Emerging parasitic diseases of sheep

There have been changes in the emergence and inability to control of a number of sheep parasitic infections over the last decade. This review focuses on the more globally important sheep parasites, whose reported changes in epidemiology, occurrence or failure to control are becoming increasingly evident. One of the main perceived driving forces is climate change, which can have profound effects on parasite epidemiology, especially for those parasitic diseases where weather has a direct effect on the development of free-living stages. The emergence of anthelmintic-resistant strains of parasitic nematodes and the increasing reliance placed on anthelmintics for their control, can exert profound changes on the epidemiology of those nematodes causing parasitic gastroenteritis. As a consequence, the effectiveness of existing control strategies presents a major threat to sheep production in many areas around the world. The incidence of the liver fluke, Fasciola hepatica, is inextricably linked to high rainfall and is particularly prevalent in high rainfall years. Over the last few decades, there have also been increasing reports of other fluke associated diseases, such as dicroceliosis and paramphistomosis, in a number of western European countries, possibly introduced through animal movements, and able to establish with changing climates. External parasite infections, such as myiasis, can cause significant economic loss and presents as a major welfare problem. The range of elevated temperatures predicted by current climate change scenarios, result in an elongated blowfly season with earlier spring emergence and a higher cumulative incidence of fly strike. Additionally, legislative decisions leading to enforced changes in pesticide usage and choices have resulted in increased reports and spread of ectoparasitic infections, particularly mite, lice and tick infestations in sheep. Factors, such as dip disposal and associated environmental concerns, and, perhaps more importantly, product availability have led to a move away from more traditional methods of pesticide application, particularly dipping, to the use of injectable endectocides. This has coincided with increased reports of sheep scab and lice infestations in some countries. Reduction in the use of organophosphate dips appears to have to some extent contributed to reported increased populations of ticks and tick activity, a consequence of which is not only of significance to sheep, but also many other hosts, including increased human zoonotic risks.     

Genetic aspects of sheep parasitic diseases

There is evidence of genetically determined host resistance mechanisms for most of the sheep parasites evaluated. The mechanisms vary; from no or reduced establishment, early expulsion, to suppression of parasites resulting in reduced size and fecundity. There is a need to integrate breeding for parasite resistance with the genetic improvement of production traits in farm animals, aiming for optimum solutions for potentially conflicting responses. Sustainable parasite control must be based on Integrated Parasite Management utilising an interdisciplinary approach.     

综合性防治舍饲羊寄生虫病

寄生虫是危害养羊业的大敌,其种类繁多、分布广,危害具有隐蔽性和渐近性,特别是农区舍饲时,由于饲养密度大,增加了寄生虫的感染机会,单纯的药物驱虫不但达不到预期的目的,而且容易造成畜产品药物残留,影响畜产品品质.只有按照"预防为主,养防结合,防重于治"的原则,并结合当地实际,采取综合性防制措施,才能有效地减少和控制舍饲羊寄生虫病的发生和流行,保障家畜和人类的健康,减少经济损失,确保养羊业的顺利发展.     

Integrated control strategies for ectoparasites in Scottish sheep flocks

Ectoparasite infestations of sheep can result in serious animal welfare and financial losses. Many of the veterinary medicines used in their control can be harmful to humans and other species. These undesirable side-effects mean that trade-offs may be necessary and make it difficult to determine ‘the best’ control strategy. This problem is common to many animal health/welfare concerns, and must be addressed if progress is to be made under the Animal Health and Welfare Strategy for Great Britain. This paper describes an approach to such cases using a disease model to identify the financially optimal ectoparasite control strategies at the farm level for Scottish conditions in a climate of changing control restrictions. Our approach takes a wider systems perspective than is usual in cost-benefit studies of animal disease. The findings demonstrate that both flock size and ectoparasite risk are determinants of optimal control strategies. In addition the benefits of livestock biosecurity practices (isolation and treatment of incoming stock) for the control of sheep scab are demonstrated. The importance of dip products for the effective control of ectoparasites is discussed and possible implications if these become unavailable or the cost of their usage increases. Interdependence between stakeholders is highlighted, indicating a need for regional co-operation between farmers and a more integrated approach to control of some farm animal diseases.     

