Home
News
ENLARGE
Understanding reproduction in sheep helps us be good ranch managers, have highly productive flocks, and use resources wisely. One of the most important points to understand is that the number of lambs produced by the ewe flock differs, depending on when you breed your sheep.
Sheep are seasonal breeders, with the majority being short-day breeders that cycle in the fall and lamb in the spring of the year. However, some breeds of sheep will cycle in the spring and have lambs in the fall. The sheep’s brain perceives the length of day and sends appropriate signals (hormones) to the reproductive system to begin the breeding season. The non-breeding time for these ewes is called seasonal anestrus.
As ewes come out of seasonal anestrus, they are in a transitional phase. During this phase some ewes begin to express estrus and ovulate before others in the flock. In mid-breeding season, all the ewes should be cycling. As the season comes to an end, a smaller percentage of the flock will be active. A similar situation is true for the number of ovulations (eggs shed) per estrus. That is, the number of ovulations per cycle starts off low, maximizes during the middle of the breeding season, and then decreases at the end. In order for the estrus to be fertile, ovulation must accompany estrus. Early in the breeding season some ewes may express estrus without an ovulation (infertile estrus) and some ovulations occur without estrus (silent estrus). What all this means is that maximum fertility occurs mid-season.
Decisions on breeding seasons need to take into account several factors, given that early, early, mid, and late seasonal differences occur for number of ewes in estrus, number of ewes ovulating, and number of ovulations per estrus. Consideration of these factors can maximize ewe pregnancy rates and lambing rates (number of lambs per ewe).
Usually the more lambs that can be born into a flock, the more profitable the operation is. This is because the overhead of maintaining ewes can be supported by the sale of many lambs. However, some marketing schemes may be profitable with lower reproductive rates because of the advantages of timing sales and specialty markets.
Genetics (across and within breed) also play a part in factoring the season for the estrus cycle. Some breeds are capable of out-of-season breeding (for example, the Dorset breed).
And, some animals within a breed are more able to express those characteristics than others. Choose a breed of sheep that matches your season of choice and then monitor your own flock for the animals that best represent that breed. Keep and use ranch records to pick replacement ewes and rams that help meet your objectives. For information on sheep productivity, visit http://extension.oregonstate.edu/douglas/lf.
Sheep are seasonal breeders, with the majority being short-day breeders that cycle in the fall and lamb in the spring of the year. However, some breeds of sheep will cycle in the spring and have lambs in the fall. The sheep’s brain perceives the length of day and sends appropriate signals (hormones) to the reproductive system to begin the breeding season. The non-breeding time for these ewes is called seasonal anestrus.
As ewes come out of seasonal anestrus, they are in a transitional phase. During this phase some ewes begin to express estrus and ovulate before others in the flock. In mid-breeding season, all the ewes should be cycling. As the season comes to an end, a smaller percentage of the flock will be active. A similar situation is true for the number of ovulations (eggs shed) per estrus. That is, the number of ovulations per cycle starts off low, maximizes during the middle of the breeding season, and then decreases at the end. In order for the estrus to be fertile, ovulation must accompany estrus. Early in the breeding season some ewes may express estrus without an ovulation (infertile estrus) and some ovulations occur without estrus (silent estrus). What all this means is that maximum fertility occurs mid-season.
Decisions on breeding seasons need to take into account several factors, given that early, early, mid, and late seasonal differences occur for number of ewes in estrus, number of ewes ovulating, and number of ovulations per estrus. Consideration of these factors can maximize ewe pregnancy rates and lambing rates (number of lambs per ewe).
Usually the more lambs that can be born into a flock, the more profitable the operation is. This is because the overhead of maintaining ewes can be supported by the sale of many lambs. However, some marketing schemes may be profitable with lower reproductive rates because of the advantages of timing sales and specialty markets.
Genetics (across and within breed) also play a part in factoring the season for the estrus cycle. Some breeds are capable of out-of-season breeding (for example, the Dorset breed).
And, some animals within a breed are more able to express those characteristics than others. Choose a breed of sheep that matches your season of choice and then monitor your own flock for the animals that best represent that breed. Keep and use ranch records to pick replacement ewes and rams that help meet your objectives. For information on sheep productivity, visit http://extension.oregonstate.edu/douglas/lf.
Shelby Filley is the Regional Livestock and Forages Specialist for OSU Extension Service of Douglas County. Shelby can be reached by e-mail at shelby.filley@oregonstate.edu or by phone at 541-672-4461.
