Performance of lambs on a clean grazing system compared with lambs on a traditional system
Fawcett, A.R.; Macdonald, A.J.
Veterinary Record 123(21): 545-546
1988
ISSN/ISBN: 0042-4900 PMID: 3206807 Document Number: 311322
Between April 18 and July 16, 1985, when weaning took place, a comparison was made between lambs grazing a 'clean pasture' which was part of a clean grazing system (grazed by cattle for 2 years before the trial) and a 'contaminated pasture' (grazed continuously by sheep for 6 years before the trial). The comparison was replicated 3 times on swards of similar height and botanical composition using 0.96 ha plots stocked with 12 Greyface ewes and their lambs. Lamb groups were balanced for sex, weight, stocking rate and genotype. All ewes were dosed with fenbendazole just after parturition and placed in appropriate plots. Lambs on clean pasture were not treated but lambs on contaminated pasture were dosed with levamisole at the end of May and 3 weeks later. Pasture helminth larval counts were very low on clean pasture and moderate on contaminated pasture, and were reflected in the faecal egg counts (mainly Ostertagia circumcincta and Nematodirus battus eggs) of the lambs which were negligible in those on clean pasture and moderate in those on contaminated pasture. PM examination of lambs at the end of the trial showed mean total worm counts (+or- sem) of 5683 (+or- 1122) in clean pasture lambs and 23 216 (+or- 4816) in contaminated pasture lambs. Live weight gains were significantly higher in the lambs on clean pasture (28.1 kg) than in those on contaminated pasture (24.6 kg).