应激降低动物生产性能的机制

动物面临着各种应激.应激降低了动物血液中的酪氨酸浓度,而酪氨酸是合成甲状腺素的原料.甲状腺机能低下时减缓了胃肠道的蠕动,延长胃的排空时间,导致动物采食量的降低,降低了动物生产性能.本文综述了这个机制.     

肠道微生物与应激和免疫的关系

肠道粘膜屏障是机体抵抗外界环境对动物造成不利影响的第一道防线。各种应激因素均会不同程度造成机体肠道损伤,乳酸菌减少,防护能力降低,继而导致动物生产性能降低。应激造成肠道损伤进而造成大量内毒素入侵是各种应激因素造成危害的核心所在。在生产中合理使用乳酸菌可以减少应激,改善动物生产性能。     

反刍动物冷应激及智能监测研究进展

在低温寒冷环境下,反刍动物的冷应激时有发生,冷应激影响动物机体的多项指标与功能,在降低动物健康水平与动物福利的同时,还严重影响到养殖场的经济效益。随着反刍动物规模化健康养殖的快速发展,具有高效率、低人工优点的动物智能监测手段愈加成熟。本文结合国内外现有研究,综述了冷应激对反刍动物的影响以及对冷应激智能监测的研究进展,为保障恶劣环境下动物的健康福利,提高养殖场的经济效益,以及未来的反刍动物冷应激研究提供参考。     

关于动物应激综合征的发生和治疗

<正>应激是动物机体对体内外环境变化刺激时的一种适应性反应。当动物受到的应激刺激过强或者刺激时间过长,机体的新陈代谢反应不足以抵抗应激刺激时,机体就会出现不良反应,生产性能降低,甚至出现衰竭和死亡现象,给养殖场(户)造成很大的经济损失。因此,在畜牧生产实践中,应尽可能预防应激特别是严重应激的发生,以免损害动物福利,影响动物生产,降低经济效益。本文从应激的概念、发病机制、影响因素、临床及病理变化、治疗和     

冬春季节养猪如何降低应激

应激的动物比正常动物更容易发病,在寒冷的冬春季节,应激对猪呼吸道疾病的影响更为严重。猪舍通风、温度、湿度、饲养密度、猪只饮水等多种因素都会造成应激。那么,冬春季节养猪如何降低应激呢?     

家畜管理中的行为学探析

动物生产管理中降低应激将提高生产力并能阻止那些导致影响研究结果或降低生产力的生理变化的情况的发生．管理中的各种应激都将降低受胎率并减弱免疫和反刍功能．饲养场的管理者如果对动物行为学有了解就会减少应激。动物有比较宽的视野使它们容易受到阴影或外面过道移动物体的惊吓,因此在坡道的一侧建有固定物如围墙将减轻动物的兴奋。由于动物的听觉很敏感．故应使噪音保持最小。     

应激对动物生产性能影响学术研讨会在京郊延庆举行

2013年7月3日,北京海正兴潮生物技术有限公司在京郊延庆举办应激对动物生产性能影响学术研讨会,会上邀请中国农业大学乔健教授就应激对动物生产性能的影响做了深入而细致的讲解,来自山东、河南、湖北、山西、江西省的业务客户50多名参会代表出席了会议。乔健教授指出应激会使动物机体的功能态发生变化,对动物的生产性能产生很严重的影响。当机体的功能态发生改变时,60％的动物会发生胃溃疡,40％的动物会出现消化机能下降的现象,这就大大影响了动物的生长性能。另外当机体处于应激的状态时,血液会重新分布,内脏的血液会减少60％,机体的免疫力降低,很容易诱发各种疾病,所以说应激是万病之源。     

有效降低猪免疫应激反应的方法

免疫应激客观存在,严重时会给动物防疫工作造成阻碍。笔者通过实例阐述了猪免疫应激发生的原因及其机制,并在此基础上提出了有效降低免疫应激反应的措施。     

应激对圈养野生动物的影响及防治措施

<正>圈养野生动物生活在一个人为改造的环境中,它们只能被动适应这种环境,在这种环境中存在的应激源很多,几乎无处不在,如高温、寒冷、拥挤、噪音、吹管注射等,这些应激对动物的影响有些是非常严重的,可以造成动物精神紧张、内分泌失调、免疫力下降,诱发各种疾病,严重的还会造成动物死亡,给动物园造成巨大损失。试验对应激的机理进行研究,采取消除或减弱应激源、添加抗应激药物、提高动物抗应激能力等措施,避免或降低应激对动物造成的不利影     

免疫系统受抑制是否影响家禽的生长

许多因素可以影响动物在应激条件下的免疫反应。要降低现代家禽生产中的死亡率,应用有效的疫苗接种计划被认为是非常必要的。然而,免疫接种有时过于频繁且接种剂量过大。不恰当的免疫接种可能会导致动物免疫系统发生应激。多项研究表明,应激不仅会影响动物肠道的功能,也影响营养物质的吸收。     

Blood concentrations of amino acids, glucose and lactate during experimental swine dysentery

