L-肉碱及其在猪营养与生产中的研究与应用

Ｌ－ 肉碱作为长链脂肪酸进行β－ 氧化的载体,在脂肪代谢中起重要作用。Ｌ－ 肉碱在猪营养与生产中的最新研究及应用进展包括：Ｌ－ 肉碱的生物学功能;动物体内Ｌ－ 肉碱的来源及体内合成与体外生产;Ｌ－ 肉碱的吸收与转运及代谢;Ｌ－ 肉碱的缺乏;猪生产中应用Ｌ－ 肉碱的效果及饲粮中的适宜添加量。     

L—肉碱对提高瘦肉率的作用

1　Ｌ—肉碱的结构和性质肉碱有两种旋光异构成:Ｄ—肉碱和Ｌ—肉碱,Ｌ—肉碱为天然成分存在于厌氧菌、植物和动物组织中,它具有生理活性;Ｄ—肉碱为合成物质,不存在于生物系统中,它对肉碱乙酰转移酶(ＣＡＴ)和肉碱脂肪酰转移酶(ＰＴＣ)有竞争性抑制作用,故一般所讲的肉碱...     

肉碱对高产期蛋鸡内脏器官的影响

选用 2 4周龄海兰褐壳蛋鸡分别饲喂添加不同肉碱浓度的日粮 ,试验期 7周 ,测定内脏器官重量 ,内脏器官中肉碱沉积量。试验表明随日粮肉碱浓度的增加 ( 0～ 75mg/kg) ,心脏、肝脏的重量显著下降(P <0 .0 5) ,肝脏、心脏和肾脏中肉碱沉积极显著增加 (P <0 .0 1 ) ,肝脏、心脏和肾脏是肉碱的主要沉积器官。     

饲料添加剂对野鲤生长、体形、体色和肉质的影响

以初始体重为(16.81±0.54)g的野鲤为试验对象,探讨饲料中添加一些添加剂对野鲤生长、体形、体色和肉质的影响。结果表明,添加螺旋藻组、肉碱组和联合添加组的平均增重率显著高于对照组、色素组和血球蛋白组(P<0.05),联合添加组的平均增重率显著高于其他各组(P<0.05)。添加螺旋藻组、肉碱组和联合添加组的脏体比显著低于对照组、色素组和血球蛋白组(P<0.05)。肉碱组和联合添加组的肝胰脏脂肪酸合成酶活性都显著高于色素组、血球蛋白组和对照组(P<0.05)。除肉碱组野鲤背皮中的类胡萝卜素与对照组差异不显著之外(P>0.05),其他各添加组都显著高于对照组(P<0.05),除肉碱组、色素组和血球蛋白组的尾鳍中的类胡萝卜素与对照组差异不显著外(P<0.05),螺旋藻组、联合添加组显著高于对照组(P<0.05)。联合添加组的野鲤的白肌胶原蛋白显著高于对照组(P>0.05)。螺旋藻组、肉碱组和联合添加组的呈味氨基酸总量显著高于对照组和其他各饲料添加组(P<0.05)。肉碱组和联合添加组显著提高了野鲤肌肉蛋白质的含量(P<0.05),肉碱组显著降低了野鲤肌肉脂肪的含量(P<0.05)。在本试验条件下,从经济性和适用性的角度综合来看,建议选择联合添加作为野鲤促生长、改善其体形、体色和肉质的饲料添加剂。     

左旋肉碱对生长肥育猪消化酶活力的影响

用分别添加0、50和100mg/kg 左旋肉碱 (L—肉碱 )的饲粮 ,饲喂“杜大长”三元猪。试验结束屠宰收集十二指肠内容物、血液和肝脏等样品。实验结果表明 :与对照组相比 ,50、100mg/kg肉碱处理提高或趋向于提高十二指肠内容物总蛋白酶、脂肪酶和淀粉酶活力 ,其中100mg/kg肉碱组显著提高总蛋白酶63.49 % (P<0.05)、淀粉酶活力285.85 % (P<0.05)、脂肪酶活力360.86 % (P<0.01)。肉碱处理刺激肝脏酮体生成 ,促进脂肪酸β-氧化利用 ;50mg/kg和100mg/kg肉碱处理使血清β-羟丁酸分别趋向升高 (P>0.05)和升高27.80 % (P<0.05) ;肝β-羟丁酸浓度提高9.80 % (P<0.05)和16.95 % (P<0.01)。结论 :肉碱处理促进脂肪酸氧化 ,用利于机体蛋白质沉积 ,增加消化酶的分泌 ,提高消化酶活力 ,改善生长肥育猪的消化性能。     

