Sheep parasitism and its control by medicinal plants: A review

Sheep production is a major source of income for resource poor farmers of the world. The main purpose of sheep raising is to fulfill the needs for mutton, milk, and wool production. Parasitic diseases, one of the principal hindrances in the development of commercial livestock business, are facilitated through favorable climatic conditions and lack of awareness. A variable prevalence ranging from 18.63 to 100% of different gastrointestinal parasite (GI) species in sheep were reported from different parts of the world. Incidence, prevalence, and intensity of parasitic infections is a multifactorial phenomenon and depends on environment, geographic location, pasture condition, host characteristics, grazing habits, and nutritional status. Prevalence of parasitic infections not only adversely affects animal health but also causes huge economic losses up to billions of rupees by decrease in milk, meat and wool production, retarded growth, parasite control measures and death of animals. For the control of GI parasites in small ruminants especially kept by resource-poor farmers, it is better to identify the burden and types of helminths along with specific risk factors associated with helminthosis of a specific area. Factors responsible for development of resistance are lavish use of anti-parasitic drugs, poor efficacy of anti-parasitic agents, inadequate dose level, low protein diet and environmental toxicity. Due to limitations of chemotherapy during the past decade, use of plants with anthelmintic properties (ethnoveterinary medicine) are under consideration around the world. A number of plant species have been identified with anti-parasitic properties that may disturb the regular physiological functions of parasites. Use of plants with anthelmintic properties is considered the best choice for control of parasites in the present scenario. In this review, sheep production, GI parasitic infection of sheep, medicinal plants, and their uses for control have been described.