Influence of growth promoting implants on fatty acid composition including conjugated linoleic acid isomers in beef fat

The influence of the growth promoting implants Synovex (SYN), Ralgro (RAL), and Revalor (REV) on the fatty acid profiles of subcutaneous fat, intramuscular fat, and phospholipids of 32 beef steers (eight steers per treatment, and eight controls) was studied. Fatty acid compositions and profiles of conjugated linoleic acid (CLA) isomers were determined by a combination of GC and triple-column Ag⁺-HPLC. Only small differences could be observed between the different treatment groups. The amount of saturated fatty acids relative to monounsaturated fatty acids was increased by all growth promoting implants in subcutaneous fat (P<0.1) and also by SYN in intramuscular fat. RAL led to slightly higher amounts of trans fatty acids in subcutaneous and intramuscular fat (P<0.1). REV-implanted steers showed some significant differences in their profiles of polyunsaturated fatty acids compared to control steers. CLA content and isomeric distribution in subcutaneous fat were affected bySYN, which reduced amounts of total CLA (0.42 mg/g fat vs. 0.53 mg/g in control steers, P<0.001) and decreased the proportions of the primary 18:2 c9t11 isomer (73% of total CLA for SYN vs. 77-78% for all other treatment groups). Slight increases of c9t11 CLA in intramuscular fat were observed in RAL- and REV-implanted steers (P<0.1). Most differences in fatty acid composition observed in this study were probably due to shifts in the storage lipid/membrane lipid ratio.     

Composition and estimation of intramuscular and subcutaneous fatty acid composition in Spanish young bulls

Sixty Pirenaica yearling intact bulls were raised and slaughtered at 519±50kg live weight and 371±18 days of age. Fatty acid composition of intramuscular lipids in longissimus dorsi muscle and subcutaneous fat were determined by capillary gas chromatography. Carcass conformation and fatness, carcass weight, ether extractable intramuscular fat percentage, marbling, dorsal fat thickness, and ultrasonic parameters were recorded to study the relationship between these traits and fatty acid profile. Lipids of subcutaneous adipose tissue had higher monounsaturated fatty acids (MUFA) percentage (49% vs. 33%) but lower saturated fatty acids (SFA) (51% vs. 46%) and polyunsaturated fatty acids (PUFA) (16% vs. 5%) percentages than intramuscular fat depots (p<0.001). Fatter carcasses had higher MUFA percentage and lower PUFA percentage (p<0.01) in intramuscular fat. Carcass weight and conformation would contribute to explain the fatty acid profile of subcutaneous fat (p<0.05). Ultrasound readings reflected the effect of fatness on fat composition.     

肌内脂肪与背最长肌肉质、脂肪酸组成的关系

研究肌内脂肪（IMF）含量与肉质以及脂肪酸含量和组成比例之间的关系。以北京黑猪背最长肌（n=20）为实验材料,测定肌内脂肪含量、肉质以及脂肪酸含量和组成。结果显示,肌内脂肪含量与滴水损失呈显著正相关（p<0.05）,与蒸煮损失、剪切力、肉色的相关性不显著（p>0.05）。随着肌内脂肪含量升高,除长链多不饱和脂肪酸(C_20:3n6、C_20:4n6)以外的大多数脂肪酸含量增加,相对比例也上升;多不饱和脂肪酸的含量增加,但是相对比例下降;长链多不饱和脂肪酸的含量和相对比例都降低。随着肌内脂肪含量的升高,饱和脂肪酸（SFA）和单不饱和脂肪酸（MUFA）的含量升高,回归方程斜率分别为197.3和248.31,多不饱和脂肪酸（PUFA）增加的幅度不大,回归方程的斜率为11.43。结果提示:肌内脂肪含量较低时（本实验平均值2.86%）,对肉质的影响不显著。随着肌内脂肪含量升高,总脂肪酸含量（TFA）增加,主要归因于SFA和MUFA含量的增加。PUFA的含量相对稳定,受肌内脂肪含量变化的影响较小。      

