Research note: Postnatal development of electrolyte transport in calf rumen as affected by weaning time.     

G Breves  R Zitnan  B Schr?der  C Winckler  H Hagemeister  K Failing  J Voigt 《Archives of Animal Nutrition》2002,56(5):371-377

In a previous study we found a positive correlation between early weaning in calves and morphological parameters which were indicative of ruminal development, i.e. the length and width of the papillae. The objective of the present study was to determine to what extent this observation could be reflected by modulations of absorptive and secretory functions of the rumen mucosa. For this purpose the short-circuit currents (Isc) as a measure of electrogenic net ion fluxes and the transepithelial conductances (G(T)) as a measure of the overall tissue permeability were measured in vitro applying the Ussing-chamber technique. Simultaneously, the unidirectional flux rates of sodium and chloride across rumen wall epithelia were determined in the absence of electrochemical gradients. Under these conditions, significant positive net flux rates (Jnet) clearly indicate active mechanisms for electrolyte absorption. For the experiments 12 male Holstein calves 7 d of age were assigned to three groups of 4 animals each: milk group (I, slaughtered after 6 weeks of age), late weaning group (II, slaughtered after 9 weeks of age) and early weaning group (II, weaned after 6 weeks of age and slaughtered after 9 weeks of age). Whereas G(T) values remained unaffected by different age and feeding, Isc values were significantly affected by early weaning but were not influenced by age. Irrespective of weaning time active absorption of Na+ tended to be higher by about 60% in 9 weeks old animals. Active absorption of chloride was significantly increased in milk fed 9 weeke old calves and this effect was further stimulated by early weaning. In conclusion, the data show an increasing active Na+ absorption with age in calf rumen that could not be influenced by early weaning. Similarly, active Cl- absorption was initially increased during postnatal development and this effect could be stimulated further by early weaning.  相似文献   

蚕沙中黄酮类化合物的提取工艺   总被引：2，自引：0，他引：2  

于善凯  金利娟  张英  沈凤明 《蚕桑通报》2001,32(2):20-22

采用L9(3^4)正交试验设计对浙江海宁蚕沙中黄酮类化合物的热回流提取工艺进行了优化，所得出最佳工艺条件为；乙醇浓度为30％，料液比1：30，提取时间3h。  相似文献   

装修与电气     

于祥礼  乔毅民 《林业科技情报》2002,34(1):78-78

本文着重地论述了由装修而引发的电气安全技术问题已到了不容忽视的程度。就此问题作 者提出了自己的观点及解决办法。  相似文献   

Announcement     

M. M. H. Sewell 《Veterinary research communications》1991,15(1):56-56

  相似文献   

新引进国外牧草品种比较试验     

余庆旺 《福建畜牧兽医》2002,24(2):5-5

为了适应我市奶业发展的需要，２０００年我们从国外新引进牧草品种４６个，第一批将９个冬季牧草品种在南平市大横现代农业科技园区引种园进行品种比较试验研究，现将这些品种试种、田间观察、考种测产及生产情况比较材料总结如下：１材料与方法１．１供试品种参试的牧草品种共有９个，即：白三叶（Trifoliumrepens）、紫花苜蓿（Medicagosativa）、多花甜皂角（Aeschynomenesp）、蒺藜草（Aesehynomenesp）、稷（Panicomcoloratum）、多花黑麦草（Loliumsp）、多年生黑麦草（Loliumperenne）、冬油菜（Kozepor）、春小黑麦（Narla）。…  相似文献   

面对WTO谈成都蚕业的发展出路     

干群  余惠岚 《蚕学通讯》2002,22(1):34-36

面对WTO，蚕业必须深化改革，加快体制改革和技术创新，从调整结构、区域化布局，探索桑地流转机制，扩大生产规模，加强生产基础，扶持龙头企业，扶持产业化，提质上档，提升蚕业内在竞争力，应对“入世”。成都蚕业的发展必须要顺应形势和战略转变，这既是蚕业生产今后的指导思想和发展方向，又是进一步地发展和振兴成都蚕业的战略重点和工作重点。本就成都蚕业发展历程、产业化现状、制约因素、发展方向、对策措施等提出一些粗浅的认识。  相似文献   