The aim of this study was to examine blood concentrations of amino acids, glucose and lactate in association with experimental swine dysentery. Ten pigs (approximately 23kg) were orally inoculated with Brachyspira hyodysenteriae. Eight animals developed muco-haemorrhagic diarrhoea with impaired general appearance, changes in white blood cell counts and increased levels of the acute phase protein Serum Amyolid A. Blood samples were taken before inoculation, during the incubation period, during clinical signs of dysentery and during recovery. Neither plasma glucose nor lactate concentrations changed during the course of swine dysentery, but the serum concentrations of gluconeogenic non-essential amino acids decreased during dysentery. This was mainly due to decreases in alanine, glutamine, serine and tyrosine. Lysine increased during dysentery and at the beginning of the recovery period, and leucine increased during recovery. Glutamine, alanine and tyrosine levels show negative correlations with the numbers of neutrophils and monocytes. In conclusion, swine dysentery altered the blood concentrations of amino acids, but not of glucose or lactate.     

Time course changes in blood metabolites during endotoxin fever in sheep.

Time course changes in the concentration of plasma amino acids, glucose, insulin, and creatinine were measured in seven mature sheep during fever induced by Escherichia coli (serotype 055:B5) endotoxin. Rectal temperature was increased above that recorded in control animals from 0.75 to 6.25 h postinjection with a maximum rise of 2.3 degrees C. Total amino acid concentrations decreased (P less than 0.05) 4.5 h postinjection and remained depressed (P less than 0.05) until 19 h postinjection. The plasma concentration of each individual amino acid decreased (P less than 0.05) at some point during the experiment with the exception of tryptophan and tyrosine. Glucose concentration decreased (P less than 0.05) and remained depressed until at least 55 h postinjection. Plasma insulin concentration was elevated (P less than 0.05) from 4.5 to 13 h postinjection. Plasma creatinine concentration increased during fever (P less than 0.05) and returned to normal by 31 h postinjection.     

Changes in amino acid levels in bacteria adhering to rumen epithelium in sheep after oral administration of very low doses of mercury

The effect of low concentrations of mercury taken in the diet (4 mg per a head and day) on the amino acid composition in the proteins of rumen bacteria adhering to the dorsal and ventral parts of the rumen was studied in six sheep. Though the mercury did not influence the amino acid concentration in hydrolyzates of epimural bacteria, low-mercury doses caused significant changes of some amino acids, as compared with the control group of animals. The levels of alanine, histidine, threonine, serine and glycine were significantly decreased and at the same time the levels of proline, valine, isoleucine, tyrosine, lysine and phenylalanine were significantly increased. It was stated in our experiment that the levels of histidine, alanine and threonine in hydrolyzates of epimural bacteria of the rumen were significantly decreased both in the sheep given the balanced feed ration with additions of mercury and nitrogen (according to the standard) and in the sheep given a low-nitrogen diet. Similarly, the levels of proline, tyrosine and phenylalanine in the hydrolizates of epimural bacteria in rumen were significantly increased both with the low-nitrogen diet and in the normal -nitrogen diet with mercury supplement. The results suggest that unexplained disorders frequently occurring in the microbial synthesis in the rumen might be caused by long-continued administration of feed contaminated with extremely low concentrations of heavy metals. The problem deserves detailed investigation in future studies, oriented to explaining the biosynthesis disorders in rumen, reducing the production ability of ruminants.     

真丝绸泛黄机理研究

本试验在模拟日光照射下,研究了真丝绸的泛黄机理。结果表明,泛黄真丝绸的黄度指数与氙灯照射时间之间是乘幂函数关系,泛黄真丝绸中的色氨酸、组氨酸及酪氨酸的损失百分率最大。其中色氨酸与酪氨酸是引起真丝绸泛黄的关键氨基酸;泛黄真丝绸的黄度指数增值与色氨酸损失率、酪氨酸损失率之间均呈线性关系,并分别求得了它们的线性方程式。     

The effect of straw meal on the crude protein and amino acid metabolism and the digestibility of crude nutrients in broiler breeding hens. 3. Digestibility of amino acids

In two experiments with colostomized broiler hens the influence of a straw meal supplement on the apparent digestibility of the amino acids of the ration and the 15N labelled basic amino acids in wheat was studied. In experiment 1 the animals received 120 g mixed feed plus 0, 20, 30 and 40 g straw meal per animal and day. The digestibility of the amino acids decreased on average from 86% to 83%, 80% and 79% with the growing straw intake. In contrast to the control variant, 20 g straw meal intake resulted in a significant decrease of digestibility for lysine, histidine, glycine, tyrosine, phenylalanine, cystine and methionine. 30 and 40 g straw meal reduced significantly the digestibility of all amino acids with the exception of arginine. The amino acid composition of the crude protein in faeces changed only very slightly due to the straw supplement. In experiment 2 15N labelled wheat was a component of the ration. Of the 15N labelled amino acids lysine, histidine and arginine, 88, 90 and 95% were apparently digested. The adaptation of the animals to straw meal intake did not change the digestibility of the amino acids.     

