Genetic and environmental parameters for lambing behaviour in
Merino lines divergently selected for ewe multiple rearing ability
S.W.P. CLOETE, J.B. VAN WYK, A.J. SCHOLTZ AND A.R. GILMOUR
Free State University, PO Box 339, Bloemfontein 9300, South
Africa
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NZSAP 2003 Abstract No. 41
Proceedings of the New Zealand Society of Animal Production
63: 169-172
Data were recorded for lambing behaviour of approximately 1000
Merino ewes lambing over a 10-year interval from 1993 to 2002. The
resource population was divergently selected from the same base
population since 1986, either for (H line) or against (L line) maternal
multiple rearing ability. Line differences (P<0.05) favoured H line
ewes for length of parturition and maternal cooperation score.
Heritability was estimated at 0.17 ± 0.04 for length of
parturition, 0.11 ± 0.04 for maternal cooperation score and 0.20
± 0.04 for the interval ewes remained on or near to the birth
site. A small service sire effect for length of parturition in ewes
amounted to 0.03 ± 0.02. Maternal cooperation score was
genetically related to the time spent on or near to the birth site (0.53
± 0.18). Genetic divergence between lines was detected in all
three traits. These results and the obtained parameter estimates
indicate that selection for improved multiple rearing ability was
feasible in paddock-reared sheep flocks.
Keywords: NZSAPAB;
Selection; lamb survival; maternal ability; breeding values
Last Updated 8/07/2004
