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1.
通过对铅锌尾矿区9种优势草本植物不同生长时期铅及氮、磷、钾含量分布特征及其相关性研究,结果表明,1)植物地上部氮、磷、钾含量均高于地下部,并随着生长时期的延长呈下降趋势; 2)在3个生长时期,9种优势草本植物均未表现出超富集铅的能力,但华中蹄盖蕨地下部能够囤积大量铅,最高含量和累积量分别达到15 542.1 mg/kg和41.81 mg/株; 3)除生长后期植物地上部氮、钾含量与铅含量存在显著的正相关关系(0.750*和0.773*)外,植物氮、磷、钾含量与铅含量在3个生长时期均未表现出显著的相关关系; 4)在植物生长前期,其地上部铅含量与地下部铅含量以及与生长旺盛期和生长后期的地上部或地下部铅含量均不存在显著的相关关系,而在生长旺盛期和生长后期,同一时期地上部和地下部铅含量之间以及不同时期地上部与地下部铅含量之间均存在显著或极显著的相关关系。  相似文献   

2.
This study evaluated the relationship between blood iron parameters and hepatic iron concentrations, and correlation of histologic findings with hepatic iron concentrations in a captive population of Egyptian fruit bats (Rousettus aegyptiacus) and island flying foxes (Pteropus hypomelanus). Blood samples were collected for complete blood counts, plasma biochemical profiles, serum iron concentrations, total iron-binding capacity, whole-blood lead concentrations, and plasma ferritin assays. Liver samples obtained by laparotomy were divided, with one half processed for histologic examination and the other half frozen and submitted for tissue mineral analysis. The histologic sections were scored by two blinded observers for iron deposition, necrosis, and fibrosis. The Egyptian fruit bats had significantly higher liver iron (mean = 3,669 +/- 1,823 ppm) and lead (mean = 8.9 +/- 5.8 ppm) concentrations than the island flying foxes (mean [Fe] = 174 +/- 173 ppm, mean [Pb] = 1.9 +/- 0.5 ppm). Hepatic iron concentrations significantly correlated with tissue lead concentrations, histologic grading for iron and necrosis, serum iron, transferrin saturation, and plasma ferritin (P < 0.001). Blood lead concentrations negatively correlated with tissue lead concentrations (P < 0.001). When the product of transferrin saturation and serum iron was greater than 51, an individual animal had a high probability of having iron overload. When the product of these two variables was greater than 90, there was a high probability that the animal had hemochromatosis. On the basis of this study, it appears that evaluation of serum iron, transferrin saturation, and plasma ferritin are useful and noninvasive methods for diagnosis of hemochromatosis in Egyptian fruit bats.  相似文献   

3.
Adult mallard ducks were administered steel pellets to determine the rate of excretion from the gastrointestinal tract. In separate studies the ducks were administered 5 number 6 lead pellets. Birds were examined for clinical signs and sacrificed at given intervals over a 20 day period to assess changes in tissue structure and concentrations of lead with time. The above studies were conducted in 2 groups of ducks, fed a low or a high fiber diet. The rate of steel pellet excretion on birds on the low fiber diet decreased with an increase in pellet size. Pellet excretion was greatly reduced in birds fed the high fiber diet. Administration of lead shot resulted in the development of green diarrhea, anorexia and weakness. It also produced high concentrations of lead in the blood, kidney, liver and bone with lower concentrations in skeletal muscle. The major lesions were destruction of the mitotically active proventricular epithelium and medullary osteocytes, destruction of pectoral muscle cells and the presence of intranuclear inclusion bodies in the proximal tubular epithelium of the kidneys. Birds on the high fiber diet demonstrated more severe clinical signs and higher concentrations of lead in the tissues.  相似文献   

