A selection experiment to breed for high (H), control (C) or low (L) faecal egg count (FEC) levels in weaned Romney lambs was established in 1985, being maintained at Rotomahana (until weaning 1988) and at Tokanui thereafter. In winter 1990, pregnant ewes (aged 2 to 6 years) were drafted into grazing groups according to expected lambing date ('early' and 'late' ewes), in order to study periparturient FEC. Non- pregnant ewes and unmated yearling females were also recorded. Faecal samples for FEC were taken from all females (n=253) before and after the pregnant ewes lambed (median lambing dates for early and late ewes being 19 August and 31 August), and then in October and in November. Lambs were also faecal sampled at 3-month weaning. A mixed model was fitted to log e (FEC + 100), with fixed effects for selection flock, group (early ewes, late ewes, non- pregnant ewes, yearlings), sample day and the interaction of group and day, and with 'animal' as a random effect. The repeatability was 0.50

AL, Hargreaves, LR Matthews, and GA Verkerk

Proceedings of the New Zealand Society of Animal Production, Volume 53, , 179-182, 1993
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