沃金黑牛母牛与阉公牛牛肉品质比较及影响因素分析

目的 对比沃金黑牛母牛与阉公牛牛肉品质, 分析其影响因素。方法 随机选取18头健康、无病、发育正常的30个月龄沃金黑牛(母牛9头, 阉公牛9头)为研究对象, 测定其背最长肌的水分、粗蛋白、肌内脂肪、氨基酸、脂肪酸、质构特性, 并基于主成分分析考察影响沃金黑牛肉肉质的因素。结果 母牛和阉公牛牛肉的水分、粗蛋白、肌内脂肪以及各氨基酸含量无显著差异(P>0.05)。母牛牛肉必需氨基酸(essential amino acid, EAA)/总氨基酸(total amino acid, TAA)为39.74%, 阉公牛EAA/TAA为39.83%, 符合联合国粮食及农业组织/世界卫生组织(Food and Agriculture Organization/World Health Organization, FAO/WHO)的理想模式。母牛和阉公牛牛肉氨基酸评分(amino acid score, AAS)接近1, 化学评分(chemical score, CS)与标准蛋白的组成还有一定差距。母牛牛肉单不饱和脂肪酸(monounsaturated fatty acid, MUFA)含量极显著低于阉公牛(P<0.01), 而多不饱和脂肪酸(polyunsaturated fatty acid, PUFA)含量显著高于阉公牛(P<0.05)。母牛牛肉MUFA:饱和脂肪酸(saturated fatty acid, SFA)极显著低于阉公牛(P<0.05), PUFA:SFA显著高于阉公牛(P<0.05)。母牛和阉公牛各质构指标均无显著差异, 咀嚼度、黏性、硬度、黏合力为影响肉质的主要因素, 且质构指标优先性强于营养指标。结论 阉公牛脂肪酸含量与母牛差异显著, 水分含量、粗蛋白含量、粗脂肪含量、氨基酸含量与组成、质构指标之间差异均不显著。质构指标比营养指标更能影响沃金黑牛肉的品质。     

宣威火腿与金华火腿中游离脂肪酸组成比较分析

以两年宣威火腿和金华火腿为对象,采用气相色谱-质谱联用法(GC-MS)分别对宣威火腿和金华火腿的皮下和肌内脂肪中游离脂肪酸的组成进行分析。结果表明:宣威火腿和金华火腿的肌内脂肪和皮下脂肪中均检测出22种游离脂肪酸,含量较高的脂肪酸为棕榈酸(C16:0)、硬脂酸(C18:0)、油酸(C18:1n9c)与亚油酸(C18:2n6c),且不同火腿及不同部位间的脂肪酸组成含量存在明显差异;金华火腿肌内及皮下脂肪中总游离脂肪酸含量分别为29.24、102.68 μg/mg,分别比宣威火腿高34.58%(p<0.05)、29.09%(p>0.05);宣威火腿和金华火腿肌内脂肪中饱和脂肪酸含量高于不饱和脂肪酸含量,皮下脂肪中不饱和脂肪酸含量高于饱和脂肪酸含量。金华火腿肌内、皮下游离脂肪酸含量均高于宣威火腿相应部位游离脂肪酸含量。     

