微量元素缺乏对乳牛繁殖机能的影响

微量元素对动物机体的生命活动起着重大的作用。它调节蛋白质代谢、脂类代谢、醣类代谢和无机盐代谢,参与许多生理活动,直接影响酶的活性、维生素的活性和吸收率,它还决定机体新陈代谢的强度。许多科技人员研究表明,铜、锌、锰、钴和碘对动物机体的激素作用和内分泌腺的正常机能有影响。缺少一种尤其是缺乏多种微量元素,会导致内分泌系统活动系乱,激     

瘤胃保护性氨基酸(RPAA)产品及其饲用效果的影响因素

<正>反刍动物蛋白质营养的实质和核心是氨基酸营养。国内外大量的研究表明,赖氨酸(Lys)和蛋氨酸(Met)是泌乳奶牛饲喂玉米为基础日粮合成蛋白质时的第一或第二限制性必需氨基酸。在制作日粮配方时,尤其对高产动物需要较高的瘤胃非降解蛋白(RUP)日粮时,只能通过饲料蛋白质添加物来达到预期的代谢蛋白质(MP)中Lys和Met的含量。而添加结品型的Lys和Met没有效果,因为它们在瘤胃中迅速     

蛋氨酸对动物生长发育及毛发生长调控作用的研究进展

蛋氨酸(Met)是动物生长必需氨基酸中唯一含硫氨基酸,其可参与机体内众多代谢途径,为动物提供甲基,合成动物生长所需要的蛋白质和生物活性物质,是动物生长和毛发生长的第一限制性氨基酸。日粮中必须添加适量的蛋氨酸才能满足动物生长需要,对毛皮动物,蛋氨酸还会影响毛发的生长和品质,所以蛋氨酸又被称为"生命性氨基酸"。本文综述了蛋氨酸在动物生长发育及毛发生长中的调控作用,以期为蛋氨酸在畜牧生产中的科学应用提供参考。     

猪的肠道微生物与宿主营养代谢

肠道中栖息着数量庞大复杂多样的微生物菌群,肠道微生物在宿主健康中发挥着重要作用,既影响着饲料消化、营养物质吸收和能量供应,又调控着宿主正常生理功能及疾病的发生与发展.动物胃肠道不仅是消化器官,还是感应器官,肠道对营养物质的感应可以通过脑肠轴调节机体生理活动.肠道微生物还能代谢蛋白质产生宿主细胞不能合成的肽类物质,并通过小肠上皮的肽类转运系统影响机体代谢,因此可能存在微生物-肠道-大脑轴.肠道微生物还可以与机体形成宿主-微生物代谢轴,对动物机体营养物质代谢和免疫稳态起重要作用.饲粮对宿主代谢的改变,常伴随有肠道微生物区系的变化,肠道微生物的代谢可能通过微生物-肠道-大脑轴以及宿主-微生物代谢轴调节宿主很多生理过程,进而影响机体整体代谢.本文概述了猪肠道微生物区系与宿主肠道营养物质代谢的关系,以加深关于肠道微生物对机体代谢贡献的认识.     

微量元素锌在养殖生产中的应用

锌是动物体所必需的微量元素之一。在必需微量元素中,锌的功能最多,作用最广。它是多种酶和胰岛素的组成部分,不仅参与和影响体内的蛋白质、碳水化合物、脂类和维生素的代谢过程,而且与胰岛素、促肾上腺素等激素的分泌活动有关。动物如果缺锌,会引起机体代谢功能紊乱、平衡失调     

反刍动物蛋白质周转的调控

蛋白质是动物机体内各器官、组织的基本成分,也是实现生命功能的重要物质基础。保证动物体蛋白质的正常周转代谢,达到最大体蛋白的沉积,实现动物最佳的生产性能已成为反刍动物营养学的重要研究领域。文章从蛋白质周转代谢的过程、生物学意义、影响因素和周转调控等方面进行综述。     