4.
Eighteen (Duroc × Landrace × Yorkshire) castrated boars,55 days of age and weighing approximately 19 kg,were used to investigate the effects of montmorillonite nanocomposite on tissue levels of lead as well as changes in blood biochemical parameters in pigs fed lead contaminated diets.The barrows were randomly assigned to one of three treatments (n=6) including a control which were fed a basal diet based on corn and soybean meal.The remaining two groups were fed the basal diet supplemented with 10 mg/kg lead either with or without 0.5% montmorillonite nanocomposite for 50 days.Pigs treated with lead had significantly increased levels of lead in their tissues.Lead accumulated in all tissues of the body with the highest accumulation found in the hair.When montmorillonite nanocomposite was given along with lead,tissue concentrations of lead did not differ from the control.Fecal excretion of lead increased significantly in lead-exposed pigs treated with montmorillonite nanocomposite.A progressive and appreciable accumulation of lead was seen in blood with a concomitant increase in zinc protoporphyrin levels during the course of treatment.However,zinc protoporphyrin levels did not differ from the control when montmorillonite nanocomposite was administered along with lead.The activity of δ-amino levulinic acid dehydratase in blood was significantly increased in lead treated pigs compared with the control.However,in pigs treated with lead and montmorillonite nanocomposite in combination,the activity of δ-amino levulinic acid dehydratase was similar to control pigs.Our results indicate that montmorillonite nanocomposite treatment of pigs exposed to lead resulted in reduced lead concentrations in body tissues.It appears that montmorillonite nanocomposite functions by increasing fecal excretion of lead.  相似文献   

5.
Eighteen (Duroc × Landrace × Yorkshire) castrated boars, 55 days of age and weighing approximately 19 kg, were used to investigate the effects of montmorillonite nanocomposite on tissue levels of lead as well as changes in blood biochemical parameters in pigs fed lead contaminated diets. The barrows were randomly assigned to one of three treatments (n = 6) including a control which were fed a basal diet based on corn and soybean meal. The remaining two groups were fed the basal diet supplemented with 10 mg/kg lead either with or without 0.5% montmorillonite nanocomposite for 50 days. Pigs treated with lead had significantly increased levels of lead in their tissues. Lead accumulated in all tissues of the body with the highest accumulation found in the hair. When montmorillonite nanocomposite was given along with lead, tissue concentrations of lead did not differ from the control. Fecal excretion of lead increased significantly in lead-exposed pigs treated with montmorillonite nanocomposite. A progressive and appreciable accumulation of lead was seen in blood with a concomitant increase in zinc protoporphyrin levels during the course of treatment. However, zinc protoporphyrin levels did not differ from the control when montmorillonite nanocomposite was administered along with lead. The activity of δ-amino levulinic acid dehydratase in blood was significantly increased in lead treated pigs compared with the control. However, in pigs treated with lead and montmorillonite nanocomposite in combination, the activity of δ-amino levulinic acid dehydratase was similar to control pigs. Our results indicate that montmorillonite nanocomposite treatment of pigs exposed to lead resulted in reduced lead concentrations in body tissues. It appears that montmorillonite nanocomposite functions by increasing fecal excretion of lead.   相似文献   

