维生素A在奶牛生产上的应用研究

本综述了维生素A与胡萝卜素的性质及相互关系，VA对奶牛血液生化指标的影响以及与营养物质的代谢，VA与免疫的关系，VA的缺乏症与防治等，提出了饲料中VA与β-胡萝卜素的建议添加量，对奶牛生产具有指导意义。     

维生素对奶牛繁殖力的影响

1VA对奶牛繁殖力的影响 VA与母牛的繁殖力和胎儿的生长发育密切相关。Michal等的研究表明，β-胡萝卜素可以降低胎衣不下和子宫炎的发病率，原因是其提高了临产前血液中β-胡萝卜素的浓度，增强了淋巴细胞和吞噬细胞的功能，进而提高宿主的抵抗能力，降低繁殖疾病的发生率。若日粮中缺乏VA，会导致母牛发生生殖器官炎症、隐性发情、发情期延长、延迟排卵或不排卵、黄体和卵泡囊肿、     

围产期饲喂β-胡萝卜素对奶牛生产性能的影响

本试验旨在研究围产期添加β-胡萝卜素对中国荷斯坦奶牛泌乳、繁殖性能的影响。选择胎次相同、产奶量、体重和体况评分值相近的中国荷斯坦奶牛36头,随机分为3组。3种处理日粮分别为:对照日粮、处理Ⅰ日粮(对照日粮 300mgβ-胡萝卜素/(头.天))、处理Ⅱ日粮(对照日粮 600mgβ-胡萝卜素/(头.天))。预试期15d,试验期120d。结果表明,在奶牛额外添加VA150000IU/d的情况下,每头奶牛添加β-胡萝卜素300或600mg/d,对前3个泌乳月的牛奶成分以及乳中体细胞数没有显著的影响(P>0.05)。但在产后3个月,对照组自然产奶量和标准乳逐月降低,而添加β-胡萝卜素组的自然产奶量和校正乳产量都有不同程度的提高。β-胡萝卜素的添加提高了血浆中β-胡萝卜素和VA的浓度(P>0.05);在产后8～12周,添加β-胡萝卜素300mg/d,显著提高了牛奶中β-胡萝卜素的含量(P<0.01)。在产后1～3月期间,奶牛额外添加VA150000IU/d同时添加β-胡萝卜素,降低了胎衣不下、子宫炎和乳房炎的发病率。在围产期β-胡萝卜素的添加提高了产奶量,提高了血浆中β-胡萝卜素和VA的浓度,提高了牛奶中β-胡萝卜素浓度,降低了胎衣不下、子宫炎和乳房炎的发病率。     

日粮V_A和油脂对肉鸡β-胡萝卜素-15及15'-加双氧酶活性的影响

通过饲养试验研究日粮VA和油脂对肉鸡β-胡萝卜素-15及15'-加双氧酶活性的影响。结果表明:无VA组的血清、肝脏VA水平低于对照组(P<0.01),小肠和肝脏βCDIOX活性显著高于对照组(P<0.05);硬脂酸组、豆油组肝脏VA水平低于对照组(P<0.01),豆油组的肠黏膜和肝脏βCDIOX活性高于对照组(P>0.05),硬脂酸组的肠黏膜βCDIOX活性低于对照组,肝脏βCDIOX活性高于对照组,但差异均不显著(P>0.05)。结果证实:日粮VA水平和油脂组成均不同程度的影响机体β-胡萝卜素-15及15'-加双氧酶活性,进而影响β-胡萝卜素的体内转化。     

日粮VA和油脂对肉鸡β-胡萝卜素-15及15'-加双氧酶活性的影响

通过饲养试验研究日粮VA和油脂对肉鸡β-胡萝卜素-15及15＇-加双氧酶活性的影响。结果表明：无VA组的血清、肝脏VA水平低于对照组（P〈0．01）,小肠和肝脏βCDIOX活性显著高于对照组（P〈0．05）;硬脂酸组、豆油组肝脏VA水平低于对照组（P〈0．01）,豆油组的肠黏膜和肝脏βCDIOX活性高于对照组（P〉0．05）,硬脂酸组的肠黏膜βCDIOX活性低于对照组,肝脏βCDIOX活性高于对照组,但差异均不显著（P〉0．05）。结果证实：日粮VA水平和油脂组成均不同程度的影响机体β-胡萝卜素-15及15’-加双氧酶活性,进而影响β-胡萝卜素的体内转化。     

