Strategic management of levels of key trace elements in breeding ewes has increased embryo production by 25% and significantly improved their subsequent retention by recipients in John Howard’s Quercus pedigree Texel flock.
The benefits of the approach have resulted in improved fertility across conventionally bred ewes as well and led to a virtual eradication of white muscle disease.
“I first read about the role of trace elements in embryo production in a report produced by Edinburgh University,” John explains.
“This showed a direct correlation between blood levels of Iodine, Selenium and Cobalt and the ability of donor ewes to produce higher numbers of mature embryos and for recipient ewes to hold, maintain and grow these.”
“Embryo transfer is an important tool in accelerating our breeding objectives and multiplying up good bloodlines, so use of micro-nutrition in this way is something I’ve been keen to try for some years.
The 55-strong flock of pedigree ewes, based at Battesby, near Great Ayton, on the edge of the North York Moors National Park, is supported by 25 MV accredited recipient ewes and every year five or so of the Texels are flushed.
“We’re looking to produce long, powerful, strong and correct stock to progress the breed and our flock in particular, whilst giving us a good selection of stock for replacements and that we can sell on through the pedigree sales.
“Flushing and embryo transfer is a notoriously ‘hit and miss’ affair – no two years are the same even if you follow identical protocols - so using a scientific approach to improve flush rates and retention is something that would be of great benefit to us.”
John’s approach involves using a ‘controlled release’ bolus given to all breeding ewes, including donors and recipients, two to three weeks before AI or tupping.
“The key to the technique working is to maintain levels of Selenium, Cobalt and Iodine from the time of administration right through to when the ewes lamb, so I went looking for a means of doing this.
“Clearly the existing lick buckets were not going to be capable of providing this level of precision or uniformity across the flock.”
In consultation with trace element specialists Agrimin, John decided to try their 24.7 Sheep bolus which is formulated to consistently deliver 0.8mg of Cobalt, 4.0mg of Iodine and 0.4mg of Selenium every day for the full 180 day period he was looking for.
Results have been both impressive and consistent, John says.
“On the flushing side, we immediately noticed a 20 – 25% improvement in embryos produced within a narrower range giving a much more consistent number produced across all the ewes.
“When these were implanted, we got much better hold rates. These can range between 25 – 95% but with the supplementation they were much steadier at around the 65 – 70% mark. We still got the highs, but the really low dips seem to be a thing of the past.
“We also noticed that the usual incidences of white muscle disease – which is linked to selenium and vitamin E deficiency – had disappeared. This tells us that animals were getting the right levels they need and we’ve never had to give injections for struggling animals since using the boluses.”
Administering the boluses couldn’t be easier with the special applicator, he says, and the process fits in easily with any number of routine management processes.
“We give the boluses around the end of July and usually when the animals are being drenched. We have a large footbath that holds six to eight ewes and we simply treat them then as they’re in there for a couple of minutes – that’s all it takes.
And at just under £1/animal treated, the cost benefit analysis of the approach is a ‘no brainer’, as John puts it.
“We sold a lamb at Lanark for 5000 guineas last year and who is to say that wasn’t from an embryo that was produced because of the trace element treatment.
“All you’ve got to get is one or two average embryos to set and hold that you wouldn’t have got otherwise and the boluses have paid for themselves umpteen times over.”