# Comparing Short Versus Long Persistency of Anthelmintics: Impacts on Dairy Sheep Production

## TL;DR

This study compares how well two types of deworming drugs work in dairy sheep, finding that one provides longer-lasting protection and improves milk production.

## Contribution

The study introduces evidence that long-persistent anthelmintics like eprinomectin are more effective than short-persistent ones in improving dairy sheep productivity and milk quality.

## Key findings

- Eprinomectin significantly reduced parasite loads in dairy ewes compared to albendazole.
- Eprinomectin improved milk yield, fat, and protein content in treated ewes.
- Both pour-on and injectable eprinomectin formulations provided prolonged protection against parasites.

## Abstract

This study compared the short-term persistent efficacy of albendazole and the long-term persistent efficacy of eprinomectin in treating gastrointestinal nematodes in dairy ewes and assessed their impact on milk yield and quality. Ewes were divided into four groups, including a control group and those treated with albendazole and pour-on or injectable eprinomectin. Fecal egg counts, milk yield and milk composition were monitored over 75 days. Results showed that eprinomectin, both pour-on and injectable, provided prolonged protection, significantly reducing parasite loads and improving milk yield, fat and protein content and somatic cell counts. These findings support eprinomectin as a superior anthelmintic choice for lactating ewes, enhancing productivity and milk quality while mitigating parasite resistance.

Introduction: Grazing dairy ewes are often heavily challenged by parasitic infections, which represent one of the most important concerns in sheep farming due to their impacts on dairy sheep production. Objectives: The objectives of the present study were (i) to compare the short (i.e., albendazole) and long (i.e., eprinomectin) persistent effect of these anthelmintics in reducing infections by gastrointestinal nematodes (GIN) in ewes and (ii) to determine these effects on milk yield and quality in naturally infected with GIN dairy ewes. Methods: On each farm, 40 selected ewes were divided into four similar groups on Day 0 based on their fecal egg counts (eggs per gram of feces; epg) as follows: Group 1—control group; Group 2—albendazole-treated group; Group 3—pour-on eprinomectin-treated group; Group 4—injectable eprinomectin-treated group. Fecal egg counts and coprocultures were performed on Days 0, 15, 30, 45, 60 and 75. The milk yield and milk quality (i.e., fat and protein concentration and somatic cell counts) were estimated on the aforementioned occasions. Results: Eprinomectin outperformed albendazole in treating gastrointestinal nematode infections in dairy ewes. Both pour-on and injectable eprinomectin formulations provided long-lasting protection by reducing fecal egg counts (i.e., from 92.1% to 99.9%). Furthermore, eprinomectin-treated ewes exhibited increased daily milk yield and improved milk composition in terms of fat and protein concentrations and somatic cell counts. Conclusions: These findings highlight the benefits of long-persistent efficacy of eprinomectin as a preferred anthelmintic treatment for lactating dairy ewes, offering enhanced productivity and milk quality, while addressing parasite resistance concerns.