The periparturient egg rise (PPER) is a well-documented phenomenon in small ruminants, whereby ewes and does suffer a temporary loss of immunity to parasites around the time of parturition. Researchers tested the impact of moxidectin at peripartum on fecal egg counts and clinical parameters of ewes and lambs in the high altitude tropical Andes of Colombia.
Twenty-nine healthy, naturally-infected ewes of four breeds (Colombian Creole, Romney Marsh, Hampshire, and Corriedale) were given moxidectin at either day ~135 of pregnancy (T1, n=15) or 48 hours after parturition (T2, n=14). Fourteen untreated ewes served as controls (C). Suckling lambs (n=58) remained untreated, but were evaluated as part of the study.
Fifteen days after treatment, significant fecal egg count reductions occurred in T1 and T2 ewes: 94.8 and 96.7 percent, respectively. No differences were observed in the T1 and T2 groups. Fecal egg counts remained low in treated ewes until pre-weaning. A significant PPER was observed in the C ewes, peaking 4-6 weeks after lambing.
A significant increase in FEC occurred in lambs during the pre-weaning period, two weeks after the FEC peak in C ewes. Although no significant differences among pre-weaning FECs were observed between lambs born to T1 or T2 ewes, offspring from untreated C ewes showed a sharper increase in egg counts and required treatment. It is possible that delayed egg excretion in lambs born from treated ewes was due to prolonged Moxidectin secretion by milk suckling.
Moxidectin applied prior to or shortly after lambing efficiently prevented PPER. The FEC increase occurring in suckling lambs at the pre-weaning period tended to be delayed by treating ewes at peripartum period. However, In order to reduce the risk of milk Moxidectin residues, late pregnancy treatment 35 days before lambing could be recommended.
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