Trialling the SmartWorm® application in New Zealand sheep farms

Gastrointestinal nematodes (GIN) remain a major health and productivity challenge for grazing livestock globally, including New Zealand where widespread anthelmintic resistance has been reported. This was a pilot study evaluating the effectiveness of SmartWorm®, an app-based decision-support tool for Targeted Selective Treatment (TST) of internal parasites to reduce drench use without compromising lamb growth under New Zealand conditions. A total of 1738 ewe lambs across three commercial farms were allocated to either a TST or Blanket Treatment (BT) group (treated every 28 days) and monitored over a 90-day period. All animals were drenched at the start of the trial, after which BT animals received treatment at each subsequent weighing. SmartWorm was used to determine drenching need for TST animals based on individual animal performance relative to expectation. Faecal egg counts (FEC), weight gain, and treatment frequency were assessed. Across all farms, TST reduced anthelmintic use by 37-57 % compared with BT, with no significant differences in liveweight gain (P = 0.510). There was a weak but significant treatment effect on FEC (P = 0.01), and a linear relationship (R² = 0.8951, P < 0.001 with one outlier removed) between BT group FEC and TST rate, indicating the system's responsiveness to parasite challenge. This study demonstrates that implementing TST using this app can enable reduced anthelmintic use without compromising performance-an important step towards sustainable parasite management on New Zealand sheep farms.