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1.
双乙酸钠（Sodiumdiacetate,简称SDA）是乙酸钠的衍生物,为白色无毒晶体,属新型多功能饲料添加剂.SDA在畜牧生产上的应用已被证实,除具有高效饲料防霉、防腐、保鲜作用外,尚能调节胃肠中pH值,提高胃蛋白酶及消化酶的活性,促进有益微生物的增殖和生存,增强吸收和增加饲料的营养价值,提高饲料蛋白质的利用率,从而促进畜禽的生产性能和防治由病原微生物所致的畜禽疾患.在国外,研究SDA已有四五十年的历史;在国内,据黄玉德等研究表明,在鸡、猪、牛、鱼日粮中添加SDA可提高动物日增重和饲料转化率,改善肉质.而目前国内少有在肉鸭日粮中添加SDA的应用效果报道.为此,试验以肉鸭为研究对象,初步探讨SDA对肉鸭生产性能和经济效益的影响,以便为生产实践提供理论依据. 相似文献
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双乙酸钠,又称二乙酸一钠,简称SDA,是乙酸钠和乙酸的分子复合物,有乙酸气味。1979年美国食品和医药品管理局(FDA)曾对SDA作过严格彻底检查,其结论是,SDA是完全安全的,没有毒性,也没有致癌物质。1987年,联合国粮农组织(FAO)和世界卫生组织(WHO)批准SDA在食品中作防腐剂使用,并制定了SDA的质量标准 相似文献
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美国明尼苏达大学动物科学系S·D·Plegge等,研究了青贮低水分紫苜蓿和高水分玉米添加双乙酸钠(Sodium Diacetate,简写SDA)对发酵速率及发酵终产物组分的影响后得出结论,添加SDA可以改善保存(暴露)于空气中的这两类饲料的稳定性。 相似文献
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双乙酸钠（Sodium Diacetate，SDA）是一种高效的饲料防霉剂和营养型添加剂，分子式为CH3COONa·CH3COOH·xH2O。SDA通过在自然状态或动物机体内释放乙酸并通过乙酸的一系列理化性质和生物学特性达到为饲料防霉、提高饲料效率、改善动物机体内环境的目的。SDA作为一种高效、廉价、无毒的防霉剂和添加剂，在饲料领域中具有广阔的发展前景。 相似文献
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双乙酸钠的应用研究进展 总被引：1，自引：0，他引：1
双乙酸钠，简称SDA，分子式为NaH（CH3COO）2，无水物相对分子质量为142．09Da，白色吸湿性晶体。略有醋酸气味，易溶于水（1g/ml）和乙醇，150℃分解，熔点为96℃。1982年SDA被美国FDA承认并通过GRAS资格，同年美国联邦政府按人类直接食用的食品添加剂的产品类别为其颁发注册号。1987年联合国粮农组织（FAO）和世界卫生组织（WHO）批准SDA在食品中作防腐剂使用，并制定了SDA的质量标准（FAO/WHO，1987），现行1994版。1988年德国禁用丙酸及其盐作面包及食品的防腐剂。推荐用SDA作防腐抑菌剂。1989年我国正式批准SDA作为食品防腐剂使用，国家标准GB2760-89，1996年修订为GB2760-1996，是我国正式批准使用的26种食品、14种饲料的防霉防腐剂之一。 相似文献
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温度是影响变温动物种群行为的最主要的环境因子。在湿度大致恒定、光照相同的条件下,判定变温动物越冬机理是休眠还是滞育的手段,主要是进行温度处理。本试验即是通过温度对越冬桑螟幼虫的处理,经过试验观察与分析,初步得知:桑螟未代老熟幼虫以休眠状态越冬;在20～30℃的温区范围内,桑螟越冬幼虫均能解除休眠,正常生长发育,尤以25℃为最适发育温度。 相似文献
8.
