第二節(jié) 維生素代謝障礙疾病.ppt

1、Vitamins Deficiencies 維生素缺乏癥,Chapter two,維生素分類,脂溶性維生素（A、D、E、K） Diseases caused by deficiencies of fat-soluble vitamins; 水溶性維生素（B、C） Diseases caused by deficiencies of water-soluble vitamins;,一、 維生素A缺乏癥（Vitamin A Deficiency ） Hypovitaminosis-A,維生素A缺乏癥（Vitamin A Deficiency）,由于維生素A及胡蘿卜素缺乏或不足而導(dǎo)致的機(jī)體皮膚、黏膜

2、上皮角質(zhì)化、變性，生長發(fā)育受阻并以干眼病和夜盲癥為特征的疾病。 多見于犢牛、仔豬、幼禽，其他動(dòng)物也可發(fā)生，但馬極少見。多發(fā)生在冬、春青綠飼料缺乏的季節(jié)。,一、Concept,a disease caused by deficiency or insufficiency supply of Vitamin A and carotene胡蘿卜素; the syndrome綜合病癥is the characterized by derma皮膚and mucous membrane黏膜keratinization角質(zhì)化, denaturalization變性, stopping growthing,

3、xerophthalmia 眼球干燥癥and night blindness .,維生素A的分布,動(dòng)物本身不能合成維生素A， 必須從飼料中攝取， 動(dòng)物源性飼料-魚肝油、魚油：維生素A 植物性飼料-維生素A原可轉(zhuǎn)變?yōu)榫S生素A 青綠飼料（包括發(fā)酵的）：含量多 如青干草、胡蘿卜、南瓜、黃玉米 棉子、亞麻子、麥麩、米糠、粕餅-幾乎無,維生素A的生理功能,保持動(dòng)物正常生長發(fā)育； 維持正常視覺，特別是暗適應(yīng)能力； 維持上皮組織細(xì)胞的完整性； 維持骨的塑型和骨的精細(xì)結(jié)構(gòu)； 提高繁殖能力； 增強(qiáng)抗病能力；,（一）病因 維生素A性質(zhì)不穩(wěn)定，非常容易氧化失活； 如在飼料加工、貯存不當(dāng)、高溫處理、日曬 存放過久、陳

4、舊變質(zhì)時(shí)，損失很大 不同生理階段，對(duì)維生素A的需要量不同，如果在配制飼料時(shí)未能補(bǔ)充足夠的維生素A，就會(huì)發(fā)生缺乏； 飼料存放時(shí)間過長或飼料發(fā)霉，維生素A及前體破壞； 胃腸道、肝膽及熱性疾病影響維生素A的吸收和利用； 舍陰暗潮濕、通風(fēng)不良、缺乏運(yùn)動(dòng)、擁擠、光照不足； 日糧中蛋白質(zhì)、中性脂肪、維生素E、微量元素（鈷錳）缺乏及胃腸道酸度過大。,發(fā)病機(jī)制 維生素A可促進(jìn)粘多糖的合成，影響細(xì)胞的代謝，它可促進(jìn)水解酶的釋放。當(dāng)其缺乏時(shí)，易感染傳染病。發(fā)生干眼??；生殖機(jī)能的障礙。 維生素A是構(gòu)成視覺細(xì)胞內(nèi)感光物質(zhì)的成分。視紫紅質(zhì)是維生素A產(chǎn)生的順視黃醛與蛋白質(zhì)結(jié)合而成。當(dāng)維生素A缺乏時(shí)，出現(xiàn) “夜盲癥”。 維

5、生素A能維持成骨細(xì)胞的正常功能。缺乏時(shí)，導(dǎo)致骨的鈣化不全和畸形，種雞缺乏時(shí)蛋的孵化率降低。,（二）癥狀 維生素A缺乏癥的癥狀一般來說是漸進(jìn)性的。 由于黏膜表皮及腺體上皮變性、不全角化，繼發(fā)感染及神經(jīng)系統(tǒng)變性的結(jié)果。 夜盲（除豬外）。是早期癥狀之一，具有診斷意義。 早晨、傍晚或月夜中光線朦朧時(shí)，盲目前進(jìn)，行動(dòng)遲緩，碰撞障礙物。 出現(xiàn)神經(jīng)炎（除馬外）。 干眼病，是角膜增厚及云霧狀形成（犬和犢牛）。 其他動(dòng)物，先分泌漿液性分泌物-角膜軟化潰瘍羞明。,羊： 與牛相似，乏困無力，運(yùn)動(dòng)失調(diào)，頭頸部肌肉震顫，并呈陣縮性痙攣。病羊側(cè)臥，頭向后仰，但無疼痛反應(yīng)，瞳孔失去對(duì)光的反應(yīng)能力。,豬： 其特征為神經(jīng)癥狀，

