The effect of citric acid on the availability of tetracyclines in calves

The effect of citric acid on the availability of tetracyclines was studied in calves. Citric acid did not significantly increase the serum levels of tetracyclines when calves were fed low doses (6-8 mg/kg) of oxytetracycline and chlortetracycline. When the dose of chlortetracycline was increased to 50 mg/kg, addition of citric acid caused higher serum levels the first two hours after feeding. The ratio citric acid: tetracyclines was 5:1 and 25:1. The palatability of the milk replacer was reduced when large amounts of citric acid was added.     

Breed differences on the plasma availability of moxidectin administered pour-on to calves

The pharmacokinetic profile of avermectin and milbemycin compounds is affected by different drug- and host-related factors. This work reports the influence of cattle breeds on the plasma kinetics of moxidectin (MXD) after topical (pour-on) administration. Parasite-free Aberdeen Angus and Holstein calves were treated with a commercial MXD pour-on formulation at 500 microg/kg. Blood samples were collected over a period of 35 days post-treatment and the recovered plasma was analysed by high performance liquid chromatography using fluorescence detection. MXD was detected in plasma from two hours up to 35 days post-treatment in animals from both breeds. A slow MXD absorption and delayed peak plasma concentration were observed in Aberdeen Angus compared to Holstein calves. Significant lower systemic availability (expressed as AUC) (P<0.01) and peak plasma concentration (C(max)) (P<0.05) were also observed in Aberdeen Angus calves, although the plasma mean residence time (MRT) and elimination half-lives (T(1/2el)) of MXD in both breeds were similar. The pharmacokinetic differences observed between cattle breeds contribute to explain the variability in the pattern of clinical efficacy for pour-on administered endectocide compounds reported in different field trials.     

动物性食品中四环素类药物残留的检测方法

本文介绍了四环素类抗生素的作用,介绍了四环素类药物在动物性食品中残留的常用检测方法。     

牛奶中四环素类抗生素残留及其检测分析

随着奶牛业的不断发展和抗生素的不断运用,牛奶中抗生素的残留越来越受到人们的关注,本文详细介绍了牛奶中四环素类抗生素残留的检测分析方法。     

The use of parenteral nutrition in calves

Parenteral nutrition has been an important adjunct to therapy of abdominal diseases in calves, with chronic diarrhea and wasting being the most common indication. Parenteral nutrition is administered on a short-term basis to prevent further protein-energy malnutrition in debilitated calves that cannot or will not consume adequate quantities of milk. Parenteral nutrition solutions consist of a protein source (amino acids) and energy sources (glucose and lipid emulsions), supplemented as needed with balanced electrolytes and vitamins. Complications due to PPN are rare, and it is the authors' clinical impression that survivability is enhanced when PPN is employed, although enhanced survivability was not demonstrated in one controlled experimental trial.     

The development of Ascaris suum in calves.

To determine the development of Ascaris suum after a primary and a secondary infection, 18 calves were inoculated with 2,000,000 infective eggs and examined from 18 hours to 13 days postinfection. At 18 hours larvae were recovered from the wall of the abomasum, duodenum and jejunum. They were found in small intestine lymph nodes on the third day, in the liver at five days and were most abundant in the lungs on days 7 and 9. The pattern of recovery of larvae from the lung between days 5 and 13 postinfection was similar after a primary or a secondary infection. Slower growth of larvae following a secondary infection was the only evidence of resistance to A. suum. There were no pathological changes observed in the alimentary canal. White foci were found on the surface of the liver as early as the third day. The rapid decline in the number of A. suum in the lungs after the ninth day was considered to be related to immobilization or death of larvae soon after the reaction to them commences.     

The aetiology of generalized alopecia in young calves

The objective of this study was to test for correlations between alopecia and ruminal drinking in young calves. 331 calves up to an age of 31 days were tested for evidence of generalized hair loss daily during their stay in the clinic. Incidence of diarrhoea and the results of ruminal fluid and blood analysis were compared between the groups with and without alopecia. Calves with alopecia showed a significantly higher incidence of diarrhoea and of ruminal acidosis persisting for at least 24 hours. Blood analysis revealed significant differences in degree of acidosis, in concentrations of D-lactate, urea, and creatinine in serum as well as in the activities of glutathione peroxidase, aspartate amino transferase, and creatine kinase. Alopecia in calves is correlated to longer periods of diseases, which are known to be accompanied by the production of D-lactate in the gastrointestinal tract, such as diarrhoea and ruminal drinking. The question, whether alopecia is due to formation of toxic substances or to deficiency of essential substances can not be answered.     

猪肉中四环素类抗生素残留的ELISA检测

采用间接竞争ELISA检测猪肉及内脏组织中土霉素、四环素、金霉素的残留量,在50~300μg/kg浓度范围内,标准添加样品回收率81.3%~122.4%,变异系数2.7%~11.1%。本方法的建立为四环素类抗生素残留的快速检验试剂盒的研制奠定了基础。     

饲料中四环素类抗生素的放射免疫分析

本实验探讨应用放射免疫法检测饲料中四环素类抗生素残留,建立快速筛选方法,确定了样品处理及控制点设定的方法,用液相色谱质谱(LC-MS)法验证了放射免疫分析法筛选的样品,符合率达100%,且该方法特异性强,与氯霉素、红霉素、链霉素、青霉素G、磺胺嘧啶等其他抗生素无交叉反应。该法能达到检测饲料中四环素类抗生素残留的要求。