28 April 1995

Silage timing is vital for output

CORRECTLY-timed silaging is vital to maximise digestibility and so enhance intake and milk output.

That is the timely advice from Tim Keady, forage and ruminant researcher at Hillsborough Research Institute near Belfast.

His trials show a 10g/kg rise in digestibility improves intake by 1.5%, prompting a 0.32kg a day lift in milk yield.

"It is date of harvest which affects digestibility," stresses Dr Keady. Work at Hillsborough proves that for each days delay after May 15-20, digestibility fades by 0.3 to 0.5 units a day. Lodging also speeds a downturn in digestibility, which impairs animal performance. "In severe cases, in flattened crops, digestibility can drop by 7 units a week."

Grass species also has an effect. Perennial ryegrass (PRG) swards usually have a higher digestibility than permanent pasture. But PRG heading dates affect digestibility.

In Hillsborough trials early and late heading varieties, with 50% ear emergence by May 20 and June 13 respectively, were compared. Results indicate that to obtain the same animal performance the later vartieties need harvesting only 7-8 days after the early types.