断奶对仔猪肠道屏障的影响及营养调控

在集约化养殖中,3~4周龄早期断奶是仔猪生命周期中一个非常紧张的时期,此时仔猪胃肠道还未发育成熟。肠道屏障由上皮、免疫和肠神经系统组成,这些系统控制上皮屏障的完整性以及肠道功能,包括肠腔营养物质、水和电解质的运输。早期断奶导致肠道通透性增加,出现胃肠功能紊乱的情况,可能对猪只一生产生长期的影响。因此,仔猪断奶饲粮需要正确水平的营养素、营养源和高质量的添加剂,鼓励仔猪快速进食,减轻或消除断奶应激综合症,降低死亡率和发病率。养猪就是养"肠道",合理使用功能性氨基酸、植物化学物质和有机酸等添加剂,能够修复由于断奶应激综合症导致的肠道屏障功能障碍。     

排酸处理对湘南黄牛氨基酸以及脂肪酸的影响

[目的]为改善湘南黄牛肉用品质,并在生产中推广应用。[方法]试验选取6头同一品种、月龄接近的湘南黄牛经同一饲喂条件育肥后进行屠宰,测定排酸前后牛肉中氨基酸、脂肪酸含量等指标。[结果]结果表明,排酸牛肉组氨酸、甘氨酸、蛋氨酸、肌氨酸、色氨酸、∑鲜味氨基酸、∑苦味氨基酸含量显著升高(P0.05);丙氨酸、缬氨酸、脯氨酸、苏氨酸、瓜氨酸、∑甜味氨基酸含量显著降低(P0.05)。排酸牛肉十二酸、十四酸、十五酸、顺-11-二十碳烯酸、饱和脂肪酸(SFA)含量显著升高(P0.05);顺-9,12,15-十八碳三烯酸、顺-8,11,14-二十碳三烯酸、顺-5,8,11,14-二十碳四烯酸、二十碳五烯酸、二十二碳六烯酸、多不饱和脂肪酸(PUFA)、PUFA/SFA、n-6 PUFA、n-3 PUFA含量显著降低(P0.05)。[结论]最终得出,通过排酸处理湘南黄牛能够满足人体从肉类摄取氨基酸的需求,同时有效改变脂肪酸含量,提高肉用品质。     

Changes in plasma bile acids,plasma amino acids,and hepatic enzyme pools as indices of functional impairment in liver-damaged sheep

Plasma bile acids, plasma amino acids, and the total hepatic pools of aspartate aminotransferase, gamma glutamyltransferase, glutamate dehydrogenase, and sorbitol dehydrogenase were compared in control sheep (Group 1), sheep with subclinical pyrrolizidine alkaloid toxicosis (Group 2), and in sheep with acute hepatocellular necrosis associated with the hemolytic phase of chronic copper poisoning (Group 3). Subclinical pyrrolizidine alkaloid toxicosis was not associated with any changes in bile acid or amino acid status but was associated with a significant decline in the hepatic pools of sorbitol dehydrogenase and aspartate aminotransferase. This observation could not be explained in terms of enzyme leakage from damaged hepatocytes and suggested that pyrrolizidine alkaloids might specifically inhibit hepatocellular enzyme synthesis. Group 3 sheep also had reduced hepatic enzyme pools which were at least partly referable to enzyme leakage from damaged hepatocytes. In these sheep, increases in plasma bile acids were a more sensitive index of hepatic function than were either increased aromatic amino acid concentration or the ratio between branched chain and aromatic amino acids.     