6.
Major contaminants identified in 1983-1984 on a pig fattening farm with an output of 60,000 pigs per annum, located in a lignite mining area and near a solid fuel power plant, were mercury, cadmium, lead, chromium and aflatoxin B1 (Tab. I, II, III, IV). Feed samples were collected from througs to assess the contamination load at feed uptake. Permissible concentrations of mercury, chromium, cadmium, aflatoxin B1, lead and atrazin in the feed were exceeded in 56, 50, 31, 19, 6 and 6% samples, respectively (Tab. I). Stable dust deposits, in which the contaminants concentrate, (Tab. I) proved to be a suitable material for assessing the type and level of environmental contamination. Permissible concentrations of mercury, cadmium and lead in porcine muscles were exceeded in 65, 51 and 24% samples, respectively (Tab. III). Corresponding values of mercury, cadmium, lead and aflatoxin B1 in the liver were 27, 27, 16 and 3%, respectively (Tab. III) and those of mercury, lead and chromium in kidneys 24, 22 and 5%, respectively (Tab. III). Rather surprisingly, elevated pancreatic concentrations of aflatoxin B1 were found (Tab. IV). Pigs fattened in the contaminated environment (i.e. fed contaminated feed mixtures, inspiring contaminated dust and absorbing percutaneously contaminants form dust deposits on the body surface) showed: 1) Impairment of the genetic apparatus (percentage of aberrant peripheral leucocytes elevated to 6.2%); 2) a certain degree of immunosuppression (concentrations of IgG, IgM and IgA reduced by 16.9, 45.1 and 45.0%, respectively); 3) higher feed consumption per 1 kg weight gain (4 kg) and lower average daily weight gain (0.57 kg); 4) increased incidence of health disorders (dermatitis in 25%, pancreatopathy in 13%, liver dystrophy in 8% and femoral fracture in 6% of the pigs). Unfortunately, the authors were not allowed to analyse ash and solid emissions from the power plant. Therefore the share of the emissions in the overall environmental contamination on the fattening farm could not be quantified. The personnel, working in the contaminated environment for a prolonged period, is endangered most of all by stable dust, being exposed to its mechanical, chemical, allergic and infectious effects (Tab. I). In addition to the chemical contaminants, 21 mould genera and species, six mite species and numerous saprophytic and some pathogenic bacteria were demonstrated in stable dust samples in our earlier experiments. Consumption of meat and organs from pigs fattened in a contaminated environment is associated with the risk of an increased uptake of various contaminants.(ABSTRACT TRUNCATED AT 400 WORDS)  相似文献   

7.
叶小齐  吴明  邵学新  梁雷 《草业学报》2014,23(6):217-224
植物化感物质普遍存在对其他植物生长的“低促高抑”现象,可能和植物对叶片资源投入或者单位叶面积光合能力有关。实验以具有较强化感作用的加拿大一枝黄花为材料,研究其提取物对玉米幼苗生长、光合能力和叶片资源分配的影响。结果表明,不同水提液浓度(0.00~0.25 g/mL)对玉米幼苗生长(总根长、株高、总叶面积和总叶长)存在着显著的影响(P<0.05),与对照处理(0.00 g/mL)相比,0.02~0.11 g/mL内各浓度处理对玉米幼苗的茎、叶和根的生长和总生物量的积累都有促进效应,而在0.13~0.25 g/mL内各浓度处理有抑制效应。不同浓度水提液处理对比叶面积和叶面积率有着相似的“低促高抑”效应(P<0.05),低浓度处理玉米幼苗对光合同化组织的资源投入增加,比叶面积和叶面积率提高,而叶生物量分配则无显著变化(P>0.05)。处理1~3 d内,具有最大生长促进效应的0.02 g/mL处理和最大生长抑制效应的0.20 g/mL处理与对照处理的玉米幼苗最大净光合速率和表观量子效率没有显著差异(P>0.05)。不同浓度处理条件下,玉米幼苗生物量与比叶面积和叶面积率呈极显著正相关(P<0.001),这说明加拿大一枝黄花水提液对玉米幼苗生长的影响是通过改变对叶片资源投入,特别是叶面积生长的投入,而不是通过单位叶面积光合能力变化所导致的。低浓度化感物质对玉米幼苗生长的促进可能是细胞伸展性增强的结果。不同浓度化感物质可能是化感作用感知受体植物胁迫能力的一种信号,因此具有一定的生态适应意义。  相似文献   