PRODUCTION OF LOW-FAT FRANKFURTERS WITH VEGETABLE OILS FOLLOWING THE DIETARY GUIDELINES FOR FATTY ACIDS

Low-fat frankfurters (10% fat) were produced with vegetable oils following the dietary guidelines for fatty acids as suggested in the currently recommended diet (CRD) by the American Heart Association, the Grundy diet (GD) and the Mediterranean diet (MD). MD-frankfurters, produced with olive oil (31.82%) and soybean oil (17.51%), had the highest (P<0.05) ratio of monousaturated fatty acids (MUFA)/saturated fatty acids (SFA) minus stearic. CRD-frankfurters, produced mainly with cottonseed oil (40.70%) and soybean oil (6.90%), had the highest (P<0.05) content of polyunsaturated fatty acids (PUFA). GD-frankfurters, produced with cottonseed oil (34.04%) and olive oil (15.19%), had the highest (P<0.05) ratio of (C18:2 n-6)/(C18:3 n-3). Compared to high-fat frankfurters (27% all animal fat), low-fat frankfurters had lower (P<0.05) stearic acid and trans ω-9 oleic acid, higher (P<0.05) content of total PUFA, higher (P<0.05) ratio of (C18:2+C 18:3)/SFA minus stearic acid, and lower cholesterol content (52.60%-59.11%), were darker, redder and more yellow, firmer and less juicy, but had similar overall acceptabily.     

北部湾海区几种常见牡蛎基础营养及脂肪酸成分比较分析

目的 比较分析北部湾海区常见的熊本牡蛎、香港牡蛎和近江牡蛎鲜品的基础营养成分及脂肪酸组成。方法 以北部湾海区熊本牡蛎、香港牡蛎和近江牡蛎为实验样品, 测定其水分、粗蛋白、粗脂肪和灰分的含量, 并用气相色谱-质谱联用法(gas chromatography-mass spectrometry, GC-MS)测定脂肪酸组成及含量。 结果 香港牡蛎的水分含量(89.44 g/100 g)、近江牡蛎粗脂肪含量(1.09 g/100 g)和灰分含量(1.77 g/100 g)均显著高于另两种牡蛎(P<0.05), 香港牡蛎粗蛋白含量(4.59 g/100 g)显著低于另两种牡蛎(P>0.05)。熊本牡蛎和近江牡蛎含有33种脂肪酸, 而香港牡蛎为34种, 其中多不饱和脂肪酸(polyunsaturated fatty acid, PUFA)含量占41.02%~50.79%; 3种牡蛎中二十碳五烯酸(eicosapentaenoic acid, EPA)、二十二碳六烯酸(docosahexoenoic acid, DHA)的含量占脂肪酸总量的27.13%~38.65%, 近江牡蛎(27.13%)显著低于另两种牡蛎(P<0.05)。结论 北部湾海区熊本牡蛎、香港牡蛎和近江牡蛎脂肪酸种类丰富, 与饱和脂肪酸及单不饱和脂肪酸含量所占脂肪酸总量相比, PUFA占比最高, 且以DHA和EPA为主, 具有优良的开发潜力。     

Vegetable Oils Replace Pork Backfat for Low-Fat Frankfurters

Low-fat frankfurters (10% fat, 12.5% protein) with olive, corn, sunflower or soybean oils, compared to control (29.1% animal fat, 10.4% protein) had 67% lower total fat, 40–45% lower saturated fatty acids, 50–53% lower calories, reduced cholesterol and 20% higher meat protein. Although they had darker red color they were 6–7.2% lower in processing yield and had higher purge accumulation, were firmer and less juicy. The type oil had no effect (P>0.05) on these characteristics but affected fatty acid composition. Frankfurters with olive oil had 41.8% higher monounsaturated fatty acids and those with seed oils 5–7 times higher polyunsaturated fatty acids. Soybean oil increased lin-olenic acid content and negatively affected overall acceptability and shelf-life.     

