淡水和海水养殖花鲈营养成分的比较

对使用同种饲料分别用淡水和海水养殖的花鲈进行感官评价、基本营养成分、脂肪酸组成及含量分析。结果表明,在感官总评价、鲜味和甜味方面,海水养殖花鲈高于淡水养殖花鲈,且淡水养殖花鲈带有明显的鱼腥味。海水养殖花鲈粗蛋白含量比淡水养殖花鲈高2.17%,粗脂肪含量比淡水养殖花鲈低34%,显示出明显差异性,但二者肌肉脂肪酸组成种类上比较相似,部分脂肪酸含量有较大差异。海水和淡水养殖花鲈鱼肉矿物质含量差异不大。海水养殖花鲈中的甜菜碱含量1.81mg/g,高出淡水养殖花鲈50%以上。     

淡水和海水养殖花鲈鱼肉中挥发性成分的比较研究

采用顶空固相微萃取(HS-SPME)结合气相色谱-质谱(GC-MS)技术,分别检测了海水养殖和淡水养殖花鲈鱼背肉加热前后挥发性成分。经GC-MS分析鉴定,共检出6类40种挥发性化合物,其中烃类和醛类化合物的含量占主要成分。以己醛、壬醛为主的醛类物质是花鲈主要挥发性气味物质,所占比重较大,其次是含量较低的二甲苯为主的芳香族化合物和以1-辛烯-3-醇为主的醇类物质,这三类挥发性物质构成了花鲈鱼肉的特征性气味成分。淡水养殖的花鲈鱼肉加热后己醛和对二甲苯含量显著高于海水养殖的花鲈。     

栉孔扇贝和海湾扇贝脂质及其脂肪酸组成分析

以栉孔扇贝和海湾扇贝为研究对象,采用Folch法提取两种扇贝肌肉和内脏中的总脂,并对其脂质和脂肪酸组成进行分析。结果表明:两种扇贝的肌肉总脂含量显著低于内脏,且肌肉总脂以磷脂为主,而内脏总脂以甘油三酯为主。两种扇贝的脂肪酸组成特征为多不饱和脂肪酸(PUFA)>饱和脂肪酸(SFA)>单不饱和脂肪酸(MUFA),其中,PUFA以n-3系列为主,主要为C20∶5n-3(16.58%~19.00%)和C22∶6n-3(11.49%~21.18%);肌肉中的n-3/n-6比值高于内脏,尤其C22∶6n-3含量显著高于内脏(P<0.01)。同时从两种扇贝中鉴定出6种脂肪醛二甲基缩醛(DMA),总量在7.77%~11.20%,并以C18∶0DMA(3.05%~6.89%)和C20∶1DMA(1.55%~4.25%)为主,且肌肉中DMA含量高于内脏,表明两种扇贝总脂中含有丰富的缩醛磷脂,肌肉总脂中的缩醛磷脂百分含量高于内脏。     