动物产品中多不饱和脂肪酸和其他脂肪酸含量变化及其影响因素

肉、蛋、奶等动物产品和肉、奶制品是单不饱和脂肪酸（MUFA）和多不饱和脂肪酸（PUFA）的重要来源。因此,提高肉及肉制品、蛋、奶及奶制品中不饱和脂肪酸含量有助于提高全民健康水平和生活质量。主要对目前富含不饱和脂肪酸的动物产品质量及影响动物产品中不饱和脂肪酸成分和含量的饲粮、动物性别和年龄以及基因类型等因素作一简要综述,以期为在生产实践中开发相关技术和产品提供理论参考依据。     

Study on bioactive compounds of in vitro cultured Calculus Suis and natural Calculus Bovis1

The purpose of the study was to investigate bioactive compounds of in vitro cultured Calculus Suis and natural Calculus Bovis obtained as valuable by‐products from animals used for meat production. The results showed that the components of natural Calculus Bovis were rich in bilirubin and biliverdin and had higher content of essential amino acids. The major amino acids of in vitro cultured Calculus Suis were identified as glycine, alanine, glutamic acid and aspartic acid, and those for natural Calculus Bovis were found to be glutamic acid, aspartic acid, proline, and arginine. The methionine and cysteine contents of precursors for glutathione in natural Calculus Bovis were significantly higher than those of in vitro cultured Calculus Suis. The mineral contents of zinc, iron and manganese of natural Calculus Bovis were significantly higher than those of in vitro cultured Calculus Suis. The major bile acids in both products were cholic acid and dehydrocholic acid, respectively. The chenodeoxycholic and ursodeoxycholic acid content of in vitro cultured Calculus Suis was significantly higher than that of natural Calculus Bovis.     

动物产品中多不饱和脂肪酸和其他脂肪酸含量变化及其影响因素

肉、蛋、奶等动物产品和肉、奶制品是单不饱和脂肪酸(MUFA)和多不饱和脂肪酸(PUFA)的重要来源。因此,提高肉及肉制品、蛋、奶及奶制品中不饱和脂肪酸含量有助于提高全民健康水平和生活质量。主要对目前富含不饱和脂肪酸的动物产品质量及影响动物产品中不饱和脂肪酸成分和含量的饲粮、动物性别和年龄以及基因类型等因素作一简要综述,以期为在生产实践中开发相关技术和产品提供理论参考依据。     

动物产品中多不饱和脂肪酸和其他脂肪酸含量变化及其影响因素

肉、蛋、奶等动物产品和肉、奶制品是单不饱和脂肪酸(MUFA)和多不饱和脂肪酸(PUFA)的重要来源.因此,提高肉及肉制品、蛋、奶及奶制品中不饱和脂肪酸(UFA)含量有助于提高全民健康水平和生活质量.本文主要对目前富含PUFA的动物产品质量及影响动物产品中PUFA成分和含量的饲粮、动物性别和年龄及基因类型等因素做一简要综述,以期为在生产实践中开发相关技术和产品提供理论参考依据.     

