14 January 2000

Care pays dividends in silage production

ATTENTION to detail to maximise silage quality has long been a top priority on one Sussex unit.

Of the herds average yield of 7606 litres, 4469 litres comes from forage.

"We aim to take our first silage cut on 1 May in the afternoon when sugar levels are high. This allows us to go for a second cut in early June meaning both cuts have a similar yield of about 6t/acre and MEs of 11.5-12," says Roger Comber of Manor Farm, Selham, West Sussex (see table).

Until five years ago, when Mr Comber began using contractors, silage making took 10 days. Now it only takes two days meaning grass can be ensiled quickly and at the correct stage to maximise quality.

"Grass is tedded and allowed to wilt for 24-48 hours before picking up and ensiling." His clamp is under cover and great care is taken over consolidation and side sheeting. It is re-opened in autumn for storage of maize silage on top of grass silage.

"Maize has yielded well this year at up to 16t/acre. Sub-soiling gets it off to a good start, packing soil down well," says Mr Comber. Harvesting maize at the right stage of maturity is also crucial to maximise digestibility of the whole plant, adds independent ruminant nutritionist David Donaldson. "Often there is too much emphasis on cob ripeness to the detriment of whole plant digestibility. Often maize is harvested when grain is too hard and the stem is woody."

Maize and grass silage are fed in a 50:50 ratio to Mr Combers 165 cows with 1.5kg a head of rapeseed meal. Mr Donaldson says keeping rations simple reduces costs.

"Too many diets contain about 10 different straights, making storage and mixing complicated and adding to cost. Feed conversion efficiency could also be better on many units; the UK average is 1kg dry matter/kg of milk. On this unit, feed conversion efficiency is good at about 1kg dry matter/1.4kg of milk."

Moving towards better feed conversion means improving forage use, explains Mr Donaldson. "There are a number of 6500 litre herds feeding lots of silage and concentrates but with poor feed conversion efficiency. Producing good quality forage and reducing concentrate input helps address this problem, providing yield is not compromised."

With about 60% of total feed costs accounted for by forage, feed conversion efficiency is a more accurate way of focusing on feed costs than margin over concentrate, which does not take account of forage costs, he says.

"Dry cows should be included in feed cost calculations. To calculate feed costs, work out the cost a tonne of dry matter a day of the whole diet – forage and concentrates – and divide by number of litres.

"For this herd, feed cost is 5.2p/litre compared with a national average of about 7.7p/litre." &#42

Silage analysis

Results from Manor Farms 1999 first cut grass silage:

D-value 71

ME 11.4MJ/kg

Crude protein 18.5%

pH 3.8

Ammonia-N

(as % of total nitrogen) 9.3