Performance of visually or objectively culled ewe hoggets
T.G. Harvey, R.L. Baker
MAFTech, Ruakura Agricultural Centre, Hamilton
Proceedings of the New Zealand Society of Animal Production.
1989, 49: 215-220
Visual culling of 16-month old Romney ewe hoggets without access
to performance records was carried out by five different groups of
farmers who had contributed rams to the Rotomahana Strain Trial.
Reasons for culling decisions were recorded and then all ewes, including
those 'culled', were retained and farmed as a single flock to compare
lifetime performance of culled and selected ewe replacements. Each
group of farmers put most of its culling emphasis on size (i.e. smaller
sheep were culled), with varying culling emphasis on mouth structure,
woolly faces and wool. Less than five percent of the culling emphasis
was for foot structure or breed type. All groups of farmers were able
to 'select' ewes that had subsequent performance (number of lambs
weaning and wool weight produced) superior to their 'culled' group of
ewes. There was about a two-fold range among breeders in the
effectiveness of their culling in terms of economic returns for lambs
weaned plus wool produced over three lambings. Evaluation of ewe
production through to seven years of age showed that the effects of
visual culling on subsequently ewe performance were maintained over the
lifetime of the ewe.
The effect of 'culling' using performance traits in the same ewe hoggets
as were subjected to visual culling was also assessed. Culling on most
performance traits in the same ewe hoggets as were subjected to visual
culling was also assessed. Culling on most performance traits was more
effective than visual culling, resulting in up to 50% greater economic
returns. Post-weaning body weights or fleece weights or a combination
of these traits, were the most useful objective culling criteria.
Keywords: NZSAPAB;
Sheep; culling criteria; visual culling; lifetime performance,
lamb production; fleece weight; body weight
Download abstract in text format
Last Updated 18-03-1997