野生和养殖红鳍东方鲀营养品质的比较分析

本试验对野生1龄、养殖1龄和养殖2龄红鳍东方鲀的一般营养成分及肌肉氨基酸和脂肪酸的组成进行测定,旨在比较野生和养殖红鳍东方鲀的营养品质。试验选取野生1龄红鳍东方鲀15尾(体重71~139 g、体长13.4~18.9 cm)、养殖1龄红鳍东方鲀(投喂冰鲜杂鱼)13尾(体重90~147 g、体长14.8~20.4 cm)、养殖2龄红鳍东方鲀(投喂冰鲜杂鱼)10尾(体重578~639 g、体长31.3~36.7 cm)作为样本。采用国家标准方法测定组织中的一般营养成分及肌肉氨基酸和脂肪酸组成,并对肌肉营养品质进行分析。结果表明:全鱼粗蛋白质含量以野生1龄红鳍东方鲀最高,为68.07%,比养殖1龄和养殖2龄红鳍东方鲀分别高出了32.3%、20.6%(P0.05),而全鱼粗脂肪含量则为养殖1龄和养殖2龄红鳍东方鲀显著高于野生1龄红鳍东方鲀(P0.05);养殖2龄红鳍东方鲀肌肉粗蛋白质含量显著高于野生1龄和养殖1龄红鳍东方鲀(P0.05),各样本间肌肉粗脂肪和粗灰分含量差异不显著(P0.05);各样本的肝脏粗蛋白质和粗脂肪含量变化较大,粗蛋白质含量按照野生1龄、养殖1龄、养殖2龄的顺序依次显著降低(P0.05),而粗脂肪含量则呈现与粗蛋白质相反的变化。野生和养殖红鳍东方鲀肌肉中均检测出18种氨基酸,而且在含量上养殖红鳍东方鲀大多数均显著高于野生红鳍东方鲀(P0.05)。根据氨基酸评分(ASS)和化学评分(CS),红鳍东方鲀肌肉中赖氨酸的含量相对较为丰富,且养殖2龄红鳍东方鲀必需氨基酸指数(EAAI)最高,其次为养殖1龄红鳍东方鲀,最后为野生1龄红鳍东方鲀。野生和养殖红鳍东方鲀肌肉中共检测出19种脂肪酸,且野生和养殖红鳍东方鲀脂肪酸组成相似,野生1龄、养殖1龄和养殖2龄红鳍东方鲀肌肉中饱和脂肪酸(SFA)含量差异不大(P0.05),多不饱和脂肪酸(PUFA)含量则以养殖2龄红鳍东方鲀最高,为51.54%,但是各样本间差异不显著(P0.05);肌肉中C20∶5n-3(EPA)和C22∶6n-3(DHA)含量均较丰富,其中养殖1龄和养殖2龄红鳍东方鲀DHA的含量分别比野生1龄红鳍东方鲀高出了24.7%、27.2%(P0.05),而且养殖1龄和养殖2龄红鳍东方鲀EPA+DHA的含量也显著高于野生1龄红鳍东方鲀(P0.05)。由此可知,红鳍东方鲀营养组成合理,且养殖红鳍东方鲀营养品质优于野生红鳍东方鲀。     

Effect of fatty acids added to the milk replacer on white scour and excretion of fatty acids in Holstein calves

In order to examine the relationship between white scour and fatty acids, we added fatty acids to the milk replacer. Twenty healthy Holstein calves were divided into 4 groups, five calves per group; a control group with no fortified fatty acid, and 3 groups fed either with oleic, stearic, or palmitic acid, respectively. The calves were fed milk replacer (5% of the calf's body weight) twice a day but the fatty acids (2 wt % of milk replacer) were added only once. The fecal and blood samples were obtained at 0, 12, 24, 36, and 48 h after feeding of the acids. All five calves in the palmitic acid group, and 3 out of 5 calves each in the stealic and the oleic acid groups had whitish feces after feeding fatty acid. The stearic acid group had a significantly elevated stearic acid concentration in the feces during 24–36 h compared to the pre-feeding level. The fecal concentration of palmitic acid increased significantly at 24–36 h in the palmitic acid group. We concluded that the long-chain saturated fatty acids are one of the causes of white scour in calves.     

Variations in protein and fat contents and their fractions in milk from two species fed different forages

This study aimed at determining the variations in milk constituents which could be varied by feed and animal species. To achieve this goal, two groups of homoparity Baladi cows and Egyptian buffaloes (n = 20 per species) were used. Each group was divided into two subgroups (n = 10): subgroup I received legume forage (Egyptian clover) and subgroup II received grass forage (sorghum forage). All experimental animals were fed the diet consisting of concentrate, forage and rice straw as 50, 25 and 25% of dry matter intake respectively. Milk samples were taken for analysis. The trial lasted until the 3rd month of parturition. The main results indicated that lactating cattle fed legume forage significantly (p ≤ 0.01) had more content of casein nitrogen (513 mg/100 ml milk), lower content of glutamic acid (23.56 g/100 g milk protein) and more content of cis‐9, trans‐11 18:2 conjugated linoleic acid (CLA) (0.77 g/100 g milk fat) compared with 433, 26.67 and 0.53, respectively, for cattle fed grass forage. With regard to the species effect, results showed that buffalo milk appeared to contain significantly higher (p ≤ 0.01) contents of casein nitrogen, phenylalanine, glutamic and arachidonic acid compared with cow's milk. However, the latter was significantly (p ≤ 0.01) more in the cis‐9, trans‐11CLA (0.59 g/100 g milk fat) than that in buffalo milk (0.47 g/100 g milk fat). The results revealed that not only forage type played a critical role in determining the variations of milk nitrogen distribution, milk amino acids and fatty acids but also animal species had a significant effect on these parameters.     

