1 October 1999

Cover low protein levels by using rape and soya

By Marianne Curtis

VARIABILITY in grass silage protein quality and quantity was highlighted as a key concern by advisors at the Dairy Event. But reasonably-priced rape and soya should allow producers to compensate for protein shortfalls.

Consultants and feed companies at the Dairy Event reported a greater overall variation in silage quality than last year, particularly on protein. However, energy levels were agreed to be mainly acceptable.

Analysis results obtained by Axient show reasonable energy levels of about 11 ME with proteins on the low side, according to Wilts based consultant Andy Thompson.

"Proteins are lower than I would like, averaging 12-13%. Last year they were nearer 15-16%, he said.

"Producers formerly feeding 3kg a cow a day of a 50:50 rape/soya blend may need to step this up to 4kg to compensate for lower silage protein content. But fortunately rape/soya blend prices are down £20-£30/t on last year at about £100/t."

Low protein quality, reflected in high rumen degradable protein values, is a concern for Wales-based ADAS consultant Ken Stebbings. "In silages made before mid-May we are seeing high levels of ammonia nitrogen, mainly derived from fertiliser applications."

High levels of ammonia nitrogen mean silage protein is very degradable and Mr Stebbings advises that increasing soya levels may be necessary to raise ration protein quality.

Bibby ruminant product marketing manager, Duncan Rose, is also uneasy about high ammonia levels seen in silage analysed by his company. "Some ammonia levels have been running above 11%; 2% higher than last year. This may be the result of too much fertiliser, too close to the cutting date.

"Where ammonia is high, this can slow feed intakes. But in a stable high lactic acid, low pH silage high ammonias are fine. Unstable silages should be analysed once a month."

But a pit of silage is not uniform and producers should check it on a monthly basis to pick up changes, warns Mr Rose.

SILAGEPROTEIN

&#8226 Lower that last year.

&#8226 Variable quality.

&#8226 Check clamp frequently.