蝎子既是名贵药材,又是美味佳肴,用途十分广泛.蝎子属于变温动物,随着气温的逐渐升高,由冬眠开始苏醒活动、生长和产仔.惊蛰到清明是蝎子的复苏期,正值蝎子的最佳养殖季节. 相似文献
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P E Hanna D H Percy F Paturzo P N Bhatt 《American journal of veterinary research》1984,45(10):2077-2083
Eight-week-old outbred male and female Crl:CD(SD)BR rats were treated with prednisolone (PR) or cyclophosphamide (CY) and were inoculated intranasally with sialodacryoadenitis (SDA) virus. The course of the disease was compared with nonimmunosuppressed, SDA virus-inoculated rats of the same stock. Criteria used to compare SDA in the 3 groups, included histologic changes in salivary and lacrimal glands, immunofluorescent microscopy of paraffin-embedded tissues, serum amylase levels, and antibody response. Based on these criteria, there was little detectable difference in the course and intensity of SDA in PR-treated and nonimmunosuppressed rats. In CY-treated rats, there was a delay in the onset of SDA, in the appearance of inflammatory cells in affected glands, and in the reparative process in the salivary and lacrimal glands. Viral antigen persisted longer in CY-treated rats than in PR-treated and nonimmunosuppressed rats. Antibody to SDA virus was not detected in CY-treated rats. The efficacy of immunosuppression by PR and CY was confirmed by the sheep erythrocyte agglutination procedure performed in selected rats. Male and female rats of the same strain were immunosuppressed beginning 4 weeks after inoculation with SDA virus to produce recrudescence of the disease. Histologic examination of salivary and lacrimal glands, immunofluorescent microscopy, serum amylase values, and viral isolation studies did not reveal evidence of reactivation of a persistent viral infection or viral shedding. Based on these studies, there is no evidence that SDA virus may persist as an inapparent infection after recovery from the disease. 相似文献
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A Kojima A Okaniwa 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》1991,53(6):1059-1063
Seventeen field isolates of sialodacryoadenitis (SDA) virus had been isolated from the lung of rats with clinical SDA during epizootics of SDA from 1976 to 1978 in the research laboratory. Based on their neutralization patterns against antisera to strains 681, 930-10, Lu-3, Lu-4 and Lu-7, these isolates were divided into 3 antigenic groups. The first group consisted of 8 isolates which were neutralized by 4 out of 5 antisera at high serum dilution. The second group consisted of 6 isolates which were neutralized by only 2 antisera at high serum dilution. The third group exhibited intermediate neutralization pattern and 3 isolates belonged to it. Considering the time course of virus isolation, it was concluded that three antigenically different SDA viruses had been spread irregularly and ocassionally two had been spread simultaneously in an animal house of rats during the several epizootics of SDA. 相似文献
13.
Eight- to 10-week-old outbred Wistar rats were inoculated intranasally with 10(2.9) medium mouse lethal infective doses of sialodacryoadenitis (SDA) virus. Sham inoculated control rats and challenged rats were killed at 1 day intervals for the first 8 days, then on days 10, 12, 14, and 20. Typical lesions associated with SDA were seen microscopically in the salivary and lacrimal glands of inoculated rats. In addition, laryngitis, tracheitis, bronchitis, bronchiolitis, and multifocal alveolitis were present during the acute stages of the disease. Viral antigen was demonstrated in epithelial cells lining airways by immunofluorescence microscopy. SDA virus was recovered from the lower respiratory tract from days 2 to 6 post-inoculation (PI). Serum antibodies to SDA virus, but not to Sendai virus or Mycoplasma pulmonis were present in rats tested at day 20 PI. These findings demonstrate that during the acute stages of the disease, significant lesions do occur in the lower respiratory tract of SDA virus-infected rats. 相似文献
14.