不同类型膳食脂肪酸对肥胖小鼠肝脏及其血液中脂肪酸组成和代谢相关基因影响

目的探讨不同类型膳食脂肪酸对肥胖小鼠肝脏及其血液中脂肪酸组成及代谢相关基因的影响。方法 8周龄雄性C57BL/6小鼠随机分为7组,即对照组(喂基础饲料)、长链饱和脂肪酸(LCSFA)组(喂猪油高脂饲料)、中链饱和脂肪酸(MCSFA)组(喂椰子油高脂饲料)、n-3多不饱和脂肪酸(n-3 PUFA)组(喂亚麻籽油高脂饲料)、n-6多不饱和脂肪酸(n-6 PUFA)组(喂大豆油高脂饲料)、单不饱和脂肪酸(MUFA)组(喂橄榄油高脂饲料)和反式脂肪酸(TFA)组(喂8%氢化大豆油高脂饲料),每组10只,共干预16周,所有种类饲料总能量均相同,基础饲料脂肪供能比为10%,各高脂饲料脂肪供能比均为45%,喂养周期结束后,禁食12 h,麻醉后立刻解剖取出肝脏。采用气相色谱法分析肝脏及其血液中脂肪酸组成的变化,实时荧光定量聚合酶链式反应(PCR)检测肝脏脂肪酸代谢相关基因的表达,肝脏脂质沉积采用油红O染色法检测。结果与对照组比较,LCSFA组、MCSFA组、n-6 PUFA组、MUFA组和TFA组小鼠肝脏中均出现明显的脂质沉积,n-3 PUFA组小鼠肝脏未出现明显的脂质沉积。与对照组比较,LCSFA组小鼠肝脏及血液中总n-6 PUFA和总PUFA含量升高; n-3 PUFA组小鼠肝脏及血液中总n-3 PUFA和总PUFA含量增加,但总MUFA含量减少; n-6 PUFA组小鼠肝脏及血液中总n-6PUFA、总n-3 PUFA和总PUFA含量升高,但总饱和脂肪酸(SFA)和总MUFA含量降低; MUFA组小鼠肝脏及血液中总SFA含量减少; TFA组小鼠肝脏及血液中C18∶1 n-9t(TFA)含量升高;以上差异均有统计学意义(P0. 05)。LCSFA组和MCSFA组小鼠肝脏脂肪酸代谢基因固醇调节元件结合蛋白1(SREBP-1c) mRNA水平高于对照组和n-6 PUFA组,差异均有统计学意义(P0. 05)。结论小鼠肝脏及其血液中脂肪酸构成与其对应的膳食脂肪酸模式一致。不同类型脂肪酸高脂饲料可通过对相关基因的表达影响肥胖状态下肝脏的脂质代谢及脂质沉积。     

网箱养殖刺鲃肌肉营养成分分析及评价

采用常规生化分析方法测定湖南芷江网箱养殖刺鲃(Spinibarbus caldwelli)肌肉(鲜样)营养成分的组成和含量,并对其营养价值进行综合评价。结果表明:网箱养殖刺鲃肌肉中水分、粗蛋白、粗脂肪、灰分的含量分别为73.44%、24.18%、3.63%、1.28%。肌肉中共检测出17种氨基酸,氨基酸总含量(TAA)为18.08%,其中必需氨基酸(EAA)含量为6.70%,占氨基酸总量的37.06%,必需氨基酸(EAA)与非必需氨基酸(NEAA)含量的比值为58.88%,其必需氨基酸比例符合FAO/WTO的理想模式。以氨基酸评分(AAS)评价,Val和Ile为肌肉第一、二限制性氨基酸;以化学评分(CS)评价,Met+Cys和Val为肌肉第一、二限制性氨基酸。必需氨基酸指数(EAAI)为58.39,鲜味氨基酸(DAA)含量为6.97%,占氨基酸总量的38.55%。肌肉中检测出饱和脂肪酸(SFA)3种、单不饱和脂肪酸(MUFA) 3种、多不饱和脂肪(PUFA)5种,共11种脂肪酸。SFA、MUFA、PUFA分别占脂肪酸总量的20.56%、54.71%、24.72%,C20:5n-3(EPA)与C22:6n-3(DHA)之和占脂肪酸总量的1.86%。研究表明,网箱养殖刺鲃肌肉具有食用营养价值。     