An epidemiological study of parasitic gastroenteritis in sheep under an intensive grazing system

Romanov X Rasa Aragonesa ewes rearing twins and kept on pasture at a mean stocking density of 35 ewes ha-1 were used to study the epidemiology of parasitic gastro-enteritis under an intensive grazing system on irrigated land in the northeast of Spain. Measurements were made of the population of infective larvae on the pasture, level of serum pepsinogen, faecal worm eggs in ewes and lambs, and lamb growth rates. In addition, postmortem worm counts from "indicator" lambs were used to establish the level of infection at each rotational grazing cycle. Two generations of parasites were identified in the experiment. One of them, derived from the eggs deposited the previous autumn, gave rise to the first infection of the animals in March and April. This was responsible for the first outbreak of parasitism in the lambs. This was indicated by an increase in serum pepsinogen levels, the appearance of diarrhoea and a significant decrease in lamb growth rates. Ostertagia spp., Nematodirus spp. and Trichostrongylus spp. were present. The second generation, which appeared during May, was derived from the eggs of the previous generation and gave rise to an outbreak of parasitism in the lambs at the beginning of May and the middle of June. Haemonchus spp. and Chabertia ovina were present. Under the conditions of this experiment, the overwintering larvae have an important epidemiological significance as the gastro-intestinal nematodes are one of the main limiting factors for developing intensive sheep production systems.     

Evaluation of Egyptian sheep production systems: I. Breed crosses and management systems

Our objective was to evaluate life-cycle performance of flocks of two Egyptian breeds, Rahmani (R) and Ossimi (O), and their crosses with Finnish Landrace (F) in two management systems. Management systems were one mating season per year (1M) and three mating seasons per 2 yr (3M). Breeds and crosses studied included purebred R and O, F1 crosses 1/2F-1/2R (FR) and 1/2F-1/2O (FO), and inter se matings of 1/4 F-3/4 R (RFR) and 1/4 F-3/4 O (OFO). A dynamic computer model was used to simulate animal performance and enterprise efficiency and profit. Two measures of lifecycle feed conversion (biological efficiency) were computed: kilograms of TDN input per kilograms of empty body weight output (TDN/EBW) and kilograms of TDN input per kilogram of carcass lean output (TDN/CLN). Profit was measured as gross margin (income minus variable costs per ewe per year, GM/EWE). Input parameters for the model were obtained from published results and analyses of data collected from experimental flocks of the same genetic stocks in Egypt. Profit for FR and RFR was 42 and 6% higher in 1M than in 3M. However, profit for all other genetic types was 4 to 8% greater in 3M than in 1M. Breed rankings changed depending on the measure of evaluation (i.e., biological efficiency or profit). Maximization of system output did not necessarily improve efficiency. Under accelerated lambing systems, greater overhead costs associated with labor and feed offset gains in ewe productivity. Genetic stocks should be matched to resources and management systems.     

Improving the assessment of the economic impact of parasitic diseases and of their control in production animals.

This paper reviews the ways in which the economic impact of parasitic diseases of production animals have been evaluated. It then discusses the shortfalls of such studies, as well as the opportunities for improving the quality of economic impact assessments and their value to decision makers in the future. The paper first identifies the impacts that are specific to parasitic diseases. It then goes on to review the abundant literature on estimating the total costs of diseases. The authors argue that this approach severely limits the opportunity for economic assessments to aid decisions in disease control and research. The paper then reviews the literature on studies of avoidable costs, before discussing ways in which economic impact assessments can be enhanced. These issues include greater emphasis on incorporating the lost productivity potential caused by parasitic diseases, greater emphasis on valuing actual rather than intended control measures, and greater emphasis on quantifying the productivity effects at the societal level, particularly in the developing world.     

Strategies for the management of donkey jacks in intensive breeding systems

Donkeys are bred throughout the world and often play an important role in agriculture. They are also bred to produce mules. Traditionally, jacks are considered challenging to breed in domestic conditions, whether for natural breeding or semen collection using either jennies or mares. The donkey's natural sexual behaviour significantly differs from that of other domestic animals. This presents challenges for in‐hand donkey breeding, particularly on mule studs where normally only jacks and mares are kept for breeding. This article describes some of the authors' observations on sexual behaviour in donkeys and practical experience of some of the strategies employed to apply this knowledge to breeding management, in order to improve the success of using donkeys for both natural service and semen collection.     

