With the prospect of strong lamb prices for the foreseeable future, and Schmallenberg virus problems threatening some flock’s productivity this year, sheep producers are being urged to maximise the value of their spring grass asset to ensure the lambs they do have get a flying start from their lactating mothers.
“Typically spring grass will contain 25% crude protein and 13ME, which is better than most bought-in sheep feeds. The dry matter of the grass may be lower, but recently lambed ewes have no restriction on bulk intake and can spend up to 20 hours a day grazing, so it makes sense to make the most of it to produce as much milk as possible,” says Rumenco technical manager David Thornton.
But he cautions against the risk of grass staggers in lactating ewes, which in seasons of plentiful, lush grazing – and on forages having a high potash (K) level – is a major threat.
“Ewes at lambing in condition score 2.5-3.0 on 4-6cm of grass produce enough milk for twins in good weather. Ewe milk yields peak at about three weeks post lambing and this determines the total milk production in the lactation. But this also drains magnesium levels and in some grazing situations the ewe can become deficient in this essential major mineral very quickly,” he warns.
David Thornton points to Moredun data suggesting a lactating ewe on high K pasture requires double the level of magnesium supplementation than a ewe on a low K pasture.
And the only practical way of supplying this additional magnesium is from Rumevite blocks or buckets in situations where ewes don’t require additional supplementary feeding.
“Where lactating ewes have plentiful supplies of spring grass available, we advise introducing Rumevite blocks because this will promote much better pasture utilisation than if compounds are fed, which only substitute the grazing rather than supplement it. In these situations the grass can get away from the ewes and require unnecessary topping later in the season.
And because blocks are available 24/7, there is also no disruption to grazing behaviour and ewes and their lambs will bond far better, ensuring the lambs get the best start they can.”