4种来源大黄鱼营养成分的比较分析

目的 比较4个不同产地大黄鱼(福建宁德养殖、浙江温州养殖、浙江舟山养殖和舟山自然海域野生)的营养组成。方法 采用国标分析方法对4个产地大黄鱼背部肌肉中的一般营养成分(水分、灰分、粗蛋白和粗脂肪)、矿物元素、氨基酸和脂肪酸含量进行定量和差异比较分析。结果 4种产地大黄鱼肌肉中,水分、灰分和粗蛋白质含量无显著性差别(P＞0.05),野生大黄鱼脂肪含量明显最低(P＜0.05),福建宁德养殖大黄鱼脂肪含量显著性最高(P＜0.05)。舟山野生大黄鱼中Mg、K,Se,Asp,Glu,Lys,∑EAA,∑TAA,∑FAA和∑BAA均含量均显著高于其它3种产地(P<0.05),Zn含量最高且明显高于福建宁德与浙江温州两产地(P<0.05),而Cu含量明显低于温州和舟山养殖大黄鱼(P<0.05)。除温州养殖大黄鱼略低外,其它3个产地大黄鱼的∑EAA/∑TAA和∑EAA/∑NEAA分别在40.73%~41.13%和68.72%~69.80%,符合优质蛋白源条件。C16:0、C18:1n9c、C22:6n3和C20:5n3是大黄鱼肌肉中最为丰富的脂肪酸,福建宁德养殖大黄鱼中FA、SFA和UFA含量均显著高于其它3种产地,舟山野生大黄鱼中ΣPUFA/ΣUFA占比高达78.6%,特别是EPA和DHA的总含量明显高于养殖大黄鱼。结论 不同产地环境及养殖方式会导致大黄鱼的营养成分有所差异。野生大黄鱼在低脂肪、有益矿物元素、鲜味氨基酸和多不饱和脂肪酸含量上较养殖大黄鱼有明显优势,但养殖鱼类可以显著提高蛋白质及脂肪酸含量,均具有较高的食用与营养保健价值。     

安福火腿游离脂肪酸、风味物质及氨基酸分析

为揭示安福火腿的品质特性及其主体挥发性风味物质成分,采用气相色谱-质谱联用、固相微萃取-气相色谱-质谱联用等对其肌内脂肪和皮下脂肪中游离脂肪酸、挥发性风味物质进行对比分析及肌肉中氨基酸的组分含量进行定量检测。结果表明,从肌内脂肪和皮下脂肪中分别检测出19、29种游离脂肪酸（皮下脂肪的总游离脂肪酸含量是肌内脂肪的7.992倍）,29、31种挥发性风味物质。采用气味活性值分析法分别得到7、14种主体挥发性风味物质,其中己醛、辛醛、壬醛、（E, E）-2, 4-癸二烯醛和双戊烯是肌内脂肪和皮下脂肪中共同呈现的关键挥发性风味物质,3-甲硫基丙醛和癸醛仅存在于肌内脂肪中。肌肉中检测出17种氨基酸,且必需氨基酸的含量丰富,占氨基酸总量的41.98%,天冬氨酸和谷氨酸两种鲜味氨基酸的含量最高,它们对安福火腿的鲜美度有着重要的贡献。此研究可为后期分析加工工艺对安福火腿品质的影响提供借鉴。     

Effect of dietary fish oil on fatty acid composition, lipid oxidation and sensory property of chicken frankfurters during storage

Broilers fed with three levels of fish oil (0, 2 and 4%) for 6 weeks were used in the manufacture of chicken frankfurters. The meat samples were vacuum-packed and stored at 0°C for 0, 10, 20 and 30 days. Cooking yield, proximate and fatty acid composition, lipid oxidation, microbial and sensory properties of the meat products were measured. Cooking yield, moisture, fat, protein, ash and cholesterol contents of frankfurters were not affected (P>0.05) by levels of dietary fish oil. Frankfurters processed from chickens fed diets enriched with 2 and 4% of supplemental fish oil had a higher (P<0.05) level of n-3 fatty acids (eicosapentaenoic acid and docosahexaenoic acid), but had a lower level of n-6 fatty acids (P<0.05) than the controls (0% fish oil). TBA values and pH values of meat samples were not affected (P>0.05) by levels of supplemental fish oil in the diets, however, pH values of the vacuum-packaged chicken frankfurters decreased (P<0.05) as the storage time increased. No differences (P>0.05) in total anaerobic plate counts were observed among the fish oil treatments during storage. Supplementation of 2 and 4% fish oil in the diets did not increase (P>0.05) the intensity of fishy flavor in chicken frankfurters.     