三江县稻田养殖红罗非鱼品质特性及肌肉营养成分分析

采用质构仪和国家标准的生化分析方法测定了稻田养殖红罗非鱼的品质特性和营养成分,并综合评价其营养价值。结果表明:稻田养殖红罗非鱼肌肉中水分含量为79.01%±0.09%,粗灰分含量1.05%±0.02%,粗脂肪含量为1.58%±0.15%,粗蛋白含量为19.83%±0.64%。稻田养殖红罗非鱼的质构特性分析表明其肌肉结实有弹性。稻田养殖红罗非鱼肌肉中检测出17种氨基酸,其中必需氨基酸(EAA)总量占氨基酸总量(AA)的40.17%,必需氨基酸和非必需氨基酸比值为67.14%,均符合FAO/WHO的评价标准;必需氨基酸指数(EAAI)为83.74,呈味氨基酸(DAA)总量占氨基酸总量的39.14%。稻田养殖红罗非鱼肌肉中共检测出15种脂肪酸,饱和脂肪酸(SFA)、单不饱和脂肪酸(MUFA)、多不饱和脂肪酸(PUFA)分别占脂肪酸总量的34.13%、30.29%、35.58%;∑SFA:∑MUFA:∑PUFA比例为0.96:0.85:1,∑n-6 PUFA:∑n-3 PUFA为3.42。综上所述,相对于其他常见稻田养殖品种,稻田养殖的红罗非鱼营养成分均衡且肉质较好。     

海水鱼与淡水鱼omega-3多不饱和脂肪酸含量的比较研究

研究杭州市场常见野生和饲养淡水鱼以及海水鱼omega-3多不饱和脂肪酸（PUFA）的成分及含量。将购买的四个品种淡水鱼（野生和饲养）和六种海水鱼鱼肉去骨切碎,用有机溶剂提取总脂肪,甲酯化后的脂肪酸用气相色谱分离分析。结果表明：总PUFA的含量为从海水刺鲳的37．2mg／100g到淡水野生桂鱼的1821．8mg／100g,其中omeg-3PUFA有C18：3n-3,C18：4n-3,C20：5n-3,C22：5n-3,C22：6n-3,总omega-3PUFA含量为从海水刺鲳的32．3mg／100g到淡水饲养黑鱼的1104．3mg／100g。不同品种鱼脂肪酸含量存在显著性差异（p〈0．001）。结论：野生和饲养淡水鱼以及海水鱼中omega-3PUFA的含量及成分均因品种不同而异,淡水鱼的摄入完全能满足人体日常所需的omega3多不饱和脂肪酸。     

鄱阳湖野生鱼类脂肪酸含量的比较研究

通过研究鄱阳湖野生淡水鱼类脂肪酸的含量,了解鄱阳湖鱼类中饱和脂肪酸、单不饱和脂肪酸和多不饱和脂肪酸(PUFA)的含量和构成比。鱼肌肉用氯仿甲醇溶液提取脂肪,碱法甲酯化后用气相色谱分析。结果显示:鱼肌肉中的PUFA的含量随鱼类品种的不同有较大的差别,范围为18.65%～43.07%;二十二碳六烯酸(DHA)和二十碳五烯酸(EPA)的含量也变化较大,其中黄颡鱼的DHA含量最高,可达10.72%,而鲹鲦的EPA含量则是所测鱼类中最高的,达4.61%。其中n-3系不饱和脂肪酸与n-6系不饱和脂肪酸的比例也相差悬殊,从1:0.7到1:2.5不等。不同科目的鱼,在C22:4n-6、C22:5n-3(DPA)含量上有显著性差异。不同生活习性的鱼,其共轭亚油酸(CLA)、C20:4n-6、C22:2n-6、C22:4n-6、C22:5n-3、C22:6n-3(DHA)均存在显著性差异。研究结果表明鄱阳湖水域中,鱼肌肉的多不饱和脂肪酸与鱼的生活习性如生活在不同的水层和食性等有较大关系,鱼的遗传因素与脂肪酸比例和含量也有一定关系。     

