21 February 1997

Dont harvest kale too early

KALE is harvested too early for optimum silage making, says Ray Jones of the Institute of Grassland and Environmental Research, Aberystwyth.

Speaking at the Birmingham venue of Alltechs annual European feed biotechnology lecture tour, Dr Jones said milk producers should budget for lower milk prices in the future and look to supplement protein from forage to minimise costs.

"Kale is an excellent protein provider, but current practice of harvesting kale for ensiling 12 to 14 weeks after sowing does not allow sufficient time for sugar levels to rise as the plant matures," said Dr Jones.

Trials conducted by IGER have shown that at least 12% sugar is needed as a feed source for bugs to promote the right pH for silage production.

"At 15 weeks sugar levels reach about 10.5% and by 20 weeks they reached about 18.5%. An extra benefit is that losses from ensiled material decrease as the plant ages, from about 13.8% at 15 weeks, down to 5.8% at 20 weeks," he said. Digestibility levels remained above 70 beyond 20 weeks.

"But crude protein levels fall from 15% at 15 weeks to 12.5% at 18 weeks. Therefore, the optimum time for harvesting lies between 15 to 18 weeks after sowing, preferably using an inoculant to further improve fermentation."

Recent advances in breeding lupins could also provide a cheap and practical form of protein.

"Plant breeders had developed new autumn sown varieties which could be harvested in July at 72 D, improving fermentation." &#42