蛋氨酸对动物表型性状的影响及DNA甲基化调控机制的研究进展

蛋氨酸(methionine,Met)是动物生长代谢过程中重要的甲基供体,同时作为必需氨基酸中唯一的含硫氨基酸,与赖氨酸一起为玉米—豆粕型日粮或微生物蛋白合成的第一或第二限制性氨基酸。另外,Met作为饲料添加剂对动物机体的生产性能、自身免疫力及疾病预防具有重要作用。随着营养表观遗传学在动物领域研究的不断发展,可实现以Met作为重要的营养素对动物进行表观遗传修饰(DNA甲基化、组蛋白修饰、染色质重塑及非编码RNA等)。DNA甲基化作为表观遗传修饰的方式之一,对于研究表型性状具有重要作用,是联系基因和表型间的纽带。文章介绍了DNA甲基化的作用机制及蛋氨酸代谢的调控机制,为今后正确理解Met与表观遗传学修饰之间的联系,进一步揭示表型性状的分子作用机制提供参考。通过基因组学进一步对Met如何在分子水平影响动物表型性状的改变进行展望与分析,也有助于掌握Met需要的个体差异,确定个体的营养需要量,实现真正的"基因饲养"模式。     

氨基酸需要量测定方法的研究

蛋白质是生命过程中的重要物质,是组成机体结构物质、体内代谢活性物质的主要成分,是组织更新、修补的原料.蛋白质对动物生命活动如此重要,一直以来科学家对蛋白质、氨基酸需要量的研究都给予了极大的关注.     

氨基酸需要量测定方法的研究

蛋白质是生命过程中的重要物质,是组成机体结构物质、体内代谢活性物质的主要成分,是组织更新、修补的原料.蛋白质对动物生命活动如此重要,一直以来科学家对蛋白质、氨基酸需要量的研究都给予了极大的关注.     

影响动物体蛋白周转的因素

蛋白质是生命活动的物质基础，是一切细胞和组织的重要组成部分。动物体内蛋白质代谢是一个动态过程，即动物合成机体组织新蛋白质的同时，原有的组织蛋白可被降解成氨基酸，降解形成的氨基酸又可用于合成组织蛋白，使组织蛋白不断更新更替。     

动物营养中胆碱同其它甲基供体间的关系

本文概述了胆碱、甜菜碱和蛋氨酸三种甲基供体的特性与共性;它们之间的代谢关系;饲养实践中的添加效应以及相互替代值。作者认为,日粮中必须含有一定数量的胆碱和蛋氨酸,分别用于合成磷脂和蛋白质。甜菜碱作为一种有效的甲基供体和抗应激剂,有明显的饲用效果。所谓甜菜碱替代蛋氨酸并非指生化途径可以替代,而只是反应在生产指标方面的相同或相近的效应,这种替代效应还受动物本身和日粮类型等因素的影响。     

Influence of abomasal infusion of high levels of lysine or methionine, or both, on ruminal fermentation, eating behavior, and performance of lactating dairy cows

Four multiparous late-lactation Holstein cows were fed a basal ration designed to be co-limiting in intestinally absorbable supplies of methionine and lysine. Cows were supplemented with no amino acids, lysine by abomasal infusion to 140% of the calculated intestinally absorbable requirement, methionine by abomasal infusion to 140% of requirement, or both amino acids in a 4 x 4 Latin square design with 28-d periods. Unsupplemented cows consumed 23.8 kg/d of dry matter and produced 36.9 kg/d of milk containing 3.70% fat, 3.22% protein, and 4.82% lactose. Cows ate less dry matter and produced less milk and milk lactose, and tended (P = .06 or .08) to produce less milk protein when abomasally infused with methionine alone or together with lysine. Infusion of lysine alone resulted in production values numerically between those of unsupplemented cows and those cows supplemented with methionine alone or together with lysine. Evaluation of the results with two metabolic models of dairy cows indicated that performance of unsupplemented cows may have been limited by delivery of metabolizable or digestible protein, or intestinally absorbable lysine, isoleucine, or histidine, depending on the metabolic model used to evaluate animal performance. Regardless, results are consistent with those using nonruminant species, which have shown that imbalanced profiles of intestinally absorbable amino acids are associated with reduced dry matter intake and animal performance. Results also show that negative effects on performance of lactating dairy cows can occur if methionine is supplied at levels substantially in excess of calculated intestinally absorbable requirements, either alone or together with lysine.     

