Use of Complementary Natural Feed for Gastrointestinal Nematodes Control in Sheep: Effectiveness and Benefits for Animals

SIMPLE SUMMARY: The massive and frequent use of drugs to control helminthiasis in sheep might lead to anthelmintic resistance and the presence of residues in the environment. A solution must be found to reduce these risks and natural extracts could be a valid alternative to drugs. The authors report the results of an in vivo study on the effectiveness of a complementary feed, based on natural extracts, without residual risk for the environment, registered for gastrointestinal nematodes control in sheep and comparing its efficacy to the drug ivermectin. This study shows the better efficacy of ivermectin as compared with natural formulations and highlights the importance of in vivo studies for the evaluation of the natural mixtures registered for the treatment of gastrointestinal nematode infections ABSTRACT: The treatments of gastrointestinal nematodes (GIN) infection in sheep is almost exclusively based on the use of synthetic drugs. In some European regions the intensive use of antiparasitic drugs is leading to widespread development of anthelmintic resistance (AR). Currently in southern Italy AR is rare, but a constant monitoring of anthelmintic efficacy and the use of effective alternative therapies is strongly recommended. The aim of our study was to evaluate the effectiveness of a complementary natural feed (natural vegetable mixture), based on natural extracts, registered for GIN treatment in sheep, and its comparison with the drug ivermectin. The study was conducted in two sheep breeding farms in southern Italy and 75 sheep were divided in groups of 15 animals each (treated and untreated groups), homogeneous by GIN eggs per gram (EPG) of faeces, using the natural anthelmintic administered at full dose (10 g/sheep/orally) in the first breeding and at double dose (20 g/sheep/orally) in the second. In the latter we compared the effectiveness of mixture with ivermectin administered at full dose (200 μg/kg/BW). To determine the effectiveness, individual faecal samples were collected to evaluate the faecal eggs count (FEC) using FLOTAC technique and FEC reduction (FECR) on different days. The formula used FECR = 100 × (1 − (T2/C2)), based on the comparison of post-treatment EPG mean of the treated and untreated group (T2 and C2, respectively), is the one recommended by World Association for the Advancement of Veterinary Parasitology (W.A.A.V.P.) guidelines to monitor drug efficacy against GIN in livestock. The results reported that complementary natural feed, at two different dosages, was ineffective against GIN, while the drug, at conventional dosage, showed good anthelmintic efficacy, also confirming the importance of in vivo effectiveness studies.