Hopefully, all you sheep farmers have good numbers of lambs running around enjoying the dry weather.
Regularly here in Northumberland lambs look really well in June and then start to slow down in the growth and lose their bloom in July.
This can be due to gut worm challenge building up, or not good enough quality of grazing (which due to the cold this year is good as there has never been too much grass which runs to seed), or commonly due to cobalt deficiency.
Cobalt deficiency can really hit lamb growth rates as they have a high requirement due to their rapid growth. This leads to missing the high priced early lamb sales and delayed finishing, meaning more costly concentrates having to be used.
Pre-ruminates have a lower requirement.
Cobalt is required by the micro-flora in the rumen and turned to vitamin B12, which is utilised by the lamb’s liver for energy production.
Low levels suppress appetite, which leads to reduced growth rates. A small reduction in appetite leads to a large reduction in growth rate as the majority of the energy a lamb consumes goes into keeping it alive.
Also the fleece can become open and there can be signs of mild conjunctivitis.
Generally, sandy hill farms have a bigger deficiency than lowland heavy clay farms, but it varies a lot.
Diagnosis can be made on lower-than-target weight gain and low serum B12 levels if a big enough sample group is taken as there is large individual variation.
Also the sheep must not be stressed for more than a couple of hours pre-bleeding by, for example, being held in the pens, or the levels are artificially raised, giving a false picture.
Response to treatment should always be measured.
There is very little store of cobalt so supplementation is difficult.
Oral dosing raises serum B12 for only a week. Soluble B12 injections last one to four weeks, depending on the severity of deficiency.
Pastures can be sprayed with cobalt sulphate, which raises the levels for about six weeks. Bolus offer continuous supplementation for up to eight months, but often contain other trace elements and are slow to administer, with possible risk of injury to the animal, and are costly.
This practice uses a novel alternative long-acting injection, which last for three to six months, depending on dose.
For further details, contact your vet.