With today's more fertile sheep breeds, inevitably there are more lambs born, which everyone thinks is a good thing. But there are management downsides that need to be dealt with over lambing, as this season in theory, all lambs will be worth saving and rearing but the reality may be different.
In the 1960s, with a national lambing percentage of under 100% (lambs born/100 ewes to the ram), most ewes had single lambs which few problems. But now with lambing percentages of 160-170%, things start to change rapidly. At this level, singles decrease and twins increase, so twins substitute for singles which is ideal.
However, above 170%, twins level off and triplets increase rapidly, and above 180% twins decline and triplets increase rapidly. Singles then remain stable at low levels.
From 220% upwards, quads increase, twins decline and triplets level off at around 30-40%. At this stage, shepherds start to realise they have extra work, extra costs and concern over profitability from these extra lambs. They may not be a 'bonus' after all.
The ideal situation would be to breed sheep that only have twins, so their genetics held litter size at that level. Currently the search is on to find such genes, but until this happens, decisions have to be made on what to do with the extra lambs, knowing that this season they'll be worth good money at sale time.
Most profit is made from getting lambs off the farm for the premium markets before Christmas, and early born singles and twins can do this. But triplets have to be left on their dams longer, or weaned early and fed better, and hence will be on the farm well into the new year, needing the extra cost of shearing, dipping, fly treatment, drenching and labour - when many farmers use this time of year to get off the farm with the family.
With quads, where one must be removed and artificially reared, these also will be longer on the farm and with extra costs of milk replacer and concentrates incurred.
Farmers who leave triplets on their ewes believe that it's best to run them with ewes suckling twins, as there are so many lambs in the paddock that a mismothered lamb can usually get a feed somewhere. Ewes with singles are too vigilant to allow a strange hungry triplet to sneak a feed.
One Coopworth farmer now with 30-40% of triplets in the flock as a result of robust selection for fertility over 30 years, has noticed that after day 10-14, orphan lambs start to appear in the paddock, which he knows are rejected triplets.
What has happened is that up to this stage, the three triplets have all had equal access to a teat, and the ewe has waited till they've all had a feed. But after day 14, two of her rapidly growing lambs have claimed a teat each, and are not willing to share it with their sibling.
You see the ewe move away after these two lambs have suckled for what she considers to be long enough, and she doesn't wait till her triplet has cleaned up any leftovers. So this triplet is gradually left behind, gives up the chase and has to steal milk from somewhere else.
So sheep farmers with high fertility flocks, need to make firm decisions on what to do with multiple-born lambs, well ahead of lambing, and base these decisions on hard economics and not sentiment.
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