Maintaining optimum blood levels of key trace elements in their lambs throughout the vital 120 days after weaning is helping Welsh producers, John and Sarah Yeoman target higher growth rates and reduced finishing times.
John and Sarah Yeoman’s approach, of using a mini rumen bolus throughout the vital 120 days after lambs are weaned, has delivered consistent results on their farm at Llwyn y Brain, near Newtown, Powys.
Mr Yeoman says: “We have known there are trace element problems on the 300 acres or so we farm, as does much of the region around here, and have successfully addressed these in our 630 Beulah ewes and ewe lambs and 70-strong beef herd.
“But we struggled to find a successful way of tackling the problem in our lambs.”
Blood tests carried out at the end of last year confirmed just how quickly key trace element levels in lambs’ blood were falling away after weaning.
He says: “It was a bit of an eye-opener really. They were well below levels for full metabolic function in a matter of weeks, so we knew it was a weak link in our system.
“For it to really eat into your margins, you only have to lose a kilogram of liveweight gain or add an extra week or two to finishing times as a result of health or vitality problems resulting from low levels.”
Llwyn y Brain rises up to more than 400 metres (1,312ft) above sea level, with land spread across eight blocks of largely mineral-based and peaty soils with longstanding trace element issues.
Mr Yeoman says: “Most hill farms in Wales have issues, particularly with cobalt, iodine and selenium, but we have big issues with copper too.
“In fact, when I took over the farm several years ago, we were achieving a lambing percentage of only 90 per cent and out of the 23 cows we had, only 10 produced calves. I knew we had to do something pretty quickly to address this.
“We started working closely with our vets, Chris Fernyhough and Oli Hodgkinson from Trefaldwyn Veterinary Practice, to establish what the best approach would be.”
At first, copper and selenium injections, then a conventional bolus were tried, but the problems persisted.
“We thought about mineral blocks until somebody pointed out 40 per cent of animals never actually go anywhere near them. Whatever we tried, we never got a consistent, managed release of nutrients for all animals, which is what our vets said we needed.
“We then decided to look at sustained release boluses which are designed to sit in the rumen for 180 days supplying a consistent supply of key nutrients and this is when things really started to pick up.”
Lambing percentage now stands at nearly 160 per cent, there are very few barren cattle, despite managing a tight calving pattern and problems with retained placentas and endometritis have been erradicated.
“All ewes get sustained release boluses pre-tupping and although lambs have benefited as a result of this, it has always been at the back of our minds whether they are getting the right amounts of trace elements once they have been weaned.”
Blood tests carried out on lambs last autumn by the Trefaldwyn Veterinary Practice presented some of the answers and revealed some uncomfortable truths.
Mr Yeoman says: “At the start of autumn, we blood tested several groups of lambs which showed selenium levels were just above the recommended threshold.
“Groups were then split with one group acting as control with no supplementation. Just five weeks later, 90 per cent of these animals were showing blood levels well below the recommended levels for healthy growth and development.
By contrast, 90 per cent of the group given the sustained release lamb bolus had blood levels well above the recommended limit.
“Four months later, all of the bolused lambs were well above the threshold, while most of the control animals were still below.”
According to trace element specialist Ieuan Davies of Agrimin, a lot has been learned in recent years about the importance of maintaining adequate levels of trace elements in developing lambs.
Mr Davies says: “Trace element issues are really best managed from conception through pregnancy to birth, with lambs benefiting from maternal transfer of nutrients during pregnancy, then in colostrum and milk at birth.
“But as lambs grow, the effect of this support diminishes and the lamb has to meet its own metabolic needs through its own nutrition.
“Lambs are particularly vulnerable to nutritional stress resulting from weaning and changes in quality of grazing, together with adverse weather conditions. And if any trace element is in short supply it can affect overall health and vitality.