Effect of pasture vs. concentrate feeding with or without antioxidants on carcass characteristics, fatty acid composition, and quality of Uruguayan beef

Thirty Hereford steers were finished either on pasture (n=10) or concentrate (n=20) to determine dietary and antioxidant treatment effects on carcass characteristics, fatty acid composition, and quality of Uruguayan beef. Half of the steers finished on concentrate were supplemented with 1000 I.U. vitamin E head(-1) day(-1) for 100 days. Postmortem vitamin C was added to ground beef (0.05% v/w) displayed for 8 days at 2?°C. Carcasses from steers finished on concentrate had greater (P<0.05) carcass weight, conformation, degree of finishing, fat depth, and ribeye area than pasture finished animals. Carcasses from pasture-fed steers showed darker (P<0.05) longissimus color and yellower (P<0.05) fat at 24 h postmortem than concentrate-fed. Initial longissimus Warner-Bratzler shear force (WBSF) values were similar (P>0.05) between pasture- and concentrate-fed animals. However, beef from pasture-fed cattle had lower (P<0.05) WBSF values at 7 and 14 days postmortem. Longissimus α-tocopherol concentrations were greater (P<0.01) for pasture- and concentrate-fed animals that were supplemented with vitamin E compared to concentrate-fed. Steaks from pasture-fed and vitamin E supplemented cattle had similar (P>0.05) TBARS values, which were lower (P<0.05) than steaks from concentrate-fed steers during 21 days of display. Ground beef from vitamin E supplemented steers had the lowest TBARS values; whereas samples from pasture-fed animals had the lowest lipid stability with higher TBARS levels than other treatments. Vitamin C addition to ground beef did not (P>0.05) reduce lipid oxidation. Vitamin E supplementation of concentrate-fed cattle had no effect (P>0.05) on color stability of ground beef or steaks. The a(?) (redness) and b(?) (yellowness) values were higher (P<0.05) when vitamin C was added to ground beef. Longissimus fatty acid content of concentrate-fed animals was twofold greater (P<0.01) than pasture-fed. The percentages of C14:0, C16:0, and C18:1 fatty acids were higher (P<0.01) in the intramuscular fat of concentrate-fed steers, whereas pasture-fed cattle showed greater (P<0.01) proportions of C18:0, C18:2, C18:3, C20:4, C20:5, and C22:5. Total conjugated linoleic acid (CLA) and CLA isomer c9t11 were higher (P<0.01) for pasture- than concentrate-fed cattle. Vitamin E supplementation of concentrate-fed steers increased lipid stability of ground beef and steaks, but was unable to improve color stability; whereas vitamin C addition to ground beef increased color stability without altering lipid oxidation. Finishing cattle on pasture enhanced the unsaturated fatty acid profile of intramuscular fat in beef including CLA and omega-3 fatty acids.     

Carcass characteristics, fatty acid composition, and meat quality of Criollo Argentino and Braford steers raised on forage in a semi-tropical region of Argentina

The purpose of this study was to characterize and compare the carcass characteristics, cholesterol concentration, fatty acid composition of intramuscular fat and subcutaneous fat, and meat quality of Criollo Argentino and Braford steers reared in an extensive system, without supplementation, and slaughtered at approximately 400 kg live weight. The Braford steers had greater (P < 0.05) carcass weight, yield, conformation score, marbling degree, fat thickness and fatness score than Criollo Argentino steers. The tissue composition of the 10th rib was: 68.1% vs. 63.6% muscle, 23.9% vs. 20.4% bone and 8.2% vs. 16.3% fat for the Criollo Argentino and Braford breeds, respectively. The meat of Longissimus muscle from Braford steers was lighter, redder, yellower and more tender than that from Criollo Argentino steers. The meat of Longissimus muscle from Braford steers had a higher fat content, similar protein and ash contents and a lower (P ? 0.001) cholesterol concentration than that from Criollo Argentino steers.     

