Production responses in adult ewes to long-acting anthelmintic treatment pre-mating: relationship with body condition score

Abstract

ABSTRACT A trial was conducted to investigate the response of mixed age ewes of different body condition scores (BCS) to a pre-mating treatment with long-acting anthelmintics. Three hundred Poll–Dorset Texel cross ewes were divided into three groups of 100 and treated pre-mating with either a 100-day controlled-release capsule containing abamectin, albendazole, selenium and cobalt, a long-acting injectable formulation of moxidectin or remained untreated. Initially, ewes of lower BCS showed a significantly larger response in liveweight gain and a BCS increase which approached significance. However, these benefits did not persist following the expiry of the anthelmintics. Although treated ewes gave birth to more lambs, by weaning there was no significant difference between treatment groups in any of the measured variables and no significant influence of ewe BCS at treatment. The results are similar to earlier studies which showed that the benefits measured at the end of a long-acting anthelmintic treatment may not persist and may over-estimate the true benefit. Although there was a temporary benefit to treatment of low BCS ewes the data in general supports the view that many factors contribute to low BCS in ewes and parasites are often only a minor contributor.