肉碱对冻融猪精子总抗氧化能力、抗氧化酶基因及凋亡相关基因表达的影响

试验旨在探究肉碱对冻融猪精子质量、抗氧化、抗凋亡及精卵结合能力的影响。试验分鲜精组和冻融组,冻融组的肉碱浓度分别为0、0.025、0.05、0.075 mg/mL,对冻融后的精子质量、总抗氧化能力、抗氧化酶相关基因及凋亡相关基因mRNA表达、精卵结合能力进行检测。结果显示,在冻融组中,经过肉碱处理的精子存活率、质膜完整率和顶体膜完整率均显著高于0 mg/mL处理组（P < 0.05）,其中肉碱浓度为0.05 mg/mL时改善效果最好;经过冻融处理的精子中丙二醛（MDA）浓度与鲜精组相比显著升高（P < 0.05）,其中肉碱浓度为0.05 mg/mL时显著低于其他肉碱处理组（P < 0.05）;与鲜精组相比,各冻融组精子总抗氧化能力均显著降低（P < 0.05）,肉碱浓度为0.05 mg/mL时总抗氧化能力最高。此外,与鲜精组相比,0 mg/mL肉碱处理组中凋亡相关基因Caspase-3与Bax的相对表达量显著升高（P < 0.05）,抗凋亡基因Bcl-2的相对表达量显著降低（P < 0.05）,抗氧化酶相关基因SOD2、CAT与GPx的相对表达量显著降低（P < 0.05）;冻融组精卵结合能力均下降,但肉碱浓度为0.05 mg/mL时可得到显著改善（P < 0.05）。结果表明,添加肉碱可以改善冻融猪精子的质量、抗氧化能力、抗凋亡能力及精卵结合能力。     

L-肉碱作为饲料添加剂的应用现状

<正>L-肉碱又称肉毒碱,维生素BT,是赖氨酸、蛋氨酸的衍生物,常以盐酸盐的形式存在,其化学结构和性质类似于胆碱。目前国内外对肉碱的研究和应用已相当广泛,如把肉碱作为机能性食品添加剂,     

L-肉碱对母猪繁殖性能的影响及其作用机理

L-肉碱的基本生物学功能在于参与长链脂肪酸在线粒体的转运过程,对于畜禽生长发育及肉质改善具有良好的作用。近年来,发现在妊娠和泌乳母猪日粮中添加L-肉碱还能改善母猪繁殖性能,主要表现为改善母猪自身体况及繁殖能力,促进胎儿的生长发育,增加仔猪的初生重及断奶重。母猪体况的改善可能与L-肉碱改变脂肪、蛋白质代谢有关;仔猪初生重的增加可能与肉碱影响胰岛素样生长因子系统(IGFs)促进胎盘生长,促进胎儿葡萄糖的氧化利用有关;而新生仔猪断奶重的提高则可能与仔猪吮乳习惯的改变和母猪泌乳量的增加有关。     