补充不同量β-胡萝卜素和VA对兔生产和繁殖能力的影响

该试验旨在研究补充不同量β－胡萝卜素和VA对兔繁殖和生产能力的影响，从而为以后的兔业生产提供科学依据。１方法按照表１配方生产的半合成日粮，除了β－胡萝卜素和VA以外，都能满足生长兔的全部营养需要，以此作为基础日粮。加入β－胡萝卜素和VA补充成分，然后制成颗粒料作β－胡萝卜素和VA的分析。该试验用新西兰成年兔单独饲养，新生仔兔由母兔带养３周（哺乳期），在体重达到１kg左右时，互相分开，用于试验。公兔喂以商品兔饲料。全部兔均自由采食和饮水。２结果生长和繁殖（试验１）：２０只６周龄的母兔分为对照组和试验组，…     

类胡萝卜素β-隐黄质结构组成及生物功能概述

β-隐黄质具有抗氧化防御功能和细胞间通讯的功能,在生物体内β-隐黄质最重要的功能是合成VA的前体。在体外动物模型和人体研究中表明,来源于食物中的β-隐黄质,相比α-胡萝卜素和β-胡萝卜素,具有更好的生物利用率。近年来,国内外学者对β-胡萝卜素研究较多,而对β-隐黄质的相关报道较少。对类胡萝卜素β-隐黄质结构组成及生物功能进行了概述,旨在为全面了解类胡萝卜素提供参考。     

β-胡萝卜素在奶牛营养中的作用

过去人们一直认为β-胡萝卜素只具有VA原的作用。直到β-胡萝卜素的抗癌功能的发现,人们才开始关注β-胡萝卜素的其他功能。大量的体内外研究表明,β-胡萝卜素可以增强机体特异性和非特异性免疫反映,提高有丝分裂原刺激淋巴细胞的增殖反映,增加特异性淋巴细胞亚群的数目,刺激多     

维生素A胡萝卜素与牛的繁殖机能

维生素A(VA)是牛的必需维生素,对其繁殖机能有重要影响.日粮中缺维生素A或不足会导致公母牛的繁殖机能降低.本文将讨论VA对公母牛繁殖机能的影响及补充VA或胡萝卜素的作用.VA和胡萝卜素的代谢饲料中的胡萝卜素含有一个不能被取代的β-芷香酮环,在小肠粘膜细胞波β-胡萝卜素15,15′一加双氧酶裂解成为视黄醛,在小肠粘膜中再生成视黄醇,进入淋巴、肝和血液循环.研究指出,日粮中VA主要以棕榈酸酯形式存在,在小肠中被胰腺分泌的视黄基酯水解酶水解.VA几乎全部以游离醇形式吸收,在肠细胞粘膜中重新酯化,再结合成乳糜微粒进入淋巴系统.VA贮存在肝脏,并以     

山羊对β-胡萝卜素与叶黄素吸收的研究

通过山羊空肠瘘管进行灌注试验 ,并结合前腔静脉采血 ,研究山羊对类胡萝卜素(β-胡萝卜素与叶黄素)的吸收。试验发现 :随灌注时间延长 ,在同一浓度下山羊对类胡萝卜素的吸收量呈上升趋势 ,血清中叶黄素与 β-胡萝卜素浓度分别在灌注后2小时与2.5小时达到峰值 ,而VA的浓度仅略有降低 ;山羊对两种类胡萝卜素的吸收均呈浓度依赖性 ,但吸收率保持不变 ,血清中类胡萝卜素的浓度随其在灌注液中浓度的升高而升高 ,但VA的浓度随灌注液中β-胡萝卜素浓度的升高而基本保持稳定 ;游离脂肪酸促进了两种类胡萝卜素的吸收 ,提高了血清内 β-胡萝卜素与VA的浓度 ,降低了叶黄素的浓度     

Heartworm in dogs in Canada in 1984

In late December 1984, 1853 institutional veterinarians and small and mixed animal clinics across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1984 and 35% of them responded. Veterinarians reported that 97,794 dogs were blood-tested to check for microfilariae and 1417 dogs (1.45% of those tested) were found with heartworm. Another 34 dogs were amicrofilaremic, but were diagnosed as having heartworm disease, to give the total number diagnosed in 1984 as 1451 (1.48%). Heartworm was reported from all provinces except Prince Edward Island and Newfoundland but most (1310) of the cases were in Ontario. In Quebec, 126 cases were reported mostly from west of Montreal.

Heartworm was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 27% of the cases were observed with clinical signs of heartworm disease and 72% had a history of not having left Canada. Southwestern Ontario continued to be the primary focus of the infection.

     

Heartworm in dogs in Canada in 1983

In late December 1983, 2 800 veterinarians across Canada were sent a questionnaire in order to assess the status of heartworm disease in Canada in 1983 and 26% of them responded. Veterinarians reported that 59 504 dogs were blood-tested to check for microfilariae and 771 dogs (1.30% of those tested) were found with Dirofilaria immitis. Heartworm disease was diagnosed in all provinces except New Brunswick and Newfoundland but most (733) of the cases were in Ontario.

