Ram effect

[Rob30]

I am preparing to rebreed some ewes in August. These ewes are mostly dorsets or cross breeds. I have isolated my rams and plan to release them in mid or late August. Most of these ewes will have 5 month old lambs running with them. What kind of results should I expect? I can't really wean the lambs because I only have one LGD right now. My other LGD other just had pups. Also the lambs are to be marketed as grass fed so keeping them in a paddock and feeding them won't work.
I am hoping to rebreed these ewes because we bought a new ram with the B gene. He is older and I want to use him while he is healthy.

[Justin-PA]

hi Rob,
5 month-old lambs running with the ewes? Are any of them intact ram lambs? If yes, they may already be doing the deed. And 5-month old Dorset ewe lambs are coming of age and your rams might end up breeding some of them as well. I learned that lesson the hard way my first year...I had 2 10-month old ewe lambs give birth. Anyways...just a word of caution against continuing to run those 5 month old lambs with their mamas...

[Rob30]

I plan to remove the ram lambs soon. I figured there is little chance of lambs breeding out of season that young. But I will be watching. For some reason only 5 out of 25 lambs born at that time were males.

[Richard Ehrhardt]

Hi,

Hard to predict your success with this plan but I would say that it is not a "sure fire" plan to get lots of ewes rebred. The ewes should be on the edge of anestrus but if they are Dorsets they may possess out of season genetics which will help. Using the ram effect which typically involves introduction of non fertile, vasectomized teaser rams to ewes that have been isolated from males for a few months, will also help bring some in heat and synchronize them. Ewes should cycle in clusters 17-18 and 22-23 days after ram introduction. Most people put the teasers in for 14 days, pull them and put in fertile rams. The fact that your ewes still have large lambs at side could make them harder to rebred for two reasons 1) they may be in suboptimal body condition 2) if lactating, the hormones of lactation may suppress estrus activity. The latter is not a certainty in most animals as many human parents know (lactational anestrus is not a certainty/absolute).

[Peg Haese]

Rob, the ewe lambs may not breed that young but some adult ewes could be cycling and already bred back to the ram lambs. It only takes one. Guess how I know this.