Average Lamb Weight at Birth and Weaning: Chart by Breed Type

The average lamb is born at about 3 to 5 kg. A single lamb of a medium-sized breed often weighs 4 to 5 kg, a twin 3 to 4 kg, and a triplet sometimes under 3 kg. Before weaning, lambs usually gain about 150 to 300 g a day, so at weaning (about 2.5 to 4 months) they weigh roughly 15 to 35 kg, depending on breed and milk supply.

These are guide figures, not official standards. Their real use is to help you spot the lambs that fall behind. For weights after weaning and for adult sheep, see our guide to sheep weight by age and breed. This article stays with the first months, the period that decides whether a lamb survives and what it will be worth at sale or at Eid.

What decides a lamb's birth weight?

Birth weight is built in the last six weeks of pregnancy, when the foetus does most of its growing. The main factors are:

• Breed and size of the ewe. A large, well-grown ewe gives heavier lambs than a small hardy grazing breed.
• Litter size. Singles are heavier than twins, and twins heavier than triplets. The total weight of the litter goes up, but each lamb is lighter.
• Late-pregnancy feeding. An underfed ewe in the last month gives light lambs and little colostrum. See feeding pregnant and lactating ewes.
• Age of the ewe. Young ewes lambing for the first time are still growing themselves and often have smaller lambs.
• Heat. Severe heat stress in late pregnancy cuts the ewe's appetite and can slow the growth of the foetus.
• Sex. Ram lambs are often born a little heavier than ewe lambs.

On the other side, a very big lamb in a small ewe raises the risk of a difficult birth. The goal is not "as heavy as possible" but a normal weight for the breed and the litter size.

Daily weight gain before weaning

While the lamb is suckling, its growth depends first on the ewe's milk, and more and more on creep feed as it gets older. Common guide figures:

• Single lamb on a good milking ewe: about 250 to 350 g a day.
• Twin lamb: about 150 to 250 g a day, because the milk is shared.
• Lamb on poor grazing with no extra feed: often under 150 g a day.

A simple rule many breeders use: a healthy lamb doubles its birth weight at about 2 to 3 weeks and reaches about three times its birth weight or more by weaning.

Lamb weight chart by age and breed type

The ranges below are approximate, for healthy lambs, males and females together. Small breeds are hardy grazing types, such as many desert, Sahel and hill sheep. Medium breeds cover most local breeds in the Gulf and North Africa. Large breeds are the big meat and show types.

Twins usually sit at the lower end of each range and well-fed singles at the upper end. A lamb clearly below the range for its breed and age deserves a closer look: worms, diarrhoea, a ewe with little milk, or a lamb that was weak from birth.

Why light lambs die more often

Birth weight is one of the best signs of whether a lamb will survive. A very light lamb, for example under about 2.5 kg in a medium breed, faces several problems at once:

1. Small energy reserves. It is born with little body fat to make heat and cannot last long without suckling.
2. It gets cold fast. Its skin surface is large compared with its weight, so cold nights and wind push it into hypothermia.
3. It suckles poorly. Weak lambs stand slowly and drink less colostrum in the first hours, so they get fewer antibodies.
4. It loses the competition. In twins and triplets, the smallest lamb is often pushed away from the udder.

What to do: identify light lambs at birth, make sure they have had colostrum, keep them out of cold and draughts, and bottle-feed if the ewe does not have enough milk. For the other causes of losses, read our guide on how to reduce lamb mortality.

How to weigh lambs properly

• Equipment. At birth, a hanging scale with a bag or bucket is enough (subtract the weight of the bag). For older lambs, a livestock scale is safer and faster.
• First weighing. Weigh within 24 hours of birth, and note whether the lamb is a single, twin or triplet.
• Fixed intervals. After that, weigh at fixed ages, for example around 30 days, 60 days and at weaning, or every 2 to 4 weeks.
• Same conditions every time. Same time of day, ideally before feeding, and check the scale with a known weight.
• Compare at the same age. A 70-day lamb and a 95-day lamb cannot be compared directly. Comparing weight at a fixed age, such as 60 or 90 days, is a fairer way to judge ewes and rams.

Recording birth and weaning weights in Throf

A weight without the lamb's number is useless. In Throf, every lamb has its own record with tag number and colour, sex, birth date, mother and father. At lambing you record the birth (single, twins or triplets) and the birth weight, then the later weighings and the weaning stage. The newborns report and the weight and body condition report then show which lambs, which ewes and which rams give the best weaning weights. That is the basis for keeping the good ewes and culling those that wean light lambs year after year. For managing the weaning itself, see weaning lambs and kids.