But AgResearch scientist Ray Moss is advocating utilising the natural inquisitiveness of what farmers sometimes call "damn pokers" to boost weaning weights - a management system he calls creep grazing.
Creep grazing involves simply replacing a stock-proof paddock gate with one with vertical bars that allow lambs, but not ewes, to pass and access higher-quality feed in the next paddock in the rotation.
He said creep grazing should start when lambs were about 7 weeks of age and when feed was not in abundance.
Trials have shown weaning weights could be boosted by between 1kg and 4kg.
Mr Moss said if there was ample feed, say more than 1500kg of dry matter per hectare, there was little point in using creep grazing.
But if feed was short, it was useful in building up the body weight of lambs ahead of weaning.
In six trials on the Canterbury plains and on easy rolling country, lamb performance improved, but it was not as successful on steep country where paddocks were large - greater than 16ha - and when there was plenty of feed, Mr Moss said.
It was a particularly successful and inexpensive management tool for twin and triplet lambs, as ewes struggled to produce enough milk for multiple lambs when they reached 5 to 6 weeks of age, he said.
Giving them a pick of fresh grass in an adjacent paddock reduced grazing pressure and competition.
Research so far has been on flocks grazed in rotation, but he was proposing to look at the use of creep grazing with set-stocked sheep.
He said current gates built with steel bars, half of which had been removed, made ideal creep-grazing gates, and cost about $200.
Ideally, the bars should be spaced at 200mm to provide adequate room.
The gates can be shifted as the mobs are rotated.
Mr Moss said the practice was trialled in the 1950s but was not successful because low lambing percentages did not create the same grazing pressure and there was abundant feed on the trial plots.