8.
Pinyon and juniper expansion into sagebrush ecosystems results in decreased cover and biomass of perennial grasses and forbs. We examine the effectiveness of spring prescribed fire on restoration of sagebrush ecosystems by documenting burn effects on soil nutrients, herbaceous aboveground biomass, and tissue nutrient concentrations. This study was conducted in a central Nevada woodland and included control and burn treatment plots sampled before and after a prescribed fire. Six native understory plant species (Crepis acuminata, Eriogonum umbellatum, Eriogonum elatum, Poa secunda secunda, Festuca idahoensis, and Lupinus argenteus) important for native sagebrush obligate foragers were chosen to represent the understory plant community. L. argenteus is also important for system nutrient cycling and nitrogen fixation. Plants were collected from three microsites (under tree canopy, under shrub canopy, and interspace) common in transitional woodlands during peak growth the summer before a spring prescribed burn and each of two summers following the burn. Soils were collected from corresponding locations at two depth intervals (0–8 and 8–52 cm) to determine the relationships between soil and plant nutrients following fire. Microsite affected soil nutrients but did not influence plant tissue concentrations with the exception of F. idahoensis. Burning resulted in increases in soil surface NH+4, NO3−, inorganic N, Ca2+, Mn2+, and Zn2+. Increases in NO3−, inorganic N, and Zn2+ were also observed in deeper horizons. Burning did not affect aboveground plant biomass or nutrient concentrations in the first year with the exception of F. idahoensis, which had increased tissue P. By the second year, all species had statistically significant responses to burning. The most common response was for increased aboveground plant weight and tissue N concentrations. Plant response to burning appeared to be related to the burn treatment and the soil variables surface K+, NO3−, and inorganic N.  相似文献   

9.
为探索植物对重金属的修复作用以及自身对重金属污染的生理效应,以基质盆栽高羊茅(Festuca arundinacea)幼苗为试验材料,比较分析了不同铅胁迫下,高羊茅的生理生化效应.结果表明:随着胁迫时间的延长,不同铅浓度下的高羊茅叶片中超氧化物歧化酶(SOD)和过氧化物酶(POD)活性整体变化为先升后降,POD变化趋势较为缓慢,表明低浓度或短时间内铅可快速诱导高羊茅保护酶活性.叶绿素总量变化为低浓度(500,1000 mg·L-1)下先增加后下降,高浓度下则为持续下降,表明高羊茅可能通过增加叶绿素来适应低铅胁迫,而高浓度下则失去了这种调节能力.3个铅浓度下的丙二醛(MDA)含量与胁迫时间及胁迫浓度均为正相关,表明随着胁迫浓度和时间的增加,细胞膜脂过氧化作用加强.脯氨酸含量在500,1000 mg·L-1铅浓度下随时间增加为先降后升,1500 mg·L-1浓度下则相反,但均高于对照,表明经铅胁迫后细胞的渗透调节能力增强.3个浓度下的可溶性糖含量变化均随时间表现出降-升-降,最终显著降低,整个变化过程低于对照.因此在铅胁迫过程中,这些生理特性的变化表明在低铅胁迫时高羊茅表现为积极适应和抵抗,而在高铅胁迫下则表现为忍耐和受损.  相似文献   

10.
OBJECTIVE: To compare the efficacy of calcium disodium EDTA (CaNa2EDTA) and meso-2,3-dimercaptosuccinic acid (DMSA) in reducing concentrations of lead in selected tissues for use in treatment of calves with experimentally induced lead toxicosis. ANIMALS: 19 sexually intact male Holstein calves that weighed 35 to 60 kg. PROCEDURE: Calves were randomly assigned to 1 of 5 treatment groups: group 1, control calves; group 2, lead only; group 3, lead and EDTA; group 4, lead and DMSA; and group 5, lead, EDTA, and DMSA. Calves in groups 2 to 5 were dosed daily with lead (5 mg/kg, PO) for 10 days. Doses of EDTA (100 mg/kg) and DMSA (25 mg/kg) were administered IV once daily for 4 consecutive days beginning on day 11. Effects of the chelators on lead concentrations in the liver, kidneys, testes, muscles, bones, and brain were compared among the various groups. RESULTS: Compared with the effects of EDTA, DMSA greatly reduced lead concentrations in renal and hepatic tissues. We did not detect significant differences for the effects of EDTA or DMSA on lead concentrations in the testes; there was an adverse interaction of EDTA with DMSA that caused an increase in lead concentrations in the testes. CONCLUSIONS AND CLINICAL RELEVANCE: DMSA is much more effective than EDTA in removing lead from renal and hepatic tissues in calves. Use of DMSA in calves with lead intoxication appears to be a viable treatment option. Combining DMSA and EDTA as a treatment modality in calves did not offer any advantages.  相似文献   