Effects of the fattening period on the fatty acid composition of fat deposits and free amino acid and inosinic acid contents of the longissimus muscle in carcasses of Japanese Black steers

The effects of the fattening period on carcass characteristics, fatty acid composition of fat deposits, and muscle free amino acid (FAA) and inosinic acid (IMP) contents were evaluated in Japanese Black steers. Ten castrated, 10-month-old calves derived from the same sire were divided into five to be slaughtered at the age of 30 months after a 20-month fattening period (20-month group) and five to be slaughtered at the age of 34 months after a 24-month fattening period (24-month group). Concerning the fatty acid composition of subcutaneous fat, the percentage of palmitoleic acid was higher ( P  < 0.05) in the 24- than in the 20-month group, but no difference was noted in any other fatty acids. For intermuscular fat, no difference was observed in any fatty acids. The percentages of oleic acid and total monounsaturated fatty acid of intramuscular and perinephric fat were higher ( P  < 0.05) in the 24- than in the 20-month group. Of the FAAs in the longissimus thoracis muscle, the threonine and tyrosine contents were lower ( P  < 0.05) in the 24- than in the 20-month group. The IMP content was higher ( P  < 0.05) in the 24- than in the 20-month group, suggesting an effect of prolongation of the fattening period.     

延边黄牛公牛与阉牛牛肉营养成分比较研究

本试验主要对延边黄牛公牛与阉牛肉质中营养成分进行比较研究,选择品种相同,年龄、体重相近,健康状况良好的延边黄牛16头,随机分为2组,每组8头,其中试验组为阉牛,对照组为公牛,在试验日粮相同、饲养条件一致的条件下,育肥373 d后进行屠宰。结果显示：①试验初期,两组间血清总蛋白、球蛋白、白蛋白/球蛋白、血糖、甘油三酯、谷草转氨酶、谷丙转氨酶含量均未表现出显著差异（P>0.05）,而试验组白蛋白、高密度脂蛋白、尿素氮及胆固醇含量极显著或显著高于对照组（P<0.01;P<0.05）;试验末期,试验组白蛋白、白蛋白/球蛋白、胆固醇含量显著高于对照组（P<0.05）,且试验组甘油三酯含量极显著高于对照组（P<0.01）,其他各成分含量两组间均无显著性差异（P>0.05）;②试验组背最长肌中油酸含量、油酸/亚油酸分别比对照组高6.51%和229.42%,差异显著或极显著（P<0.05;P<0.01）;对照组背最长肌中亚油酸、硬脂酸含量均极显著高于试验组（P<0.01）;③对照组背最长肌中脯氨酸、甘氨酸、丙氨酸、精氨酸含量均高于试验组,差异显著（P<0.05）,其他氨基酸均无显著性差异（P>0.05）。由此可知,延边黄牛阉牛体脂肪沉积较好,不饱和脂肪酸含量高,尤其是油酸含量明显高于公牛,肉质及口感好,适合生产高档牛肉。     

Comparison Research on Nutrient Composition of Meet between Yanbian Yellow Bulls and Steers

