One hundred and forty Polled Dorset lambs were randomly allocated to graze one of seven herbages (n = 20/herbage) and either trickle dosed (n=12) with a total of 108,000 third stage gastrointestinal nematode larvae (50% Trichostrongylus colubriformis and 50% Ostertagia circumcincta) over 6 weeks, or undosed (n=8) and allowed to ingest any nematode larvae on pasture. After 28 days on the trial lambs dosed with larvae had higher (P<0.001) faecal egg counts (FEC's) than undosed lambs but after 42 days egg counts did not differ (P>0.05) between dosed and undosed groups. Dosing with larvae did not significantly alter the liveweight gain (LWG). Herbage species affected LWG, being highest on lotus (Lotus pedunculatus cv Maku) and lowest on ryegrass/white clover (Lolium perenne/Trifolium repens), with other treatments being intermediate. Dosed lambs grazing chicory (Chicorium intybus) had more faecal dags than any other group of lambs. Those grazing G27 red clover (Trifolium pratense) were worst afflicted by a dermatitis type condition commonly referred to as trefoil dermatitis. Plasma pepsinogen levels differed significantly (P<0.05) only between dosed and undosed groups grazing pawera red clover, ryegrass/white clover and sulla (Hedysarium coronarium). Worm counts were undertaken on ryegrass/white clover and sulla grazed lambs. Both dosed and undosed groups grazing ryegrass/white clover had higher (P<0.05) abomasal worm counts than sulla grazed lambs, intestinal worm counts were highest in dosed lambs grazing ryegrass/white clover, intermediate in the dosed lambs grazing sulla and in undosed lambs grazing ryegrass/white clover, and lowest in the undosed lambs grazing sulla.

JF, Williamson, ST Morris, and TG Harvey

Proceedings of the New Zealand Society of Animal Production, Volume 53, , 413-416, 1993
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