Weight targets for early lambing

NSW Department of Primary Industries (DPI) sheep performance development officer Tracy Lamb, Cowra, said research had shown puberty would generally occur within the range of 40 to 60 per cent of mature ewe live weight.

"The studies show the poor performance people generally associated with early joining occurs when live weight at joining is below 35kg," she said.

Across the national flock, only 10pc of ewes are mated as lambs and these are mostly crossbred ewe lambs.

Ms Lamb said joining ewe lambs was suited to autumn and should not be considered for spring joinings.

To allow a smooth joining process, Ms Lamb said producers must maintain a focus on nutrition and give maiden ewe lambs high priority to ensure they were heavy enough to reach puberty.

"Producers need to set targets to achieve adequate weaner growth rates which may include supplementary feeding and needs to be budgeted for."

According to Ms Lamb, in a winter rainfall area crossbred ewe lambs required a growth rate of about 290 grams per head per day until weaning for a February/March joining, possible on good quality pasture prior to paddocks "haying off" in October.

"A growth rate after weaning of 180 grams per head per day would require the lambs to graze lucerne while a cereal grain supplement of about 500g/h/d will extend the grazing life of the lucerne to maintain this growth rate for longer."

If there was no lucerne or pasture available however, a supplement of cereal grain and a high protein feed like lupins would be required, she said.

"Expected feeding rates of up to 1kg/h/d of 80pc cereal grain and 20pc lupins supplement would be required depending on the digestibility of the available dead pasture."

Ms Lamb said it wasn't only the period up to joining that was important to monitor closely for a successful early joining program.

"Better nutrition and more management skills, for both the sheep and pasture, are necessary before joining, during pregnancy and from lambing until the second joining.

"During lactation, ewe lambs need to be fed at a level that ensures they lactate to their potential while still growing themselves.

"If it's not well managed future live weight data and productivity can be affected."

While Ms Lamb said there was no scientific data to show any detrimental effect on the ewes from lambing at one year of age, she said there was an increase in on-farm costs, reduced management flexibility and an increase in work load.

"However we wouldn't recommend anyone trying to implement lambing at 12 months during dry conditions such as the one we are going through now - the result could be disastrous."