In order to compare the nutrient composition of meet between Yanbian Yellow bulls and steers,16 healthy beef cattles from same breed group with similar age and body weight were chosen and randomly divided into two groups with 8 cattles per group.The experimental group was made up by steers and control group was bulls,all cattles were slaughtered after feed for 373 d.The results showed that:① At the early stage of experiment,the total protein,globulin,A/G,blood glucose,triglyceride,aspertate aminotransferase,alanine aminotransferase levels of the two groups had no significant difference (P>0.05),and albumin,high-density lipoprotein cholesterol, urea nitrogen and cholesterol of experimental group were extremely significantly or significantly higher than that of control group (P<0.01;P<0.05);At the end of the experiment,albumin,A/G and cholesterol of experimental group were significantly higher than the control group (P<0.05),and the triglycerides content was extremely significantly higher than control group (P<0.01);There was no significant difference in other indexes between the two groups (P>0.05);② The oleic acid content and C18:1 n9/C18:2 n6 in longissimus dorsi of experimental group were 6.51% and 229.42% higher than that in control group,the difference were significant or extremely significant (P<0.05;P<0.01),respectively.The linolic acid and octadecoic acid in control group were extremely significantly higher than that of experimental group (P<0.01);③The proportion of Pro,Gly,Ala and Arg in longissimus dorsi of control group were significant higher than that in experimental group (P<0.05),while other amino contents were no significant difference between two groups (P>0.05).In conclusion,the fat deposition,unsaturated fatty acid,especially oleic acid content in Yanbian Yellow steers were significantly higher than bull and it had good meat quality and good taste which was suitable for the production of high-grade beef.     

Comparison on the physico‐chemical and nutritional qualities of normal and abnormal colored fresh chicken liver

This study evaluated the differences of physico‐chemical and nutritional qualities between abnormal colored chicken livers (ANCCLs) and normal colored chicken livers (NCCLs) and the safety of the both livers. Compared with NCCLs, ANCCLs were lower in protein, water contents (P < 0.01), pH and pigment contents (P < 0.05). NCCLs contained higher polyunsaturated fatty acid (PUFA) and saturated fatty acids (SFA) (P < 0.05). The PUFA/SFA ratio of NCCLs was 0.453, higher (P < 0.05) than that of ANCCLs. The contents of alanine, valine, tyrosine, lysine and histidine in NCCLs were higher (P < 0.05) than in ANCCLs. The contents of K, Na, P, Cu, Fe and Se of NCCLs were higher (P < 0.05), but the Ca content was lower (P < 0.05). The content of the heavy metals (As, Hg, Pb and Cd) of the two types of livers complied with food safety requirements. Although NCCLs had higher nutritional value than ANCCLs, both livers were acceptable for human consumption.     

不同生境芦苇的营养成分分析

本文分析了分布在不同生境条件下的芦苇的营养成分，结果表明，（１）单位面积地上部生物量以沼泽芦苇为最高，沙丘芦苇次之，过渡带芦苇较低，盐化草甸芦苇最低；碳水化合物总量沙丘芦苇＞沼泽芦苇＞过渡带芦苇＞盐化草甸芦苇；粗蛋白含量由高到低顺序为：盐化草甸芦苇、沙丘芦苇、沼泽芦苇、过渡带芦苇。（２）４种生境芦苇的总氨基酸和游离氨基酸中均含有１８种天然氢基酸，其中１０种必需氨基酸含量因生境条件不同而备有差异。但总氨基酸及结构氨基酸中必需氨基酸含量均在１０％以上。由此得出，４种生境芦苇利用价值由高到低的顺序依次为：沙丘芦苇、沼泽芦苇、过渡带芦苇、盐化草甸芦苇。     

The Effect of Gender on Slaughtering Performance and Meat Quality in Sunite Sheep

