Mortality percentages related to heartwater and the economic impact of heartwater disease on large-scale commercial farms in Zimbabwe

A postal questionnaire asking for data concerning heartwater deaths was sent to all large-scale commercial farmers in Zimbabwe's lowveld, where heartwater is endemic. One hundred and fifty returns (24% return rate) provided usable data, with 85 farms (57% of sample) reporting heartwater deaths in 1990/91. The median heartwater mortality percentage for calves (0–12 months) was 2.3%. This was statistically significantly different (Wilcoxon signed rank test, P < 0.005) from the median mortality percentage of 0.6% for cattle 13 months and older. Heartwater accounted for 51% of all mortalities on farms reporting heartwater deaths. There were no meaningful correlations between farm or herd size and heartwater mortality percentages. A plot of the farms reporting heartwater deaths found that the heartwater endemic area in 1991 is essentially unchanged from 1979. Inspection of the geographic distribution of farms reporting heartwater showed no obvious patterns, and distances from communal land farms were not significantly correlated to heartwater mortality percentages. An economic model found that the annual financial impact of heartwater on large-scale commercial farms in Zimbabwe to be some Z$19.4 million (1991 prices). The upper bound, that allowed for inflation since 1991, was Z$33.4 million. The lower bound estimate was Z$8.1 million (Z$3 = US$1, 1991 rates). Eighty-nine percent of these costs can be attributed to the cost of dipping. Since it has been shown experimentally that the carrier state of heartwater may not affect the productivity of cattle, intensive dipping may not be the best means of controlling heartwater.     

Seroprevalence of brucellosis and its associated risk factors in cattle from smallholder dairy farms in Zimbabwe

A cross-sectional study was conducted to investigate seroprevalence of brucellosis and the associated risk factors in cattle from smallholder dairy farms in Gokwe, Marirangwe, Mushagashe, Nharira, Rusitu and Wedza areas of Zimbabwe. A total of 1,440 cattle from 203 herds were tested serially for Brucella antibodies using Rose Bengal test and the competitive ELISA. Weighted seroprevalence estimates were calculated and risk factors in individual cattle investigated using logistic regression analysis. The overall individual animal brucellosis seroprevalence was low, with mean of 5.6% (95% confidence interval (CI), 4.4%, 6.8%). Gokwe had the highest individual (12.6%; 95% CI, 3.9%, 21.4%) and herd-level (40.0%; 95% CI, 22.1%, 58.0%), while Wedza had the lowest individual (2.3%; 95% CI, 0%, 5.3%) and herd-level (8.0%; 95% CI, 0.0%, 18.9%) brucellosis seroprevalence, respectively. In individual cattle, the area of origin, age and history of abortion were independently associated with brucellosis seroprevalence. While the seroprevalence was independent of sex, it decreased with increasing age. Cattle 2–4 years old had higher odds (odds ratio (OR) = 3.2; 95% CI, 1.1%, 9.1%) of being seropositive compared to those >7 years. Cows with a history of abortion were more likely to be seropositive (OR = 7.9; 95% CI, 3.1, 20.1) than controls. In conclusion, the area-to-area variation of brucellosis may be linked to ecological factors and differences in management practices. The implementation of stamping out policy, bleeding and testing animals before movement and promoting the use self-contained units are likely to significantly reduce the public health risks associated with Brucella infections in cattle.     

规模化养猪场疫病防控新措施

在当今的规模化养猪生产中,疫病造成的损失较大,直接导致了许多农户和规模猪场的猪只大量发病和死亡,造成了一定的经济损失。如何制定和实施一系列的疫病防控措施以确保猪场安全生产,是业内人士亟须认真探讨和解决的问题。     

现代化规模猪场猪伪狂犬病防控探讨

猪伪狂犬病是目前规模猪场主要防控的病毒病之一,2018年12月华北地区某现代化规模猪场,妊娠母猪出现流产现象。通过发病背景、临床症状及死胎剖解、现场情况、实验室血清学及病原学检测,此次妊娠母猪流产是由伪狂犬病毒野毒感染所致。采用优质伪狂犬基因缺失疫苗进行紧急接种、改善通风、消除贼风引起的应激措施后,得到了有效的控制。该措施从猪场的饲养管理角度并结合疫苗防控来控制疫病,以期为现代化规模猪场伪狂犬病的防控提供参考。     

An assessment of the economic impact of heartwater (Cowdria ruminantium infection) and its control in Zimbabwe.

