DESPITE an exceptional year for grass growth, technicians are warning that cobalt deficiency is threatening to limit lamb growth rates.

Nia Williams, Nettex technical marketing manager, said farmers had reported that while early lambs had got away well, later lambs had not been flourishing.

She said: “Although grass growth has been unhindered this season, forage mineral analysis performed by Nettex has identified levels of essential trace elements below the optimum.

“Average cobalt levels in forageonly rations have been recorded as below lamb average daily requirements.

The wet weather last winter and spring has contributed to trace elements being leached from soils.

“This, combined with grazing quality now declining, and in some cases drying up owing to the recent hot weather, has meant lambs are not thriving and the lack of cobalt seems to be a contributing factor.”

Trace elements play a significant role in lamb health and performance.

“Cobalt is especially important as it is an essential component of vitamin B12. Rumen bacteria require a level of cobalt to be able to synthesise vitamin B12, vital for energy metabolism and efficient lamb growth.

“However, lambs have a limited capacity to store cobalt in the body and therefore require supplementation to ensure sufficient daily intake, particularly in regions where cobalt deficiency is prolific.”

She said ewes synthesised their own vitamin B12 of which a proportion was passed onto the lamb through her milk. Lambs also make their own vitamin B12 from forage intake.

“As lambs are weaned, the loss of vitamin B12 via the milk, combined with their delayed increase derived from grazing, can mean lambs do not push on as well, particularly in areas that are deficient in the trace element,” she said.

Weaned lambs are, therefore, most at risk of clinical cobalt deficiency, known as “pine”.

Symptoms include ill-thrift and lack of appetite, resulting in longer finishing times and reduced carcase weights.

Farmers who think their lambs may be suffering from cobalt deficiency are advised to seek help from an independent expert.

“Having forage analysed or blood samples taken is recommended to confirm animals are suffering from cobalt deficiency and to clarify that other factors are not contributing to poor performance.

Assuming a deficiency, the next step is to administer cobalt.”

Nettex has two products designed to combat cobalt deficiency post-weaning. The Cobalt, Selenium and Vitamin B12 Drench immediately provides the lamb with trace element and vitamin supplementation that can be rapidly absorbed to aid cobalt and vitamin B12 levels.

The Nettex Cob-I-Sel 25, Cobalt Micro Bolus, releases a daily dose of cobalt for a period of 25 days, providing a longer-term solution.

The alternative modes of action of the Nettex products allow farmers to adapt a treatment and management programme to suit their system.

For farmers regularly handling animals, a drench is a quick and easy way to administer cobalt, with rapid effect. For those with limited access to handling systems or where regular intervention is impractical, the bolus provides protection for up to a six- to eightweek period.

Nia said: “If farmers are aware they are in an area where cobalt is deficient, an initial drench administered to lambs, followed by a bolus from the age of five weeks, can be an effective programme to avoid the risk of deficiency post-weaning.

“Research has proven the Cob-ISel bolus can help increase lambs’ daily live weight gains by 40g per day in areas of deficiency, and provides a cost-effective long-term solution for farmers when combined with drenching in the first weeks of life.”