Dietary supplementation of stearidonic acid (SDA; 18:4n-3) has been considered a possible strategy to increase n-3 unsaturated fatty acid content in ruminant products; however, little is known about its metabolism in the rumen. In vitro batch incubations were carried out with bovine ruminal digesta to investigate the metabolism of SDA and its biohydrogenation products. Incubation mixtures (4.5 mL) that contained 0 (control), 0.25, 0.50, 0.75, 1.00, 1.25, or 1.50 mg of SDA supplemented to 33 mg (DM basis) of commercial total mixed ration based on corn silage, for dairy cows, were incubated for 72 h at 39°C. The content of most fatty acids in whole freeze-dried cultures was affected by SDA supplementation. Branched-chain fatty acids decreased linearly (P < 0.01), and odd-chain fatty acids decreased quadratically (P < 0.01), particularly from 1.00 mg of SDA and above, whereas most C18 fatty acids increased linearly or quadratically (P ≤ 0.04). Stearidonic acid concentrations at 72 h of incubation were very small (<0.6% of total fatty acids and ≤0.9% of added SDA) in all treatments. The apparent biohydrogenation of SDA was extensive, but it was not affected by SDA concentration (P > 0.05). Biohydrogenation followed a pattern similar to that of other C18 unsaturated fatty acids up to 1.00 mg of SDA. Stearic acid (18:0) and vaccenic acid (18:1 trans-11) were the major fatty acids formed, with the latter increasing 9-fold in the 1.00 mg of SDA treatment. At greater inclusion rates, 18:0 and 18:1 trans isomers decreased (P ≤ 0.03), accompanied by increases in unidentified 18:3 and 18:4 isomers (P = 0.02), suggesting that the biohydrogenation pathway was inhibited. The present results clearly indicate that SDA was metabolized extensively, with numerous 18:4 and 18:3 products formed en route to further conversion to 18:2, 18:1 isomers, and 18:0. 相似文献
15.
Depletion of salivary gland epidermal growth factor by sialodacryoadenitis virus infection in the Wistar rat 总被引：1，自引：0，他引：1
Male and female Wistar rats 2 to 15 months of age were inoculated intranasally with sialoda-cryoadenitis (SDA) virus and killed at 8 to 21 days post-inoculation (PI). Submandibular glands were evaluated by light and electron microscopy, and levels of salivary gland epidermal growth factor (EGF) were quantitated by cytochemistry and competitive radioreceptor assay. Apical granules in the epithelial cells of the granular convoluted tubules (GCT) were selectively depleted during the acute and convalescent stages of the disease. In addition, levels of immunoreactive EGF were reduced in affected submandibular glands, especially at 8 to 14 days PI with SDA virus, but some evidence of EGF depletion was seen at up to 3 weeks PI. A corresponding transient depletion of EGF receptor reactive salivary EGF was seen between 1 and 3 weeks after experimental SDA infection. These studies suggest that a clinical (or subclinical) infection with SDA virus could have significant effects on experimental studies on EGF-dependent functions, including reproductive physiology and carcinogenesis. 相似文献
16.
Mice with a severe combined immunodeficiency in B and T lymphocytes and natural killer cells (SCID-beige) were inoculated intranasally with sialodacryoadenitis (SDA) virus, a coronavirus of rats. Animals were killed at designated intervals and tissues were examined for evidence of viral infection by light microscopy and immunofluorescence microscopy. Based on these criteria, there was no evidence that these immunodeficient mice were susceptible to infection with SDA virus. 相似文献
17.
Coronavirus infections in the laboratory rat: degree of cross protection following immunization with a heterologous strain. 
