Evaluation of Moxidectin as a strategic dosage of the prepartum in sheep

Abstract

A study has been made with the objective of evaluating the action of Moxidectin (MXD) in gatrointestinal nematodes, as a prelambing strategic drench of ewes lambing on contaminated pastures. The study design was a factorial that combined the antihelmintic tratment (MXD injectable, MXD oral and a combination of LVM+IVM) and the reproductive status (lambing and rearing one lamb, lambing and not rearing the lamb and no-pregnancy). We used 138 sheeps, 15 from these were not pregnant and 123 were pregnant with one lamb. The ewes were sincronizated by intravaginal pessaries containing medroxiprogesteron. It was inserted on 23.3.99 and retires on 8.4.99. The mating was between 9-14 April with a 10% of rams. On 26.5.99 ewes were scanned using real time ultra sound. To form the experimental groups we used the reproductive status, the eggs per count (epg) and the live weight. The lambing was between 4-14 September. The 3 groups were A) MXD injectable at 200 meg/kg, B) MXD oral at 200 meg/kg and C) IVM+LVM oral, at 200meg/kg and 7.5 mg/kg (in treatments separated in time). The pasture was contaminated by grazing of parasited wethers between 20.6.99+20.8.99, and then this paddock was sundivided into three, so as they grazed separately. The prelambing drenching was on 17.8.99 and after 6 days they were taken to the corresponding paddocks. We tested the evolution of the parasitism thrpugh the epg and we made larval cultures to identify the nematods generous. The spring rise appeared the 7º week post lambing, only in lactating sheeps, except on the MXD inj group. They had 477 aritmetic mean 13 weeks post lambing. The epg counting of the lambs had a high correlation with their mothers'. (0.92) At the age of 3 months the geometric mean of MXD inj. group was 6 epg. MXD oral 81 epg and IVM+LVM 677 epg. The larval cultures showed that Haemonchus spp. was the most prevalent generous.