虎纹蛙肌肉挥发性成分和脂肪酸分析

对虎纹蛙肌肉中的挥发性成分和脂肪酸分别进行测定。采用顶空固相微萃取-气相色谱-质谱联用技术(HS-SPME-GC-MS)分析虎纹蛙肌肉中的挥发性成分。结果共鉴定出36种成分,其中醛类化合物有15种,且含量最高,占挥发性成分总量的68.76%;己醛、(Z)-4-庚烯醛、(E,Z)-2,4-癸二烯醛、(E,E)-2,4-癸二烯醛、1-辛烯-3-醇和2,3-戊二酮等可能对虎纹蛙肉的整体风味贡献较大;虎纹蛙肌肉脂肪酸主要由不饱和脂肪酸(UFA)组成,占脂肪酸总量的72.89%;在日常饮食中,虎纹蛙肉为n-3多不饱和脂肪酸(n-3 PUFA)较为丰富的食物资源;亚麻酸(C18:3 n-3,ALA)、二十碳五烯酸(C20:5 n-3,EPA)和二十二碳六烯酸(C22:6 n-3,DHA)为主要的n-3 PUFA。UFA为虎纹蛙肉的重要风味前体物质。     

杂交鲍Haliotis discus hannai × Haliots discus discus体内食源性脂肪酸的标志分异

本文研究了底播增殖的杂交鲍的内脏团、肌肉和消化腺内的得到公认的几种食源性脂肪酸标志的分布特征,可为杂交鲍的长期食源的判别提供依据。同等大小的杂交鲍,其内脏团、消化腺和肌肉内的硅藻脂肪酸标志(∑C16/∑C18和C20:5n-3)之间无显著无差异;消化腺内的绿藻脂肪酸标志(C18:2n-6+C18:3n-3)显著高于肌肉中的(p5%);肌肉中的褐藻脂肪酸标志(C20:4n-6)显著低于肌肉内的(p5%);异养细菌脂肪酸标志(C18:1n-7/C18:1n-9)在同等大小的杂交鲍内脏团、消化腺和肌肉中无差异。内脏团脂肪酸标志受性腺发育的影响;肌肉内脂肪酸含量较低;消化腺中脂肪酸组成的季节变化由食物的季节变化所致且总脂含量较高。从影响脂肪酸组成的因素及测试方法的灵敏度来看,消化腺用于脂肪酸标志法判断杂交鲍的长期食源更适宜。     

Fatty acid content and composition of UK beef and lamb muscle in relation to production system and implications for human nutrition

Although ruminant meats normally have a low ratio of polyunsaturated fatty acids (PUFA) to saturated fatty acids (P:S ratio), the muscle contains a range of C(20) and C(22) PUFA of both the n-6 and n-3 series of potential significance in human nutrition. However, information on the amounts of these fatty acids in muscle and how they are modified by production system is limited In this study, the content and composition of fatty acids was determined in several muscles from beef steers fed grass (grazed) and bulls fed cereal concentrates. These are the two main types of beef production in the UK and Europe. Muscle fatty acids were also determined in lambs fed grass (grazed on pasture). The total fatty acid content of all muscles studied was less than 35 g kg(-1). The percentages in total fatty acids of all n-3 PUFA were higher in muscles from steers fed grass than from bulls fed concentrates whereas all n-6 PUFA were higher in the latter. The gluteobiceps muscle contained the largest amounts of fatty acids including PUFA and the m. longissimus dorsi the least amounts of PUFA in beef and lamb, and m. longissimus contained the lowest percentages of PUFA. Arachidonic acid was the major fatty acid in the C(20) + C(22) PUFA in beef from both production systems with twice as much in muscles from bulls fed concentrates. The P:S ratios were higher in the latter animals, range 0.21-0.34 compared with 0.08-0.13 in the steers fed grass. However, the n6:n-3 ratio was much less desirable in the bulls, 15.6-20.1 compared with 2.0-2.3 in the steers fed grass. These effects of production system in ruminants are larger than previously reported. Lamb muscle P:S ratios resembled those in grass-fed beef but the n-6:n-3 ratios were lower. The percentage of trans unsaturated 18:1 fatty acids was similar in both cattle production systems but lamb muscles contained twice as much as beef. Although the concentrations of the C(20) and C(22) PUFA are much lower than in fish, maintaining high n-3 levels in ruminant meats through grass feeding may be advantageous in human nutrition since meat is more widely consumed.     

