Ewe efficiency monitored

01-08-2010 | Not Specified

Ewe performance was an important aspect of the Lincoln University trial. The management team was aiming for a scanning percentage of 175%, a tailing percentage of 150% and 145% weaning.

While scanning targets were achieved and exceeded in the past two years, tailing and weaning targets were not; in the first year, tailing percentages were 129.9% and 111.5% on the grass and legume farm respectively.

This year the tailing percentage on the grass farm was 136.6% and on the legumes 132.5%. That percentage is lambs tailed to ewes scanned.

The poor reproductive performance is mainly to do with the extended age structure of the flock and the stocking rate pressure on these

ewes. On the legume farm the stocking rate over lambing was getting up to 18-23su/ha because the lucerne paddocks were not available for grazing. This put pressure on the animals and the result was ewe death rates that ranged between 6.4 and 11.7% over the three-year trial.

Outbreaks of Salmonella Brandenburg and bad weather contributed to this high attrition rate. To try to mitigate stress, the management team tried giving the ewes bigger breaks going into lambing. This reduced the stocking pressure and minimised disturbance when technicians were weighing and tagging sample animals at lambing.

While reproductive performance may have been disappointing, lamb growth rates were not and the management team achieved, and in some cases exceeded, target lamb growth rates of 300gm/day from birth to sale.

On the grass farm the lambs were growing at up to 400gm/day; on the legume farm lambs were putting on an average of 350gm/day.

This meant that this year 76% and 73% of the lambs off the grass and legume farm respectively were sold prime. This was a big improvement on the first year of the trial where 68% and 28% of lambs drafted off the grass and legume farms respectively were sold prime.

The disappointing lamb growth rates on the legume farm in that first year were due to older lucerne stands running out.

Plaintain and chicory were direct-drilled into the existing stands as a temporary solution, but the stands did need replacing.

In the first year of the trial, the management had a policy of not pre-lamb drenching the ewes, but this resulted in a large larval contamination on the pastures which hit lamb growth rates. This forced a change in policy; from the second year of the trial, the ewes were pre-lamb drenched with Cydectin and vaccinated with a 5-in-one vaccine.

On the grass farm, a block of lucerne was set aside as a "clean" paddock for lambs after weaning.

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