Project update: October 2025

What has been done?

A mineral audit was undertaken through Farming Connect in the spring/summer of 2025 which assessed all feed and supplements given to sheep and compared total intake of key minerals and trace elements against stock requirements.

This highlighted the following key issues noted in Table 1:

Issue

Impact

Recommended Action 

High K:Mg Ratio

Risk of grass staggers in grazing animals.

Supplement with magnesium.

High K:Na Ratio

Sodium deficiency; affects palatability and nerve function.

Increase sodium supplementation.

Low Selenium

Weakened immunity, poor growth, white muscle disease.

Administer selenium bolus or drench.

Low Cobalt

Vitamin B12 deficiency; poor growth and ill-thrift.

Supplement with cobalt.

Low Iodine

Reproductive issues, goitre in lambs, poor growth rates and ill-thrift.

Target supplementation in affected areas.

High S & Mo (Copper Interference)

Reduced copper availability; coat discoloration, lameness.

Increase copper supplementation carefully, or use injectable forms.

It was therefore decided to set up a trial to compare proprietary drenches with a home mix trace element drench concentrating on the issues that would be affecting growing lambs (Selenium, Cobalt, Iodine and Copper).

Approximately 150 Welsh Mountain male lambs were randomly allocated to one of three treatment groups on 4 July, Table 2.  

Table 2: Allocated groups

Group nameGroup 1Group 2Group 3
TreatmentControlControl + higher Cu levelsHome recipe + higher Cu levels
No of lambs50 lambs50 lambs50 lambs
Drench usedAdministered off the shelf mineral drench, containing low levels of Cu (product normally used on farm)Administered off the shelf mineral drench, containing no Cu (version of product normally used on farm that does not contain CuAdministered Home recipe drench, containing Co, Se and I 
Drench cost£26.20/litre£24.80/litre£3.11/litre
Drench applications2 weeks prior to weaning and at 6 weeks intervals thereafter later.2 weeks prior to weaning and at 6 weeks intervals thereafter later.2 weeks prior to weaning, 2 weeks post weaning and every 3 weeks thereafter until end of project
Coparods – 12.7p/capsuleNon administeredAdministered Cu capsule 2 weeks prior to weaning that will increase the amount of Cu in supplementation.Administered Cu capsule 2 weeks prior to weaning that will increase the amount of Cu in supplementation.

On 16 or 17 July, all lambs received their initial treatment. A second treatment was administered to the lambs in group 3 on 11 August, and a final treatment was given to all lambs on 4 September. On that same day, blood samples were collected from six lambs in each treatment group by a veterinarian.

Grass supplies have unfortunately been limited through the summer due to the dry weather and due to fields being taken out of the rotation for reseeding, hence lamb growth rate has been disappointing. Some health issues were also reported with some fly-strike cases.

On 4 September ticks were noticed on some lambs and blood tests confirmed tick borne fever (high temperature, loss of appetite, increased respiratory rate, weight loss etc). These lambs were treated according to veterinarian guidance and removed from the trial.

All groups' weight gains were very similar over weaning and post weaning.

Blood samples were taken at the end of the first 6 week period and confirmed that selenium levels were well above the target level, copper was at the top end of the recommended range and cobalt (Vit B12) was on average low in control and control plus Coparods but above the recommended threshold for the home mix. This suggests that more regular drenching (every three weeks) is more effective at maintaining cobalt levels than drenching at 6 weekly intervals with a proprietary drench. All lambs were low in iodine. 

Next steps

The trial is continuing, and with the lambs now grazing on aftermaths and red clover reseeds, we expect to see an increase in daily live weight gains (DLWGs) across all groups.

Blood samples will be taken again at the end of the second six-week period to continue monitoring mineral levels. We will also track the weights of all lambs every three weeks until the trial concludes on 26 November.

Figure 1: Trial in progress at Brynllech