蒙古斑点马不同部位脂肪和肌肉组织中脂肪酸组成的比较研究

通过对蒙古斑点马不同部位脂肪和肌肉组织中脂肪酸组成进行分析比较,旨在明确蒙古斑点马体脂脂肪酸组成特点。选择3 匹成年蒙古斑点马,屠宰后采集肾周、肠周和皮下脂肪以及肩肌、背最长肌和臀肌样品,利用气相色谱法测定脂肪酸组成及含量。结果表明：蒙古斑点马不同脂肪组织中均检出19 种脂肪酸,其中饱和脂肪酸（saturated fatty acid,SFA）含量34.77%～37.38%,不饱和脂肪酸（unsaturated fatty acid,UFA）含量达60%以上,UFA中单不饱和脂肪酸（monounsaturated fatty acid,MUFA）含量33.04%～36.39%,多不饱和脂肪酸（polyunsaturated fatty acid,PUFA）含量26.47%～27.51%,其中皮下脂肪C10:0、C18:0、C20:0含量显著低于肾周和肠周脂肪（P＜0.05）;MUFA在皮下脂肪的沉积程度较其他2 个部位高,但均无统计学差异;PUFA中C18:3 n-3含量最高,其在各脂肪组织间无显著差异。3 个不同部位肌肉中均检出15 种脂肪酸,其中SFA含量占总脂肪酸含量的38.32%～40.04%,MUFA含量占35.70%～40.19%,PUFA含量占15.25%～20.33%;SFA中背最长肌和臀肌C12:0含量显著高于肩肌（P＜0.05）,其余SFA在不同部位肌肉间无显著差异;MUFA中背最长肌C16:1含量显著高于肩肌和臀肌（P＜0.05）;肩肌n-6/n-3 PUFA比值显著高于背最长肌和臀肌（P＜0.05）;皮下脂肪的C18:3 n-3和总PUFA含量显著高于背最长肌（P＜0.05）。综上所述,蒙古斑点马不同部位脂肪和肌肉组织脂肪酸组成各具特点,但UFA含量均较高。     

不同日龄、性别、部位Hyla兔系肌内脂肪酸组成变化

以Hyla配套系肉兔为对象,研究不同日龄、性别、部位Hyla兔系肌内脂肪酸组成的动态变化,探讨肉兔生长过程中脂肪酸的沉积规律及营养价值。结果表明：随着日龄的增加,Hyla公兔和母兔背部最长肌（longissimus dorsi,LD）、左后腿肌（left-hind leg muscle,LL）和腹肌（abdominal muscle,AM）的肌内总脂肪含量均显著增加（P＜0.05）,且AM中含量最高,LL次之,LD最低,公兔整体低于母兔;经气相色谱分析,共鉴定出21 种脂肪酸,其中不饱和脂肪酸（unsaturated fatty acids,UFA）的含量丰富,尤其是长链（C20～22）多不饱和脂肪酸（polyunsaturated fatty acids,PUFA）;随着Hyla兔的生长,3 个部位肌内脂肪的PUFA/SFA值、n-6 PUFA含量及n-3 PUFA含量显著下降（P＜0.05）,n-6/n-3值因日龄、性别和部位的差异有着不同的动态变化,比值范围为6.5～8.5;经偏最小二乘回归分析可知,日龄、性别与部位均能够显著影响Hyla兔系肌内脂肪酸组成,其中,幼龄公兔LL脂肪酸组成更优,而成年母兔LD更适宜加工。     

Effect of grass or concentrate feeding systems and rate of growth on triglyceride and phospholipid and their fatty acids in the M. longissimus thoracis of lambs