6、早期見有頭彎向一側(cè)，步態(tài)搖晃，后軀不穩(wěn)或呈半麻痹狀。隨著病勢(shì)的發(fā)展，視覺和聽覺減弱并出現(xiàn)夜盲，也有干眼病和角膜軟化。妊娠母豬患病時(shí)可發(fā)生早產(chǎn)、早期胎兒被吸收和干尸化。,雞： 食欲不振，消瘦，羽毛松亂，爪、喙色淡，冠白而有皺褶，腿趾無力，甚至趾爪皺縮，步態(tài)不穩(wěn)或不能站立，往往用尾支地，產(chǎn)蛋減少及蛋的孵化率降低。,毛皮獸： 早期母狐、貂性周期紊亂，最早出現(xiàn)頭向后仰，外界輕微的刺激就可引起長時(shí)間的驚悸不安而回轉(zhuǎn)，常有腹瀉，糞呈水樣，混有大量黏液和血液。 狗： 除有視力障礙和神經(jīng)癥狀外，尚有骨骼變形和腹瀉且糞便帶血比較明顯。,病理變化 1.各種上皮角化脫落，胃、腸、腦、心、肝、血管等均有漿液性出血性變

7、化； 2.反芻獸皺胃黏膜有炎癥、水腫，并有透明牽縷樣黏液附著和彌散性出血、充血及上皮脫落； 3.腸系膜淋巴結(jié)切面多呈點(diǎn)狀出血，心外膜的冠狀血管亦有出血點(diǎn)，有時(shí)擴(kuò)散到主動(dòng)脈部，肝松軟而大，膽汁濃稠，肺的炎癥變化多在心葉。,診斷 根據(jù)飼料分析，出現(xiàn)眼病及視力障礙，上皮角化，神經(jīng)癥狀，胚胎畸形等臨床特征作為初步診斷。確診需參考病理變化特征，血漿和肝臟中維生素A及胡蘿卜素水平。,防治 平時(shí)要調(diào)制、保管好，防雨淋、曝曬和發(fā)霉變質(zhì)，豆類及餅渣不要生喂，要及時(shí)治療肝膽和慢性消化道病。 發(fā)病后在增喂胡蘿卜、青苜蓿、維生素A時(shí)，要加倍添加，增補(bǔ)動(dòng)物肝臟，也可內(nèi)服魚肝油、肌肉注射維生素A、D，與此同時(shí)也可增加復(fù)合

8、維生素的喂量。 對(duì)于急性病例治療，一般常用440IU/kg體重（133g/kg）的維生素A皮下注射效果較好；對(duì)于慢性病例，因不可能完全康復(fù)，應(yīng)盡早淘汰。,dry eye (干眼) ophthalmitis(眼炎，結(jié)膜炎) keratomalacia(角膜軟化癥) an infected corneal ulcer (角膜潰瘍) disorder presented with bilateral conjunctival xerosis,二、Etiology,an absolute deficiency of vitamin A or its precursor carotene in the

9、diet; the dietary supply of the vitamin or its precursor is adequate, but their digestion, absorption or metabolism is interfered.,Ruminants on pasture,during periods of drought, clinical vitamin A deficiency does not always occur; hepatic storage is usually good; the period of deprivation not suffi

10、ciently long for these stores to reach a critically low level.,三、Clinical findings,in general, similar syndromes in all species; some variations in tissue and organ response because of species differences.,Major clinical findings,night blindness;夜盲 Exophthalmia;眼球突出 changes in the skin;皮膚病變 body wei

11、ght;體重下降 reproductive efficiency;生產(chǎn)力下降 nervous system.神經(jīng)系統(tǒng)癥狀,1、Night blindness,this is an important diagnostic sign inability to see in dim light (twilight黎明or moonlit night) ; the earliest sign in the spicies In the pig, until plasma vitamin A levels are very low.,2、Xerophthalmia 眼球干燥癥,only in the

12、calf, with thickening and clouding of the cornea角膜; In other species, a thin , serous mucoid 黏液樣的discharge from eyes followed corneal角膜的keratinization角質(zhì)化, clouding, and sometimes ulceration潰瘍and photophobia畏光, 羞明 .,3、changes in the skin,in pig a rough粗糙的, dry coat with a shaggy毛發(fā)粗亂的appearance; 皮膚干燥，

