Integrated control of gastrointestinal nematodes in lambs using a bioactive feed×breed approach

Forages rich in condensed tannins have repeatedly shown potential to reduce gastrointestinal nematode infection in sheep. Similarly, several breeds of sheep have shown a relative resistance to gastrointestinal nematodes (GIN). We hypothesised that additive or even synergic effects may arise from the combination of a relatively resistant breed and a diet rich in condensed tannins. In study I, 160 lambs of the native Red Engadine Sheep (RES) and 113 lambs of the Swiss White Alpine sheep (SWA) were artificially infected with GIN and subsequently grazed for 52 days. The lambs were then distributed to 2 groups for a 14-day experimental feeding period. One group received a diet with a proportion of 55% sainfoin and was compared to a control group on the basis of faecal egg counts (FEC). In study II, 25 RES and 27 SWA lambs grazed infectious pastures for 37 days and were subsequently fed for 13 consecutive days with approximately 100% sainfoin or control forage. In addition to the FEC determination at the start and the end of the experimental feeding, the 52 lambs in study II were slaughtered and necropsied to determine their worm burden. FEC at the end of the feeding period were significantly lower in sainfoin fed lambs compared to controls in study I (p