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Independent.ie

Thursday 19 January 2017

Our rate of barren ewes from AI is still way too high

Published 27/01/2016 | 02:30

French farmers demonstrate and block the access to Le Mans as they protest against falling prices of dairy and meat products on January 21, 2016, in Le Mans, north western France. Photo: AFP
French farmers demonstrate and block the access to Le Mans as they protest against falling prices of dairy and meat products on January 21, 2016, in Le Mans, north western France. Photo: AFP

Ewes at Lyons were shorn on January 13 and they are still housed. This is a well established part of our winter housing routine and gives an increase in lamb birth weight of approximately 0.5kg per lamb.

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When ewes are housed their pregnancy is actually shortened by around two days due to the altered environment. However when we shear these housed ewes, their pregnancy returns to its normal duration. This is largely responsible for the increase in lamb birth weight, but increased intake is also observed.

At a very practical level it allows for about 20pc more sheep to be housed in the same area, provided feed space allows. It's important to bear in mind that a minimum of eight weeks wool re-growth is required prior to turn out, so once you commit to shearing you are committing to a two month housing period.

Ewes were scanned here on January 5. We recorded an increase in litter size from last year with an overall scanned litter size of 1.75. This is still well below our target on 2.1 but is an increase of 0.1 on last year's levels.

Disappointingly we are still seeing a low conception rate to AI of only 73pc.

Consistent with previous years, our barren rate is still way too high at 7pc. This is an issue which has occurred here since the AI programme began. The majority of the ewes that are barren did not repeat.

It's a familiar issue - the so-called 'deep-end anoestrus', whereby a ewe that fails to conceive to the AI service subsequently stops cycling.

If we were to extend our breeding season we would most likely pick up these ewes after 10-12 weeks, but we do not want to extend lambing to that extent.

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Obviously, AI is a big part of the problem, so if we were not involved in this for research purposes we certainly would not be using AI on a commercial flock.

Scans

On the positive side, the ewes that conceived to AI had a scanned litter size of 1.9. Across the entire ewe flock there are 28pc singles, 49pc twins and 16pc triplets.

The ewe lambs scanned at 1.1 to the ram, but there appears to be an abortion issue here with 30pc empty. This is most likely going to deteriorate further prior to lambing.

As we do not routinely purchase replacements we do not vaccinate ewe lambs, but that policy is now under review.

Of the ewe lambs that were pregnant at scanning, the average litter size is 1.5, including some triplets. This indicates that the genetics of the flock in terms of prolificacy is on a sound trajectory.

All ewe lambs and triplet-bearing ewes were treated with ivermectin post scanning. As silage quality is good this year no ewes are receiving meals at this stage, but all ewe lambs started on 250g of a 14pc crude protein concentrate this week

Meanwhile, Connie Grace recently presented the results of her multi-species grazing study at the Sustainable Livestock Production conference in Bristol.

This work, which I have reported on here throughout the year was extremely well received.

The large performance responses of the animals grazing the multi-species swards came in for a lot of attention, and Connie's work was referenced by some of the key note speakers at the conference.

This is a great achievement for any PhD student and is appropriate reward for the work Connie has put in over the last two years.

Dr Tommy Boland lectures in sheep production and ruminant nutrition at UCD's Lyons research farm at Newcastle, Co Dublin

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