Abstract
Due to the widespread resistance of small ruminant gastrointestinal nematodes (GIN) against anthelmintic drugs the established control strategies need to get adapted, aiming to reduce their high dependence from chemical drugs. Host-specific development of GIN can be used as a tool when grazing different species on the same pastures. The aim of this study was to estimate the effect of mixed grazing with cattle on the development of GIN infections in goats. Goat flocks with 3 heifers (Group Mix; Visp: n = 12, Chur: n = 15) and without heifers (Group Solo; Visp: n = 7, Chur: n = 15) were grazed separately on pastures at altitudes of 910 m (location Chur) and 1240 m (location Visp) above sea level resp. during one grazing season each. The composition of the mixed groups aimed to achieve a similar intake of roughage of both species. The stocking rate and the availability of roughage in the solo groups was balanced proportionately according to the situation in the mixed groups. The individual GIN egg excretion, the composition of the GIN larvae in the faeces, the FAMACHA©-Score and the pasture contamination with infective GIN larvae was determined in monthly intervals. At both sites the goats in the mixed groups showed a significantly lower mean GIN egg excretion compared with those of the Solo groups (p < 0,00001). Goats from the Solo groups excreted on average 2,7 times (Visp) and 1,4 times (Chur) more Haemonchus-eggs per gram faeces, compared with those of the mixed groups. The mean GIN larval counts on pastures of the Solo groups were about twice as high compared with those of the mixed groups (p = 0,005). Group Mix from Chur showed a significantly better mean anaemia score compared with group Solo (p = 0,009), whereas in the trial Visp there was no significant difference (p = 0,4). Calculated over both experimental sites the frequence of anthelmintic treatments was significantly higher in the Solo groups compared with the mixed groups (p = 0,02). The results indicate that goats may profit significantly with respect to GIN infections when kept in a mixed grazing system with cattle. This concept should therefore be used as a complementary strategy in goat GIN management.
Bucher, E