Evaporation and drift losses from sprinkler irrigation systems under various operating conditions

Quantitative determinations of evaporation and drift losses from sprinkler systems were carried out under different operating conditions.Evaporation losses determined by an electrical-conductivity method ranged from 1.5 to 16.8% of the total sprinkled volume. Wind velocity and vapor pressure deficit were the most significant factors affecting the evaporation losses. Exponential relationships between the evaporation losses and both wind velocity and vapor pressure deficit have been found. For the operating pressures used in this study the least effect on evaporation was found.Drift losses measured by the magnesium-oxide method varied from 1.5 to 15.1%. Drift losses increased with the second power of the wind velocity, and decreased with increasing distance in the downwind direction.Combined losses from a sprinkler system for a given set of operating conditions have been estimated by using the results obtained from the experiments. Combined losses ranged from 1.7 to 30.7% of the applied water.     

Influence of Escherichia coli endotoxin-induced endotoxaemia on the pharmacokinetics of enrofloxacin after intravenous administration in rabbits

The main goal of present study was to determine the effects of an Escherichia coli endotoxin-induced endotoxaemic status on disposition of enrofloxacin after a single intravenous dose (5 mg/kg) in rabbits. Septic shock was induced by the i.v. bolus administration at a single dose of E. coli lipopolysaccharide. Six adult New Zealand White rabbits were used. Concentrations of drug in plasma were determined by HPLC. The plasma pharmacokinetic values for enrofloxacin were best represented using a two-compartment open model. Total plasma clearance (Cl(T)) decreased from 2.11 (l/h/kg) in healthy animals to 1.50 (l/h/kg) in rabbits with septic shock, which is related to an increase in the AUC(0-->infinity). In endotoxaemic rabbits, volume of distribution at steady state (V(dss) = 3.61 l/kg) was significantly lower (P < 0.05) than in healthy animals (V(dss) = 4.97 l/kg). However, the elimination half-life of enrofloxacin was not affected by lipopolysaccharide administration.     

Effect of supportive therapy on the pharmacokinetics of intravenous marbofloxacin in endotoxemic sheep

The purpose of this study was to determine the influences of supportive therapy (ST) on the pharmacokinetics (PK) of marbofloxacin in lipopolysaccharide (LPS)-induced endotoxemic sheep. Furthermore, minimum inhibitory concentration (MIC) of marbofloxacin against Escherichia coli, Mannheimia haemolytica, Pasteurella multocida, Klebsiella pneumoniae, Salmonella spp., and Staphylococcus aureus was determined. The study was performed using a three-period cross PK design following a 15-day washout period. In the first period, marbofloxacin (10 mg/kg) was administered by an intravenous (IV) injection. In the second and third periods, marbofloxacin was co-administered with ST (lactated ringer + 5% dextrose + 0.45% sodium chloride, IV, 20 ml/kg, dexamethasone 0.5 mg/kg, SC) and ST + LPS (E. coli O55:B5, 10 µg/kg), respectively. Plasma marbofloxacin concentration was measured using HPLC-UV. Following IV administration of marbofloxacin alone, the , AUC_0–∞, Cl_T, and V_dss were 2.87 hr, 34.73 hr × µg/ml, 0.29 L hr⁻¹ kg⁻¹, and 0.87 L/kg, respectively. While no change was found in the MBX + ST group in terms of the PK parameters of marbofloxacin, it was determined that the Cl_T of marbofloxacin decreased, AUC_0–∞ increased, and and MRT prolonged in the MBX + ST + LPS group. MIC values of marbofloxacin were 0.031 to >16 µg/ml for E. coli, 0.016 to >16 µg/ml for M. haemolytica, 0.016–1 µg/ml for P. multocida, 0.016–0.25 µg/ml for K. pneumoniae, 0.031–0.063 µg/ml for Salmonella spp., and 0.031–1 µg/ml for S. aureus. The study results show the necessity to make a dose adjustment of marbofloxacin following concomitant administration of ST in endotoxemic sheep. Also, the PK and pharmacodynamic effect of marbofloxacin needs to be determined in naturally infected septicemic sheep following concomitant administration of single and ST.     

