A trial was undertaken to investigate the effect of condensed tannins (CT) extracted from pine (Pinus radiata) bark on gastrointestinal (GI) nematodes. Gastrointestinal parasitism is a significant cost to the sheep industry affecting health and productivity. Previous research has shown CT from some forage species can inhibit parasite egg hatching, larval development and reduce worm numbers in the GI tract. However, the forages containing CT tend to be less productive than ryegrass pasture, so this research investigated pine bark extract (PBE) which contains CT and is abundant in New Zealand, on Trichostrongylus colubriformis nematodes. In the in vitro incubations, 150 µg CT/ml prevented larval development and halved egg hatching. Effects of CT in vivo (35g/day) were evaluated using 12 wether sheep, fitted with abomasal cannulae and infected with T. colubriformis larvae. The sheep were either drenched at six hourly intervals or the PBE was infused into the abomasum over four days. Neither treatment affected faecal egg count (1,700/g faeces), egg hatching or development of eggs to L3 larvae. Lambs were slaughtered after four days of treatment. Nematode numbers were similar for all treatments (average 21,100/animal). Despite inhibitory effects on hatching and development in vitro, PBE had no anthelmintic benefits for the sheep and may reduce intakes.
Proceedings of the New Zealand Society of Animal Production, Volume 71, Invercargill, 304-308, 2011
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