Changes in intramuscular fat, fatty acid profile and cholesterol content induced by zeranol implantation strategy in hair lambs

BACKGROUND: The effect of zeranol implantation strategy on intramuscular fat, fatty acid profile and cholesterol content of the longissimus dorsi muscle of hair lambs was studied. Four treatments were tested: C, control group; Z12, 12 mg zeranol; Z24, 24 mg zeranol in a single application; and RZ12, 12 mg zeranol given twice. One‐way analysis of variance was employed to estimate the effect of treatments (P < 0.05). To separate the effect of the mean, orthogonal contrasts were tested: C1, C versus Z12 + Z24 + RZ12; C2, Z12 versus Z24 + RZ12; and C3, Z24 versus RZ12. RESULTS: A decrease (P < 0.05) in intramuscular fat content was observed from implanting (C1 effect) and zeranol reimplantation (C3 effect). Implanted lambs exhibited an increase (P < 0.05) in monounsaturated fatty acids compared with control group (40.60% versus 35.35%). All contrasts were significant for the sum of n‐6 and n‐3, with values lower (P < 0.05) in the control (n‐6: 0.84% and n‐3: 1.38%) and higher in the RZ12 treatment (n‐6: 7.55% and n‐3: 14.9%). Cholesterol decreased by 78% with implantation and increasing the dose. CONCLUSION: The results indicate that it is possible to induce favorable changes in the fatty acid profile and cholesterol content using a zeranol implantation strategy on hair lambs. Copyright © 2011 Society of Chemical Industry     

A comparison of carcass and meat quality characteristics of Creole and Large White pigs slaughtered at 90kg BW

The effect of breed in combination with sex (gilts or barrows) on carcass composition and meat quality characteristics were studied in two replicates involving a total of 40 Creole (CR) and 40 Large White (LW). This trial was conducted in the experimental facilities of INRA in Guadeloupe (French West Indies, 16° Lat. N. and 61° Long. W). All the pigs were slaughtered at about 90kg BW. No interaction between breeds and sex was found for all criteria studied. Carcass dressing weight was higher in CR than in LW (832 vs. 810g/kg, P<0.001) in connection with their lower internal organs weight (34.0 vs. 41g/kg; P<0.001). Fat cuts weight (i.e., back and leaf fat) was higher in CR than in LW (192 vs. 90g/kg; P<0.001). Creole pigs showed higher intramuscular fat percentage (IMF), higher percentage of monounsaturated fatty acids (MUFA) and lower percentage of polyunsaturated fatty acids (PUFA) in Longissimus dorsi (LD) muscle than LW pigs (4.72% vs. 2.29%, 50.2% vs. 45.0% and 7.9% vs. 13.8%, respectively). Whatever the muscle considered the ultimate pH was higher (P<0.05) in CR than in LW pigs. The drip and cooking losses of LD muscle were lower in CR than in LW (8.2% vs. 9.7% and 28.9% vs. 30.1%, respectively; P<0.05). Whatever the breed, the females were leaner than barrows (P<0.01) but the effect of sex was significant only on a few parameters.     

不同部位牛油脂肪酸组成和挥发性风味成分分析

以1 000 kg牛脂肪为每个样品量提炼牛油,对得到的肾周脂、腹脂和分割脂3种不同部位的牛油采用气相色谱进行脂肪酸组成分析,并使用气相色谱–嗅闻–质谱联用进行了挥发性风味成分检测。结果表明：3种牛油的饱和脂肪酸以棕榈酸、硬脂酸为主,不饱和脂肪酸以油酸为主。3种牛油的棕榈酸含量无显著差异（P>0.05）,腰油与肚油的硬脂酸、油酸含量无显著差异（P>0.05）,而分割油与腰油、肚油的硬脂酸、油酸含量都具有极显著性差异（P<0.01）。3种牛油中挥发性风味成分主要有醛、酸、醇、酮、酯和杂环6大类,其中醛类与酸类含量之和可占总量70%以上。不同部位牛油之间挥发性风味成分含量具有显著差异（P<0.05）。腰油中挥发性风味物质总量最高,肚油中醛类含量占比达到59.90%;分割油中挥发性风味成分种类最多,其中酯类、杂环类挥发性风味成分占比分别达到8.49%与7.61%。脂肪酸测定和挥发性风味成分分析揭示了不同部位牛油之间的特征与差异,可为食用牛油产品的合理开发利用和风味品质控制提供参考数据。     