饲粮中添加DL-肉碱复合物和复合胆汁酸对斑点叉尾鮰生长性能的影响

本试验研究了在斑点叉尾鮰饲粮中添加DL-肉碱复合物和复合胆汁酸对其生长性能的影响.采用单因子三重复试验设计,以135尾平均体重(30.6±0.2)g的斑点叉尾鮰随机分为3组.对照组饲喂基础饲粮,DL-肉碱复合物组饲喂在基础饲粮中分别添加DL-肉碱复合物200 mg/kg的饲粮,DL肉碱复合物-复合胆汁酸组饲喂在基础饲粮中添加DL-肉碱复合物200 mg/kg+复合胆汁酸37.5 mg/kg的饲粮.试验期为8周.结果表明:与对照组相比,在饲粮中添加DL-肉碱复合物能够显著提高饲料效率17.28%(P<0.05),显著降低饲料系数15.43%(P<0.05),提高特定生长率12.50%;补充添加DL-肉碱复合物+复合胆汁酸后特定生长率和饲料转化效率较DL-肉碱复合物单独添加组分别降低4.27%和5.76%,差异不显著.     

基于两种液质联用技术研究西门塔尔种公牛精子活力与精浆肉碱的关系

旨在研究西门塔尔种公牛精子活力与精浆肉碱的关系。本研究共采集26份西门塔尔种公牛精液,根据精子活力进行分组,其中异常组12个样本,正常组14个样本。采用超高效液相色谱-四极杆-飞行时间质谱(UPLC-Q-TOF MS)技术对样品进行非靶测定,同时应用超高效液相色谱-三重四极杆-飞行时间质谱(UPLC-Q-Trap MS)技术进行广靶脂质测定,对于测定结果应用主成分分析(PCA)和正交偏最小二乘法-判别分析(OPLS-DA)进行统计分析。结果显示,异常组精浆代谢轮廓较正常组发生明显变化,将两种方法检测出的差异显著的肉碱进行分析,在精液活力异常组中,L-氯化棕榈酰肉碱、L-棕榈酰肉碱、硬脂酰肉碱、游离肉碱、乙酰肉碱、羟丁基-肉碱、3-羟基辛基肉碱、肉毒杆菌-肉碱、己烯基肉碱浓度显著高于活力正常组(P0.05)。这些肉碱浓度与西门塔尔种公牛精液活力呈负相关,为研究牛精液品质的判定提供新的方法和思路。     

Metabolic functions of L-carnitine and its effects as feed additive in horses. A review.

L-carnitine, a betaine derivative of beta-hydroxybutyrate, is found in virtually all cells of higher animals and also in some microorganisms and plants. In animals it is synthesized almost exclusively in the liver. Two essential amino acids, i.e., lysine and methionine serve as primary substrates for its biosynthesis. Also required for its synthesis are sufficient amounts of vitamin B6, nicotinic acids, vitamin C and folate. The first discovered ergogenic function of L-carnitine is the transfer of activated long-chain fatty acids across the inner mitochondrial membrane into the mitochondrial matrix. For this transfer acyl-CoA esters are transesterified to form acylcarnitine esters. Thus, in carnitine deficiency fat oxidation and energy production from fatty acids are markedly impaired. Skeletal muscles constitute the main reservoir of carnitine in the body and have a carnitine concentration at least 200 times higher than blood plasma. Uptake of carnitine by skeletal muscles takes place by an active transport mechanism which transports L-carnitine into muscles probably in the form of an exchange process with gamma-butyrobetain. In young animals including foals, the capacity for biosynthesis of carnitine is not yet fully developed and apparently cannot meet the requirements of sucking animals. Sucking animals depend therefore on an extra supply of carnitine which is usually provided with milk. Additionally, young animals including foals possess a lower concentration of carnitine in blood plasma than adult animals. Besides its role as carrier of activated acyl groups, L-carnitine functions as a buffer for acetyl groups which may be present in excess in different tissues during ketosis and hypoxic muscular activity. Other functions of L-carnitine are protection of membrane structures, stabilizing of a physiologic CoA-SH/acetyl-CoA ratio and reduction of lactate production. Animal's derived feeds are rich in L-carnitine whereas plants contain usually very little or no carnitine. Carnitine is absorbed from the small intestine by active and passive transport mechanisms. From the increase in renal excretion of L-carnitine after oral supplementations of 10 g/d to horses it has been concluded that the efficiency of absorption of L-carnitine is rather low (about 5 to 10% of the supplied dose). A further decrease in fractional carnitine absorption was observed when the oral dose of carnitine was increased. L-carnitine is virtually not degraded in the body and renal excretion of carnitine is comparatively small under normal conditions. The concentration of L-carnitine in blood plasma of horses varies markedly between animals and between different days. In addition, circadian changes in carnitine concentration in plasma have been reported. Peak concentrations were found during late afternoon, being up to 30% higher than those in the morning. In breeding mares the carnitine concentration in blood plasma declines with onset of lactation. In resting skeletal muscles about 90% of the total carnitine content is present as free carnitine with the remaining part being available as carnitine esters. With increasing exercise intensity a continuing greater proportion of free carnitine (up to 80%) is converted into carnitine esters, mainly into acetylcarnitine. This shift from free to acetylcarnitine is readily reversed within about 30 min after termination of exercise. It appears that acute exercise does not have a marked effect on the content of total carnitine in skeletal muscle whereas training seems to elevate its total concentration in the middle gluteal muscle of 3 to 6 year old horses and to reduce variation of its concentration compared to age-matched untrained horses. Oral supplementations of 5 to 50 g of L-carnitine per day to horses elevated the carnitine concentration in blood plasma to about twice its basal concentration. No clear relationship existed, however, between the orally administered dose of carnitine and the increase of L-carni     

