Mating, Gestation, and Birthing of Sheep

Today, I got to study the mating, gestation, and birthing of sheep! I found a really interesting article (which is linked below) about it. Enjoy!

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Spring lambing
Mother Nature meant for sheep to mate in the fall so that lambs would be born in the spring when the weather is mild and the grass is plentiful. This scenario offers the best chance for lambs to survive and thrive. Of course, it also creates a food supply for young predators that are born in the spring.

For this reasons, ewes are considered "short-day "breeders. When day length becomes shorter (in the fall), this triggers the ewe's brain to release hormones that jump start her reproductive system. The further away from the equator the sheep breed originated, the more likely it is to exhibit these seasonal breeding patterns.

Conversely, sheep breeds developed in the tropics or nearer to the equator are less likely to display seasonal breeding patterns. Breeds in the U.S. that have less seasonal breeding patterns include the Dorset, Rambouillet, Polypay, Karakul, Merino, Finn, and hair sheep.

Ewes are "seasonally, polyestrus" because their reproductive cycle is controlled by the photoperiod (season) and they come into heat (estrus) every ~17 days (until they become pregnant), but only during their fertile period. Photoperiod is the relationship between light and dark in a 24-hour period. It is possible to manipulate the photo period and "fool" ewes into thinking it's fall.

During their fertile period, ewes will come into estrus (heat) every approximately 17 days until they are bred or their fertile period is over. Only during estrus will a ewe allow a ram to mate her. The duration of estrus is 24 to 36 hours. A ewe in heat will seek out the male. She may sniff, lick, or nuzzle him. She may fan her tail. The classic behavior response of the ram when he detects a ewe in heat is to lift his nose in the air and curl his upper lip. This is called the Flehmen response.

First-time moms
Though it depends upon breed, nutrition, and management, ewes can become mothers by the time they reach their first birthday. This is okay if the ewe lamb has achieved approximately two-thirds of her mature size (weight) before being bred. Thus, for some producers, it is commonplace to breed well-grown ewe lambs when they are 7 to 9 months of age. Other producers wait until their ewes are 18 months old before breeding them to lamb as 2 year olds. Different breeds of sheep reach puberty (sexually maturity) at different ages.

Rams
A healthy, mature ram can probably mate 100 (or more) ewes during a breeding season, though a ratio of 1 mature ram to 30 to 50 ewes is more common to make sure lambing is not too spread out. Six to 7 month old ram lambs that have achieved approximately 50 percent of their mature size can be used for breeding. Ram lambs are usually put in with fewer ewes, 15 to 25. It's best not to mix young rams with mature rams. Some rams may show a preference for ewes of their own breed or kind.