BP神经网络模型用于气象因素对PRRS发病预测的研究

对气象数据和猪蓝耳病发病率进行相关性分析,结合动物流行病学理论确定影响猪蓝耳病发病的关键气象因素.利用Matlab软件进行BP(Back-propagation)神经网络预测模型构建,计算预测值与实际发病率的误差绝对值和决定系数R2对所建预测模型进行检验.结果表明,将13种气象因素作为预测研究的关键气象因子,BP神经网络模型其决定系数R2=0.821,证实预测效果较好.初步构建出猪蓝耳病发病的神经网络预测模型,探索性地将BP神经网络理论在动物疫病预测研究领域中运用,为进一步展开动物疫病预测的研究提供理论参考.     

基于BP神经元网络的鱼塘溶氧预测模型研究

为了能够提高水产养殖中水体溶氧量短期预测精度,提出将遗传算法和反向传播(BP)神经网络相结合的预测模型。根据相关研究,采用对池水含氧量影响较大的几个影响因素,作为预测模型的输入端变化量;BP神经网络优化的阈值和初始权值通过遗传算法来获得,遗传算法具有全局搜索能力。采用改进后的BP神经网络建立起短期鱼塘含氧量预测模型,该方法具有较高的预测精度。     

新城疫血凝和血凝抑制试验(HA/HI)中红细胞浓度对结果的影响

新城疫是由新城疫病毒引起禽的一种急性、热性、败血性和高度接触性传染病,具有很高的发病率和病死率。除家禽外,至少有200多种鸟类可以自然或实验感染新城疫病毒,此病是危害养禽业的一种主要传染病,被世界动物卫生组织列为A类动物疫病,我国将其列为一类动物疫病。由于新城疫对畜牧业的危害和对国家政治、经济的影响     

冬春季节肉鸡新城疫的综合防控

正新城疫是由新城疫病毒引起的一种急性、烈性、高度接触性传染病,我国将其列为重大动物疫病和一类传染病。近年来,由于疫苗的广泛应用,肉鸡新城疫的发生呈现出高发病率、低死亡率、高淘汰率、非典型性等特点,严重影响肉鸡养殖效益。(一)发病情况新城疫病毒主要侵害鸡和火鸡,     

基于人工神经网络的狼尾草属牧草品质近红外光谱预测研究

本研究利用近红外光谱通过人工神经网络(Artificial neural network, ANN)建立狼尾草属(Pennisetum Rich)牧草水分、粗蛋白、木质素、酸性/中性洗涤纤维及灰分含量的预测模型。结果表明：基于人工神经网络的狼尾草属牧草品质预测模型总体优于全光谱偏最小二乘法(PLS)模型效果。在人工神经网络的方向传播(BP)网络模型中,6项表征牧草品质指标的校正均方根误差(RMSEC)、预测均方根误差(RMSEP)均显著低于PLS模型,同时校正集决定系数(R■)、预测集决定系数(R■)显著提高,除灰分含量预测不理想外,其他预测效果均理想。同时人工神经网络的BP网络对于近红外光谱的非线性数据具有良好的拟合能力,其预测模型对于指导狼尾草属牧草品质预测和分级管理研究具有广阔的应用前景。     

基于PCA-BP神经网络的羊肉价格预测研究

价格波动受到多种因素的影响,准确的价格预测对市场稳定具有重要的作用。为了更好地服务于市场经济,笔者选取苏尼特羊为研究对象,提出了基于PCA和BP神经网络结合的价格预测方法,首先对影响羊肉价格的指标数据进行PCA降维,选取主成分特征最大的因子为BP神经网络的输入层,羊肉价格作为输出层建立预测模型,将预测结果与已有的苏尼特羊肉价格进行比对验证。结果表明:与标准的BP神经网络相比,结合PCA降维的BP模型具有更小的拟合误差和更高的精度。     