畜禽粪污清洁堆肥——机遇与挑战

好氧堆肥技术是处理畜禽粪污的有效手段,然而传统的好氧堆肥技术存在着氨气和温室气体排放量大、重金属活性高、病原微生物和抗性基因残留高、腐殖化程度低等瓶颈问题,因此开展畜禽粪污的清洁堆肥就显得非常必要。清洁堆肥是指从堆肥原材料选取、堆肥过程到堆肥产品使用整个过程中,选取无害化原料、过程中严格控制污染物的排放,并使其最终产品无害化的过程。本文围绕当今我国畜禽养殖业发展特征和畜禽粪污污染现状,深度剖析了传统堆肥的优势及其所面临的挑战,展望了畜禽粪污清洁堆肥的机遇与发展趋势,以期为畜禽粪污资源的可持续利用提供理论支持。     

鸡球虫病流行病学、防治药物与疫苗研究进展

家禽养殖业是畜牧业的基础性产业,我国家禽年出栏量达 146 亿羽,约占全球养殖量的 22%,而鸡球虫病是一种严重危害养禽业健康发展的寄生性原虫病,每年给养鸡业造成巨大的经济损失。该病由一种或多种艾美耳球虫寄生于鸡肠道粘膜上皮细胞引起,可导致大量肠上皮细胞受损、出血甚至死亡。近 70 年来,国内外学者一直致力于鸡球虫病防治药物和疫苗的研制,传统的抗球虫药物有聚醚类离子载体抗生素和化学合成类药物,传统的鸡球虫病疫苗有强毒活卵囊疫苗和弱毒活卵囊疫苗。近年来,新药与新型疫苗研发技术平台不断发展,为新型抗球虫药物（天然产物药物）和新型疫苗（亚单位疫苗、DNA 疫苗和活载体疫苗等）的研制提供新的手段和思路。结合鸡球虫病流行病学、防治药物等方面的研究概况,重点阐述抗球虫药物与鸡球虫病疫苗研发等方面的研究进展,以期为鸡球虫病的综合防控提供理论依据。     

The effect of tilmicosin on cardiac superoxide dismutase and glutathione peroxidase activities

In this study, the effect of tilmicosin on cardiac superoxide dismutase and glutathione peroxidase activities was investigated. Forty male BALB/c mice were used as material. Ten mice served as a control group, and 30 mice were injected with tilmicosin (25 mg/kg body weight, subcutaneously, with a single injection). After drug administration, they were monitored for 3 days. Tilmicosin caused decreases in cardiac superoxide dismutase and glutathione peroxidase activities.     

Determination of intracellular concentrations of free and two types of liposome-encapsulated enrofloxacin in anatolian shepherd dog monocytes

In this study, it was evaluated the accumulation of free and two types of liposome-encapsulated enrofloxacin (LEE) at the doses of 0.25, 0.5 and 1 microg/ml, which were clinically relevant concentrations into monocytes of healthy Anatolian shepherd dogs. Enrofloxacin was encapsulated with two different types of liposome in multilamellar large vesicles (MLV). Type A MLV composed of 15 mg egg phosphatidylcholine and 35 mg cholesterol, Type B MLV composed of phosphatidylcholine (PC), cholesterol and enrofloxacin, in a molar ratio of 1 : 1 : 1. The mean sizes of Type A and Type B liposome were found to be 7.65 and 4.27 microm, respectively. However, the mean encapsulation rate determined of Type A (13 +/- 2%) was found lower than Type B liposome (44 +/- 3%). The amounts of intracellular enrofloxacin concentrations were determined by high performance liquid chromatography. Type B LEE accumulated significantly higher level into monocytes when compared to free drug or Type A liposome. This study showed that Type B LEE markedly concentrated within monocytes and may improve the antibacterial efficacy of the antibiotic.     

Pharmacokinetics of enrofloxacin following intravenous and intramuscular administration in Angora rabbits

The pharmacokinetic behaviour and bioavailability of enrofloxacin (ENR) were determined after single intravenous (iv) and intramuscular (im) administrations of 5mg/kg bw to six healthy adult Angora rabbits. Plasma ENR concentrations were measured by high performance liquid chromatography. The pharmacokinetic data were best described by a two-compartment open model. ENR pharmacokinetic parameters were similar (p>0.05) for iv and im administrations in terms of AUC0-infinity, t1/2beta and MRT. ENR was rapidly (t1/2a, 0.05 h) and almost completely (F, 87%) absorbed after im injection. In conclusion, the pharmacokinetic properties of ENR following iv and im administration in Angora rabbits are similar to other rabbit breeds, and once or twice daily iv and im administrations of ENR at the dose of 5mg/kg bw, depending upon the causative pathogen and/or severity of disorders, may be useful in treatment of infectious diseases caused by sensitive pathogens in Angora rabbits.