Susan Schoenian, Sheep & Goat Specialist, University of Maryland Small Ruminant Extension Program
(Previously published on the Maryland Small Ruminant Page)
Breeding ewe lambs and doelings. 
Should ewe lambs and doelings be bred to produce their first offspring when they are approximately one year of age? Or should you wait until they are yearlings to breed them for the first time? The answer depends. There are many factors to consider and there are pros and cons to each breeding decision.
Breeding ewe lambs and doe kids allows you to exploit their reproductive and genetic potential. It is well-documented that ewes that are mated as lambs will have a higher lifetime production than ewes that are mated for the first time as yearlings.
One of the most compelling reasons to consider breeding ewe lambs and doe kids is genetic improvement. Your lambs and kids should have the best genetics on your farm. Breeding them early will reduce the generation interval and accelerate genetic improvement.
At the same time, ewe lambs and doe kids have lower conception rates, give birth to fewer offspring, produce less milk, and are more likely to experience problems during the periparturient period. In addition, there may be sacrifices in growth. Ewes and does that are bred early may not catch up (in weight) until their second or third mating. For this reason, producers who show yearlings often delay breeding.
Size (weight) is a more important consideration than age when deciding if/when to breed ewe lambs and doelings. Ewe lambs and doelings should achieve approximately two-thirds of their mature weight (at the start of the breeding season) before being bred.
It is often necessary to feed some grain to get ewe lambs and doe kids big enough for breeding. At the same time, ewe and doe replacements should not be fed for maximum gain, as this could be detrimental to future milk production. Fat deposits in the udder, caused by overfeeding, may negatively impact milk production.
Though heavily influenced by nutrition, ewes and does vary in the age at which they reach puberty (sexual maturity). Some breeds of sheep may not reach puberty until they are almost a year of age. Crossbred females usually reach puberty earlier than purebred females. Ewe lambs born in the fall are not likely to conceive until the next fall.
It makes sense to breed ewe lambs and doe kids away from the main flock, as they are less competitive for the male’s service. Ewe lambs and doe kids should not be bred to males with large birth weights or heavy front-ends. They should be bred to males from the same (or smaller) breed. Nor should they be mated to large males that could cause them injury.
Because pregnant ewe lambs and doelings are still growing, they have higher nutritional requirements than mature females. They are also less aggressive at the feed trough. For these reasons, they should be fed and managed separately from mature females. In fact, they should not be mixed with the mature flock until they have weaned their first offspring. Better yet, they should not be mixed with mature females until they are bred for the second time. Yearlings that are nursing offspring, especially multiples, should be more closely monitored for signs of low performance and internal parasitism (worms) when reared on pasture.
With good management and nutrition, producers can successfully breed ewes and does to produce offspring at approximately one year of age. Without good management and nutrition, breeding ewe lambs and doe kids can be disastrous.