Heartworm disease was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 31% of the cases were observed with clinical signs of heartworm disease and 64% had a history of not having left Canada. Southwestern Ontario continues to be the focus of the infection and most of the dogs there had not left the province previously.

     

Heartworm in dogs in Canada in 1991

In late November 1991, 1883 clinics in Canada were sent a questionnaire to assess the status of Dirofilaria immitis in dogs in 1991 and there was a 60.0% response. There were 344,031 dogs tested for heart-worm (HW), 627 were found infected and the prevalence of HW infection was 0.18%. There were 417 dogs with HW in Ontario, 116 in Manitoba, 38 in Quebec, 53 in British Columbia, three in Alberta, and one in Nova Scotia. In British Columbia, all of the infected dogs but one were from the Okanagan valley which, as from 1991, is a new focus of infection in Canada. Most dogs with HW had not been on preventive medication in 1990, and the prevalence among dogs tested and unprotected was 0.59%. That prevalence was considerably higher in endemic areas. Companion dogs, over three years of age and maintained primarily outdoors in rural areas, were most frequently infected. One cat was diagnosed with D. immitis and 33 dogs had Dipetalonema reconditium.     

Heartworm in dogs in Canada in 1985

In late December 1985, 1485 institutional veterinarians and small and mixed animal clinics across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1985 and 44% of them responded. Veterinarians reported that 137,300 dogs were blood-tested to check for microfilariae and 1210 dogs were found with heartworm. Another 36 dogs were amicrofilaremic but diagnosed with heartworm disease to give the total number diagnosed in 1985 as 1247 (0.91%).

Heartworm was reported from all provinces except Prince Edward Island, Newfoundland and Saskatchewan but most (1126) of the cases were in Ontario. Southwestern Ontario continued to be the primary focus of the infection in Canada. From Quebec, 91 cases were reported mostly from and around Montreal. From Manitoba, 19 cases were reported from Winnipeg and surrounding areas. Heartworm was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 28% of the cases were observed with clinical signs of heartworm disease and 78% had a history of not having left Canada.

     

Heartworm in dogs in Canada in 1988

In late November 1988, 1581 small and mixed animal clinics and institutional veterinarians across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1988, and 46% of them responded. Veterinarians reported that 181,577 dogs were blood-tested for heartworm disease and 367 dogs were found with D. immitis microfilariae. Another 60 dogs were amicrofilaremic but diagnosed with heartworm disease to give the total number of cases diagnosed in 1988 as 441 (0.24%).     

Heartworm in dogs in Canada in 1989

In late November 1989, 1732 clinics and institutional veterinarians were sent a questionnaire to assess the status of Dirofilaria immitis, and 51.7% responded. Of 247,716 dogs tested, 394 had D. immitis microfilariae and 51 were amicrofilaremic for a total of 445 cases and heartworm prevalence of 0.17%. Most (408) of these dogs had no preventive medication and the prevalence among dogs tested and unprotected was 1.01%. That prevalence was considerably higher in endemic areas. Thirty-seven dogs with heartworm had preventive medication. Heartworm was most frequent in companion dogs over three years of age maintained outdoors in rural areas. About 75% of the cases had never left Canada, 26% had clinical signs and 125 were not treated.

Heartworm was reported from British Columbia, Manitoba, Ontario, Quebec, Nova Scotia and Newfoundland, but 383 cases were in Ontario. South-western Ontario was the primary focus of infection. There were 33 cases in Quebec and 24 in Manitoba, mainly found in and around Metropolitan Montreal and Winnipeg respectively.

     

Heartworm in dogs in Canada in 1987

In late November 1987, 1246 institutional veterinarians and small and mixed animal clinics across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1987, and 50% of them responded. Veterinarians reported that 165,428 dogs were blood tested for heartworm disease and 511 dogs were found with D. immitis microfilariae. Another 78 dogs were amicrofilaremic but diagnosed with heartworm disease to give the total number of cases diagnosed in 1987 as 589 (0.35%).     

Heartworm in dogs in Canada in 1986

In late December 1986, 1224 institutional veterinarians and small and mixed animal clinics across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1986; 46% of them responded. Veterinarians reported that 150,989 dogs were blood-tested for microfilariae and 869 dogs were found with heartworm. Another 65 dogs were amicrofilaremic but diagnosed with heartworm disease and one was found with heartworm at necropsy to give the total number diagnosed in 1986 as 935 (0.62%).

Heartworm was reported from Manitoba, New Brunswick, Ontario and Quebec, but most (810) of the cases were from Ontario. South-western Ontario continued to be the primary focus of the infection in Canada. There were 103 cases reported from Quebec, mostly from and around Montreal, and 21 cases from Manitoba, from Winnipeg and surrounding areas. Heartworm was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 33% of the cases were observed with clinical signs of heartworm disease and 81% had a history of not having left Canada.