Abstract

The aim of this study was to evaluate rumen fluid sampling as a novel method for quantifying nematode challenge encountered by grazing sheep. In Experiment 1, rumen fluid samples were seeded with known numbers of third stage infective larvae (L3) of Teladorsagia circumcincta, Trichostrongylus colubriformis and Cooperia curticei. Immediate recovery rates averaged 92% (Coefficient of variation, 13%), 53% (15%) and 50% (30%) for each species respectively. Recovery rates from rumen fluid stored at 7°C decreased to 44% (29%), 33% (18%) and 0% (0%) after 72 hours. In Experiment 2, 15 ewe hoggets maintained indoors were dosed with 5,000 L3 T. circumcincta and 5,000 L3 T. colubriformis. At 1, 2 and 12 hours after dosing the numbers of L3 recovered from the rumen fluid were 0.2 (125%), 0.16 (145%) and 0.01 L3/mL (300%) respectively. In Experiment 3, rumen fluid samples were taken from small groups of lambs grazing four paddocks with variable herbage infestation rates of mixed species of L3. Species composition of L3 on the herbage and in the rumen fluid was T. circumcincta 8% and 0%; T. colubriformis 27% and 19%; C. curticei 0% and 5%; Nematodirus spp. 63% and 69% and Haemonchus contortus 2% and 9%. A significant number of technical challenges remain before the method has a practical application.

AJ, Litherland, and DL Deighton

Proceedings of the New Zealand Society of Animal Production, Volume 68, Brisbane, Australia, 130-133, 2008