Heartwater, caused by the rickettsial organism Cowdria ruminantium, is a serious constraint to livestock development in much of sub-Saharan Africa. Traditionally, the disease has been controlled by the use of chemical acaricides to control the vector tick. The University of Florida/USAID-supported heartwater research project (based in Zimbabwe) is developing a new inactivated vaccine to control the disease. In order that the vaccine is used effectively, the project has been studying the epidemiology of the disease in different livestock production systems of Zimbabwe, and evaluating the economic impact of the disease and of its future control using a vaccine such as the one under development. Initially, field studies were conducted to characterise the communal and commercial livestock-productions systems at risk from heartwater and to understand the epidemiology of the disease. The data from these studies were then applied to an infection-dynamics model of heartwater, which was used to provide estimates of disease incidence and impact under various scenarios over a period of 10 yr. Two principal outputs of the epidemiological model (cumulative annual heartwater incidence and infection-fatality proportion) were key inputs into an economics model. The estimated total annual national losses amount to Z$ 61.3 million (US$ 5.6 million) in discounted value terms over 10 yr. Annual economic losses per animal in the commercial production system (Z$ 56 discounted values) are 25 times greater than the losses in the communal system (Z$ 2.2). The greatest component of economic loss is acaricide cost (76%), followed by milk loss (18%) and treatment cost (5%). Losses in outputs other than milk (beef, traction and manure) appear to be minimal. A new vaccine has the promise of a benefit: cost ratio of about 2.4:1 in the communal and 7.6:1 in the commercial system. A control strategy based on a new vaccine would yield additional non-financial benefits to farmers and the government resulting from reductions in the use of chemical acaricides.     

Management and control of gastrointestinal nematodes in communal goat farms in Zimbabwe

Goats are an important source of livelihood especially in smallholder communities. Infections with gastrointestinal nematodes (GIN) remain the most prevalent parasitic diseases affecting small ruminants. The study was conducted to assess management, the level of knowledge and control of gastrointestinal nematodes. Surveys were conducted in Chipinge, Shurugwi, Binga, Tsholotsho and Matobo districts, representing the five natural/agro-ecological regions (NR) in Zimbabwe. Data was collected in 135 households using a pre-tested semi-structured questionnaire. Results indicated that goats were ranked the most important livestock species, with high flock sizes in NR IV and V. Partitioning of roles was such that the adult males were involved in decision-making while females and children were involved in day-to-day management of animals. Farmers showed low levels of input use, with natural pasture (98.4%) being the main feed source and indigenous breeds (73.2%) being kept. Farmers ranked food and financial benefits as the main reasons for keeping goats. Gastrointestinal nematodes ranked the highest as the most common disease, with majority of farmers (57%) not controlling or treating animals and 63% of farmers not having knowledge on the spread of GIN. Access to veterinary services, anthelmintic class used and breeds used by the farmers had the highest effects on parasitic infections in households. Farmer education is required for capacitation of farmer in terms of disease prevention and control so as to improve goat production.     

The natural control of heartwater vectors

Socio-economic factors and environmental considerations have increasingly encouraged the search for methods of tick control other than acaricidal treatment. Biological control management regimes have, so far, not proved to be sound replacements for acaricides. The major natural control methods employed successfully at present are host resistance and pasture management. The former has been extensively studied and utilized in a one-host-tick situation, and its potential specificity for the Amblyomma species is discussed. Pasture management in the form of tick-resistant plants and habitat modification affecting vector ecology and viability is discussed, as is host availability. Parasites and predators affecting tick populations are gleaned over with the accent on predacious birds (Buphagus species) which may play a limited role in integrated control programmes. Reference is made to the possibilities of genetic manipulation, problems accompanying the implementation of sterile male techniques, and hybrid sterility. In conclusion, a plea is made to ensure a thorough understanding of target vector ecology before any control measures are employed. This should be preferably from an integrated point of view rather than from a standpoint of unilateral reliance.     

