Farm Ireland

Thursday 23 November 2017

Ewe selection now critical for 2011 lamb crop

John Shirley

We are at a pivotal point in the sheep farming calendar. You are making decisions on numbers, breeds, lambing dates and which ewes to cull. Management of the flock over the next period will impact on the size of the lamb crop and even on your workload come next spring.

Can you identify the ewes that gave trouble last spring so that they won't be around next spring? Ewes that prolapsed, or threatened to do so this year will likely do so again next year, for this condition has a genetic component.

When buying ewes, look for the tell-tale sign of stitching around the vulva. Chronic lameness, broken mouths and damaged udders are easy enough to check out. If you hold onto such ewes you can expect trouble, although I know that some flock owners will hold onto a young ewe that has lost a teat on the basis that she will rear a single lamb or maybe even two on the one teat. Sometimes a ewe will still have all her front teeth but will be very thin. It may be that she has damaged cheek teeth or has one of a dozen reasons that turn a ewe into a piner. If you have a ewe that is not gaining weight on good grass and you have treated it for the obvious items, such as fluke, lameness or trace element deficiency, get rid of her. My experience is that such ewes are bad news.

Over the past 12 months, ewes lost condition and died from a new threat called rumen fluke. The only drug effective against this type of fluke is Oxyclozanide, which is found in Zanil and Levafas Diamond. The presence of rumen fluke is established from faecal samples sent into a regional veterinary laboratory.

In general, ewes are in good condition this year. Once it got going, grass has been plentiful. The ideal is to run the weaned ewes as a single flock on tight grazing, but some thin ewes may need preferential grazing.

About six weeks before the ram is introduced, get going with the pre-mating flushing to boost the lamb crop size for next year. Some scientists reckon that ewe weight, per se, is more important than having the ewe gaining weight at mating time. I have seen such good results from slimming ewes and then flushing that I remain convinced that it is the right approach.

Some recent work from the Scottish Agricultural College suggests that both good condition and gaining in condition at mating have positive effects on lamb crop size. Of course, research has also shown that overfatness in ewes at mating has a negative effect on prolificacy.

Cooler weather and shorter days help get the ewe into heat cycling. The ram effect, where rams are introduced after a period of total absence, can be used to both start cycling and to synchronise heat. Some farmers are convinced that late summer shearing before mating gives a boost to the lamb crop size, but research has not measured this. Equally, flock owners are convinced about the merit of pre-mating trace- element supplementation. Again, the researchers are not convinced of this.

Also Read

With abortion becoming an ever-bigger threat, many flock owners like to vaccinate their replacement ewe lambs or ewe hoggets against Toxoplasmosis or Enzootic abortion. Unfortunately, this may not be an option this summer.

The two products, Toxovax and Enzovax, need to be given four weeks before mating. Both products have run out, even in Northern Ireland, this week. There's a slight chance of Enzovax returning to the market in October and a lesser chance for Toxovax.

Breeding ewes are expensive but cull ewes are also at a record high, so depreciation costs of replacing the culls with fresh young ewes may even be a little less this season. To date, this year in Tullow Mart, hogget ewes sold for €130-160/hd, but the tops of the cull ewes have sold for €120 each. Fingers crossed that the demand for cull ewes continues past the Ramadan season.

Irish Independent