coefficient(1.24±0.25)was significantly higher and fat percentage(20.59 ± 1.13)was significantly lower(P ﹤ 0.05)than those in bar n feeding group(1.03±0.08 and 25.19±4.82), but lean meat percentage, bones percentage stomach and guts coefficient had no difference compared to the barn feeding group.Meat quality:In grazing group, the intramuscular fat content,marbling score, cooking percentage and tot al amino acid content were significantly increased(P﹤0.05),shear force, water loss rate and drop loss were signi ficantly decreased(P﹤0.01), and saturated fatty acid content was si gnificantly decreased(P﹤0.05).There was no diff erence in the content of unsaturated fatty acids palmitoleic acid and oleic acid.Blood biochemical indexes:In grazing group, bilirubin cont ent was significantly increased(P﹤0.05),carbon dioxide binding force was extremely i ncreased(P﹤0.01), and albumin, standard calcium and total calcium content were significantly decreased(P﹤0.05).The total content of cholesterol and urea nitrogen was extremely significant(P﹤0.01).Ge ne expression:In grazing group, the m RNA level of MyHCⅡb in longissimus dorsi was extremely significantly higher(P﹤0.01),and MyHC Ⅱ x mRNA level i n psoas major muscle was significantly higher(P﹤0.05). no significant difference in the mRNA levels of CAST and LPL was observed.In conclusion, grazing can improve meat quality, producting high-grade pork.