氟雷拉纳在动物寄生虫疾病控制中的应用进展

氟雷拉纳是一种新型应用于动物的驱体外寄生虫长效药,属于异噁唑啉类的广谱驱虫药,最早被使用在农业杀虫,新型的高效 GABA 控氯离子通道干扰剂,与环戊二烯类、苯基吡唑类和大环内酯类等杀虫剂的作用靶标类似。氟雷拉纳对蜱目、蚤目、虱目、半翅目和双翅目等昆虫均表现出很好的杀灭效果,并且对哺乳动物无明显的毒性影响。近年来,氟雷拉纳被国内外动物医学和农业科学学者关注,用于动物体外寄生虫病的治疗和预防。本文就氟雷拉纳国内外动物寄生虫方面的研究进展进行了分析。     

庆城县羊梭菌病的调查与防治

1自然地理概况 庆城县隶属甘肃省庆阳地区管辖,地处陇东黄土高原残塬沟壑区,总面积约2600km^2,其中耕地面积54866．67hm^2,天然草场面积126666．67hm^2,人工种草35333．3hm^2,其中紫花苜蓿14666．67hm^2。县内山、川、塬兼有,地势北高南低,从北向南倾斜,海拔1000—1600m,     

Utilisation of dried caged-hen manure and cassava peels for intensive sheep production

Summary Twenty grower ewes with an average weight of 14·3 ± 3·7 kg were allotted to 5 dietary treatments. The diets contained 0, 13, 25, 35 and 45% dried caged-hen manure which replaced 0, 25, 50, 75 and 100%, respectively of the conventional protein supplements. The animals were fed 55·0 g/w^0·75 kg/day of the concentrate food during a 104 days growth study. Air dried cassava peels and water were also providedad libitum.The differences in average total dry matter intake were not statistically significant. The higher the manure content in the diets, the lower the energy content and the higher the cassava peels intake. No statistical differences were found in growth rates. The efficiency of food conversion decreased progressively though insignificantly.It was concluded that sheep can be fed caged-hen manure as the sole protein supplement in cassava peel based diets.

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Utilizacion De Gallinaza De Aves De Jaula Y Cortes De Yuca Para La Alimentacion Intensiva De Ovejas

Resumen Veinte ovejas en crecimiento con un peso promedio de 14·3 ± 3·7 kg se sometieron a 5 tratamientos. Las dietas contenian 0, 13, 25, 37 y 45% gallinaza, la que remplazó 0, 25, 50, 75 y 100%, respectivamente del suplemento proteínico normal. Los animales comieron 55·0 g/w^0·75 kg/día del alimento concentrado durante los 104 días del estudio. Rebanadas de yuca seca y agua se les proporcionóad libitum.Las diferencias en el promedio de ingestión de materia seca no fueron estadísticamente significativa. Entre más gallinaza había en la dieta, más baja era la energía y más alta la ingestión de rebanadas de yuca. No se encontraron diferencias estadísticas en la tasa de crecimiento. La eficiencia en la conversión alimenticia decreció progresivamente aunque en forma insignificante.Se concluye, que las ovejas pueden alimentarse con gallinaza de aves de jaula, como sola fuente de proteína en dietas basadas en yuca desmenuzada.

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Utilisation De Fientes Dessechees De Poules Pondeuses Et De Pelures De Manioc Pour La Production Ovine Intensive

Résumé Des rations différentes ont été données à 20 brebis en croissance, d'un poids moyen de 14,3 ± 3,7 kg, réparties en 5 groupes. Elles contenaient de 0, 13, 25, 35 et 45 p. 100 de fientes desséchées en remplacement respectivement de 0, 25, 50, 75 et 100 p. 100 de compléments protéiques conventionnels. Les animaux ont reçu 55g/p 0,75kg/jour d'aliment concentré pendant les 104 jours de l'étude. Des pelures de manioc desséchées à l'air et de l'eau ont été mises en leur disposition,ad libitum. Les différences de quantités volontairement ingérées de matière sèche totale n'ont pas été statistiquement significatives. Plus la quantité de déjections dans la ration était élevée, plus faible était la teneur en énergie du régime et plus la consommation de pelures de manioc était élevée. Les vitesses de croissance n'étaient pas statistiquement différentes. L'indice de consommation a diminué progressivement, bien que de façon non significative, avec l'augmentation du taux de fientes dans les rations. Les auteurs ont conclu que les fientes de volailles peuvent être utilisées comme complément protéique unique dans des rations à base de pelures de manioc.