Thirty-two male Ile-de-France lambs were used in a factorial 2×2 design to analyse the effects of feeding systems (grass outdoor, G, or concentrate and hay indoor: stall, S) and of growth rate (low, L, or high, H) on total lipids, triglyceride (TG) and phospholipid (PL) contents and their fatty acid composition in the longissimus thoracis muscle (L.T.). Contents were lower for TG (10.4 vs. 15.8 mg/100 g fresh tissue, P<0.05) and higher for PL (6.4 vs. 5.8 mg/100 g fresh tissue, P <0.05) in grass-fed lambs compared to stall-fed ones. TG of grass fed lambs displayed lower proportions of palmitic acid (C16:0), monounsaturated fatty acids (MUFAs), linoleic acid (C18:2n-6) and other (n-6) polyunsaturated fatty acids (PUFA) and higher proportions of stearic acid (C18:0), linolenic acid (C18:3n-3), cis 9, 11 trans C18:2 and trans monounsaturated fatty acids. In PL of the same lambs only lower MUFA, C18:2n-6 and (n-6) PUFA and higher C18:3n-3, (n-3) PUFA and cis 9, 11 trans C18:2 were observed. Growth rate had no effect on lipid, TG or PL contents of longissimus thoracis. However C18:0 proportions were higher in TG and lower in PL for low growth rate lambs. Low growth rate lambs had also lower cis 9, 11 trans C18:2 in TG. Thus, irrespective of growth rate, the muscle lipids characteristic of grass fed lambs fulfilled the recommended features of human food components much better than that of stall fed lambs, namely for CLA and C18:3n-3. The lower ratios of (n-6) to (n-3) PUFA displayed in grass fed lambs both in TG and in PL were also useful to discriminate all the grass fed lambs from all the stall fed animals.     

澳洲美利奴羊肉脂肪酸组成

选择3 只澳洲美利奴羔羊的背最长肌、臀肌及臂三头肌,利用气相色谱-质谱联用技术对其脂肪酸含量进行测定及分类探讨。结果表明：澳洲美利奴羊肉中共含有脂肪酸35 种,其中C15:1、C16:0、C17:1、C18:0、C18:1 n-9c脂肪酸含量较高,3 个部位肌肉中：不饱和脂肪酸含量＞饱和脂肪酸含量＞单不饱和脂肪酸含量＞多不饱和脂肪酸含量,且每个部位肌肉中单不饱和脂肪酸含量比多不饱和脂肪酸含量均高出2～3 倍;n-3脂肪酸亚麻酸甲酯（C18:3 n-3）在臂三头肌中的含量显著高于背最长肌（P＜0.05）;与另外2 个部位相比,臂三头肌总脂肪酸、饱和脂肪酸、不饱和脂肪酸、中链脂肪酸及长链脂肪酸含量均最高;臂三头肌中多不饱和脂肪酸与饱和脂肪酸含量比值最高,背最长肌中最低。     

Effects of breed and a concentrate or grass silage diet on beef quality in cattle of 3 ages. I: Animal performance, carcass quality and muscle fatty acid composition

An increase in the intake of the n-3 series polyunsaturated fatty acids (PUFA) is recommended by nutritionists for the human diet and beef is a significant source of these fatty acids. Enhancing the n-3 PUFA content of beef is important in view of the generally saturated nature of fatty acids in ruminant meats and the potentially negative effect this can have on human health. This study examined the effects of breed and diet on the fatty acid composition of beef M. longissimus. Ninety-six steers were used, 48 Aberdeen Angus cross (AA) and 48 Holstein-Friesian (HF). At 6months of age, 3 groups were identified, to be slaughtered at 14, 19 and 24months, respectively. Each group consisted of eight steers of each breed fed on a concentrate or a grass silage diet, rich in n-6 and n-3 PUFA, respectively. The intake of the concentrate diet was restricted so that steers of each breed grew at a similar rate on each diet. The early maturing AA produced heavier, fatter carcasses with better conformation. Animals fed grass silage had higher carcass fatness and conformation scores and higher levels of neutral lipid and total lipid in muscle than those fed concentrate. When all animals were pooled, a decline in PUFA% as total muscle lipid increased was evident. Feeding a grass silage diet rich in α-linolenic acid (18:3n-3) increased levels of this fatty acid in muscle neutral lipid by a factor of about 3.0 compared with the concentrate diet, as well as enhancing the synthesis of the n-3 series long-chain C20-22 PUFA in the phospholipid fraction, including docosahexaenoic acid (DHA, 22:6n-3). In contrast, both levels and proportions of linoleic acid (18:2n-6) and the n-6 series C20-22 PUFA were higher in animals fed the concentrate diet. The proportions of 18:1trans and conjugated linoleic acid (CLA) in muscle neutral lipid were higher in animals fed concentrate compared with silage in all 3 groups. This was partly due to increased consumption of 18:2n-6. The ratio of PUFA to saturated fatty acids (P:S) in muscle was reduced by feeding grass silage, partly as the result of increased fat deposition. However, the increase in levels of n-3 series fatty acids with silage-feeding resulted in beneficially low n-6:n-3 ratios in muscle in all age groups (approximately 1.2 compared with 12.0 in the concentrate diet). Subtle breed differences in PUFA amounts and proportions were noted. Holstein-Friesians had higher proportions of PUFA and higher P:S ratios compared with AA, partly due to a higher proportion of phospholipid in total lipid. In phospholipid itself, HF in the 19 and 24months groups had higher proportions of most n-3 PUFA. In all age groups the ratio of DHA to its precursor, 18:3n-3 was higher in HF.     