浅谈规模猪场母猪子宫内膜炎的防治

近年来母猪子宫内膜炎在集约化养猪场的发病呈上升趋势,尤其是夏天高温季节,母猪产后发病率明显增加,有的养猪场发病率高达40％～60％。本文针对规模猪场的实际情况,提出一些切实可行的措施,为母猪子宫内膜内炎的治疗提供参考。     

Viability of smallholder dairying in Wedza, Zimbabwe

Viability differences in smallholder dairy farming are a result of differences in access to markets and services. It is hypothesized that innovations that improve productivity and market linkages also improve returns and viability. The viability of smallholder dairying in Wedza was characterised by interviewing 52 households using semi-structured questionnaires. Information on demographics, production, marketing, livestock numbers, assets and constraints was obtained. Farmers were resource-constrained with differences in access to resources. The highly resourced farmers had higher milk output and numbers of livestock. Almost 40 % of the households were female-headed, and these dominated the poor category. Household sizes ranged from 4 to 13 persons. Milk off-take was low (3.7?±?0.53 l/cow/day), due to various constraints. Only rich farmers had viable enterprises in purely financial terms. Per litre cost of milk was more than selling price (US$0.96) for most farmers except the relatively rich. Operating ratios were 1.7, 0.6, 1.4 and 1.1 for the poor, rich, sub-centre and milk collection centre farmers, respectively. This means incomes from the dairy activities did not cover costs. Sensitivity analysis indicated that increases in total variable costs and labour reduced returns. Milk production and viability were influenced by access to resources and markets.     

规模猪场肺炎支原体感染的诊断及综合防控措施

由猪肺炎支原体(Mycoplasma hyopneumoniae)引起的猪支原体肺炎(MPS)也称地方流行性肺炎或猪喘气病,是猪只呼吸道感染最为严重的疾病之一.近年来,猪肺炎支原体多与其他病原混合感染,使病情复杂化,病程延长,给养猪业造成了严重的经济损失.     

Risk factors and indicators of reduced welfare of grazing dairy cows from selected smallholder dairy farms in Midlands Province,Zimbabwe

Zimbabwe’s smallholder dairying faces many challenges that affect the welfare of dairy cows; however, the status of this welfare has not yet been determined. A cross-sectional study was conducted in Midlands Province on 41 active smallholder dairy farms with 86 cows in winter and summer to determine the risk factors and indicators to impaired cow welfare. These objectives were achieved using farmer questionnaires and direct observations. Eleven percent of the observed cows were severely lame in summer while only 5% were severely lame in winter. Lameness was significantly associated with season, absence of shade, breed, and low dipping frequency; 58% of the cows had low body condition scores (BC?<?3) and this low BC was associated with low frequency of protein (p?=?0.002) and vitamin (p?=?0.012) supplementation recorded in more than 52% of the farms visited. In winter, only 11% of the observed cows were heavily soiled (score 3), while in summer 64% of the cows were heavily soiled and this was associated with slurry accumulation in more than 80% of the observed cattle pens as well as the study season (p?<?0.001). A quarter (26%) of the studied animals had visible teat lesions on the teat skin and this was associated with the type of lubricant used (p?=?0.011). Only 34% of the cows allowed an approaching stockman to touch them and this was associated with shouting (p?=?0.012) and whipping of cows (p?=?0.002). The study concluded that welfare of dairy cows was poor in most of the smallholder dairy farms studied.     

Productivity of crossbred cattle on smallholder farms in Southern Malawi

Summary A 10-year set of dairy records from a smallholder dairy scheme in the Republic of Malawi was analysed. Environmental and breed effects on the reproductive and productive parameters were evaluated. Age at first calving for 110, 1/2 Friesian and 55, 3/4 Friesian cows were 36·7 and 40·1 months respectively; calving intervals based on 432 and 145 records were 488 and 482 days; total lactation yields on 554 and 227 records were 1,950 and 2,452 kg. Geographical area of operation, parity of cow, year and month of calving and their interactions did not exert a significant influence on reproductive traits but significantly influenced milk production traits. Deficiency in feed supplies was believed to be a possible cause of problems in reproductive performance.

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Productividad De Ganado Cruzado En Pequenas Granjas En El Sur De Malawi

Resumen Se analizan en este trabajo, un grupo de registros provenientes de pequeñas unidades lecheras en la Republica de Malawi. Se evaluaron los efectos de ambiente y raza, sobre los parámetros productivos y reproductivos. La edad a la primera parición de 110 vacas media sengre Friesian y de 55 vacas 3/4 Friesian, fue de respectivamente 36.7 y 40.1 meses; el intervalo entrepartos basado en 432 y 145 registros fue de 488 y 482 dias, respectivamente; la lactación total tomando 781 registros, fue de 1950 y 2452 kg. El área geográfica de operación, el número de pariciones, el año y el mes de parición y la interacción de estos factores, no tuvo influencia significativa sobre rasgos reproductivos. La penuria forrajera, fue considerada la causa principal de problemas en cuanto a la función reproductiva se refiere.

