Maximising pre-weaning lamb growth rates

// Rearing and Weaning

Ewes in early lactation require a massive amount of feed to provide adequate milk for their lambs while maintaining or recovering body condition.

image of two lambs

In a Beef + Lamb New Zealand’s Knowledge Hub video “Optimising Lamb Growth Before Weaning,” Farm Systems Scientist Tom Fraser explains that between week six and nine, a ewe feeding twins requires 4.27 to 3.84 kg DM/day (respectively) to meet her energy requirements.

This means ewes and lambs should be running onto pasture covers of 1,300–1,400kg DM/ha.

If pastures covers are too low, a ewe cannot physically take in enough food to meet her needs.

In the video, North Canterbury hill country farmers Tom and James Maxwell explain how they rotationally graze small mobs of around 200 ewes and lambs as soon as possible after lambing. This ensures both ewes and lambs are getting the pick of the best possible feed.

The mobs are rotated around six or seven paddocks and moved every two to three days.

Tom and James admit that it is a lot of work, as many mobs will have been shifted over 25 times before weaning, but they believe it is well worth the effort.

The Maxwells make use of the subterranean (sub) clover endemic in their hill country pastures to drive pre-weaning growth rates. 

This means actively managing the sub clover to allow it to set seed in late-spring and early summer and not grazing it too hard.

They also found a pre-weaning drench has made a big difference to lamb weaning weights. All lambs are drenched at eight weeks and while it makes little difference to the top lambs, it significantly lifts the bottom 30–40 percent of the mob.

By achieving good weaning weights, the brothers find it is not too much of a push to get the ewe lambs up to mating weight in autumn.

Farm consultant Jansen Travis says farmers often fall down in that late lactation period by not having the high-quality feed lambs need.

“In the early phases, pre-tailing, quantity is the issue, but after tailing it’s about quality.”

He says high-legume systems, or where legumes have been introduced, hold their quality and this is reflected in lamb performance.

Another North Canterbury farmer, Henry Pinckney describes how legumes have helped lift his weaning weights from 27kg to 33–34kg.

Establishing 150ha of red clover has made a huge difference to Henry’s farm system and enabled him to get 60 percent of his lambs away prime at the weaning draft.
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