The assessment of crystals derived from Aloe spp. for potential use as an herbal anthelmintic thereby indirectly controlling blowfly strike

Abstract

Dagginess predisposes sheep to breech strike and can be controlled with management practices (e.g. mulesing, crutching) or by treating the animal with an anthelmintic. The effect of regular treatment with crystals derived from Aloe spp as a natural anthelmintic was assessed in yearling Merino progeny born in 2004 (Trial 1) and 2005 (Trial 2), while the short-term effect of aloe treatment over 14 days was also considered (Trial 3). Animals were randomly allocated to a treatment group (aloe or distilled water). Natural challenge was used to ensure that all animals received an adequate gastro-intestinal nematode challenge, prior to being drenched with an aloe solution, or distilled water as a control treatment. Following treatment, gastro-intestinal nematode egg counts (FEC) were obtained at regular intervals to assess the effect of aloe treatment. Dag scores were also recorded prior to shearing as hoggets. The experimental outlay of all trials was factorial, with aloe treatment and sampling date as main effects. Recordings of FEC were subjected to a cube root transformation prior to analyses to normalise the distribution in all cases. When monthly FEC was considered in Trial 1 and 2, there was also no evidence of a reduced parasite burden in the treated group. No change was accordingly found in Trial 3, where the short-term effect of treatment was considered. The mean dag scores of individuals in Trials 1 and 2 were accordingly not affected by treatment with aloe. Alternative strategies for the reduction of FEC and flystrike thus need to be considered.

Keywords: Aloe, anthelmintic, nematode egg counts, Merino, breech strike