Experimental poisoning of pheasant chicks with nitrates and nitrites in drinking water

The effect was studied of nitrates and nitrites in drinking water on the methemoglobin level in blood and pathomorphological changes in fourteen-day-old pheasant chickens. The concentrations of 500 ppm of NO3- and 15 ppm NO2- in the drinking water were not lethal, they caused only the increase in the methemoglobin in blood to 7.1% (NO3-) and 16.5% (NO2-). The pheasants exposed to NO3- suffered from hyperaemia of liver, kidneys and mucosa of the small intestine and from the multiplication of the eosinophilic granulocytes in the villus stroma. The exposition to NO2- resulted in the non-specific dystrophic changes in liver and kidneys and in the villus edema of the small intestine. Lethal levels of nitrates and nitrites in drinking water were estimated in relation to the age of pheasants.     

Transmammary transfer of nitrates and nitrites in ruminants and methemoglobin blood levels in the young and their mothers

Transmammary transfer of nitrates was studied in ewes as model animals and in a dairy cow during the colostrum period and shortly after it. Ewes were administered per os 35 mg NaNO3.kg-1 of live weight twice daily during five days post partum and the dairy cow 50 g KNO3 during ten days post partum. Methaemoglobinaemia in ewes and their lambs had consistent dynamics during the whole period of study with slightly higher values in lambs than in ewes. Differences in the averages of methaemoglobin (MtHb) concentrations in blood were statistically higher from the fourth till the 72nd hour after administration. NaNO3 concentration in milk highly and significantly increased after the first administration, with a subsequent decline to an insignificant level during further clays, as compared with the initial data. NO2 ions were not observed to be present in any milk sample. Dynamics of methaemoglobinaemia in the dairy cow and her calf was the same as in the ewes, with a tendency of regular increasing four hours after administration. The increase in methaemoglobinaemia the last day of the trial was at the limit of significance. NaNO3 content in milk significantly increased on the 3rd, 9th and 10th day after administration. Nitrates in urine showed similar trend as in milk with a significant increase only on the 2nd and 10th day post partum. The finding of 14.5 mg.l-1 NaNO3 in the amniotic fluid provides evidence of a simultaneous transplacental transfer of nitrates.     

畜禽生产中氨的危害及防治措施

畜禽养殖会产生大量的氨(NH3)气。集约化养殖的动物圈舍常常含有较高浓度的氨,它是动物胃肠道和排泄的粪尿中的尿素在微生物脲酶作用下的水解产物。一定浓度的氨不仅会影响动物健康,进而影响动物的生产成绩,而且这些氨最终会排放到大气中,造成一系列的环境污染问题。欧美等国家和地区很早就开始重视氨对环境影响的问题。在欧洲,关于过多NH3沉积的研究早在15￣20年前就已经开始了,主要集中在其对土壤酸化(acidification)和超营养作用(eutrophication)的研究上(Battye等,1994;IKC/RIVM,1995)。美国环保署(Environm entalProtection Agen…     

Effect of high oral doses of nitrate on salivary recirculation of nitrates and nitrites and on bacterial diversity in the saliva of young pigs

Ingested nitrate is absorbed in the small intestine, recirculated into the saliva and reduced to nitrite by oral bacteria. In pigs receiving a moderate dietary addition of nitrate, the recirculation into the saliva is modest, so we aimed to assess the effect of higher nitrate doses to find out how the animal reacts to this new situation and to evaluate if a higher nitrate level could enhance the nitrate reduction process, improving the nitrite production Trial 1. Six piglets received 100 g of a commercial diet with 2.45% KNO₃. In relation to baseline values, nitrate in blood serum and saliva increased 15 times, and declined after 6 h vs. 2 h. Salivary nitrite increased seven times after the addition and declined after 6 h vs. 2 h. Trial 2. Six piglets were fed a diet with or without 1.22% KNO₃ for 2 weeks. Salivary nitrate and nitrite increased with the addition of KNO3: nitrate increased from d0 to the end of the trial, nitrite increased 15 times after 1 week, but decreased after 2 weeks to 4.5‐fold the control. After 2 weeks, nitrate reduced Shan diversity index of salivary microbiota. The present results indicate that the long exposure to high quantities of nitrates impairs the oral reduction of nitrate to nitrite and engenders a reduction of the mouth’s microbiota diversity.     

