27 February 1998

No gain feeding maize on good spring grass

By Sue Rider

FEEDING maize silage as a buffer to high yielding dairy cows at well-managed spring grass fails to increase milk yields, according to a joint Milk Development Council/Maize Growers Association-funded trial at ADAS Bridgets, Hants.

Speaking about the project at this weeks MGA conference at Shepton Mallet, Robert Bull, ADAS Bridgets farm manager, said there is no clear economic advantage in feeding maize silage as a buffer to high yielding cows at turnout in spring. Cows can average 29 litres a day from grazed grass alone, and when given ready access to maize silage, they eat less grass.

The high merit cows were rotationally grazing well managed, high quality spring grass, he stressed. This allowed cows to sustain average yields of 29 litres a day over 10 weeks, producing 2000 litres of milk from grass. A further 12-16 weeks grazing were then left to achieve target milk yields approaching 5000 litres a lactation from grazed grass alone.

However, feeding maize silage did offer one advantage – it consistently reduced milk urea levels.

This is significant in that high milk urea is associated with infertility and lower cheese quality.

The project, repeated over two years, involved 60 high merit cows, stocked at up to 20/ha (8/acre) over 10 weeks during April, May and June. Cows were split into three groups. One third received no supplementary maize silage, another third was offered 6kg dry matter maize silage, the rest 3kg DM of maize silage, offered as two feeds, after each milking.

Cows grazed rotationally, with each paddock managed so that target sward height on entry was 12 -18cm (4.7-7in); cows stayed in the paddock for three days. To maintain quality sweeper cows cleared up on the fourth day.

Unsupplemented cows grazed harder than maize-fed groups and tended to lose more weight, but provided there was plenty of grass available, this was not significant.

DM availability was reduced in cold, wet conditions, or by poor grass management, cows with access to maize were able to eat more energy, so produced more milk than unsupplemented animals, and lost less weight. In such situations, cows can be offered up to 3kg DM a head a day maize silage to help maintain yields, said Mr Bull.

MAIZE AT SPRING GRASS

&#8226 Offers no benefits if sufficient grass DM available.

&#8226 Yields of 30 litres a cow a day possible off grass alone.

&#8226 If wet and cold, and low grass DM, 3kg DM/day maize silage will help maintain milk and component yields.

&#8226 Producer/processors could consider supplementing grass with maize, to help maintain manufacturing quality.

&#8226 Reduces milk urea, so could help improve fertility.

MAIZE AT SPRING GRASS

&#8226 Offers no benefits if sufficient grass DM available.

&#8226 Yields of 30 litres a cow a day possible off grass alone.

&#8226 If wet and cold, and low grass DM, maize silage helps maintain milk and component yields.