Many more livestock farmers should consider the potential of adding red clover to their grass leys to reduce the cost of protein in the diet, according to the Institute of Grassland and Environmental Research.

Recent trials run by Grassland Challenge in Cornwall have revealed dry matter yields of 12-14t/ha (4.9-5.7t/acre) and a crude protein content of 14-25% in a red clover and perennial ryegrass mix.

This resulted in a cost per unit of protein of 11p/kg, compared with a white clover and perennial ryegrass mix at 14.7p/kg.

“In the UK, we have very few reliable protein crops,” says Raymond Jones, head of livestock systems at IGER. “Red clover fits that niche well.”

When ensiled it has a 60-65% true protein content – which the ruminant can actually make use of – compared with 50% in white clover, grass or lucerne.

With high protein, high dry matter and long fibre it works extremely well in dairy cow diets, says Mr Jones. “Research has shown a 22% rise in milk production when feeding red clover compared with grass silage.”

Lambs fed on red clover silage also did well, reaching their market weight 10 days earlier than those fed on perennial ryegrass – and with a 1kg heavier carcass weight at the 3L classification, he adds. “That is quite a substantial return.”

Red clover also fixes about 120-150kg/ha (96-120 units/acre) of nitrogen in the soil, and has long roots, making it an excellent soil conditioner and fertility builder before cereals in both organic and conventional rotations.

However, the crop does require careful management, warns Mr Jones. “It really is a crop for silage making rather than for grazing.

With such aggressive growth it can smother perennial ryegrass when grown in a mix, so is better to grow with Italian or hybrid ryegrass.”

Trials with high sugar ryegrasses have also been promising.

But it can also be grown alone.

The crop or mixed ley should be cut three or four times a year, and it will lasts two to four years, depending on the mix.

However, some red clover varieties are susceptible to stem eelworm and clover rot, so a break of five to six years should be left between leys.

Red clover can also decrease ovulation in ewes, so care should be taken when grazing sheep on the sward.

Aber Ruby, Milvus and Merviot are currently the most disease resistant varieties on offer, but true resistant varieties are still some three to five years away, says Mr Jones.

fwlivestock@rbi.co.uk