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Productivite Du Betail Croise Dans De Petites Fermes Du Sud Du Malawi

Résumé On a analysé les résultats laitiers d'une action de développement laitier de petites unités laitières en République du Malawi. Les effects de l'environnement et de la race sur les paramètres de reproduction et de productivité ont été évalués. L'âge au premier vélage, chez 110, 1/2 Frisonnes et 55, 3/4 Frisonnes vaches a été de 36,7 mois et 40,1 mois respectivement; l'intervalle interelage base sur 432 et 145 enregistrements a été de 488 et 482 jours; les rendements de lactation totale chez 781 enregistrements ont été de 1950 et 2452 kg. L'aire géographique de l'opération, la parité de la vache, l'année et le mois du vélage et leurs interactions n'excluent pas une influence significative sur les traits de reproduction, mais influent significativement les traits de production laitière. On suspecte une déficience dans la fourniture de la ration comme cause possible des problèmes de reproduction.

     

规模化猪场防控高致病性猪蓝耳病的主要措施

高致病性猪蓝耳病是由猪繁殖与呼吸综合征(Porcine Reproduc tive and Respiratory Syndrome,PRRS)病毒变异株引起的一种急性高致死性疫病。仔猪发病率可达100%,死亡率50%以上,     

规模化猪场大肠杆菌病防控策略探析

猪大肠杆菌病是养猪生产过程中比较容易发生一种细菌性传染病,能够造成哺乳仔猪发生黄痢、白痢,以及保育猪发生水肿病.虽然猪场规模化程度得到很大的提升,但猪大肠杆菌病仍是困扰猪场管理者的重要猪病,影响着猪场的盈利水平.因此,文章主要从临床分类、临床症状、病理变化、防控策略4个方面进行阐述,以期为猪场管理者、兽医工作者防控该病...     

The control of heartwater by means of tick control

Two main methods are currently being used by farmers in the heartwater regions to control this disease in cattle and other stock, namely strategic control of ticks and total control of ticks. Some farmers make successful use of the latter method, particularly in areas which are marginal for the disease. Total tick control requires top managerial skills, which includes continual expert supervision, a relatively rare asset. The majority of farmers, often unintentionally, apply strategic control of ticks to control heartwater, either without or with vaccination against the disease. In this case the objective of tick control is to minimize "tick worry" without interfering too drastically with natural transmission of the disease. This method would make provision for natural immunization of young animals (a more uncertain method than vaccination) and the maintenance of immunity. In practice these methods appear to diminish deaths from heartwater appreciably, but do not protect all animals from the disease. Furthermore, they appear to be more effective in cattle than other stock. Although strategic control has an evolutionary background and considerable merit under African conditions, it is being applied in an empirical way because of paucity of information on the epidemiology of heartwater. More information on the infection rate in and infectivity of ticks (percentage of infected ticks) offer challenging research possibilities.     

规模化猪场仔猪黄痢的诊断及综合防控

仔猪黄痢是由大肠埃希氏菌(EsherichiaColi)的某些致病血清型引起的猪的一类传染病,主要发生于1-7天龄的初生仔猪,尤其以1-3天龄最为常见。该病以拉黄色糊状稀粪为主要特征,发病率很高。若不采取措施,其死亡率可高达90%～100%。由于大肠杆菌极易产生耐药性,而且血清型众多,血清     

规模化猪场母猪子宫内膜炎的病因及防治对策

笔者在规模化猪场多年的生产实践及广泛的调查中发现，规模化猪场的母猪（包括经产母猪和后备母猪）经常发生子宫内膜炎，发病率为20％左右，有的猪场高达40％。患猪若得不到及时有效的治疗，往往会转为隐性或慢性感染，或不愿给仔猪哺乳；或泌乳量减少、无乳；或乳汁质量差，致使哺乳仔猪拉稀，发育不良；或发情周期紊乱，屡配不孕；或产仔少，产死胎；或继发感染败血症等，严重地影响了猪场的生产力，造成较大的经济损失。如何解决这一日渐突出的问题，笔者总结多年的生产实践探索，就其症状、病因及防治等实践体会简介如下，供同行参考。     

