Glascoed Trace Element Trial

Key Results

• Lambs on the three treatments grew at almost the same rate throughout the trial suggesting that trace element supplementation with selenium, iodine and cobalt was not the limiting factor on performance. 
• Poor weather and low dry matter grazing may well have been the root cause of the low growth rates although more thorough investigation of the copper status of lambs may well prove worthwhile to help understand if copper is also needed. This can be done by blood sampling or more accurately by measuring liver copper stores.  
• Although the trial appears to have shown no difference between the three methods of supplementation, the results do emphasise that significant amounts of money can be wasted on supplements if other more important factors – like weather, nutrition and health have an overriding influence.  
• The cost of the three treatments was very different with the purchased drench and bolus supplements working out much more expensive than the home mixed drench.  It would be worthwhile to repeat the work, possibly including copper in one or all treatments.  

Background

Trace element deficiencies have been identified at Glascoed in recent years and a mineral audit part-funded through Farming Connect Advisory Service in 2021 showed that iodine and selenium were of particular concern. There was also some concern about copper since sulphur and molybdenum levels in forage were relatively high which could be impacting on copper absorption.  Monitoring of copper through liver and blood analysis was recommended.  

Purpose of the work: 

Since all the named elements have an impact on lamb health and performance it was decided to compare three different supplements and to assess their effect on lamb growth rate and health. 

What we did

Lambs were randomly allocated to one of three groups and given one of the following treatments:

• Proprietary lamb bolus (B)
• Proprietary sheep drench (PD)
• Home mixed drench including cobalt, selenium and iodine (HM)

Lambs were a mix of crosses; Aberfield, Highlander, Oxford and Texel. There were over 55% females as most lambs on trial were sired by maternal rams and ewe lambs were retained. The few Oxford and Texel lambs were very late born RamCompare lambs. 

Health

• All lambs were given Scabivax (to prevent orf) and Click Extra (dicylanil) to prevent flystrike, on 30 April for those going to the common and on 27 May for those staying at home.  
• All dirty lambs were given Albex (benzimidazole) between 25-28 May. 
• Using a targeted selective treatment approach all lambs gaining less than 150g/d were given the appropriate dose of Animec (ivermectin) between 20-25 June. 
• Lambs gaining less than 150g/day were treated with Animec between 19-21 July. 
• Lambs were vaccinated against clostridial diseases using Bravoxin between 20-24 August. 
• Lambs gaining less than 120g/day were given Chanavern (levamisole) between 4-6 September and all lambs were given the treatment between 21 and 23 September. 
• Ewe lambs were vaccinated against toxoplasmosis (Toxovax) and enzootic abortion (Enzovax) on 10 October. 
• Once weaned, lambs were in two groups (all treatments fairly represented in each group) all on recent reseeds or herbal leys. Ewe lambs were pulled out in early October and concentrates introduced to the rest which were housed on 24 October (end of trial). 

Treatments

The home mixed drench was made up on the farm (taking all necessary safety precautions) dissolving 4.2g sodium selenate, 20g of potassium iodide and 33 g cobalt sulphate in 5 litres of water. The total cost of ingredients was £15.58/5 litres or £3.27p/10.5ml dose. This was enough to treat 100 weaned lambs every 3 weeks at 10.5ml/drench – 4 times with some left over.  The formulation of each product is shown in table 1 below.

Table 1 – Product formulations 

The first lambs to go on trial were weighed on 20 July (96 days on trial) and randomly allocated to treatments and given the prescribed dose or bolus. Additional lambs were added to the groups on 28 July (88 days), 9 August and 13 August.  The bolus was given as the lambs joined the trial as were the drenches, but the home mix and the proprietary drenches were repeated four/five times at approximately 3 weekly intervals. 

Outcomes

• Lambs were generally healthy throughout the trial period with approximately one third of lambs wormed when growth rate fell below target on 20 July, 5 September and 22 September.
• FEC testing is carried out routinely on farm and internal parasites were not considered to be a significant problem in summer/autumn 2024, despite the poor weather.  
• A small number of lambs were on trial for less than 40 days and these were excluded from the calculations of daily live-weight gain. All lambs were weighed when they joined the trial and again on 14 August, 6 September and 24 October, unless they were selected for slaughter.  During the trial a total of 8, 2 and 6 wether lambs were sold from the HM, B and PD groups respectively. Daily live weight gain (DLWG) was worked out for each lamb for the duration of the trial and averages calculated.  Lamb performance was generally poor, averaging around 87g/day from July to October which is considered well below target for lambs of 4 to 6 months of age (150g/day or more target). 
• The poor weather conditions of summer 2024 were possibly to blame with well above average rainfall reducing grass dry matter, lamb dry matter intake and restricting growth. 

Remember to consult your vet and independent nutritionist before making changes to your flock supplementation.

Table 2: Results

Acknowledgements

Many thanks to Alwyn Nutting for hosting and managing the trial, treating the animals and gathering the data. Thanks to Farming Connect for supplying the trace element supplements.