鸡氨气中毒及其防治对策

鸡氨气中毒包括氨气重度、中度与轻度中毒.一般地,在25 mg/L以下或长期处于低浓度氨气的环境中可导致慢性中毒;在25～50 mg/L导致中度中毒,可诱发难于根除的其它呼吸道疾病;当鸡舍内氨气浓度达50 mg/L或以上时,发病率为100%,导致鸡重度中毒,死亡率为28.1%以上.     

浮萍防治草鱼烂鳃病、肠炎病和赤皮病效果试验

在运用中医基础理论初步探讨了草鱼的烂鳃病、肠炎病和赤皮病"三病"并发与经络学说和藏象学说的相关性基础上,以二龄草鱼种为试验对象,用浮萍防治草鱼"三病"取得了极为显著的效果,并根据中药药理学和浮萍的有效化学成分对其作用机理进行了探讨,为今后有效防治草鱼"三病"开辟了一条新途径.     

基层动物防疫存在的问题及解决措施

随着我国畜牧业不断发展,人们生活水平不断提高,畜产品安全问题、生存环境问题越来越受消费者的关注.由于种种原因,我国在基层动物防疫工作开展中仍存在不少问题,需让广大基层防疫人员认识到防疫工作的重要性,按照相关要求,切实做好动物的防疫工作.     

构建基层动物防疫体系应着重抓什么

基层动物防疫体系是畜牧业支持保护体系的重要组成部分,建立完善基层动物防疫体系,是推进基层防疫管理,做好动物防疫工作,控制和扑灭重大动物疫病,保障畜牧业持续健康快速发展,促进农民增收的需要;是保障畜产品质量安全和人民群众身体健康,防控突发性社会公共卫生安全事件的需要;是维护社会稳定,全面建设社会主义新农村的需要.笔者认为,构建基层动物防疫体系应着重从以下几方面来抓.     

草带在防治坡耕地土壤侵蚀中的作用

介绍了水土保持耕作法——草带间作,以及它在控制水土流失方面的作用,草带种植的几种方式,草带草种的选择等,并对这种治理坡耕地措施的发展趋势进行了展望。     

王草和象草在云南省亚热带地区的适应性研究

对王草和象草在云南省亚热带地区的适应性研究结果表明，两者在产量和养分的季节变化动态上有一定差异，在早期生长速度，再生性，年总产量和抗寒性等方面差异较小，多次刈割利用时，两者均表现出再生性好，饲草产量高的特点，其鲜草，干物质和粗蛋白的年总产，象草平均为298t/hm^2,53.7t/hm^2和4．18t/hm^2，王草为276t/hm^2,58.2t/hm^2和4．30t/hm^2，种植利用时两者可相互替代。     

Dynamics of methemoglobin levels in the blood of calves in relation to the ingested quantity of nitrates and the transrenal transport of nitrates]

Changes of methaemoglobin levels were investigated in the blood of suckling calves. Transrenal passage of nitrates was determined in dependence on the ingested amount of nitrates. The experiments were conducted under defined husbandry conditions; no excessive nitrate and nitrite supplementation of the calves by feeds and water could be stated. Imitation of possible field conditions when mainly water, but feeds too, may contain higher nitrate and nitrite levels, was carried out by peroral administration of an aquaeous solution of KNO3 to calves. The administered dose was increased from one to 2, 5 and 10 g per animal and day, respectively, in weekly intervals. MtHb determination in the blood of experimental calves on day 1 and 5 of the administration of 1 g KNO3 revealed no significant values. On day 1 and 5 of the administration of 2, 5 and 10 g KNO3 per animal and day, respectively, a significant increase of MtHb levels in the blood of calves was observed 2 and 3 hours after administration, followed by a decrease 4 hours after administration. The maximum values of MtHb in the blood of experimental calves, observed 3 hours following application of the respective KNO3 dose, were within the tolerance limits of the reference values. In urine, 3 hours after the administration of 10 g of KNO3 a mean nitrate value of 941.40.