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21.
Characteristically the metabolism of microbial nitrogen (N) compounds in ruminants involves the degradation of dietary N and synthesis of microbial protein (MP), compounds including a small amount of peptides and free amino acids, which may account for 75–85% of total N and the remainder are nucleic acids (NA: DNA and RNA). Generally rumen microbes contain 10–25% NA‐N of the total N while 70–80% is in the form of RNA. This paper describes the degradation and synthesis of NA in the rumen and their fate in the lower digestive tracts. Their physiological and nutritional significance in different types of ruminant animals is also discussed. The research works on NA metabolism in ruminants has been mainly on metabolism of purines after rumen microbial digestion and absorption in the lower gut. Subsequently, the fate of absorbed purines has been intensively investigated to assess the extent of MP synthesis in the rumen. The method for predicting ruminal synthesized MP and subsequently digested MP has been proposed using urinary purine derivative (PD) excretion in sheep and cattle fed on ordinary feed. The latter approach has now been adopted for calculation of protein supply in some feeding standards, although there are still difficulties in predicting representative samples of rumen microbes, and also uncertainties in variations of non‐renal and endogenous purine losses.  相似文献   
22.
现行群体间遗传距离的度量方法都以等位基因频率的计算为依据,这些方法的缺点之一是在位点不多,多态笥不高时要求群体有较大的取样个体数目,另外,这些方法所建造的树素图不能反映群体是由混血引起还是由长期进化引起这一问题,针对这些问题,本文提出了以个体间蛋白质多位点基因型比较为基础的群体间遗传距离和群体内基因杂合度的度量方法,以十个主要中国黄牛群体的遗传关系分析为例,比较圆满的解决了上面几个问题。  相似文献   
23.

Background

Recurrent colic and unexplained weight loss despite good appetite and adequate feeding and management practices are common conditions in the horse. However, little information has been published on the systematic diagnostic evaluation, response to treatment, prognostic factors or outcome of either presentation. The aims of this study were to 1) identify possible prognostic indicators and 2) report the short- and long-term response to treatment with corticosteroid therapy of a variety of horses with a presumptive diagnosis of inflammatory bowel disease (IBD).Thirty-six horses with a history of recurrent colic and/or unexplained weight loss were screened with a detailed clinical, clinicopathological and diagnostic imaging examination. Twenty horses were subsequently selected that had findings consistent with inflammatory bowel disease based on the fulfilment of one or more of the following additional inclusion criteria: hypoproteinaemia, hypoalbuminaemia, malabsorption, an increased intestinal wall thickness on ultrasonographic examination or histopathological changes in rectal biopsy. These 20 horses were treated with a standardized larvicidal anthelmintic regime and a minimum of three weeks of corticosteroid therapy.

Results

The initial response to treatment was good in 75% (15/20) of horses, with a 3-year survival rate of 65% (13/20). The overall 3-year survival in horses that responded to initial treatment (12/15) was significantly higher (P = 0.031) than in those that did not respond to initial treatment (1/5). The peak xylose concentration was significantly (P = 0.048) higher in survivors (1.36 ± 0.44 mmol/L) than non-survivors (0.94 ± 0.36 mmol/L).

