Farmers warned over the nutritional value of grass

Even if autumn grass is plentiful, its nutritional value can be deceptively low, according to vet Dr Elizabeth Berry. “But this year on many Northern Ireland farms, the combination of sparse grazing and poor quality could have a serious bearing on suckler cow fertility, calf growth rates and post-weaning recovery of ewes ready for breeding,” she says.

“Perhaps surprisingly, human intuition plays an important part in misjudging things. We all know that ruminants have evolved to eat grass. So it’s not surprising if we add two and two to get five by assuming that pasture can supply all nutrients needed for high performance in cattle or sheep.

“Even if it’s plentiful and supplying all the energy and protein needed, most grazing in this country is deficient in one or more trace elements. Their essential roles in metabolic processes mean that shortages will limit all ruminants’ ability to utilise nutrients in grazed grass fully. In most places, the deficient trace elements are cobalt, iodine and selenium.”

Cobalt is needed by rumen bugs for producing vitamin B12, an essential component in energy metabolism and producing red blood cells. Iodine regulates metabolism and conversion of food into energy, while selenium is needed for enzyme synthesis and plays a crucial part in immune function and fertility.

Where copper is also deficient, most farmers already know about it from past bad experience. But for the most part, Dr Berry says, it’s understandable if shortages of the other three go unnoticed if those looking after cattle or sheep get used to a certain level of performance as the norm.

“Perhaps it’s become acceptable to get 75 calves per 100 cows each year, a calf taking 18 months from birth to 450kg liveweight, or 1.5 lambs per ewe,” she suggests. “However, each of these is only modest performance.

“Financially, the difference between these figures and 90 calves, 14 months or 180 per cent is massive. On some farms, addressing unseen trace element deficiencies with the Tracesure range of boluses can make the difference.”

The boluses have a 180-day slow-release ‘leaching’ mechanism developed and patented by Animax, not available from other sources.