Investigations on the seasonal patterns of strongyle infections in grazing lambs, and the occurrence of anthelmintic resistance on sheep and goat farms in western Anatolia, Turkey

Abstract

The seasonal patterns of strongyle infections in untreated, weaned lambs were determined on four governmental farms during a grazing season. In three farms, the infection level (predominantly Teladorsagia spp. and Trichostrongylus spp.) measured by egg counts or worm burdens remained low throughout the study; higher egg counts mainly caused by Haemonchus contortus were transiently recorded on the fourth farm. Significant body weight gains were observed in all groups, but they varied between farms irrespective of the level of strongyle infections, suggesting that the economic effectiveness of anthelmintic treatments of weaned lambs is doubtful under the extensive grazing conditions and the hot, dry climate in the region. In the second part of the study, faecal egg count reduction tests were performed for albendazole, thiabendazole, tetramisole and ivermectin on 12 sheep and goat farms to provide first information on anthelmintic resistance in trichostrongyles of small ruminants in Turkey. There was no hint of benzimidazole resistance, and unequivocal evidence of ivermectin resistance was missing. In contrast, tetramisole resistance was detected on one sheep farm.

Checklist of small ruminant gastrointestinal nematodes and their geographical distribution in Turkey

“…The seasonal activity of the parasites differs according to animal species and age, parasite species, and geographic locality (15,17,36,37). The most effective factors are temperature and relative humidity on the seasonal activity of GI nematode species and development of eggs and larvae (6,36).…”

“…The most effective factors are temperature and relative humidity on the seasonal activity of GI nematode species and development of eggs and larvae (6,36). Several studies done at different times in the same region show that the variety of GI nematode genus/species and their maximum levels result from different climate conditions in the study period (Table 2) (17,37,(45)(46)(47).…”

“…circumcincta) (11,37,40,48), followed by Trichostrongylus (T. axei, T. capricola, T. colubriformis, and T. vitrinus), Nematodirus (N. spathiger, N. filicollis, and N. abnormalis) (11,35,(48)(49), and H. contortus (Table 1). In the southern Marmara Region, Tinar et al (37) reported that an increase in egg shedding was observed in October and November and maximum worm counts were detected during midsummer. Haemonchus contortus was found only during the first 3 months on pasture, and in autumn only Teledorsagia spp.…”

“…The different articles cover the major risk factors for GI nematodosis that have been found in Turkey, such as breed (33), nutrition (34), age, sex (11,12,35), and season (15,17,(36)(37)(38). These factors were particularly evaluated as follows.…”

Impact of treatment of gastrointestinal nemathelminths on body weight of sheep and goats

“…Helminth parasites are the cause of impaired output in small ruminants all over the world (Tinar et al 2005) including India (Shende et al 2007) where the environmental conditions like temperature, humidity and rainfall are favourable for perpetuation of parasites as compared to temperate regions (Singla 1995;Haile et al 2010). They limit the productivity of animals as some of them are voracious blood suckers like Haemonchus spp.…”