Ram and ewe fertility both can be improved with targeted and timely bumps in nutrition.
At the recent Ontario Sheep Convention Richard Ehrhardt of Michigan State University shared his tips for making sure rams are ready for successful breeding and that ewes are healthy enough to successfully carry a lamb.
Why it matters: Sheep farming is a tight-margin business, so reproductive efficiency is key for many farmers to make money.
They can keep their feed costs down by grazing sheep and rams on inexpensive pasture, but Ehrhardt argues that bumping up feed before breeding time can be one of the best investments sheep farmers make.
Getting rams ready
Rams can use a good-quality, lower-protein feed for the four weeks before the breeding period begins. Ehrhardt said that feeding two times the maintenance diet during that period will help make sure rams are in good condition for breeding. They can lose body condition during the breeding period, so making sure they are in good condition first is critical to keeping them healthy and doing their job. Be careful not to provide too much protein, which is easier to grow in an area with rich forages like Ontario.
Ehrhardt had several other tips for making sure a ram is ready to breed ewes, although he acknowledged a lack of small ruminant veterinarians can be a challenge:
- Palpate testicles to make sure they are healthy.
- Put the rams with teaser ewes and observe their activity level. He avoids using young rams for spring breeding.
- Make sure rams’ hips are healthy.
- A lot of semen activity can be seen with a basic microscope.
- A light priming protocol may help ready the rams for out-of-season breeding.
Ehrhardt said light priming is consistent across breeds.
The ram effect — isolating ewes from rams for 30 days and then exposing them to the rams to induce estrus — is especially important when trying to breed ewes from Feb. 15 to Aug. 15. Ehrhardt said this is because there are few ewes that cycle well throughout the year. Exposing the rams to the ewes at a coverage rate of at least two per cent can induce estrus in ewes. It won’t work for ewes that are deep in anestrus, he said.
There are differences among breeds: Dorsets, Fins and Rambouillet-crosses are more affected by ram exposure than the longer wool breeds.
“There is a cost to teaser rams, but you should use them for off-season breeding for sure,” he said.
Increased feeding can mean a 30 per cent bump in lambing percentage, Erhardt said. Farmers ask their ewes to get pregnant again about three weeks after weaning the previous crop of lambs in an accelerated lambing system, so they have limited time to make sure they are in good enough condition to go through another pregnancy, birthing and lamb feeding cycle.
Flushing, or feeding up the ewes before they hit the breeding period, is a high-return-investment practice for sheep farmers, Ehrhardt said.
“If you are not flushing your ewes, you are kind of missing out,” he said.
In a trial at Michigan State, where he is a small ruminant extension specialist, they looked at low, maintenance and highly fed ewes. They found that the ewes fed three weeks at double the maintenance ration had a 30 to 40 per cent higher profitability due to their higher reproductive productivity. Ewes fed a maintenance ration were barely better than those fed a low ration.
“We have these highly productive sheep, but we don’t know how to feed them. We need to be able to get the most out of them,” he said.
Nutritional cues affect ovulation rate, he said. Underfed ewes won’t cycle as well as those that are well fed.
Farmers can monitor their ewes based on body condition or weight gain as a percentage of body weight (an amount of weight gain can’t be recommended as a good measure because sheep breeds vary significantly in their mature size). Ehrhardt aims for a 0.5 increase in body condition score over the flushing period.
Flushing ewes by feeding them more before breeding is all about managing energy balance. Ewes that can get through lambing and into lactation feeding their lambs and maintaining a positive energy balance will maintain better body condition and be in better condition to conceive the next time they are bred.
Ehrhardt recommended aiming for a flushing ration with 65 to 73 per cent total digestible nutrients and about 11 per cent crude protein.
Farmers can achieve the extra feed level with grazing, he said, as long as the nutrients are there in the pasture and the stocking density is lower. A specialty crop can be grown for grazing for ewes as a cover crop after winter wheat harvest. Others use corn silage, or added corn in a total mixed ration to achieve the higher-energy diet.
One other caveat Ehrhardt offered includes making sure ewes are completely dried off from their previous lactation before starting a flushing program, in order to avoid mastitis. He suggests gradually lowering feed intake by feeding ewes a lower-energy diet, then removing the lambs over four to five days. Then transition ewes into the higher-energy flushing diet.