Effects of strategic anthelmintic treatments on the milk production of dairy sheep naturally infected by gastrointestinal strongyles

The present paper was aimed at assessing the benefit of strategic anthelmintic treatments on milk production in four commercial dairy sheep farms in Southern Italy whose animals were naturally infected by gastrointestinal (GI) strongyles and Dicrocoelium dendriticum. The scheme was based on two treatments timed in relationship to parturition, i.e. the first with moxidectin in the periparturient period and the second with netobimin at the mid/end of lactation. On each farm, two similar groups (20 animals each) were formed, one untreated control group and one group treated according to the above-mentioned scheme. Faecal egg counts (FEC) were performed on each study animal at the start of the trial and then monthly until the end of the study; in addition, milk production was recorded for each animal fortnightly in each farm for the lactation period. The results showed a significant increase in milk yield across all four farms that ranged from 19% to 44% improvement in milk yield. The benefit in milk yield in addition to considerably reduced egg output of the treated animals provide clear evidence that the two main aims of prophylactic parasite control, i.e. to maintain or improve animal performance and to reduce pasture contamination, can be achieved using strategic anthelmintic treatments.