11.
铅胁迫下转DREB1A高羊茅对铅的吸收与耐受性研究   总被引：2，自引：0，他引：2  
通过水培试验,研究转DREB1A高羊茅对铅的吸收与耐受性。分别用浓度为100 mg/L、200 mg/L、500 mg/L、1000 mg/L、1500 mg/L、2000 mg/L的铅溶液对生长1个月的高羊茅进行胁迫处理,3周后测算了高羊茅植株的铅含量、枯黄率、根系耐性指数、迁移率、富集系数、转运系数等指标。结果显示,相同的铅胁迫条件下,转基因高羊茅的生长状况较好,对铅的富集与转运能力也较强。但无论是在生长状况方面还是在铅含量及分布方面,两种高羊茅对铅胁迫的反应趋势基本相同。表明DREB1A基因未改变高羊茅对铅的转移运输机制,但提高了高羊茅对铅的富集能力及耐性,转DREB1A高羊茅可成为修复铅污染土壤的备选植物。  相似文献   

12.
AIMS: To investigate the prevalence of lead exposure in hens and eggs from backyard poultry in a sample of Auckland households, the relationship between concentrations of lead in the blood of the hens and in the shells and yolks of eggs from the same household, and to examine associations with measures of hen health, environment and husbandry factors.

METHODS: Thirty households participated in the study from August to November 2016, each providing one adult hen for sampling, an egg from the household if available, and completing a questionnaire on hen husbandry. Concentrations of lead in blood were determined using a portable lead analyser. Eggs were analysed for concentrations of lead in the yolk and shell using inductively coupled plasma mass spectrometry after biological digestion with a mixture of nitric and hydrochloric acid.

RESULTS: Twenty three of 30 hens (77%) showed evidence of lead exposure, with median concentrations of lead in blood of 0.77 (min?<0.16, max 8.02) μmol/L. All eggs showed evidence of lead exposure, with concentrations of lead in the yolk ranging from 0.003–1.07?mg/kg, and concentrations of lead in the eggshell ranging from <0.1–0.82?mg/kg. A positive correlation existed between concentrations of lead in the blood of a hen and concentrations of lead in egg yolk from the same hen (R2=0.97), and both the yolk (R2=0.58) and shell (R2=0.30) of an egg from her flock. No association was found between concentrations of lead in blood and hen health indices measured in this study. Concentrations of lead in blood were higher in hens from properties with homes built before 1941 than between 1941–1960 (p=0.03), and in hens from properties with weatherboard homes than brick homes (p=0.049).

CONCLUSIONS AND CLINICAL RELEVANCE: There was a high prevalence of lead exposure in this sample of Auckland backyard chickens, with the majority of hens being sub-clinically affected. Associations were found between concentrations of lead in the blood of the hens, and properties with homes built before 1941 and clad in weatherboard. Concentrations of lead in over half the egg yolks sampled were at levels sufficient to warrant human health concern. The assessment of concentrations of lead in backyard poultry and eggs intended for human consumption is recommended to protect human and bird health.  相似文献   


13.
A ranch in central South Dakota had a number of dead calves because of arsenic poisoning. The clinical picture included diarrhea, central nervous system signs, and death. Gross necropsy findings included adequate body fat, stomachs full of normal-appearing ingesta, and large amounts of greenish brown watery fluid in the intestine and colon. Microscopically there was severe lymphoid tissue necrosis in the mesenteric lymph nodes and gut-associated lymphoid tissue. Chemical analysis of kidneys showed no significant amounts of lead; however, kidney arsenic concentrations were 25 to 44 ppm. The source was a small pile of Paris Green (common name for cupric acetoarsenite) found in an old dump site in the pasture.  相似文献   

