The Goat as a Risk Factor for Parasitic Infections in Ovine Flocks

Abstract

Small ruminants in northwestern Spain are frequently managed in mixed flocks. Sheep–goat joint management has not been considered a risk factor for parasite infection, so the main objective of this study was to establish if mixed management with goats supposes a risk factor for parasitic infections in ovine flocks. Two thousand and ninety-three sheep were sampled from 74 commercial meat ovine flocks for diagnostic of the main parasites. Goat contact was a risk factor for sheep to be infected by protostrongylids, Dictyocaulus filaria, gastrointestinal nematodes and Eimeria spp. In contrast, Moniezia, Fasciola hepatica, Dicrocoelium dendriticum and Paramphistomidae prevalences were not influenced. Sheep–goat mixed management can be considered as a risk factor, since goats would act as a source of pasture contamination for interspecific parasites (protostrongylids, Dictyocaulus filaria and gastrointestinal nematodes). In relation to host-specific parasites, such as Eimeria spp., goats cannot be considered as a source for sheep, but competition for food and spaces between both small ungulates can suppose a reduced grazing area to sheep, provoking high environmental contamination and stress that facilitate their infection. Future epidemiological studies for parasitic infections in small ruminants should consider sheep–goat mixed management as a possible risk factor to be included in multivariate analyses.

Rumen and Liver Fluke Infections in Sheep and Goats in Northern and Southern Germany

“…Despite this limitation, it can, however, be assumed that the prevalence of rumen flukes in goats is indeed very low in Germany. The observed difference in prevalence between goats and sheep, as well as cattle, is also reflected in previous studies [ 10 , 38 , 39 , 42 , 50 ]. A possible explanation is the different feeding behavior of the three ruminant species.…”

“…It was also below the prevalence of 5.5% recently identified in German cattle by our research group using identical methods (Lower Saxony: 10.9%, Bavaria: 4.4%) [ 6 ]. In comparison to cattle, a lower rumen fluke prevalence in small ruminants has also been observed in most other European studies which simultaneously studied or conducted comparable studies in all these species [ 10 , 38 , 39 , 42 , 44 , 54 , 65 ]. The detected prevalence of patent F. hepatica infections was similar to the percentages of positive farms or samples identified in previous German studies [ 41 , 48 , 50 ], despite considerable differences in farm numbers, representation, and farm or sample selection.…”

“…A comparison of our results to previous European studies is difficult due to the great variation in the conditions for participation, sampling, examination methods, and climate and the lack of representativeness of the selected areas or farm types [ 10 , 38 , 39 , 40 , 42 , 43 , 46 , 48 , 50 ]. For example, a rumen fluke prevalence of 8.0% was reported in the Netherlands, but the authors discuss that this may be an overestimation due to a bias in participating flocks located in areas with a high risk of F. hepatica infections [ 10 ].…”

“…It is possible that the applied sedimentation technique was not sufficiently sensitive to detect low egg counts and thus contributed to a potential underestimation of the prevalence in this coproscopical study. Sedimentation techniques are, however, a common method for the detection of rumen and liver fluke eggs [ 1 , 61 ] and have been widely used in comparable studies [ 8 , 9 , 14 , 39 , 42 , 44 , 46 , 54 ]. Further potential reasons for the difference between historically reported and coproscopically identified rumen fluke infections are examinations during the prepatent period [ 68 ], or very low egg excretion, possibly due to (still) low adult fluke burdens.…”

Prevalence of Gastrointestinal Parasites in Small Ruminant Farms in Southern Spain

“…The higher cumulative FOC of Eimeria spp. in goats compared to sheep aligns with previous studies [41], and contrasts with other authors where the opposite situation was observed [24]. As anticipated, the development of robust immunity with aging resulted in a lower cumulative FOC observed in our study in adults compared to pre-adults in both species, which is consistent with previous studies [5,24,36].…”