“The problem is it is like a ‘hidden hunger’ which you do not really see until it is too late to do much about, but the key giveaways are usually poorer liveweight gain than you would expect and greater susceptibility to illness. For example, a cobalt problem is usually evidenced by listlessness and loss of appetite.”
Rumen micro-organisms need a constant supply of cobalt in order to produce vitamin B12 which is essential in breaking down feed and a more efficient conversion to bodyweight. If this is missing, it can severely affect growth rates and overall development.
Selenium, in contrast, promotes growth by improving the correct functioning of muscles and vital organs, such as the liver.
Mr Davies says: “The anti-oxidant function of selenium means it works closely with Vitamin E. Selenium problems cause poor growth, muscle weakness and white muscle disease. A good level of selenium promotes a healthy immune system.”
Iodine is needed for healthy and consistent growth rates with modern production systems often unwittingly compounding the problem, he adds.
“Iodine is incorporated into hormones produced by the thyroid gland. A healthy functioning thyroid means more efficient weight gain.”
“But, what many producers do not realise is the use of rape, roots or other brassicas can inhibit the absorption of iodine in ewes which then affects uptake in the developing lamb.”
Poor weather conditions can make problems worse by affecting availability of key nutrients, with soil interactions often causing lock-up of vital trace elements.
“Land and soils can have inherent long-term trace element issues which obviously need addressing, but poor pasture growth in difficult years can lead to acute trace element problems.
“In fact, there is growing evidence the more variable weather conditions we are currently experiencing are causing acute trace element issues in certain years, even on farms which have not experienced problems before.”
Mr Yeoman says they have been aware their problems are made worse by cold, wet weather, but is confident the programme they now have in place is sufficient to counteract these.
“Our experience is trace element management is an area you just do not take risks with – the downside is just too great.
“When our problems were at their height, we would be lucky to produce a lamb with a carcase weight of 14kg. Now, we are consistently hitting 20kg.
“It gets down to monetary benefit. Treatment with the new lamb bolus costs about 65p per lamb and it is about making margin gains – you have got to get as much working in your favour as possible.
“At current prices, a kilogram liveweight is worth about £2, so if we can add an extra kilogram or two or shorten finishing time, the cost of effective trace element supplementation is negligible.
“Extending the successful trace element programme we already have in ewes and beef to our lambs is really the final link in the chain for us. And, hopefully, it will mark the end of a fairly long journey, coming to terms with shortcomings of our land and forage.”
Trace element supplementation in lambs should be managed in a planned way in much the same way as in ewes, says independent sheep specialist Dr Catherine Nakielny of KN Consulting.
She says: “Severe trace element deficiencies in lambs can lead to real issues regarding growth rates and overall health, with selenium and cobalt problems being the most common ones we see in the UK.
But problems vary from area to area, with many having copper deficiencies which can lead to swayback too, she says.
“Many farmers recognise cobalt deficiencies can lead to clinical or sub-clinical production losses post-weaning, but other deficiencies might not be so well understood.
“Iodine deficiency, for example, can be a problem, particularly with animals fed on forage brassicas. This is something which always needs to be considered when feeding these.”
High levels of worm infections can lead to reduced uptake of trace elements, so avoiding clinical signs of disease is important, she says.
“The healthier the animal, the more likely it will be to be able to make the most of nutrients consumed, so good trace element management should take into account growth rate targets, vaccination and parasite control.”
It is important to remember oversupply of some trace elements is toxic and can affect lamb survival, so methods which regulate this and deliver consistent levels are important.
“For ewes needing trace element supplementation, a good sustained release bolus is likely to be the best method as the effect of drenches does not last long.
“A similar approach in lambs with a specifically designed and reliable bolus, would be a good solution for the same reasons regarding consistency of supply.”
Anybody with concerns over the trace elements needs of their lambs should talk to their vet, Dr Nakielny says.
“If you think you might have trace element problems and are worried these might be affecting lamb performance, it is always a good idea to discuss carrying out some appropriate testing and maybe a dose response trial.”