14.
铅胁迫对草木樨抗氧化系统的影响   总被引：3，自引：0，他引：3  
用盆栽法研究了重金属铅胁迫对草木樨Melilotus suavena中超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性,丙二醛(MDA)和体内铅含量的影响。结果表明:在0~1 500 mg/kg铅浓度梯度处理范围内,SOD、POD、CAT活性和MDA含量随铅处理浓度增加而上升。植株体内各器官的铅含量随外源铅处理浓度的增加而上升,根系铅含量与铅处理浓度呈正相关(R2=0.972**)。草木樨在29.942 g/kg的土壤铅浓度下仍能正常生长,体内最大铅积累量达654.93 mg/kg。根部铅的含量大于地上部总的含量,茎中的含量高于叶的含量。  相似文献   

15.
In an examination of 50 Danish common eiders, the liver and kidney content of cadmium, copper, lead and mercury was determined. Eiders were chosen for analysis, because this species feed almost exclusively on the common mussel (Mytilus edulis), which is known to accumulate heavy metals. The concentrations recorded of cadmium, copper, and mercury were lower than what is usually regarded as toxic for birds, except for one eider which carried more than 2000 mg copper/kg liver tissue (dry weight). Of the 42 eiders analysed for lead, four had toxic levels, i.e., more than 7 mg per kg liver wet weight, and two other had increased levels, i.e., 3-7 mg lead per kg liver wet weight. The mean Cd concentration was 3.3 mg/kg liver (ww). This means that by consumption of ab. 160 gram liver from the common eider, the weekly tolerable intake of cadmium suggested by FAO/WHO would be exceeded.  相似文献   

16.
The normal values of lead in the organs and tissues of clinically healthy slaughter cattle were determined by the method of atomic absorption spectrophotometry and by the polarographic method. Animals of various age categories came from several farms of the East-Slovakian region. The lead found in the liver of young fattened cattle was not determined polarographically, since its concentration was under the threshold of sensitivity of the method (1.0 ppm). In the older category of animals (4-16 years old dairy cows) the following lead levels were revealed by the method of atomic absorption spectrophotometry: liver: (n = 76) 1.4 ppm, kidney cortex (n = 51) 1.5 ppm, bone tissue (n = 37) 3.3 ppm, muscle (n = 24) 1.0 ppm. The animals coming from different places had diverse amounts of lead in their tissues. The fact that the organs and tissues of slaughter cattle contained lead as a non-biogenic element is attributed mainly to environment pollution. The normal concentrations of lead, as determined in our study, can be used in chemical diagnosis of poisoning and in the evaluation of the hygienic safety of foodstuffs of animal origin.  相似文献   

17.
Matrix metalloproteinases (MMPs) are enzymes that play key roles in angiogenesis, tumor invasion, and metastasis in a wide variety of species. The purpose of this study was to evaluate pro and active MMP 2 and 9 concentrations in tumor, normal stromal tissue, and serum from tumor-bearing cats. We hypothesized that serum concentrations of pro and active forms of MMPs 2 and 9 would be predictive of MMP concentrations in tumor tissue and that these MMP concentrations would correlate with the histopathologic grade of the malignancies. Pro and active forms of MMPs 2 and 9 were determined by gelatin zymography and subsequent computerized densitometry from tumor and nearby stromal tissue and serum from 49 cats with various malignancies. The serum concentrations of MMPs from these tumor-bearing cats were compared with serum concentrations of MMPs from 44 normal cats of similar age and gender. Measurable concentrations of MMPs 2 and 9 were found within tumor, stromal, and serum samples. Mean concentrations of total pro and active MMPs 2 and 9 within tumor tissue were significantly higher (P values <.0001, .0031, <.001, and .0064, respectively) when compared with stromal tissue from the same animals. Serum MMP concentrations from tumor-bearing cats were higher than those from normal cats. Poor correlation was found between serum MMP concentrations and tissue MMP concentrations of increasing histologic grades of malignancies.  相似文献   