Conjugated linoleic acid (CLA) and polyunsaturated fatty acids in muscle lipids of lambs from the Patagonian area of Argentina

The concentrations of fatty acids were measured in total lipids, triacyglycerol and phospholipid fractions of intramuscular fat (IMF) from the Longissimus dorsi (LD) muscle of 10 lambs reared to approximately 30kg live weight on natural pasture with their dams. Fatty acid composition was also measured in 25 (five of each) Semitendinosus (ST), Semimembranosus (SM), Rectus femoris (RF), Gluteus (GLU) and Tensor fascia latea (TFL) muscles. Intramuscular fat percentages were similar for all muscles. Aspects of the fatty-acid patterns of relevance to human nutrition tended to favor the leg muscles with lower saturated fatty acids (SFA %), n-6/n-3 fatty acid ratios (p<0.01) and higher concentrations of the conjugated linoleic acid (CLA) (p<0.05). The estimated fatty acid concentrations (mg/100g of meat) showed higher contribution of arachidonic (C20:4 n-6), eicosapentanoic (C20:5 n-3), docosapentanoic (C22:5 n-3) and docosahexanoic (C22:6 n-3) acids in leg compared to LD lipids.     

Endogenous production of n-3 and n-6 fatty acids in mammalian cells

Polyunsaturated fatty acids (PUFA) are important components of mammalian diets, and the beneficial effects of n-3 PUFA on human development and cardiovascular health have been well documented. Caenorhabditis elegans is one of the few animals known to be able to produce linoleic (LA, 18:2n-6) and alpha-linolenic (ALA, 18:3n-3) essential fatty acids. These essential PUFA are generated by the action of desaturases that successively direct the conversion of monounsaturated fatty acids (MUFA) to PUFA. The cDNA coding sequences of the C. elegans Delta(12) and n-3 fatty acid desaturases were each placed under the control of separate constitutive eukaryotic promoters and simultaneously introduced into HC11 mouse mammary epithelial cells by adenoviral transduction. Phospholipids from transduced cells showed a significant decrease in the ratios of both MUFA:PUFA and n-6:n-3 fatty acids relative to control cultures. The fatty acid profile of transduced cellular phospholipids revealed significant decreases in MUFA and arachidonic acid (20:4n-6), and increases in LA, ALA, and eicosapentaenoic acid (20:5n-3). The fatty acid composition of triacylglycerols derived from transduced cells was similarly, but less dramatically, affected. These results demonstrate the functionality of C. elegans fatty acid desaturase enzymes in mammalian cells. Expression of these desaturases in livestock might act to counterbalance the saturating effect that rumen microbial biohydrogenation has on the fatty acid profile of ruminant products, and allow for the development of novel, land-based dietary sources of n-3 PUFA.