藏猪和杜藏猪生长、肉质性状及脂肪沉积相关基因的表达差异分析

【目的】明确藏猪和杜藏猪(杜洛克父本与藏猪母本杂交F₁代)的生长和胴体性状及肉质指标等表型差异,并分析背最长肌中脂肪沉积相关基因的表达差异,为藏猪种质资源利用及猪脂肪沉积规律研究提供参考依据。【方法】以藏猪和杜藏猪为研究对象,分别测定其体长、体高和胸围等生长性状,屠宰率、背膘厚及眼肌面积等胴体性状,以及pH、肉色、蒸煮损失及肌内脂肪含量等肉质指标;并通过荧光实时定量PCR检测脂肪沉积相关基因在2种猪背最长肌中的表达情况。【结果】杜藏猪的左胴体重、右胴体重、屠宰前重、胴体长、体长、体高、管围和胸围均高于藏猪,且差异显著(P<0.05,下同),眼肌面积(33.00±3.84 cm2)也显著大于藏猪(16.83±1.81 cm2),背膘厚(13.15±2.48 mm)则显著低于藏猪(22.83±2.80 mm),藏猪与杜藏猪的皮厚、腹围和屠宰率无显著差异(P>0.05,下同);杜藏猪肌肉的pH-24 h、熟肉率、剪切力和含水率显著高于藏猪肌肉,而杜藏猪肉色的a-24 h值(10.30±1.06)和肌内脂肪含量(2.48±1.44)%]显著低于藏猪。除GHR基因外,其他脂肪沉积相关基因的相对表达量均表现为杜藏猪低于藏猪,其中,ADIPOQ基因和FASN基因的相对表达量显著低于藏猪,IGF1基因、TNFa基因和Leptin基因的相对表达量极显著低于藏猪(P<0.01)。相关分析结果显示,GHR基因相对表达量与杜藏猪肌内脂肪含量呈显著正相关,FASN基因相对表达量与藏猪肌内脂肪含量呈显著正相关,IGF1基因相对表达量与藏猪背膘呈显著负相关。【结论】杜藏猪的肉质性状与藏猪相似,但杜藏猪具有更佳的生长性能,说明以杜洛克为父本与藏猪母本杂交得到的杜藏猪具有更优的生产效率。藏猪和杜藏猪的肌内脂肪含量差异与脂肪沉积相关基因的表达差异有关,即猪的肌内脂肪含量受多种脂肪沉积相关基因调控。

Analysis of differences in growth,meat quality traits and expression of genes related to fat deposition between Tibetan and Duzang pigs

【Objective】To clarify the phenotypic differences in growth,carcass traits and meat quality indexes between Tibetan and Duzang pigs(F₁ generation crossed between Duroc male and Tibetan pig female)and to analyze the differences in the expression of fat depositing-related genes in longissimus dorsi muscle,so as to provide a reference for the utilization of Tibetan pig germplasm resources and the study of pig fat deposition.【Method】Tibetan and Duzang pigs were used as the research objects,and their growth traits such as body length,height,chest circumference,slaughter rate,back fat thickness,eye muscle area and meat quality indicators such as pH,meat colour,cooking loss and intramuscular fat content were measured respectively.The expressions of fat deposition-related genes in the longissimus dorsi of the two pigs were also detected by real-time quantitative PCR.【Result】The left carcass weight,right carcass weight,preslaughter weight,carcass length,body length,body height,tube circumference,and chest circumference of Duzang pigs were higher than those of Tibetan pigs.The difference was significant(P<0.05,the same below),and the eye muscle area(33.00±3.84 cm2)was also considerably larger than that of Tibetan pig(16.83±1.81 cm2),the thickness of back fat(13.15±2.48 mm)was significantly lower than that of Tibetan pigs(22.83±2.80 mm).At the same time,there was no significant difference in skin thickness,abdominal circumference and slaughter rate between Tibetan pigs and Duzang pigs(P>0.05,the same below).The p H-24 h,cooked meat rate,shearing force and water content of Duzang pig muscle were significantly higher than those of Tibetan pig muscle.The colour a-24 h value(10.30±1.06)and intramuscular fat content(2.48±1.44)%]of Duzang pigs were significantly lower than those of Tibetan pigs.Except for GHR,the relative expression of ADIPOQ and FASN were significantly lower in Duzang pigs than in Tibetan pigs,and the relative expression of IGF1,TNFa and Leptin were extremely lower than in Tibetan pigs(P<0.01).The results of correlation analysis showed that the relative expression of GHR was significantly positively correlated with the intramuscular fat content in Duzang pigs.Furthermore,the relative expression of FASN was significantly positively correlated with the intramuscular fat content in Tibetan pigs.In addition,the relative expression of IGF1 was significantly negatively correlated with the back fat of Tibetan pigs.【Conclusion】The meat quality traits of Duzang pigs are similar to those of Tibetan pigs,but Duzang pigs have better growth performance,indicating that Duzang pigs obtained by crossing Duroc male and Tibetan pig female have better production efficiency.The difference in intramuscular fat content between Tibetan and Duzang pigs is related to the difference in the expression of fat deposition-related genes.That is,a variety of fat deposition-related genes regulate the intramuscular fat content of pigs.