【作者】 田春庄；

【导师】 彭健；

【作者基本信息】 华中农业大学 ， 动物营养与饲料科学， 2008， 硕士

【摘要】 本研究在母猪妊娠后期-泌乳期和断奶仔猪日粮中分别添加7%的鱼油(富含LCn-3PUFA)和猪油(富含饱和脂肪酸),旨在研究鱼油中的LCn-3PUFA对断奶仔猪肌肉块重量、骨骼肌肌纤维类型和肌肉发育相关基因表达的影响,并探讨母猪日粮中鱼油对仔猪肌肉生长的远期效应。为日粮n-3PUFA影响仔猪骨骼肌发育以及相关基因表达提供理论依据。试验一试验采用2因子设计,分妊娠后期-泌乳期和断奶期两个阶段进行。选择20头妊娠后期(103d)杂交健康经产母猪(长×大),按胎次、体况和预产期相近的原则随机分成2组:对照组(C),基础日粮中加7%的猪油;处理组(T),基础日粮中加7%的鱼油。每组10头母猪,每个重复一头母猪,单栏饲养。来自两个不同处理组母猪的仔猪分别合群,选择35d阉公猪和小母猪56头(公母各半)随机分为两组:对照组(C),基础日粮中加7%猪油;处理组(T),基础日粮中加7%鱼油。根据母猪日粮和仔猪日粮处理的不同,进入断奶期阶段试验的仔猪形成四个不同的处理组:CC,CT,TC和TT。每组14头仔猪,分为7个重复,每个重复2头仔猪(1公1母,同栏饲养)。每组选择4头仔猪70d屠宰,剥离并准确称重前、中、后躯主要肌肉块,旨在研究日粮中鱼油不同的添加阶段和方式,对断奶仔猪前中后躯主要骨骼肌生长发育的影响。试验结果如下:1.仔猪日粮中添加7%鱼油显著增加了70d仔猪背最长肌和瓣膜肌(P＜0.05)的重量,斜方肌和股二头肌也有增加的趋势(P=0.056,P=0.09);2.母猪妊娠后期-泌乳期同粮中添加7%的鱼油极显著增加了腰小肌的重量(P＜0.01),并一定程度上改善了臀中肌和腓肠肌的重量,对所测定的前躯肌肉块无显著影响(P＞0.05)。试验二仔猪屠宰后,迅速采集臂三头肌、背最长肌和股二头肌样品,—80℃保存。Trizol一步分离法提取肌肉中总RNA,采用半定量RT-PCR技术测定肌球蛋白重链基因(myosin heavy chain,MHC)4个亚型(MHC-Ⅰ、MHC-Ⅱa、MHC-Ⅱx和MHC-Ⅱb)和IGF-1、GHR、MRF4、MyoG、PGC-1a mRNA在三块骨骼肌中的丰度。结果表明:1.母猪妊娠后期-泌乳期和仔猪日粮中添加7%富含LCn-3PUFA的鱼油可显著影响臂三头肌、背最长肌和股二头肌中MHC亚型的mRNA丰度(P＜0.05),主要是上调了Ⅱ型MHC基因表达水平。另外,仔猪日粮效应整体上大于母猪日粮处理,而且对不同的肌肉块影响也不同,依赖于其所在的解剖学部位。2.在本试验条件下,母猪和仔猪日粮添加鱼油均显著增加了70 d仔猪臂三头肌、背最长肌和股二头肌中IGF-1和GHR的表达(P＜0.01),并且两处理之间存在明显的互作作用(P＜0.01)。结果提示:母猪日粮中鱼油对仔猪骨骼肌中生长轴基因表达的作用会影响仔猪阶段日粮的处理效应。3.母猪和仔猪日粮中添加n-3PUFA对三块肌肉中的MyoG表达均无显著影响(P＞0.05)。仔猪日粮中添加鱼油显著上调了臂三头肌和股二头肌中MRF4基因表达,极显著增加了三块肌肉中PGC-1a的mRNA表达量(P＜0.01),但有下调背最长肌中MRF4 mRNA的表达量的趋势(P=0.079);母猪日粮处理显著上调了背最长肌中MRF4 mRNA和臂三头肌PGC-1a的表达量(P＜0.01),并有增加股二头肌中的MRF4、PGC-1a和背最长肌中的PGC-1a mRNA水平的趋势(P=0.107,P=0.088,P=0.081)。本研究通过上述试验可得如下结论:1)母猪妊娠后期-哺乳期和断奶仔猪日粮中添加7%的鱼油可通过改变肌肉中脂肪酸的组成,而促进70d仔猪部分骨骼肌的生长,且主要集中在中后躯的骨骼肌;母猪日粮对仔猪骨骼肌生长的影响有明显的母体效应。2)日粮中的LCn-3PUFA增加部分肌肉块重的原因是调控了骨骼肌的肌纤维类型,主要是增加了骨骼肌中MHC-Ⅱb和MHC-Ⅱx型基因的表达。LCn-3PUFA调控肌纤维的过程,可能是通过上调肌肉生长和肌纤维类型转化相关基因,包括生长轴基因、MRF4、MyoG和PGC-1a的表达来实现。更多还原