18.
The concentrations of receptors for epidermal growth factor (EGF-R), oestrogen (ER) and progesterone (PR) were measured in 108 samples from canine mammary tumours and 132 samples of normal mammary tissue removed surgically from 84 bitches. The history and clinical signs were also recorded. Binding sites of high affinity were detected in 70 per cent of both types of tissue and no significant variations in EGF-R concentrations or positivity were observed with the histology, location, size or number of mammary tumours or the age of the animal. A significant direct correlation (P=0002) was observed between the concentrations of ER and EGF-R only in malignant tumours. The concentrations of EGF-R were significantly correlated (P=0.04) in normal mammary tissues adjacent to and distant from the lesions, but not between normal tissue and tumour tissue. No significant differences were observed in the expression of EGF-R in normal and neoplastic tissues from the same bitches. The direct correlation between the concentrations of EGF-R and ER in malignant tumours could be related to an oestrogen-dependent expression of EGF-R or to a similar pattern of regulation of the receptors.  相似文献   

19.
Lead poisoning is commonly diagnosed in cattle. In this study, 3 groups of cattle from different herds accidentally exposed to discarded lead batteries on pasture were intensively studied to determine the extent and severity of exposure. The losses from acute death due to lead toxicity were substantial in all the 3 study groups at 12%, 17%, and 4%. Blood samples were taken from all cattle around the time of the first diagnosis and then later in 2 of the 3 herds to monitor the change in lead concentrations over time. Asymptomatic lead toxicosis was observed in these herds. In these 3 groups, between 4% and 12% of asymptomatic cattle had blood lead concentrations consistent with acute lead poisoning (> 0.35 ppm), and between 7% and 40% of these asymptomatic animals were in the high-normal range (0.1-0.35 ppm). Because of the consistently high number of asymptomatic cattle with elevated lead levels, all cattle potentially exposed to a lead source should be tested before sale or slaughter to minimize the entry of lead into the food chain. The blood lead concentrations, which were monitored for months after the initial diagnosis, decreased slowly after the cattle were removed from the lead source. The prolonged retention of lead may be due to continued release and absorption of lead from metal particles in the reticulum or rumen. The mean reduction in the lead level was 0.046 ppm (95% CI, 0.017-0.075 ppm) every 30 days for these 2 herds. Using a single-component exponential model, the half-life of lead in the animals retested from Herds 1 and 2 was highly variable. The median half-life was 63 days (interquartile range, 34-107 days). One out of 8 pregnant heifers with high blood levels had a stillborn calf. There were no abortions or calf mortalities in this group. Blood samples were'collected from the calves around the time of birth. The concentrations of lead in the blood of the calves exposed in utero were low (0.010-0.095 ppm).  相似文献   

20.
This study describes the epidemiology of acute lead poisoning in western Canadian cattle over the 16-year period of 1998 to 2013 and reports background bovine tissue lead concentrations. Case records from Prairie Diagnostic Services, Western College of Veterinary Medicine, identified 525 cases of acute lead toxicity over the investigational period. Poisonings were influenced by year (P < 0.0001) and month (P < 0.0001). Submissions were highest in 2009 (15.6%), 2001 (11.2%), and 2006 (9.9%). Most cases were observed during May, June, and July (62.3%). Cattle 6 months of age and younger were frequently poisoned (53.5%; P < 0.0001). Beef breeds were predominantly poisoned. Mean toxic lead concentrations (mg/kg wet weight) in the blood, liver, and kidney were 1.30 ± 1.70 (n = 301), 33.5 ± 80.5 (n = 172), and 56.3 ± 39.7 (n = 61). Mean normal lead concentrations in the blood, liver, and kidney were 0.036 ± 0.003 mg/kg (n= 1081), 0.16 ± 0.63 mg/kg (n = 382), and 0.41 ± 0.62 mg/kg (n = 64).  相似文献   

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