营养学中氨基酸平衡的度量

本文基于聚类分析理论,提出了失衡度(IBD)这一新的化学指数,借以定量地研究蛋白质营养中的氨基酸平衡问题。当样品中氨基酸完全平衡时,IBD取值为零;而当其氨基酸平衡最差时。IBD取值为1。IBD的氨基酸增量模型为非对称最大值式;且IBD与变异系数(CV)之间有着密切的关系。通过IBD这一指数,可以对各种单一饲料的蛋白质营养价值加以分类列等;通过计算两种以上饲料蛋白质混合物的IBD,可以从理论上预测它们之间是否互补,以及何时发生最佳互补关系。若引申IBD的概念框架,还可以用来研究其它养分之间的平衡关系,并有助于实现计算机配方过程的自动鉴别和筛选。     

面对目前奶业形势,奶农、企业、政府应采取的对策--调整牛群结构、强化技术培训、建立股份合作体、加强乳业市场预测和监管力度是其今后工作的重点

1当前的奶业形势据统计．2004年全国奶牛存栏1063万头，比1998年增长了149％．年均增长16．4％；奶类总产量2368万吨．比1998年增长了217％，年均增长21．2％。乳品加工每年以30％的速度增长，加工能力已初具规模。但自2003年下半年以来．我国奶业进入低谷。     

警犬在治安防范中的优势

一、利用警犬灵敏的听觉和嗅觉来执行巡逻、守候、警戒等任务,往往能起到事半功倍的效果。犬的听觉、嗅觉灵敏性很高,超过人很多倍,常常在我们还没有觉察出原因的情况下表现出警觉或吠叫报警,当我们在100米处模模糊糊听到声音时,警犬却能在1500米的远处听到人类听不到的那种超频音,可见用犬来执行警戒、巡逻、守候等任务是一种行之有效的方法。     

湘西黄牛肉质特性研究

为研究我国南方优良地方品种湘西黄牛的肉质特性,选用8头湘西黄牛青年公牛,对肉质中的常规营养成分、氨基酸和脂肪酸进行了测定.结果表明:鲜肉中脂肪含量为4.80％,蛋白质含量为23.21％;饱和脂肪酸(SFA)含量为48.43％,不饱和脂肪酸含量(UFA)为41.00％,不饱和脂肪酸在总脂肪酸(TFA)的比例为45.85％...     

温度及预处理对苏丹草种子萌发的影响

本实验采用15～30℃和20～30℃2种变温,7℃、10℃、15℃和20℃4种恒温,以及0℃、5℃和10℃3种低温和硝酸钾预处理等技术,测定了苏丹草种子的萌发特性。结果表明:苏丹草种子室内最适萌发温度为20～30℃变温;预处理可破除种子休眠率达71.43～100％,并能提高幼苗的长度和简化活力指数,其中,以10℃低温预处理6天效果最好。建议苏丹草种了早春播种应以地温达15℃以上为宜。     

Ectoparasites are the major causes of various types of skin lesions in small ruminants in Ethiopia

Ectoparasites are the major causes of skin lesions in animals. Clinical, skin scraping examination, and histopathological studies were conducted to identify and characterize skin lesions in small ruminants caused by ectoparasites. Mange mites, lice, sheep keds, and ticks were collected from the skin of affected animals for species identification. Skin biopsies were collected from affected part of the skin and fixed in 10% neutral buffered formalin for histopathology. Of 1,000 sheep and 600 goats examined, 815 (81.50%) sheep and 327 (54.5%) goats were infested with one or more types of ectoparasites. Sarcoptes scabiei var ovis, Demodex ovis, Psoroptes ovis, Bovicola ovis, Melophagus ovinus, and Amblyomma variegatum and other tick species were identified from sheep. S. scabiei var caprae, Demodex caprae, Linognathus stenopsis, and A. variegatum and other tick species were identified from goats. Gross skin lesions or defects observed on the skin include stained and ragged wool, loss of wool/hair, nodules, crusts, lichenification, and fissuring. Microscopic evaluation of H and E stained skin sections revealed lesions in the epidermal layer such as hyperkeratosis, acanthosis, and melanin inconsistency on the basal cells of the epidermis. Follicular keratosis, perifolliculitis, frunculosis, perivasculitis, and aggregates of inflammatory cells (of acute and chronic type) with fibrosis were experiential in the dermal layer of the skin. Most of the skin lesions caused by ectoparasites are overlapping. Thus, ectoparasites control program should be executed to reduce skin lesions as skins are the major export commodity of the country.     