基于烟花算法的BP神经网络预测含根土抗剪强度

为了解决BP神经网络在对含根土抗剪强度的预测中存在的预测精度低，计算收敛速度较慢，容易陷入局部极值等问题，本研究通过直剪试验、团聚试验、根系分形分析试验等探究了不同因素对含根土抗剪强度的影响，并对各因素进行相关性分析，从中选取了大团聚体含量（R0.25）、平均重量直径（MWD）、几何平均直径（GMD）、土壤分形维数（Dd）、根表面积、平均直径6个影响含根土抗剪强度的因素作为模型输入层节点，含根土的抗剪强度作为输出层节点。参考FangfaGorman理论公式、Kolmogorov理论公式以及一种经验公式分别计算，并对结果进行讨论，确定了本研究中神经网络的最佳隐含层节点数量为13。建立6∶13∶1的BP神经网络模型，并引入了烟花算法（FWA）对BP神经网络进行优化。结果显示，BP神经网络、粒子群算法（PSO）优化的BP神经网络、FWA-BP神经网络的预测值与期望值的最大相对误差分别为11.12%、9.06%、7.44%，平均相对误差分别为4.60%、3.24%、1.96%，相较于BP神经网络和PSO-BP神经网络，FWA-BP神经网络预测误差值有明显降低；对比引入的统计参数，均方根误差（R...     

鸡非典型新城疫发生的免疫因素分析

鸡新城疫是由新城疫病毒引起的一种急性、热性、高度接触性传染病,是危害养禽业最严重的传染病之一,国际兽医疫局将其定为＂A类传染病＂,我国将其列为＂一类动物疫病＂。近些年来,我国新城疫的发病呈现新的流行病学变化,高发病率、高死亡率和表现典型临床症状以及病理变化的鸡新城疫越来越少,     

西宁市H5亚型禽流感、H7亚型禽流感、新城疫流行病学调查及结果分析

<正>禽流感(avian influenza,AI)和新城疫(Newcastle disease,ND)是严重危害禽类的病毒性疾病,常以单独或混合感染的方式感染家禽,发病率和死亡率都很高[1]。疫苗免疫是我国控制这两种疫病的有效措施之一[2-3]。为了做好2015年西宁市春季防疫期间高致病性禽流感、新城疫流行病学调查工作,分析动物疫病发生规律,科学判断动物疫病发生风险和流行趋势,系统评估动物疫病流行状况和控制措施效果,不     

3种不同方法对肉牛胴体性状预测能力的比较研究

本研究为了寻求一种对肉牛胴体性状预测准确性较高的方法,运用DPS数据处理系统和SAS软件比较偏最小二乘回归、GM(1,N)灰色系统和BP神经网络3种常用的预测模型对肉牛胴体性状的预测能力。选择肉牛7个宰前生长性状(体高、体长、胸围、腹围、管围、宰前活体质量、平均日增体质量),对2个重要的胴体性状(胴体质量和净肉质量)进行预测。结果表明:偏最小二乘回归方法在肉牛胴体性状预测方面准确性最高;GM(1,N)灰色系统和BP神经网络预测准确度偏低。本研究还将3种预测结果相结合,取其均值,大大提高了预测的准确性。这一研究将为肉牛生产实践提供一定的科学参考。     

Phase I evaluation of CCNU (lomustine) in tumor-bearing cats

1-(2-Chloroethyl)3-cyclohexyl-1-nitrosourea (CCNU) is an alkylating agent in the nitrosourea subclass. A prospective evaluation of CCNU was done to determine the maximally tolerated dosage of CCNU in tumor-bearing cats. Response data were obtained when available. Twenty-five cats were treated with CCNU at a dosage of 50-60 mg/m3 body surface area. Complete hematologic data were available for 13 cats. Neutropenia was the acute dose-limiting toxicity. The median neutrophil count at the nadir was 1,000 cells/microL (mean, 2,433 cells/microL; range, 0-9,694 cells/microL). The time of neutrophil nadir was variable, occurring 7-28 days after treatment, and counts sometimes did not return to normal for up to 14 days after the nadir. Based on these findings, a 6-week dosing interval and weekly hematologic monitoring after the 1st treatment with CCNU are recommended. The nadir of the platelet count may occur 14-21 days after treatment. The median platelet count at the nadir was 43,500 cells/microL. No gastrointestinal, renal, or hepatic toxicities were observed after a single CCNU treatment, and additional studies to evaluate the potential for cumulative toxicity should be performed. Five cats with lymphoma and 1 cat with mast cell tumor had measurable responses to CCNU. Phase II studies to evaluate antitumor activity should be completed with a dosing regimen of 50-60 mg/m3 every 6 weeks.     