【Abstract】 In the current study,7%fish oil(rich in LCn-3PUFA) or lard(rich in saturated fatty acid) was added to the diet for sows during pregnancy and lactation and for weaned pigs to test the hypothesis that dietary long-chain n-3PUFA has the effects on muscle mass,the mRNA abundances of four myosin heavy chain(MHC) isoforms and muscle development related genes(MRF4,MyoG and PGC-1α) in weaned pigs.In addition,we investigated the effect of maternal nutritional of fish oil on skeletal muscle development in weaned pigs.The objective of the study is to provide theroy basis for the effects of n-3PUFA on skeletal muscle growth and related genes in piglets.Experiment 1:the experiment uses the two factors design,divides to three stages, late gestation,lactation and nursing.Twenty later gestation(103 d) multiparous sows (Landrace×Large White) were randomly allocated into two groups:control group(C) and treatment(T),respectively.Ten sows were allocated into per treatment,with a sow as one experimental unit.Two isoenergetic and isonitrogenous diets were formulated to meet the nutrient requirements of late gestation and lactation of sow,and one of which was the control diet including lard at the level of 7%and another one was the treatment diet including fish oil at the level of 7%.For the postweaning growth phase of the experiment, barrows and gilts(n=56) selected from each litter of two groups were randomly allocated into two groups,control group(C) and treatment(T).Two diets were formulated to meet NRC requirements for nursery and growing pigs,and one of which was the control diet (including lard) and another one was the treatment diet(including 7%fish oil), respectively.Thus,there are four groups,CC,CT,TC and TT of nursery piglets,with seven replications per treatment and one barrow and one gilt as an experimental unit.At the 70 d,16 pigs(2 barrows and 2 gilts of each group) were slaughtered and dissected, and most of skeletal muscle in anterior part,middle and posterior part of body were weighed.The results were as follows:1.Dietary 7%fish oil of weaned pigs significantly increased the mass of Longissimus and Semimembranosus(P＜0.05),and improved the mass of Trapezius and Biceps femoris muscles(P＜0.10) in 70d weaned pigs;2.The results showed that,7%fish oil adding to the diet for sows during pregnancy and lactation significantly increased the mass of Lesser posas(P＜0.01),and improved the mass of Gluteus medius and Gastrocnemius muscles(P＜0.10),but there was no significant difference on skeletal muscles in anterior part of body we measured(P＞0.05); Experiment 2:skeletal muscle samples of the Triceps brachii(TB),Longissimus muscle(LM) and Biceps femoris(BF) were immediately removed after slaughter and exsanguination,wrapped in foil,and frozen in liquid nitrogen to be stored at -80℃for subsequent total RNA extraction.Total RNA was extracted from the skeletal muscle samples using the Trizol regent.The mRNA expression of IGF-1,GHR,MRF4,MyoG and PGC-1 was measured using semi-quantitative reverse transcription PCR,and relative expressions of four MHC isoforms(MHC-Ⅰ,MHC-Ⅱa,MHC-Ⅱx and MHC-Ⅱb) were using a multiplex PCR procedure in threes muscles,respectively.The results as follows:1.Supplemented 7%fish oil in diet for sows during pregnancy and lactation and weaned pigs all resulted in an significant influence expressions of MHC in the Triceps brachii(TB),Longissimus muscle(LM) and Biceps femoris(BF)(P＜0.05),especially up-regulated MHC-ⅡmRNA level,including MHC-Ⅱα,MHC-Ⅱb and MHC-Ⅱx.In addition,the effects of fish oil adding to the diet for weaned pigs on expressions of MHC in skeletal muscles in 70d was higher than adding to the diet for sows,and depended on anatomic location of muscles.2.In our experiment,adding 7%fish oil to diets of sows and weaned pigs diet all resulted in an significant increase expressions of IGF-1 and GHR in the Triceps brachii (TB),Longissimus muscle(LM) and Biceps femoris(BF)(P＜0.05),and there was a significant interaction between two stages(P＜0.01).These data indicated that,the effects of dietary fish oil for sows on expressions of growth-axis genes affected the effectiveness of dietary fish oil for weaned pigs.3.The level of MyoG in in threes muscles were not affected by 7%fish oil adding to sows diet or weaned pigs(P＞0.05).Dietary fish oil of weaned pigs significantly increased expressions of MRF4 in the Triceps brachii(TB) and Biceps femoris(BF)(P＜0.01),and significantly increased expressions of PGC-1αin the three muscles(P＜0.01),while MRF4 mRNA in Longissimus muscle(LM)had a trend of decrease(P=0.079).Furthermore, dietary fish oil of sows significantly up-regulated abundance of MRF4 mRNA in Longissimus muscle and PGC-1αmRNA in the Triceps brachii(TB)(P＜0.01), meanwhile,the levels of MRF4 mRNA in Biceps femoris(BF) and PGC-1αmRNA in Biceps femoris(BF) and Longissimus muscle(LM) had a trend of increase(P=0.107, P=0.088,P=0.081).The following conclusion of this study can be drawn from:1) Supplemented 7%fish oil to the diet for sows during pregnancy and lactation and for weaned pigs enhance growth of skeletal muscles,which were located in middle and posterior part of body especially,by modifying muscle phospholipid.In addition,there was significant maternal nutritional effectiveness of fish oil on skeletal muscle development in weaned pigs.2) Dietary long-chain n-3 fatty acids increased skeletal muscle mass in different part of body by altering composition of muscle fiber tapes,especially increased proportion of MHC-Ⅱb and MHC-Ⅱx.The effects of n-3PUFA in muscle on muscle fiber tapes may be mediated,at least in part,by up-regulating expression of muscle development and muscle fiber tapes transformation related genes,including growth-axis genes,MRF4,MyoG and PGC-1.更多还原