Lamb health at risk after dry spring
1st July 2025
The very dry, warm spring has raised red flags over cobalt and selenium levels, prompting concerns over lamb health.
Weather conditions such as these can disrupt the natural availability of key trace elements, with serious implications for lamb growth and immunity before and after weaning.
Sarah Gallimore, technical associate at livestock health and husbandry specialist Nettex, said:
“Cobalt and selenium play vital roles in post-weaning lamb health. Low levels can impact immune function and growth at a time when lambs are already under stress from weaning and potentially facing parasite challenges.
“Identifying the issue and finding a suitable drench or bolus can help prevent disease and improve post weaning weight.”
Deficiencies on farm
Research from Teagasc reinforces this concern:
- 73% of surveyed sheep farms had cobalt-deficient herbage
- Only 11% had herbage with sufficient levels of selenium.
The same research showed cobalt supplementation significantly boosted lamb performance post-weaning, resulting in higher carcass weights.
Selenium is key to supporting immunity and preventing white muscle disease, while cobalt is vital for vitamin B12 synthesis in the rumen, which is a crucial factor in energy metabolism and liveweight gain.
As cobalt cannot be stored in the body, a steady supply throughout the grazing season is essential.
What are the signs?
Sarah said: “Deficiencies often go unnoticed until lamb performance starts to decline. Weaning is a vulnerable period, and any nutritional shortfall can cause a growth check or increased susceptibility to disease.”
Typical signs of cobalt deficiency include poor growth, dull fleece, loss of appetite, runny eyes, and increased worm burdens due to reduced immunity.
Top tips
Sarah recommends forage analysis as a first step. “Testing forage gives farmers clarity on what’s lacking and allows them to supplement effectively – whether via drenches, boluses, free access or in-feed options.
“It’s about ensuring lambs continue to thrive, not just survive, after weaning.
“When choosing a supplementation product, it’s also important to consider how long those animals are on the farm for and what is in the products.”
She suggests lambs that are leaving the farm, but need supplementation, can benefit from a Nettex’s Cobalt, Selenium and B12 drench.
Alternatively, a micro-bolus such as Cob-I-sel 60 can be used to deliver iodine, selenium and multi-vitamins over 60 days.
“With rapidly changing grass quality and increasing demands on youngstock, it’s important farmers understand the trace element situation on their farm and act now to safeguard lamb health and performance,” she said.
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