不同脱脂米糠水平日粮对苏淮猪胴体性状及肉品质的影响

旨在研究不同脱脂米糠水平日粮对苏淮猪胴体性状及肉品质的影响。选取35头初始体重为（62.9±0.8）kg的健康纯种苏淮阉公猪，随机分为5组，每组7个重复，每个重复1头猪，使用奥斯本种猪生产性能测定系统（OTSS）饲喂。对照组（CTRL）饲喂不含脱脂米糠的基础日粮，试验Ⅰ~Ⅳ组分别饲喂7%、14%、21%和28%脱脂米糠的试验日粮，5组日粮的中性洗涤纤维（NDF）水平分别为8.89%、11.80%、12.93%、14.35%和17.94%，各组日粮除纤维水平不同外，其他营养成分基本一致。试验预饲期10 d，所有猪饲喂基础日粮；正式期28 d，分别饲喂基础日粮和试验日粮。试验结束屠宰全部试验猪，测定其胴体性状（胴体重、屠宰率、胴体直长、胴体斜长、眼肌面积、平均背膘厚和皮厚）；采集肉样用于测定肉质性状（滴水损失、剪切力、熟肉率、肌内脂肪含量、pH和肉色）；采集背最长肌样品用于猪滴水损失主效基因磷酸化酶激酶γ1（phosphorylase kinase gamma1，PHKG1）表达分析。结果表明：1）日粮脱脂米糠水平对苏淮猪的胴体重、屠宰率、胴体直长、胴体斜长、眼肌面积、平均背膘厚和皮厚等胴体指标没有显著影响。2）随脱脂米糠水平的提高，苏淮猪背最长肌的滴水损失呈先降低后上升的二次曲线变化（P<0.05），猪肉的剪切力线性降低（P<0.05）；熟肉率、pH_{24 h}随脱脂米糠水平的增加呈线性增加的趋势（P=0.061，P=0.068）；日粮脱脂米糠水平的增加有降低L_{24 h}^*的趋势（线性，P=0.085），脱脂米糠水平对其它肉质指标均无显著影响。3）PHKG1基因的相对表达量随脱脂米糠水平的增加趋于二次方升高（P=0.085）。综上所述，日粮脱脂米糠水平对苏淮育肥猪的胴体性状无显著影响，但在日粮中适度添加脱脂米糠可降低苏淮猪猪肉的滴水损失及剪切力，改善苏淮猪猪肉品质，但其背后的机制还有待进一步深入研究。

Effect of Diets with Various Levels of Defatted Rice Bran on Carcass Traits and Meat Quality of Suhuai Pigs

The study aimed to evaluate the effect of varying levels of defatted rice bran (DFRB) on carcass traits and meat quality of Suhuai pigs. Thirty-five healthy purebred Suhuai castrated boars with an initial body weight of (62.9±0.8) kg were randomly selected and allotted to 5 dietary groups (7 replicates for each group and 1 pig for each replicate). Pigs were fed by the Osborne Testing Stations System (OTSS). The control group (CTRL) was fed with basic diet without DFRB, and the experimental group Ⅰ to Ⅳ were fed the diet with 7%, 14%, 21%, 28% DFRB. Neutral detergent fiber (NDF) levels of 5 groups were 8.89%, 11.80%, 12.93%, 14.35% and 17.94%, respectively. Except the fiber content of the diet was different, the other nutrients were basically the same among 5 groups. The pre-feeding period was 10 days, and all pigs were fed basic diet; the formal period was 28 days, and pigs were fed basic diet and experimental diets, respectively. At the end of the experiment, all pigs were slaughtered to measure the carcass traits(carcass weight, dressing percentage, carcass straight length, carcass inclined length, loin eye area, average back fat thickness and skin thickness) of Suhuai pigs; meat samples were collected to measure the meat quality traits (drip loss, shear force, cooked meat percentage, intramuscular fat content, pH and meat color); and the longissimus dorsi muscle samples were collected for the expression analysis of phosphorylase kinase gamma 1(PHKG1), a major gene of drip loss in pigs. The results showed that:1) The substitution of DFRB had no effect on the carcass traits such as carcass weight, dressing percentage, carcass straight length, inclined length, loin eye area, average back fat thickness and skin thickness. 2) With the increase of DFRB level, the drip loss of Suhuai pork decreased first and then increased (quadratic, P<0.05), and the shear force of pork decreased linearly (P<0.05); the cooked meat percentage and pH_{24 h} intended to increase linearly with the increase of DFRB level (P=0.061, P=0.068); there was a tendency for a decrease in L_{24 h}^* as DFRB increased (linear, P=0.085). There was no significant difference in other meat quality traits among 5 groups. 3) The relative expression level of PHKG1 gene was not affected by the increase of DFRB level (quadratic, P=0.085). In conclusion, dietary DFRB fiber level had no effect on carcass traits of Suhuai fattening pigs. Adding proper level of DFRB to the diet could reduce the drip loss and shear force and improve the quality of Suhuai pork, but the mechanism behind it needs further study.