The purpose of this experiment was to study the effect of gender on the slaughter performance and meat quality of Sunite sheep.Twelve 6-month-old Sunite rams and ewes at the same body condition were selected from the grazing herds of the Sunite Zuoqi Improvement Station Breeding Farm to determine their slaughter performance and meat quality.The slaughter test results showed that the bone quality and bone-meat ratio of the rams were significantly higher than that of the ewes (P<0.05),and the net meat quality and net meat rate of the ewes were significantly higher than that of the rams (P<0.05).The results of meat quality traits showed that the drip loss of ewes were significantly lower than that of rams (P<0.05),and the other indicators were not significantly different (P>0.05).The results of conventional nutrient composition of muscles showed that the intramuscular moisture content of the rams were significantly higher than that of the ewes (P<0.05),and the intramuscular fat content of the ewes were significantly higher than that of the rams (P<0.05),while the other indicators were not significantly different (P>0.05).The results of amino acid determination showed that the essential amino acid ratio in muscle of sunite ewes were significantly higher than that of rams (P<0.05),but there was no significant difference between the rams and ewes that formed the precursor amino acid content of meat flavor (P>0.05).Fatty acid measurement results showed that the saturated fatty acid ratio in the subcutaneous fat of rams was significantly lower than that of ewes (P<0.05).There was no significant difference in the ratio of saturated fatty acids in muscle fat and tail fat (P>0.05);The ratio of monounsaturated fatty acids in ewes tail fat was significantly higher than that of rams (P<0.05).The ratio of monounsaturated fatty acids in subcutaneous fat and intermuscular fat was not significantly different between rams and ewes (P>0.05).The ratio of polyunsaturated fatty acids in intermuscular fat of rams was significantly higher than that of ewes (P<0.05),and there was no significant difference in the content of polyunsaturated fatty acids in subcutaneous fat and tail fat (P>0.05).In summary,it showed that gender had a certain influence on the slaughter performance and meat quality of 6-month-old Sunite sheep.     

不同性别苏尼特羊屠宰性能与肉品质研究

本试验旨在研究性别对苏尼特羊屠宰性能和肉品质的影响。从苏尼特左旗改良站种羊场放牧群中选取体况相同、6月龄苏尼特羊24只（公母各半）,测定其屠宰性能和肉品质。屠宰试验结果显示,公羊骨重和骨肉比显著高于母羊（P<0.05）,母羊净肉重和净肉率则显著高于公羊（P<0.05）。肉质性状测定结果表明,苏尼特母羊的滴水损失显著低于苏尼特公羊（P<0.05）,其余指标则差异不显著（P>0.05）。肌肉常规营养成分结果表明,公羊肌内水分含量显著高于母羊（P<0.05）,母羊粗脂肪含量则显著高于公羊（P<0.05）,其他指标差异不显著（P>0.05）。氨基酸测定结果表明,苏尼特母羊肌肉必需氨基酸比率显著高于公羊（P<0.05）,形成肉品香味的前体氨基酸含量在公母羊间无显著差异（P>0.05）。不同部位脂肪酸含量测定结果表明,公羊皮下脂肪中饱和脂肪酸比率显著低于母羊（P<0.05）,肌内脂肪和尾脂中饱和脂肪酸比率公母羊差异不显著（P>0.05）;母羊尾脂中单不饱和脂肪酸比率显著高于公羊（P<0.05）,皮下脂肪和肌间脂肪中单不饱和脂肪酸比率在公母羊间差异不显著（P>0.05）;公羊肌内脂肪中多不饱和脂肪酸比率显著高于母羊（P<0.05）,而在皮下脂肪和尾脂中多不饱和脂肪酸含量在公母羊间差异不显著（P>0.05）。综上所述,性别对6月龄苏尼特羊屠宰性能和肉品质均有一定影响。     

