Epidemiologic situation and control of gastrointestinal parasites in sheep

Internal gastrointestinal parasites can be a major problem for sheep. Most often found internal parasites of sheep include roundworms, tapeworms and protozoa (e.g. coccidia) that live within the digestive tract. These organisms cause a range of problems including decreased growth rate of lambs, poor reproductive performance of ewes, and can kill animals if left unchecked. Damage to the lining of the stomach and/or intestine can be severe enough to prevent nutrient absorption causing diarrhea and severe weight loss. Certain types of worms ingest blood, causing anemia and weakening the animal. With repeated exposures, sheep can develop a natural resistance to parasite infections. Even though adult animals will be relatively immune, if they are not managed properly they can contaminate the environment increasing the likelihood that vulnerable animals will be infected. Implementing a well planned parasite management program is a very important aspect of every flock health program. Effective control of internal parasites can make a large difference in the productivity and profitability of every flock. Effective flock health program development requires huge amount of knowledge and experience. Lithuanian experience in sheep growing is relatively small, that is why there is a big risk in making mistakes, which could cause such a problems like loss of profit due to poor growth of lambs, or even bigger problems like development of parasite resistance to anthelmintic treatment. The aim of Master thesis was to evaluate the intensity of invasion of gastrointestinal parasites in sheep in two flocks, taking into account farms’ size, age of animals, as well as to analyze the efficacy of parasite management strategy in these flocks. Two flocks of sheep (over 2000 and over 200 animals) in Lithuania were analyzed. Parasite management programs, which include chemical dewormers and pasture management in one flock (2000 animals), and only pasture management in other flock (200 animals), were evaluated. Chemical dewormers’ efficacy (used in 2000 animals having farm) was calculated. L3 stage larvae were cultured in order to identify gastrointestinal nematodes by species. During experiment, feces of lambs and adult sheep were investigated from April to October, 2012. Parasite species were identified. The number of eggs per gram was calculated. This number was the guideline for parasite program management efficacy evaluation. The parasite variety found in gastrointestinal tract correlate with the information given in scientific literature. They include: gastrointestinal nematodes (Trichostrongylidae spp.), tapeworms (Moniezia spp.), protozoa (Eimeria spp.) The results of the performed study showed that there is a lack of systemic approach to parasite management. The insufficiency of only pasture management without chemical dewormers was indicated even in brand new farm. Good knowledge of parasite life cycles, influence of climate to parasite development, chemical dewormers characteristics should be known and used by every flock holder. Only this approach brings a possibility of efficient parasite management in the flock