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下载免费PDF全文 One hundred and twenty-one specific pathogen-free male Wistar rats eight to ten weeks of age were used to evaluate the efficacy of Parker's rat coronavirus (PRC) in affording cross protection on subsequent challenge with virulent sialodacryoadenitis (SDA) virus. Sixty-two animals were inoculated intranasally on day 0 and 21 days later with approximately 10(2) median tissue culture infective doses (TCID50) of the tenth passage of PRC replicated in L-2 cells. Animals were selected at random postvaccination to evaluate the safety and efficacy of PRC by histopathology, immunohistochemistry and serology. At three and six months postvaccination (PV), vaccinated and seronegative control rats were inoculated intranasally with approximately 10(3) TCID50 doses of virulent SDA virus. Challenged rats were then killed at 6, 10 and 14 days postchallenge and necropsied. Evaluations were based on lesion indices in lacrimal and salivary glands and respiratory tract, the presence of viral antigen by immunohistochemistry, and antibody response. Lesions were observed in rats killed PV, but in general, they were significantly reduced compared with those present in seronegative animals post-exposure to virulent SDA virus (p < or = 0.05). However, they were still considered to be an unacceptable level for a routine vaccination procedure. Potvaccination antibody titers to rat coronavirus were evident in all animals tested at three or six months prior to challenge with SDA virus.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
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Coronavirus infection in the laboratory rat: immunization trials using attenuated virus replicated in L-2 cells. 下载免费PDF全文
下载免费PDF全文 Sixty-nine specific pathogen-free male Wistar rats approximately eight weeks of age were used to evaluate the efficacy of an attentuated strain of sialodacryoadenitis (SDA) virus in providing protection against infection on subsequent challenge with virulent SDA virus. Fifty-four animals were inoculated intranasally with approximately 10(3.5) median cell culture infectious doses of the 25th passage of SDA virus in L-2 cells. Randomly-selected vaccinated animals were killed in order to evaluate the safety and efficacy of attenuated virus by histopathological examination of the salivary glands, lacrimal glands, and lower respiratory tract, and titration of sera for antibody to SDA virus. At three months and six months postvaccination (pv), animals were selected at random and challenged with virulent SDA virus. Seronegative, age-matched animals were also challenged, and served as controls. In animals examined at six to ten days pv, lesions were absent in submandibular and parotid salivary glands and lacrimal glands, but transient lesions were present in major airways of the lower respiratory tract. In a comparison of the incidence and extent of lesions, and antibody titers in challenged vaccinates and seronegative controls, lesions were minimal or absent in vaccinates compared to challenged naive rats, particularly in animals inoculated at three months pv. In addition, antibody titers in challenged vaccinates were much higher than were postinoculation titers in inoculated controls. In a comparison of lesions in salivary and lacrimal glands in vaccinated and control animals challenged at six months pv, there was a significant reduction in the number of animals without lesions in the vaccinated group (p = less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
19.
Sequential changes in the harderian and exorbital lacrimal glands in Wistar rats infected with sialodacryoadenitis virus 总被引：1，自引：0，他引：1
A sequential light and electron microscopic study of the exorbital and Harderian lacrimal glands was done on 2.5- to 15-month-old Wistar rats exposed to sialodacryoadenitis (SDA) virus. Typical coronaviral particles were readily demonstrated in cytoplasmic vesicles of Harderian and exorbital glands examined at 6 days post-inoculation. Lesions were seen in a relatively high percentage of lacrimal glands in infected animals of all ages, with no obvious age-related variations in the incidence and extent of changes. Lesions frequently persisted for a longer interval post-exposure in lacrimal glands than in salivary glands. The persistence of lesions commonly seen in Harderian glands was attributed, at least in part, to the cytotoxic effects of porphyrin-containing secretions released during the acute necrotizing stages of the disease. The persistence of lesions in some lacrimal glands indicates that they are useful tissues for microscopic examination for the retrospective provisional diagnosis of SDA. Persistent lesions also indicate that normal functions of these glands may be compromised for up to several weeks following outbreaks of SDA. 相似文献
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M Pal C Onda A Hasegawa 《Nippon juigaku zasshi. The Japanese journal of veterinary science》1990,52(6):1171-1174
Isolation of Cryptococcus neoformans was carried out on sunflower seed agar medium (SFA) and Sabouraud dextrose agar (SDA). Out of 346 environmental substrates (133 fruits, 107 avian extreta, 91 vegetables and 15 wooden scrapings) tested, 3 specimens were positive for C. neoformans. The positive isolations came from the fruits of 2 banana (Musa sapientum) and a potato tuber (Solnum tuberosum). The pathogen could not be demonstrated in 107 samples of avian droppings and 15 of wooden materials. All the 3 isolates of the yeast were obtained on SFA, while they were not cultured on the plates of SDA with chloramphenicol which were badly contaminated with rapidly growing molds, yeasts and bacteria. To the present author's knowledge, this appears to be the first reports of the isolation of this pathogenic basidiomycetous yeast from contaminated fruits of banana. We suggest more comprehensive ecological surveys to search for environmental niche of C. neoformans var. neoformans and C. neoformans var. gattii as the latter variety is also implicated in the etiology of cryptococcosis. 相似文献