能量水平对舍饲育肥牦牛肌肉理化指标和氨基酸、脂肪酸组成及含量的影响

本研究旨在探讨能量水平对舍饲育肥牦牛肌肉理化指标和氨基酸、脂肪酸组成及含量的影响。选取60头体况良好、平均体重为（192.66±3.64）kg的3周岁左右的舍饲育肥麦洼公牦牛,采用完全随机试验设计,每组20个重复,每个重复1头牦牛。饲喂粗蛋白质（CP）水平为14.81%,增重净能（net energy for gain,NE_g）分别为4.17（低能量组,LE）、4.48（中能量组,ME）、4.79 MJ/kg（高能量组,HE）的3种日粮。试验期共97 d,其中预试期7 d,正试期90 d。结果显示,各处理组牦牛肌肉的pH、熟肉率和滴水损失3个理化指标均无显著差异（P>0.05）;各处理组牦牛肌肉常规营养成分的水分、粗蛋白质、粗脂肪、钙和磷含量无显著差异（P>0.05）;除ME组牦牛肌肉中的脯氨酸（Pro）和组氨酸（His）含量显著高于其余两组外（P<0.05）,总氨基酸和其他种类的氨基酸含量差异不显著（P>0.05）;ME组单不饱和脂肪酸、多不饱和脂肪酸及总不饱和脂肪酸相对含量显著高于LE、HE组（P<0.05）,HE组总饱和脂肪酸显著高于LE、ME组（P<0.05）。对于各种类脂肪酸,ME组的C15：1 n-3、C16：1 n-2和C18：1 n-8 3种单不饱和脂肪酸含量均显著大于其余两组（P<0.05）;而HE组的C17：0含量则有显著高于其余两组的趋势。在本试验条件下,舍饲育肥牦牛日粮中适宜的NE_g水平为4.48 MJ/kg（日粮DM）,适宜日粮NE_g水平能提高牦牛肌肉中脂肪酸的含量。     

水貂、狐、貉胴体脂肪的高级脂肪酸测定

利用气象色谱仪对水貂、狐、貉胴体脂肪的脂肪酸组成进行测定,并通过不饱和脂肪酸所占比例和必需脂肪酸中亚油酸含量对其生物学价值进行了初步评定。     

Effects of Energy Level on Physical and Chemical Indicators,Composition and Content of Amino Acids and Fatty Acids in Muscle of House-fed Yaks

This experiment was conducted to investigate the effects of energy level on the physical and chemical indicators,the composition and content of amino acids and fatty acids in muscle of house-fed yaks.A complete randomized design was adopted in this study,and sixty healthy and 3-year-old Maiwa yaks with an average body weight of (192.66±3.64)kg were randomly divided into 3 groups with 20 replicates per group and 1 yak per replicate.Diets for all groups were of the same crude protein content (14.81%) and different net energy levels for gain (NE_g) with 4.17(LE),4.48(ME) and 4.79 MJ/kg (HE),respectively for 97 days (7-day pretrial period,and 90-day feeding trial).The results showed as follows:The level of energy had no effect on the value of pH,cooking yield,drip loss,moisture,crude protein (CP),crude fat (EE),calcium (Ca) and phosphorus (P) (P>0.05).Except for the content of proline and histidine in muscle of group ME were significantly higher than the other groups (P<0.05),the content of total amino acids and other kinds of amino acids had no significant difference (P>0.05).The content of monounsaturated fatty acids,polyunsaturated fatty acids and total unsaturated fatty acids in ME group were significantly higher than the LE and HE groups,and the content of total saturated fatty acids in HE group higher than the LE and ME groups.For all kinds of fatty acid,the content of C15:1 n-3,C16:1 n-2 and C18:1 n-8 three monounsaturated fatty acids in ME group significantly increased than the other two groups (P<0.05);And the content of C17:0 in HE group had a significat rise trend.In conclusion,we recommend 4.48 MJ/kg (DM basis) as a diet appropriate NE_g level for the barn feeding of fattening yak under this experimental condition,appropriate NE_g level of diet could improve the fatty acids content in muscle of the yaks.