The effect of a single intramammary infusion of a biological response modifier in cows at drying off

Biological response modifiers (BRM) are compounds that interact with the immune system to regulate specific aspects of host response. The objective of this study was to describe clinical and morphological changes during involution of bovine mammary gland following a single-dose infusion of a BRM containing lipopolysaccharide and cellular fractions of Escherichia coli incorporated into liposomes. A massive leukocyte response and increased subepithelial stroma infiltration of mononuclear cells, eosinophils and mast cells was observed in BRM-treated quarters compared with untreated controls; however, morphologic parameters assessed at 11 days post infusion were indicative of only slightly accelerated involution compared with untreated controls. In addition, BRM infusion at the end of lactation did not interfere with mammary epithelial cell proliferation and caused only mild systemic effects.     

<Emphasis Type="Italic">Streptococcus uberis</Emphasis>-specific T cells are present in mammary gland secretions of cows and can be activated to kill <Emphasis Type="Italic">S. uberis</Emphasis>

The presence, phenotype and function of Streptococcus uberis-specific T cells in the mammary gland secretion (MGS) and blood of cows exposed to S. uberis were assessed. MGS T cells in the udder were purified and incubated with autologous blood monocytes as antigen-presenting cells (APC). Most cows, irrespective of prior S. uberis infection status and lactation status, were shown to have S. uberis-specific T cells both in MGS and in the blood. When cells from a subgroup of cows were studied, it was found that the S. uberis-specific T cells produced high levels of interferon-gamma (IFN-γ), but low levels of interleukin-10 (IL-10). A high percentage of responding T cells were of the CD8 ⁺ memory (CD45RO) subset. T cells from the MGS specific for S. uberis were propagated from animals during the drying off period and expanded in vitro using interleukin-2 (IL-2) and S. uberis antigens. This led to the accumulation of T cells of the CD8 ⁺ subset bearing memory cell markers (CD45A ⁻ , CD45RO ⁺ ), which released high levels of IFN-γ. Four of the five T cell lines derived from the MGS of three animals had substantial direct killing activity towards S. uberis in vitro. It is concluded that there is an emergence of S. uberis-specific bactericidal T cells in the MGS of cows after infection or environmental exposure to S. uberis. Vaccines aimed at activating and expanding this T cell population in the mammary glands of cattle may offer an avenue for the prevention of mastitis caused by S. uberis.     

Sero-prevalence and identification of <Emphasis Type="Italic">Ornithobacterium rhinotracheale</Emphasis> in broiler flocks in south-eastern Iran

Ornithobacterium rhinotracheale is a gram negative bacterial pathogen causing respiratory tract infections in poultry. Tracheal, lung and serum samples were obtained from 21 broiler flocks of 8 farms from a slaughterhouse located in south-eastern of Iran. Among 630 tracheal and lung samples from samples resulting from 315 chickens, 11 (3.5%) ORT isolates were identified using biochemical tests. The isolates originated from 9 (42.9%) flocks out of 4 farms. All of the isolates were recovered from tracheal swabs and showed an API 20NE identification biocode 0-2-2-0-0-0-4. Of the 420 serum samples examined by ELISA, 134 (31.9%) sera from 17 (81.0%) flocks were positive for ORT antibodies. These results indicate that ORT is present in most broiler flocks with respiratory disorders in southeast Iran.     

Pharmacokinetic studies of levofloxacin after oral administration in healthy and febrile cow calves

The present experiment was designed to study the pharmacokinetics of levofloxacin in six healthy cross bred female cow calves (4 to 6 months age) weighing between 40 to 80 kg. Plasma from blood was separated by centrifugation at 10,000 rpm. Quantitative estimation of levofloxacin was done by UV-VIS spectrophotometer at 286 nm. The mean maximum plasma concentration (Cp_max ) of levofloxacin in febrile calves (5.28?±?0.32 µg/ml) did not differ significantly as compared with healthy calves (4.50?±?0.22 µg/ml) after single dose (20 mg/kg) oral administration. The mean therapeutic plasma concentration ( Cp_ther ) of levofloxacin was maintained for longer period in febrile calves (10 h) as compared to healthy calves ( 8 h). The mean maximum urine concentration (Cu_max) in febrile (40.86?±?2.19 µg/ml) also did not differ significantly as compared with healthy calves (39.38?±?2.43 µg/ml). No significant difference in various pharmacokinetic parameters of plasma was observed in healthy calves ( β?=?0.23?±?0.01/h ; t1/2 β?=?3.00?±?0.17 h and MRT?=?4.66?±?0.14 h ) and febrile calves ( β?=?0.23?±?0.01/ h; t1/2 β?=?3.05?±?0.16 h and MRT?=?5.04?±?0.14 h ) . The mean value of β, and t ½ β calculated in urine also did not differ between healthy and febrile calves. However, the value of MRT(3.79?±?0.07 h) and Cl_B(1.65?±?0.09 ml/kg/min) calculated in urine of febrile calves significantly(p?B?=?2.09?±?0.13 ml/kg/min). Based on kinetic profile levofloxacin may be given orally at the dose rate of 1.49 mg/kg B.W.at 8 h intervals in febrile calves.