Fatty acid and triglyceride profiles of intramuscular and subcutaneous fat from fresh and dry-cured hams from Hairless Mexican Pigs

The study was designed to compare the fatty acid profiles and triglyceride composition of subcutaneous and intramuscular fat of raw and cured hams from Hairless Mexican Pigs. Curing (180 days) was developed throughout several ordered steps: salting, stabilization, drying and ripening. For the salting step, hams were rubbed with nitrate salt, and kept on salt 1 day per kilogram at 0-4?°C and at relative humidity of 80-85%. The rest of the process consisted of small increments of temperature (from 0-24?°C) and small decrements of relative humidity (from 82-68%). The curing process decreased (P<0.05) significantly the proportion of unsaturated fatty acids (raw: 59.2±0.3% and cured: 55.3±0.4%) and increased the saturated ones (raw: 34.4±0.3% and cured: 39.4±0.5%). Subcutaneous and intramuscular fat had similar (P>0.05) percentages of unsaturated (57.60±0.3 and 56.88±0.4%, respectively) and saturated fatty acids (37.5±0.33 and 38.3±0.4%, respectively). With the exception of the monopalmitate, the curing process decreased (P<0.05) the levels of all acylglycerols studied.     

Influence of ewe feeding systems on fatty acid composition of suckling lambs

The main objective of this study was to evaluate the effects of ewe dietary treatments on the intramuscular fatty acid composition of suckling lambs. Twenty-four pregnant Italian Merino ewes were divided into two equal groups. One group (pasture-fed group) was allowed to graze a natural pasture and the other group (stall-fed group) was penned indoors and fed with hay and concentrate. After lambing, all ewes stayed with their respective lambs for the whole experimental period. Lambs were slaughtered at 100 days of age with an average live weight of 20kg. Fatty acid profiles of milk and lamb meat (longissimus lumborum muscle) were analysed. Intramuscular fat from pasture-fed lambs showed higher (P<0.001) proportions of polyunsaturated fatty acids. The percentage of lauric (C12:0; P<0.05), palmitic (C16.0; P<0.001) and oleic (C18.1; P<0.001) fatty acids were higher in the intramuscular fat from stall-fed lambs, whereas pasture-fed lambs showed greater proportions of linolenic (C18:3; P<0.001), eicosapentaenoic (C20:5; P<0.001) and docosapentaenoic (C22:5; P<0.05) fatty acids. Moreover, the intramuscular fat from pasture-fed lambs displayed a higher (P<0.001) PUFA/SFA ratio, and a lower (p<0.001) n-6/n-3 ratio. The conjugated linoleic acid (CLA) tended to be higher (P=0.07) in the intramuscular fat from pasture-fed lambs. This study confirmed that pasture enhanced the unsaturated fatty acid profile of intramuscular fat in lambs including n-3 fatty acids.     