香菇“9101”菌株选育研究报告   总被引：2，自引：0，他引：2  

刘振钦  刘晓龙  李玉 《吉林农业大学学报》2002,24(2):18-22,41

1991－1998年从长白山采集的野生香菇子实体中，通过分离、筛选、生物学测定、出菇试验、品种对比试验等方法，选育出适合吉林省气候条件的香菇菌株－9101。“9101”属于低温型菌株，生育期约160d，有效积温3200℃，中晚熟种，出菇中心温度7－18℃，适合北方地区代料栽培，也可用于段木栽培。  相似文献   

Milk fever and subclinical hypocalcaemia--an evaluation of parameters on incidence risk, diagnosis, risk factors and biological effects as input for a decision support system for disease control.     

H Houe  S ?stergaard  T Thilsing-Hansen  R J J?rgensen  T Larsen  J T S?rensen  J F Agger  J Y Blom 《Acta veterinaria Scandinavica》2001,42(1):1-29

The present review analyses the documentation on incidence, diagnosis, risk factors and effects of milk fever and subclinical hypocalcaemia. It is hereby evaluated whether the existing documentation seems sufficient for further modelling in a decision support system for selection of a control strategy. Several studies have been carried out revealing an incidence of milk fever most often in the level of 5-10%. Few studies indicate that the incidence of subclinical hypocalcaemia is several times higher than milk fever. The diagnosis based on clinical or laboratory methods or based on presence of risk factors is outlined. The clinical symptoms of milk fever are highly specific and the disease level may thus be determined from recording of treatments. Diagnosis of subclinical hypocalcaemia needs to include laboratory examinations or it may be determined by multiplying the incidence of milk fever by a certain factor. From the documentation on risk factors, it is very complex to predict the incidence from the exposure level of the risk factors. Due to uncertainty, sensitivity analyses over a wide range of values for each parameter are needed. The documentation of cow characteristics, nutrition, environment and management as risk factors are described. Among cow characteristics, parity or age, body condition and production level were found to be important. Risk factors associated with nutrition included most importantly dietary cation-anion difference and calcium level whereas the importance of general feeding related factors like type of feed stuff and feeding level were less clear. Environment and management included season, climate, housing, pasturing, exercise, length of dry period and prepartum milking. Several of the parameters on environment and management were confounded among each other and therefore firm conclusions on the importance were difficult. The documentation of the effect of milk fever includes the downer cows, reproductive disorders, occurrence of other diseases and the effect on milk production, body weight and culling. The reproductive disorders included most importantly dystocia, uterine prolapse, retained placenta, metritis and repeat breeding, and occurrence of other diseases included ketosis, displaced abomasum and mastitis. The documentation was substantial and often quantifiable within certain limits. Overall it is concluded that the present documentation on milk fever concerning incidence, diagnosis, risk factors and effects seems sufficient for a systematic inclusion in a decision support system. A model on milk fever should take into consideration the variation in biological data and individual herd characteristics. The inclusion of subclinical hypocalcaemia would be more uncertain and probably should await further documentation on possibilities of determining the herd level incidence and also the effect of this condition on production.  相似文献   

为了“绿色”的承诺——浙江桐庐金鑫宾馆创建“绿色饭店”纪实     

余伟 《绿色中国(综合版)》2005,(9):78-78

随着全球生态的日益恶化，“绿色”便成了广大民众的呼唤与期待。1999年，浙江省旅游局开展了“创建绿色饭店”活动，并于2000年6月评出了浙江省第一批“绿色饭店”。从此时起，桐庐金鑫宾馆就把创建“绿色饭店”作为对社会和宾客的承诺，作为全体员工共同努力的目标。  相似文献   

Symmetry in running     

M H Raibert 《Science (New York, N.Y.)》1986,231(4743):1292-1294

Symmetry plays a key role in simplifying the control of legged robots and in giving them the ability to run and balance. The symmetries studied describe motion of the body and legs in terms of even and odd functions of time. A legged system running with these symmetries travels with a fixed forward speed and a stable upright posture. The symmetries used for controlling legged robots may help in elucidating the legged behavior of animals. Measurements of running in the cat and human show that the feet and body sometimes move as predicted by the even and odd symmetry functions.  相似文献