Furosemide continuous rate infusion in the horse: evaluation of enhanced efficacy and reduced side effects

Continuous rate infusion (CRI) of furosemide in humans is considered superior to intermittent administration (IA). This study examined whether furosemide CRI, compared with IA, would increase diuretic efficacy with decreased fluid and electrolyte fluctuations and activation of the renin-angiotensin-aldosterone system (RAAS) in the horse. Five mares were used in a crossover-design study. During a 24-hour period, each horse received a total of 3 mg/kg furosemide by either CRI (0.12 mg/kg/h preceded by a loading dose of 0.12 mg/kg IV) or IA (1 mg/kg IV q8h). There was not a statistically significant difference in urine volume over 24 hours between methods; however, urine volume was significantly greater after CRI compared with IA during the first 8 hours ([median 25th percentile, 75th percentile]: 9.6 L [8.9, 14.4] for CRI versus 5.9 L [5.3, 6.0] for IA). CRI produced a more uniform urine flow, decreased fluctuations in plasma volume, and suppressed renal concentrating ability throughout the infusion period. Potassium, Ca, and Cl excretion was greater during CRI than IA (1,133 mmol [1.110, 1,229] versus 764 mmol [709, 904], 102.7 mmol [96.0, 117.2] versus 73.3 mmol [65.0, 73.5], and 1,776 mmol [1,657, 2.378] versus 1,596 mmol [1,457, 1,767], respectively). Elimination half-lives of furosemide were 1.35 and 0.47 hours for CRI and IA, respectively. The area under the excretion rate curve was 1,285.7 and 184.2 mL x mg/mL for CRI and IA, respectively. Furosemide CRI (0.12 mg/kg/h) for 8 hours, preceded by a loading dose (0.12 mg/kg), is recommended when profound diuresis is needed acutely in horses.     

Prevalence of gastric lesions in racing Alaskan sled dogs

Human and equine athletes are reported to have a high prevalence of gastric disease, and anecdotal evidence suggests a similar phenomenon applies to racing sled dogs. To investigate the prevalence of gastric disease in racing sled dogs, we conducted 2 gastroscopy studies on dogs competing in the annual Iditarod Sled Dog Race. A pilot study of dogs that were either dropped from the 2000 Iditarod Sled Dog Race because of illness or that finished the race indicated that, approximately 5 days after competing, 10 of 28 dogs (35%) had endoscopic evidence of gastric ulceration, erosion, or hemorrhage. The next year, an endoscopic study of 73 dogs participating in the 2001 Iditarod race was performed in order to evaluate a larger population of dogs. Data from 70 of these dogs could be used; 34 (48.5%) had ulceration, erosion, gastric hemorrhage, or some combination of these findings. When this group of 70 dogs was compared retrospectively to a control group of 87 dogs presented to the Texas A&M University (TAMU) Veterinary Medical Teaching Hospital, the Iditarod sled dogs had a significantly higher prevalence (P = .049) of gastric lesions. These findings suggest that, similar to athletes of other species, elite canine athletes have an increased prevalence of gastric disease compared to the canine population at large.     

Internal Parasites and Haematological Values in Cattle Slaughtered in Buea Subdivision of Cameroon

Tropical Animal Health and Production -     

The Epidemiology of Gastrointestinal Nematodes of Dairy Cattle in Central Kenya

The epidemiology of H. placei and of other gastrointestinal nematodes in yearling dairy cattle was examined on two farms in Kiambu District, central Kenya during each of 13 one-month periods from April 1993 to April 1994. On each farm, 32 newly weaned dairy calves were given a single dose of albendazole and then placed on experimental pastures. Twelve of the animals were designated for bi-monthly slaughter (n = 2) and analysis of worm population characteristics and 20 were designated for blood and faecal collection and for weighing. Two parasite-free tracer calves were grazed alongside the weaner calves each month throughout the study period and were also slaughtered for analysis of worm populations. Faecal egg counts, haematological and serum pepsinogen determinations, herbage larval counts, and animal live weight changes were recorded monthly. The study revealed that Haemonchus placei, Trichostrongylus axei, Cooperia spp. and Oesophagostomum radiatum were responsible for parasitic gastroenteritis and that H. placei was the predominant nematode present in the young cattle on both farms. Faecal egg counts from resident cattle and necropsy worm counts revealed that pasture larval levels were directly related to the amount of rainfall. The total worm burdens in the animals were highest during the rainy season (March–June and October–December) and lowest during the dry seasons (July–September and January–February). The very low recovery of immature larvae of H. placei from the tracer calves indicated that arrested development is not a feature of the life cycle of this parasite in central Kenya. The maintenance of the parasite population depended on continuous cycling of infection between the host and the pasture. The agroclimatic conditions of the study area were such that, in general, favourable weather conditions for the development and survival of the free-living stages of gastrointestinal nematodes existed all year round.     