Conclusions

The overall prognosis for long-term survival in horses with a presumptive diagnosis of IBD appears to be fair to moderate, and the initial response to anthelmintic and corticosteroid therapy could be a useful prognostic indicator. The findings of the present study suggest that a low peak xylose concentration in absorption testing is associated with a less favourable prognosis, supporting the use of this test.  相似文献   
24.
The objectives of the present study were to quantify the amount of nucleic acids, to examine the nucleobase composition and to determine the digestibility of individual nucleobases in diets containing various products from bacterial biomass grown on natural gas, including autolytic and hydrolytic fractions, using mink (Mustela vison) as a model animal. The diets consisted of cod fillet (control), commercial basic BioProtein, and five experimentally produced autolytic and hydrolytic fractions of the bacterial protein meal as protein sources. Each diet was assigned to four adult male mink, housed individually in cages equipped for controlled feeding and quantitative collection of faeces. Faeces were collected for 4 days, and the individual nucleobases in diet and faeces were analysed by HPLC after hydrolysis using HClO(4). The content of nucleobases in the diets containing bacterial protein meal was 37% to 205% higher than in the control diet. The nucleobase-nitrogen in the control diet amounted to 4.3% of the total nitrogen content, whereas the experimental bacterial protein diets contained from 7.4% to 17.4% of the total N content in the form of nucleic acids. The various methods used to produce the bacterial protein fractions clearly affected both the amount of nucleic acids and the molar proportions of the individual nucleobases. The average digestibility of the nucleobases was 95%, and all the individual nucleobases were highly digestible. Uracil showed the highest digestibility (on average 96.8%), whereas thymine showed the lowest digestibility (on average 93.6%).  相似文献   
25.
26.
The Brucella mdh gene was successfully cloned and expressed in E. coli. The purified recombinant malate dehydrogenase protein (rMDH) was reactive to Brucella-positive bovine serum in the early stage, but not reactive in the middle or late stage, and was reactive to Brucella-positive mouse serum in the late stage, but not in the early or middle stage of infection. In addition, rMDH did not react with Brucella-negative bovine or mouse sera. These results suggest that rMDH has the potential for use as a specific antigen in serological diagnosis for early detection of bovine brucellosis.  相似文献   
27.
The experiment was conducted to discuss the difference of binding time of green fluorescent protein B.melitensis M5 (GFP-M5) and B.abortus S19 (GFP-S19) infecting the mouse macrophagocyte (RAW264.7),lysosome,endoplasmic reticulum and golgi body in the initial stage and compare the binding rate of GFP-M5,GFP-S19 with organelle in different timeline,respectively,by confocal laser scanning microscope (CLSM) and flow cytometry.The result showed that GFP-M5 and GFP-S19 were successfully constructed.The intracellular survival ability of Brucella M5,Brucella S19,GFP-M5 and GFP-S19 were not obvisouly affected after infecting RAW264.7.GFP-M5 and GFP-S19 could enter the macrophagocyte in 30 mins,and in 2 h the Brucella could reach lysosome,endoplasmic reticulum and golgi body.In addition,the binding time for two attenuated vaccine did not show differences in 1,2,3 and 4 h.The content of GFP+ cell produced by RAW264.7 infected by GFP-M5 and GFP-S19 did not show significant differences (P>0.05).Therefore,the two strains did not have significant differences in the invasion ability in the initial stage of infecting host cell.  相似文献   
28.
从北京两个主要牛场共采得187头中国荷斯坦奶牛的血样,提取基因组DNA,通过PCR-RFLP方法对Kappa酪蛋白、Beta乳球蛋白(βlg)和Alpha乳白蛋白(α-la)进行了基因型的鉴定,并结合产奶性状进行统计分析,结果表明,牛群中上述3种乳蛋白基因的基因频率分别为K-cnA79%,K-caB21%,β-lgA43%,β-lgB57%,α-lgB100%,K-CN和β-lg基因位眯对产奶量没  相似文献   
29.
乳酸菌代谢研究已进入一个新的时代,本文主要阐述目前乳酸菌在糖代谢、柠檬酸代谢及蛋白质代谢等方面的研究,以及基于下一代测序技术的基因组学、比较基因组学和宏基因组学等技术手段在乳酸菌代谢研究中的应用,旨在为现代乳酸菌代谢研究提供理论支持。  相似文献   
30.
水解蛋白婴儿配方奶粉的研究   总被引:1,自引:0,他引:1  
赵红霞 《乳业科学与技术》2011,34(3):112-113,117
本文介绍了婴儿对牛乳蛋白过敏的原因,并根据水解蛋白防过敏的特性生产加工了低过敏婴儿配方奶粉,通过研究分析发现其感官品质和营养成分与常规配方婴儿奶粉无明显差异。  相似文献   
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