Concentrations of L-carnitine and parameters of lipid metabolism during estrus in broodmares

In the present study the concentrations of L-carnitine (total carnitine, free carnitine, and acyl carnitine) and several parameters of the lipid metabolism were measured during the estrus in 10 broodmares. The carnitine concentrations varied in a wide range between the mares. The differences of the mean carnitine concentrations during the estrus did not reach the level of significance (P < 0.05). There was no relationship between the concentrations of total and free carnitine to the follicle size; however, the concentration of acyl carnitine was significantly correlated (r = -0.42). Because of the individual variations of carnitine concentrations, the non-significant differences of carnitine concentrations between the estrus days, and the weak relationship between the carnitine concentrations and the follicle size, it seems impossible to estimate the time of ovulation based on the carnitine concentration, as it was suggested in a previous study. The parameters of lipid metabolism did not show any significant changes during the estrus period.     

Effects of fish oil and conjugated linoleic acids on carnitine homeostasis in laying hens

1. The effects of n?3 polyunsaturated fatty acids (PUFA) and conjugated linoleic acids (CLA) on genes involved in carnitine homeostasis were compared in laying hens. Three groups of laying hens were fed on a control diet or a diet with either 3% of fish oil or CLA for 4 weeks.

2. Feed intake and egg production rate did not differ between the three groups. Diets with fish oil or CLA had only a weak effect on mRNA levels of PPARα target genes (ACO, CPT-I) in the liver and did not influence mRNA concentrations of the most important carnitine transporter OCTN2, enzymes of involved in carnitine synthesis (TMLD, TMABA-DH, BBD) or concentrations of carnitine in plasma, liver and total egg contents.

3. Hens fed the CLA diet had lower concentrations of free and total carnitine in egg yolk but higher concentrations of carnitine in albumen than control hens (P? 4. In conclusion, the study showed that feeding fish oil or CLA causes only a weak activation of PPARα in tissues of laying hens that probably explained the lack of effect on carnitine homeostasis. The results contrast with those in humans and mice that show a significant effect of synthetic PPARα agonists on carnitine homeostasis in humans and mice.     

Plasma, tissue, and urine carnitine concentrations in healthy adult cats and kittens

Mean carnitine concentrations [( carnitine]) were higher (P less than 0.05) in adult cats than in kittens for skeletal muscle (total and free carnitine), myocardium (free carnitine), and urine (total and free carnitine). The free/total carnitine ratio was lower (P less than 0.05) in kittens than in adults for liver, myocardium, and urine. Carnitine concentrations were similar between genders in kittens, but in adult cats, [carnitine] in plasma (total, free, and esterified carnitine) and liver (total and free carnitine) were higher (P less than 0.05) in female than in male cats. Total and free plasma [carnitine] were correlated to total and free liver [carnitine], respectively. Skeletal muscle [carnitine] was not correlated to plasma [carnitine]. Correlations in [carnitine] between plasma and myocardium, kidney, or urine were inconsistent.     