Lipid coating as a mode of protecting free methionine from ruminal degradation

A method of protecting free methionine from partial ruminal degradation utilizing a lipid-protein matrix was developed. Eight wether lambs were fitted with abomasal cannulae and utilized in a 4 X 4 Latin square design experiment to determine the effectiveness of the protection matrix. The squares were blocked by animal and time, with each animal receiving each of the four diets. The diets were: (1) a negative control tall fescue and corn-based diet containing no added methionine; (2) a positive control diet that contained 3 g of methionine with ground corn, zein, coconut oil and methionine each added individually; (3) the control diet 1 supplemented with a methionine, ground corn, zein and coconut oil matrix that provided 3 g methionine/d; and (4) the control diet 1 containing the methionine matrix to provide 6 g methionine/d. Digestibility and balance data were obtained by collecting feces and urine over a 7-d period, followed by a day of blood sampling at 2, 4 and 6 h postfeeding. Abomasal samples were then subsequently collected over 3 d on a time schedule that represented every 2 h. Feeding protected methionine decreased (P less than .08) urinary N by .69 g/d and increased (P less than .08) N retention by 1.07 g/d. Plasma urea N was decreased (P less than .003) by 2.06 mg/100 ml and plasma free methionine increased (P less than .001) by 1.94 mumol/100 ml in lambs fed the protected methionine matrix. These data indicate that coating free methionine with the preparation described herein was partially effective in delivering methionine to the absorptive sites and subsequently to the tissues of the ruminant animal.     

胆碱降低动物脂肪沉积的营养作用机理

胆碱是动物生长发育所必需的维生素。饲料中添加胆碱可显著降低动物脂肪沉积。基于胆碱代谢和蛋氨酸代谢,本文从胆碱氧化、蛋氨酸再甲基化、脂肪酸氧化三者之间的联系探讨了胆碱降低动物脂肪沉积的营养作用机理。     

甜菜碱对动物生产性能的影响

甜菜碱(Betaine)作为甲基供体参与了体内蛋氨酸的循环,提高动物生产性能其作用主要通过节约部分Met实现。此外,甜菜碱也可通过影响动物体内激素水平而提高动物的生长性能。     

The effect of DL-methionine, N-hydroxymethyl-DL-methionine calcium salt (Mepron) and DL-methionine hydroxy analog calcium salt (MHA) on the N-deposits of calves

Digestibility and N balance experiments with calves showed that the methionine requirement of the host animal is covered by microbial protein synthesis even in the already ruminant animal. A supplement of the ration with DL methionine is only effective when it is provided in milk replacer. The MHA substitution of the ration has only little influence on N retention, independent of its supply in milk replacer or concentrated feed. MEPRON proved to be the most effective methionine derivative. As supplement both with the fluid feed and with the concentrated feed this compound shows exclusively positive results even in already ruminant calves with regard to live weight gain, N retention and the content of free methionine in the blood serum of the test animals.     

畜禽肌肉肌苷酸研究进展

文章综述了畜禽肌肉呈味物质肌苷酸的研究现状、呈味机理、代谢途径和影响因素,提出了现阶段肌苷酸研究过程中存在的问题并对未来的研究方向进行了展望,以期为目前动物营养工作者在畜禽风味品质方面的研究提供借鉴与参考。     

烟酸在反刍动物营养中的研究进展

烟酸与动物体内脂肪、蛋白质和碳水化合物代谢过程密切相关,对动物生产性能的充分发挥起着重要作用。作者综述了烟酸在反刍动物体内的吸收代谢、影响因素及其烟酸对瘤胃微生物、血液酮体及生产性能等方面的影响,以期为生产实践中科学合理的利用烟酸提供一定的理论依据。     

蛋氨酸及其羟基类似物的吸收和代谢

本文概述了蛋氨酸及其类似物的吸收、转运机制和代谢途径等方面内容,并结合实际分析了二者生物学效价存在较大争议的各方面原因,指出要解决分歧的关键在于更加深入地了解二者吸收和代谢的机制。