Effect of dietary energy and protein levels on fatty acid composition of intramuscular fat in double-muscled Belgian Blue bulls

Seventy six Belgian Blue (BB) bulls, with double-muscled conformation, were randomly allocated to six dietary treatments in a 2 × 3 factorial experiment. The treatments included low (N(L)=127 g CP/kg DM), medium (N(M)=153 g CP/kg DM) and high (N(H)=172 g CP/kg DM) levels of dietary protein in combination with low (E(L)=7.38 MJ ME/kg DM) and high (E(H)=8.03 MJ ME/kg DM) levels of dietary energy. Fatty acid composition was determined on total lipid samples of the M. longissimus thoracis of all animals and on the separated triacylglycerol and polar lipid fatty acid fractions of the medium-protein group. Dietary energy and protein levels influenced the carcass characteristics of BB bulls but the effects were small. Carcass fat cover score, carcass fat content and intramuscular fat content were slightly but significantly higher in the animals on the high versus the low energy diets. The overall intramuscular fat content was very low (<1%) and the overall polyunsaturated:saturated fatty acid ratio (0.39) high compared to normal figures for beef. The high versus the low dietary energy level increased the monounsaturated (P<0.001) and decreased the polyunsaturated (P<0.001) fatty acid proportion with no change in the saturated fatty acid proportion. This may have been due in part to the addition of beef tallow to increase the energy level of the diet. Concomitant shifts in the individual fatty acids included increased proportions of C14:0 (P<0.001), C16:0 (P<0.03), C16:1 (P<0.01), C18:1 (P<0.001) and decreased proportions of C18:2 (P<0.001) and C20:4 (P<0.001). Increasing dietary protein levels had inconsistent effects on the fatty acid profiles. The proportion of polar lipid fatty acids in the total fatty acids was 0.34 and 0.25 for the E(L) and E(H) group, respectively, in the Nm treatment group. Changes in fatty acid proportions of the triacylglycerol fatty acid fraction were similar to those seen in the total lipid fatty acids when related to dietary energy level, but no significant changes in the polar lipid fatty acid proportions were observed. Significant linear relationships were found between measures of carcass and muscle fatness and fatty acid proportions. With increasing muscle total fatty acid content, saturated and monounsaturated fatty acid proportions increased (r=0.38 and r=0.55, respectively, P<0.01) and the polyunsaturated fatty acid proportion decreased (r=-0.73, P<0.01). The diet had some effects but the relatively unsaturated intramuscular fatty acid composition was mainly related to the low total fat content of the BB animals.     

澳洲白羊与小尾寒羊杂交F1代背最长肌肉品质与皮下脂肪组织膻味物质分析

选取8月龄澳洲白羊与小尾寒羊的杂交一代母羊（澳寒羊,n=10）并与其同月龄母本小尾寒羊为对照（n=7）,测定其屠宰性状、肉质指标、脂肪酸组成和膻味物质含量,探究澳洲白羊与小尾寒羊杂交后其后代的肉品品质和膻味物质的变化。结果表明:在肉品质方面,澳寒羊的a*值显著高于小尾寒羊,肌内脂肪含量和pH₀值显著（P<0.05）低于小尾寒羊。固相微萃取-气相色谱-质谱（SPME-GC-MS）联用的测定分析显示,皮下脂肪的脂肪酸组成中,澳寒羊肉豆蔻酸（C_14:0）含量显著（P<0.05）高于小尾寒羊,亚油酸（C_18:2）含量显著（P<0.01）低于小尾寒羊,但总饱和脂肪酸和不饱和脂肪酸含量二者之间无显著差异（P>0.05）;膻味物质含量的测定表明,澳寒羊脂肪中的4-乙基辛酸（EOA）含量显著（P<0.01）低于小尾寒羊,而4-甲基辛酸（MOA）、4-甲基壬酸（MNA）、4-甲基苯酚（MP）和3-甲基吲哚（MI）的含量二者之间差异不显著（P>0.05）。但与小尾寒羊相比,澳寒羊的宰前活重、胴体重、屠宰率都得以极显著提高（P<0.01）。显然,以澳洲白羊为父本杂交小尾寒羊,其后代的肉品品质和膻味物质与小尾寒羊相比未发生实质性变化,EOA含量和剪切力等少数指标尚有改善;同时,产肉性能得到了极显著的提高, 可以作为小尾寒羊杂交改良和商品肉羊的生产方式,可为养殖者带来良好的经济效益。