Effect of low levels of dietary tyrosine on the hair colour of cats

Experiments were conducted to investigate the basis for the change in hair colour of black cats to reddish-brown. Black cats were given purified diets based on gelatin, casein plus lactalbumin, or crystalline amino acids as protein sources. Diets that caused the colour of hair to change to reddish-brown were associated with a reduction in melanin in hair (observed by direct microscopic examination), a decreased total melanin concentration and low concentrations of tyrosine in plasma. Reddish hair coat was induced in black kittens born to queens given a tyrosine-deficient diet during pregnancy. Black hair colour was maintained or restored by diets containing a high concentration of tyrosine or phenylalanine. Current dietary recommendations for dietary tyrosine and phenylalanine for cats are below those required to support maximal melanin synthesis in black cats. The requirement appears to be greater than a combination of 4.5 g tyrosine plus 12 g phenylalanine/kg diet but less than 24 g phenylalanine alone/kg diet.     

利血平对化脓隐秘杆菌大环内酯类外排基因mefA表达的影响

化脓隐秘杆菌(Trueperella pyogenes,T.pyogenes)是一种能够引起动物和人化脓性感染的重要病原菌.随着抗生素的广泛使用,该菌已对临床常用的大环内酯类、四环素类等药物产生不同程度的耐药性.本试验拟探讨外排泵抑制剂利血平对T.pyogenes大环内酯类外排基因mefA mRNA及蛋白表达的影响,将...     

Influence of Heat Stress on the Cortisol and Oxidant‐Antioxidants Balance During Oestrous Phase in Buffalo‐Cows (Bubalus bubalis): Thermo‐protective Role of Antioxidant Treatment

In the present study, the effect of heat stress, which is commonly observed in the animals of Upper Egypt area in summer, as well as the effect of antioxidant treatment as a thermo‐protective was examined. In this study, the animals (n = 120) were divided into winter group (n = 40, bred during winter) and summer group (n = 80, bred during summer) as well as, animals in the summer group were divided into first subgroup animals (n = 40) and injected with Viteselen intramuscularly (15 ml) twice weekly for 10 weeks and second subgroup animals (n = 40) were not treated (as control). Serum levels of progesterone (P4), oestradiol (E2), cortisol, superoxide dismutase (SOD), lipid peroxidase (LPO) and nitric oxide (NO) were measured. The pregnancy rate of all animals was detected rectally. The levels of oestradiol and the activity of the antioxidant SOD were decreased in serum of animals in behavioural oestrus during summer as compared with those in winter. During the same time period the levels of oxidants such as LPO and NO were increased in the serum of animals again in the phase of oestrus. In another group of animals treated by intramuscular injection with 15 ml viteselen (antioxidant) twice weekly for 6 weeks during hot months, the activities of serum SOD showed an increase and the levels of oxidants and cortisol decreased. Moreover, the levels of oestradiol were increased during the oestrous behaviour. The pregnancy rate was decreased in animals under heat stress and the pregnancy rate was enhanced dramatically when these animals received antioxidants during the heat stress. This means that the heat‐stress in Upper Egypt may affect the fertility of animals and pregnancy rate and this effect may be through an increased production of free radicals and decreased production of antioxidants as well as increased levels of cortisol. Treatment of animals or supplementation with antioxidants before the beginning of months of heat‐stress and also during the stress period may correct the infertility due to heat‐stress through the decrease in cortisol secretion and a decrease in the oxidative stress. These results resulted in an increase in pregnancy rate in treated animals.     

The "effects" of Rev-1 vaccination of sheep and goats on human brucellosis in Greece

Vaccination of young animals (3-6-month-old sheep and goats) with Rev-1 vaccine for 15 years in Greece, importantly decreased the abortions in sheep and goats as well as the incidence of brucellosis in humans. After the stop of vaccination in 1994, all over Greece, the prevalence of brucellosis in animals and the incidence in humans quickly increased. It was a positive rank correlation (0.90) among these variables. Once an emergency mass-vaccination programme of young and adult animals with Rev-1 vaccine was started in 1998, the human incidence again decreased. The association of the vaccination coverage of animals and incidence of brucellosis in humans was not linear; the decrease in human brucellosis incidence was observed when the vaccination coverage of animals was >30%.     

Serum neopterin levels in female dogs with malignant mammary tumours

In this study, we have determined serum neopterin levels in female dogs with primary malignant mammary tumours. The study involved 50 female dogs which had a malignant mammary tumours removed surgically (32 animals with carcinoma, 12 animals with sarcoma and 6 animals with carcinosarcoma) and 10 clinically healthy female dogs. Serum neopterin levels were determined using a commercial ELISA kit. The mean neopterin levels were lower in the malignant tumour groups than in healthy animals but differences were statistically significant only in carcinoma and sarcoma groups. The decrease of neopterin levels in animals with malignant mammary tumours may suggest their decreased cellular immunity. Moreover, it might indicate that decreased activity of cellular mechanisms of the anti‐neoplastic response is one of the factors associated with the development and course of malignant mammary tumours in female dogs; however, further studies are necessary.