     

Technological characterization of sheep production systems in Brazil

Sheep production has expanded in Brazil focusing on lamb meat, mostly to meet demanding internal markets in the state of São Paulo. Such markets present a demand which internal production is insufficient to meet. However, sheep farmers face many technical difficulties to produce quality lambs at viable costs. This study aimed at investigating the main characteristics of sheep production systems of the state of São Paulo, Brazil, in order to provide resources for the development of technologies, policies and other initiatives focused on the activity. We designed in panel meetings the characteristics of representative sheep farms in five regions of the state, concerning: (i) property and manpower profile; (ii) flock; (iii) handling techniques; (iv) facilities and equipment; (v) food production; and (vi) technical indicators. Results demonstrate that the predominant sheep farming in the state employs low technology, presenting low productivity despite its evolution in recent years. We verified great technical deficiency regarding farmers, who are new in this business and usually do not have access to technologies. Producers' unawareness about basic handling procedures and techniques as well as their lack of flock records can contribute to the activity's unsustainability. There is need for improving rural extension and diffusion of technologies.     

规模化养鸡场的疾病控制

湖北省农业科学院畜牧兽医研究所家禽研究开发中心有着几十年历史,1995年以前种鸡规模尚不足1万套,在这种严峻形势下,却能够在市场中站稳脚步,并逐步发展壮大,现发展为月存栏种鸡3万套、育成鸡近10万套的中型种禽场.奥秘何在,除了有坚强的科研实力作后盾,其灵活的管理机制、人尽其才的用人机制和对疾病的一整套综合防制体系缺一不可.现在我们分析一下其疾病综合防制的成功经验.     

牦牛主要寄生虫病高效低残留防治技术研究(中)

为制定埃普利诺菌素(EPR)休药期及建立牦牛主要寄生虫病高效低残留防治技术提供科学依据。采用荧光高效液相色谱法(HPLC-FLD)检测埃普利诺菌素(EPR)注射剂在牦牛奶中的残留消除规律。结果表明:给泌乳牦牛皮下注射EPR注射液0.2mg·kg^-1剂量,EPR在牛奶中分布浓度较低,在给药后54.00h,牛奶中的EPR浓度达到峰值7.38±2.61ng·mL^-1,该值低于美国规定的EPR在牛奶中的最高残留限量(12ng·mL^-1)和欧盟及联合国粮食与农业组织(FAO)规定的EPR在牛奶中的最高残留限量(20ng·mL^-1)。给泌乳牦牛皮下注射EPR注射液0.4mg·kg^-1剂量,EPR在牛奶中分布浓度较低,在给药后42.00 h,牛奶中的EPR浓度达到峰值8.42±4.62 ng·mL^-1,最高值低于欧盟和联合国粮食与农业组织(FAO)规定的EPR在牛奶中的最高残留限量(20 ng·mL^-1),略高于美国规定的EPR在牛奶中的最高残留限量(12ng·mL^-1);在给药后56.00 h,牛奶中的EPR浓度达到峰值6.98±2.98 ng·mL^-1,该值低于美国规定的EPR在牛奶中的最高残留限量(12ng·mL^-1)和欧盟及联合国粮食与农业组织(FAO)规定的EPR在牛奶中的最高残留限量(20ng·mL^-1)。国产药物试验组与进口商品化制剂对照组的两种EPR浇泼剂在牦牛血浆中的残留消除规律,分别于1.67±0.2d与1.83±0.61d(Tmax)在血浆中达到最高药物浓度(Cmax)7.88±2.68ng·mL^-1与5.94±2.80ng·mL^-1,两种EPR制剂的生物等效性无显著性差异。国产和进口两种制剂的残留均低于联合国粮食与农业组织(FAO)所规定的最高残留限量(20ng·mL^-1)。研究结果表明,EPR注射剂0.2mg·kg^-1、0.4mg·kg^-1,EPR浇泼剂0.5mg·kg^-1推荐剂量用于泌乳牦牛无需弃奶期,牦牛乳用时无需休药期或建议休药期为1d。为建立牦牛主要寄生虫病高效低残留防治技术提供了依据。     

鸡病防治中存在的问题及对策浅议

近年来,随着养鸡业的迅速发展,特别是城郊养鸡规模的不断扩大,鸡病越来越多,对养鸡业本身和环境都已造成了严重影响,急需解决.现就我县为例,谈谈鸡病防治中存在的问题及对策.