Irish sheep farmers are advised to be wary of misleading 'go faster stripes' on supplements for weaned lambs that claim vitamin B inclusion. This alert comes from vet Dr Elizabeth Berry of Animax.
"For ruminants, supplementary B-vitamins are no more than pixie dust," she says. "As long as the diet contains sufficient cobalt, ruminants make their own B12, for example.
"Moreover, vitamin B1 and most others in this group are also made by rumen bugs as long as rumen function is good. At best, inclusion in a supplement is a placebo."
For farms producing finished lambs, Dr Berry says getting them to target weight as quickly as possible without concentrates clearly makes good business sense. Among factors governing the conversion of grass into meat, she advises that one of the most critical in lambs is the role of cobalt.
"In all ruminants, cobalt is essential for the synthesis by rumen bacteria of vitamin B12, which is critical in energy and protein metabolism," she explains. "While lambs are suckling, milk provides their cobalt requirement in full. But post-weaning, cobalt levels in grass are deficient in many parts of Ireland."
Without supplementation, the usual sign of deficiency is slow growth due to poor appetite. This can be followed by weakness, anaemia and emaciation.
This year in particular, Dr Berry says heavy rainfall in February and March will have leached cobalt from topsoil.
"Since then, of course, we've seen rapid grass growth but the resulting dilution effect creates extra-low cobalt levels in herbage. So for maximum growth rates off grass, supplementation is even more important than usual.
For convenience and reliability, Dr Berry recommends a cobalt trickle charge leaching bolus. Called Allsure Cobalt, it contains premium cobalt sources with high bioavailability, which is not universally the case.
"To avoid doubt," she says, "these boluses do not contain B-vitamins because, as long as cobalt inclusion is sufficient, they're unnecessary."
Leaching bolus technology is patented by and unique to Animax, designed to release trace elements at a regulated rate. The company's livestock specialists are available to farmers for free advice.