Radioimmunoassay of milk progesterone as a tool for fertility control in smallholder dairy farms

This study focused on the use of radioimmunoassay of progesterone in milk for the diagnosis of post-partum ovarian cyclicity and accurate detection of oestrus and non-pregnancy in cows in the artificial insemination (AI) programme in Bangladesh. In Investigation 1, milk samples were collected on day 0 (day of AI), day 9–13 and day 21–24 from 444 milking cows of various breeds presented for the first post-partum insemination by 413 farmers living at 182 villages/regions in Mymensingh District from 6 AI centres and sub-centres. Each cow was then examined three times after each AI until it stopped returning to oestrus. Sixty to 90 days after the last AI, the cows were examined per rectum to confirm the pregnancy. Milk progesterone data on day 21–24 contributed to a clear diagnosis with respect to non-pregnancy in 100% cows, indicating a possible use of this progesterone assay for identifying non-pregnant cows in AI programmes. In Investigation 2, milk progesterone was monitored two times in a month with a 10-day interval in 88 cows. The samples were taken between 10 days after calving and the first detected oestrus, followed by two more samples 10 days apart. The proportion of cows accurately detected in oestrus was 30%. Another 30% were stated to be in oestrus when they were not (false positive) and 40% were not detected when they were in oestrus (false negative). The mean intervals between calving and oestrus and between calving luteal activity were 40 to 362 days (median = 120, n = 82) and 34 to 398 (median = 111, n = 64) days, respectively. The body condition scores at calving and at the initiation of luteal activity influenced the interval between calving and luteal activity (p < 0.05). Cows suckled twice daily initiated luteal activity earlier than their counterparts suckled several times daily (p < 0.05). Determination of progesterone in milk on day 21–24 is a good means for detecting non-pregnant cows.     

Calf health and management in smallholder dairy farms in Tanzania

Smallholder farmers’ knowledge and practice of dairy calf management on 129 farms with calves less than 10 months of age in Southeastern and Southern Highland areas of Tanzania was assessed. The method of study included both a farm visit and completion of a questionnaire. Most of the farmers were female, with a primary level of education, and majority kept 1–3 milking cows that yielded 6–10 l milk/cow/day. Most of the calves were fed milk using a residual calf suckling system. Weaning age was 3–8 months. Overall, the body condition of the calves was poor, ranged from 1 to 2.5 with a mode of 2. The majority of the farmers believed that helminthosis was the most common disease condition affecting the calves; diarrhea was ranked as the second. Calf death was reported by 20% of the farmers to have occurred in their herd lasting the 2 years prior to the study. Calf body condition score was related to body weight for calves younger than 9 weeks, and older than 23 weeks of age, whereas no such relationship existed in the age group 9 to 23 weeks. The sex distribution was skewed with less male calves being older than 23 weeks. We hypothesize that male calves experience inferior management compared with female calves. This study demonstrates a low level of knowledge on, and poor practices of calf management among the surveyed farmers that suggest the need for educational intervention.     

The clinical pathology of heartwater. II. Studies on cardiac and pulmonary function in 4 calves with experimentally-induced heartwater

Studies to evaluate cardiac and pulmonary function were undertaken in 4 calves suffering from experimentally-induced heartwater. There was a marked variation in the course of the disease. Three of the calves recovered spontaneously after developing clinical signs. These included a rectal temperature in excess of 40 degrees C, anorexia and listlessness but no neurological signs. The remaining calf died 2 days after developing a fever and neurological signs. In the 3 calves that recovered, a mild hypoxemia developed during the acute stage of the disease. Arterial CO2 tension remained within normal limits, but there was a tendency towards an alkalosis. Increases in pulmonary dead space and fluctuations in venous admixture were observed. The calf that died showed similar mild changes in blood gas parameters, despite the presence of a marked reduction in minute volume, and a lung oedema was demonstrated on post-mortem examination. No marked changes in systolic and diastolic blood pressures and in right cardiac intraventricular pressures were observed. Terminally, however, there were marked decreases in stroke volume and cardiac output. These changes were associated with a sharp increase in heart rate. No primary cardiac pathology was observed on clinical and post-mortem examinations.