Concentrations of carnitine in the seminal fluid of normospermic, vasectomized, and castrated dogs

Concentrations of total carnitine (free and esterified) were determined in seminal fluids from 12 normospermic dogs before treatment and from the same 12 dogs after assignment to control, vasectomized, or castrated treatment groups (4 dogs each). Before treatment, the mean concentration (+/- SD) of carnitine in seminal fluid was 946 +/- 345 nmol/ml and was not significantly different (P greater than 0.05) among groups on any seminal collection day. After surgery, mean concentrations of carnitine in seminal fluid from vasectomized and castrated dogs were 49 +/- 9 and 14 +/- 5 nmol/ml, respectively and were lower (P less than 0.001) than the mean concentration in control (sexually intact) dogs. Dogs with obstructive azoospermia may be distinguished from those with aspermatogenesis (secretory azoospermia) by measuring seminal carnitine concentration. Seemingly, the epididymis is the major source of carnitine in canine seminal fluid, because the concentration of carnitine in prostatic fluid was only 58 +/- 53 nmol/ml, whereas the concentration of carnitine in 6 pools of epididymal fluid was 18.8 +/- 3.9 mumol/ml.     

Effects of L-carnitine on nitrogen retention and blood metabolites of growing steers and performance of finishing steers

Two experiments were conducted to evaluate L-carnitine supplementation to cattle fed grain-based diets. In Exp. 1, seven Angus-cross steers (216 kg) were used in a 7 x 4 incomplete Latin square experiment to evaluate the effects of supplemental L-carnitine on N balance and blood metabolites. Steers were fed a corn-based diet (17.5% CP) at 2.5% of BW. Treatments were 0, 0.25, 0.5, 1.0, 1.5, 2.0, and 3.0 g/d of supplemental carnitine. The 18-d periods included 13 d for adaptation and 5 d for collection of feces and urine. Blood was collected before feeding and 3 and 6 h after feeding on d 18 of each period. Dry matter intakes tended to be highest when 1.5 g/d of carnitine was supplied, but N retention was not affected by carnitine and averaged 29.3 g/d. Plasma carnitine concentrations and urinary excretion increased with increasing carnitine supply, indicating that at least some of the carnitine escaped ruminal degradation and was absorbed by the steers. Plasma concentrations of NEFA demonstrated a treatment x time interaction; they decreased linearly in response to carnitine before feeding but increased linearly in response to carnitine at 6 h after feeding. Serum insulin and plasma glucagon, IGF-I, cholesterol, triglyceride, and amino acids were not affected by carnitine. Plasma concentrations of glucose, glycerol, urea, and beta-hydroxybutyrate all were increased by some of the levels of carnitine supplementation, but results for these measurements did not follow easily described patterns and seemed to be related to differences in DMI. In Exp. 2, 95 crossbred steers (357 kg initial BW) were fed finishing diets (14.5% CP) for 129 d. Diets were based on steam-flaked corn and contained 6% alfalfa and 4% tallow. Feed intakes, gains, and feed efficiencies were not affected by supplementation with 2 g/d L-carnitine. However, steers receiving L-carnitine tended to have fatter carcasses, as indicated by tendencies (P < 0.2) for thicker backfat, higher marbling scores, and higher yield grades. In conclusion, carnitine supplementation did not alter lean deposition in growing steers but it did alter plasma NEFA concentrations of growing steers fed a corn-based diet and also seemed to increase fat deposition in finishing cattle.     