Diversity of Ectoparasites in Sheep Flocks in Sa~o Paulo,Brazil

The occurrence of ectoparasites in sheep flocks is frequently reported but seldom quantified. Sheep production used to be a predominantly family activity in the state of Sa~o Paulo (Brazil), but it began to become a commercial activity in the past decade. Thus, information about the ectoparasites existing in sheep flocks has become necessary. The present data were obtained by means of questionnaires sent to all sheep breeders belonging to the `Associaça~o Paulista de Criadores de Ovinos' (ASPACO; Sa~o Paulo State Association of Sheep Breeders). Response reliability was tested by means of random visits paid to 10.6% of the respondents. Most of the properties (89.5%) reported the presence of one or more ectoparasites. Screw-worm (Cochliomyia hominivorax) was the most frequent ectoparasite (72.5%), followed by bot fly larvae (Dermatobia hominis, 45.0%), ticks (Amblyomma cajennense) and Boophilus microplus, 31.3%) and finally lice (Damalinia ovis, 13.8%). Combined infestations also occurred, the most common one being screw-worm with bot fly larvae (36.0%) followed by bot fly larvae with ticks (13.9%), screw-worm with ticks (9.3%), bot fly larvae with lice (6.9%), and ticks with lice (5.0%). The most common triple combination was screw-worm, bot fly larvae and ticks (12.8%). Breeds raised for meat or wool were attacked by bot fly larvae and ticks more often than other breeds. Lice were only absent from animals of indigenous breeds. The relationships among these ectoparasites are discussed in terms of sheep breeds, flock size, seasonality and the ectoparasitic combinations on the host.     

Chemotaxis of macrophage in inflammation

Our particular attention in this article was given to natural mediators for macrophages isolated from the sites of tissue injury. A number of chemotactic factors, which may satisfy many criteria making them acceptable as inflammatory leucocyte chemotactic factors, has been separated. Among them, our laboratory has isolated three macrophage (monocyte) chemotactic factors (MCF-a, -b and -c). Their purification, characterization and functional specificity are discussed.     

Evaluation of biohydrogenation rate of canola vs. soya bean seeds as unsaturated fatty acids sources for ruminants in situ

An experiment was conducted to study disappearance of C14 to C18 fatty acids, lag times and biohydrogenation (BH) rates of C18 fatty acids of ground soya bean and canola seeds in situ. Three ruminally fistulated Dallagh sheep were used to determine ruminal BH of unsaturated fatty acids (UFAs). Differences in the disappearance of fatty acids through the bags and lag times were observed between the oilseeds. We saw that the longer the incubation time of the oilseeds in the rumen, the lower the content of C18:2 and C18:3. Significantly higher lag times for both C18:2 and C18:3 were observed in ground canola compared to ground soya bean. BH rates of C18:2 and C18:3 fatty acids in soya bean were three times higher than those of canola. These results suggest that the fatty acid profile of fat source can affect the BH of UFAs by rumen micro‐organisms. So that UFAs of canola had higher ability to escape from ruminal BH. It seems that fatty acid profile of ruminant products is more affected by canola seed compared to soya bean seed.     

Serum biochemical values and mineral element contents of tissues in yaks

Serum biochemical values and the wet weight to dry weight ratios of tissues were determined in yaks in Shandan county of Gansu province. The liver, kidney, heart and muscle contents of seven elements in yaks were also analysed. Most serum biochemical values were similar to those of cattle, camels and sheep, but the calcium concentration was considerably above the normal range for other ruminants. The liver contained the highest concentrations of copper, manganese and cobalt and the kidney of selenium, iron and calcium.Abbreviations Alb albumin - ALT alanine aminotransferase - AST aspartate aminotransferase - BUN blood urea nitrogen - Chol cholesterol - Glob globulin - -GT -glutamyl transpeptidase - IP inorganic phosphorus - TP total protein