Effective trace element supplementation will help ensure lambs maximise growth and are ready for market on specification and on time.
While lambs finishing on grass may receive adequate energy and protein, growth rates may be reduced if their daily requirements for trace elements are not met.
Grazed grass can be low in many key trace elements, a problem which becomes worse when grass growth becomes variable and as quality declines, which are two problems associated with mid and later season grazing.
Annie Williams, animal scientist with Agrimin, says: “After a cold wet start to the season, growth rates have increased rapidly in recent weeks and are currently ahead of average.
“The current warm dry spell growth will continue to accelerate growth, but we may see grass shooting to head, which will have the effect of reducing digestibility and quality.”
Ms Williams says grazing typically only supplies low concentrations of cobalt, iodine and selenium, which are the key trace elements for optimal lamb growth.
The cold start to the grazing season will have reduced the ability of plants to take up trace elements from the soil, which is a notoriously slow process anyway.
She says it is likely some form of supplementation could have a positive impact on performance, especially when grass availability is varied and unreliable from July onwards.
Ms Williams says the key is to ensure every lamb is adequately supplemented with the appropriate trace minerals every day to ensure a consistent supply to meet requirements.
Ms Williams recently collated results from a validated farm study in Cornwall to assess the benefits of supplementing lambs.
It involved twin Romney lambs which were allocated to a treatment and a control group based on liveweight.
All blood samples were taken and analysed by the farm’s own vets, while all weights were taken using the farmer’s own handling facility.
Ms Williams says: “Lambs were managed as one group and weighed every four weeks for 16 weeks. We also blood tested animals to examine the effect of the boluses on selenium, iodine and cobalt. Iodine was of particular interest, as the farm had a history of low iodine levels.”
Ms Williams says the blood tests showed the benefits of bolusing: “At the start of the trial, all lambs showed low blood iodine levels, indicating inadequate recent iodine intakes. By 12 weeks, levels in supplemented lambs had risen significantly, while unsupplemented lambs were still below the level indicating adequate intakes.
“The selenium status of supplemented lambs was also significantly higher than the unsupplemented group.”
Ms Williams says supplemented lambs showed a significantly improved growth rate. By week 12 of the trial, supplemented lambs had grown 20 per cent more than unsupplemented lambs.
She says: “Ensure optimal growth rates in lambs has a big impact on overall management and profitability.
“This can ensure more lambs hit the desired market specification quickly, reducing pressure on grazing and allowing more grass to ewes in the lead up to tupping. It can also help reduce the number of lambs having to be stored.”