Effect of L‐carnitine on proliferative response and mRNA expression of some of its associated factors in splenic mononuclear cells of male broiler chicks

The effect of L‐carnitine supplementation on mitogen (concanavalin A, Con A) induced proliferation of mononuclear cells (MNC) in the spleen was investigated in broiler chickens at different ages. Day‐old chickens were fed a diet supplemented with or without L‐carnitine (100 ppm) for 24 days. The carnitine‐supplemented group showed greater proliferation of MNC in the spleen in response to Con A than that of the control group at 24 days of age. In addition, at 24 days of age the carnitine‐supplemented group showed higher expression of interleukin (IL)‐2 and interferon (IFN)‐γ mRNA, but lower expression of inducible nitric oxide synthase (iNOS) in the Con A‐stimulated splenic MNC than the control group. The enhancement effect of L‐carnitine on MNC proliferation and IL‐2 mRNA expression was not found in chicks at 14 days of age. Addition of L‐carnitine (50 nmol/mL) to the culture medium enhanced proliferation and IL‐2 mRNA expression of splenic MNC obtained from 24‐day‐old but not from 14‐day‐old broiler chickens. The results suggest that L‐carnitine is capable of enhancing MNC proliferation in broiler chickens at 24 days of age partly through increasing IL‐2 and IFN‐γ production and decreasing NO production.     

l-carnitine supplementation and lipid metabolism of rats fed a hyperlipidaemic diet

Until now, there has been no clear knowledge about the effect of dietary carnitine supplementation on lipid metabolism. Therefore, this study was conducted to investigate the effect of a dietary l -carnitine supplementation (500 mg/kg) onx the lipid metabolism of adult rats. Rats fed a hyperlipidaemic basal diet containing 15% lard and 1% cholesterol were used as an animal model. The feeding period was 6 weeks. As parameters of lipid metabolism, the concentrations of individual lipids in plasma, lipoproteins and liver and the fatty acid composition of liver and erythrocyte total lipids were determined. There were no significant differences between the control group and the group receiving the diet supplemented with carnitine on parameters of animal performance (daily body weight gains and feed conversion ratio). As expected, plasma, very low-density lipoproteins (VLDL) and liver exhibited high concentrations of cholesterol. Concentrations of triglycerides and phospholipids in plasma and individual lipoproteins as well as the concentrations of triglycerides, cholesterol and phospholipids in the liver were not significantly altered by dietary carnitine supplementation. The concentration of cholesterol in plasma and liver was increased by dietary carnitine. The fatty acid composition of liver and erythrocyte total lipids was not influenced by dietary carnitine supplementation. In conclusion, this study does not indicate a lipid-lowering effect of dietary carnitine supplementation in hyperlipidaemic rats. Probably, the essential functions of carnitine in metabolism were realized by carnitine which was synthesized endogenously.     

Assessment of plasma carnitine concentrations in relation to ceroid lipofuscinosis in Tibetan Terriers

OBJECTIVE: To determine whether the late onset form of inherited ceroid lipofuscinosis (CL) in Tibetan Terriers is accompanied by low plasma carnitine concentrations prior to the appearance of clinical signs. ANIMALS: 129 healthy Tibetan Terriers, 12 Tibetan Terriers with CL, and 95 healthy purebred dogs of other breeds. PROCEDURE: After withholding food, blood samples were collected from all dogs into tubes containing EDTA. Blood samples were analyzed for plasma-free carnitine and acyl-carnitines concentrations. RESULTS: Neither the mean plasma total carnitine concentration nor the mean fraction of carnitine in the free form differed significantly between Tibetan Terriers with CL and healthy Tibetan Terriers. Among Tibetan Terriers and the general dog population, plasma carnitine concentration increased with age. Castrated males had an overall increase in plasma carnitine concentrations and variability, compared with sexually intact males. By comparison, plasma carnitine concentrations were not significantly different between spayed and sexually intact females. The mean plasma carnitine concentration in the Tibetan Terriers was approximately 22% higher than in the general population of healthy dogs of other breeds. CONCLUSIONS AND CLINICAL RELEVANCE: Contrary to what is seen in early onset CL in English Setters and in humans with some forms of CL, plasma carnitine concentrations are not decreased in the late-onset disorder in Tibetan Terriers. Our large-scale study establishes reference range values for plasma carnitine concentrations in dogs as functions of age and sex that will be useful in evaluating potential carnitine deficiencies in other disorders in dogs.