13、被毛粗亂 seborrheic刺激泌脂的dermatitis皮炎(not specific) 溢脂性皮炎 splitting of the bristle豬鬃tips. 豬鬃頂部分叉,3、changes in the skin,in cattle Excessive keratinization;(poisoned with chlorinated 氯化naphthalenes衛(wèi)生球) 過度角化 Heavy deposits of 糠, 麩bran-like scales鱗; 像麩樣的鱗片大量沉積,4、Body Weight,inappetence;食欲不振 weakness;虛弱 stunt

14、ed阻礙 growth; emaciation;瘦弱,4、Body Weight,Sheep Maitain their body weight under extreme deficiency conditions; With very low plasma vitamin A levels.,5、reproductive efficiency,In the female abortion;流產(chǎn) birth of dead;死胎 weak young;弱胎 placentak retention.胎衣不下,5、reproductive efficiency,In the male Libid

15、o性欲is retained； but degeneration惡化of the germinative 有發(fā)育力的epithelium上皮細(xì)胞of the seminiferous tubules輸精管 reduction in the of motile normal spermatozo 精子,5、reproductive efficiency,In young rams, the testicles睪丸may be smaller,6、Nervous system,damage of nervous system include: paralysis of skeletal骨骼的mus

16、cles; 麻痹 Encephalopathy;腦病 Blineness.目盲,(1)、paralysis,abnormalities of gait(hindlegs firstly) stiffness堅(jiān)硬of the legs; initially with a stilted踩高蹺的gait步態(tài); Flaccidity;軟弱, 沒氣力 knuckling of the fetlocks球關(guān)節(jié); sagging of hindquarters;后肢下彎 complete limb paralysis.,(2)、Encephalopathy腦病,Convulsions(beef calve

17、s at 6-8m); Collapse(syncope昏厥); a陣攣的clonic-tonic convulsion; Death.,四、Congenital defects,in calves, congenital bindness Optic nerve construction; encephalopathy腦病.,四、Congenital defects,in piglets complete absence of the eyes(anophthamos無眼) small eyes(microphthalmos);小眼 degenerative changes in the l

18、ens晶狀體and retina視網(wǎng)膜;,四、Congenital defects,in pigs cleft palate上鄂 and harelip兔唇; accessory ears;附耳 malformed hindlegs; subcutaneous 皮下的cysts囊;,四、Congenital defects,In pig abnormally situated kidneys; cardiac心臟的defects; hydrocephalus腦積水. herniations 形成疝of the spinal cord; generalized edema水腫.,四、Congen

19、ital defects,In pig stillborn; 死產(chǎn)的 weak; unable to stand or may be quite active; weak pigs lie on their sides; Paddling搖搖晃晃 movements with their legs; squawk叫聲plaintively.,五、Clinical Pathology,plasma vitamin A; plasma retinol視黃醇;(16.5 g/dL) plasma carotene胡羅卜素; cattle,optimum:150 g/dL 9g/dL,clinical

20、 signs hepatic vitamin A; 60 g/g vitamin A-(2 g/g critical level) 4.0 g/g(carotene)-(0.5 g/g critical level) cerebrospinal fluid腦脊液.,1、Normal serum vitamin A,cattle, 25-60g/dL;(optimum levels:25 g/dL 8.89-18.05 g/dL, lost body weight; 4.87-8.88 g/dL, ataxia and blindness; Below 4.88 g/dL, convulsion

21、s and optic nerve constriction; 5 g/dL, clinical signs. pig, 23-29 g/dL (11.0 g/dL) ; Lamb,45.1 g/dL (6.8 g/dL),六、Confirmation of Diagnosis,toxicology:50g liver,500g(vit A(feed assay) histology組織學(xué): 甲醛formalin-fixed parotid腮腺salivary唾液gland(duct) rumen瘤胃, pituitary垂體, pancreas胰腺, brain cervical spina

22、l cord.頸部脊髓 Bouins-fixed eye(LM).,六、Confirmation of Diagnosis,green feed or vit A supplements are not being provided; In ruminants detection of papilledema視神經(jīng)乳頭水腫; night blindness; incoordination,paralysis,convulsions(pig); increase of CSF pressure(pig,calves); Vit A in plasma and liver. Response to

23、 treatment; Confirmation at necropsy驗(yàn)尸； Histological examination of parotid腮腺salevary唾液.,七、Treatment,Vitamin A; at dose rate equivalent to 10-20 t/d; as a rule,440IU/kg.BW. parenteral腸胃外的injection of an aqueous (oily solution) severe cases:rapid, complete; chronic cases;:irreversible; calves(convulsive):48h return to normal; cattle(blind):slaughtered,八、Control,dietaty requirement; supplementation method parenteral injection; oral vitamin A;,1、dietaty requirement,The minimum daily requirement:40IU/kg.BW During pregnancy, rapid gr