Clonakilty Agricultural College Dairy Update

The current experiment in Clonakilty Agricultural College is investigating the use of white clover and nitrogen fertiliser in intensive dairy systems. Brian Mc Carthy and Aine Murray give an update on their research to date.

The white clover and nitrogen fertiliser experiment has four grazing treatments all stocked at 2.75 cows/ha;

• a grass-only sward getting 250 kg nitrogen/ha,
• a grass-only sward getting 150 kg of nitrogen/ha,
• a grass-clover sward getting 250 kg nitrogen/ha and
• a grass-clover sward getting 150 kg nitrogen/ha.

Currently we are building grass covers on the farm for the autumn, using our autumn budget, and average farm cover is on target at around 800 kg DM/ha for the grass-only 250 and grass-clover 150 and 250 treatments. However, the grass-only 150 treatment is slightly behind target at just over 700 kg DM/ha. Growth ranged from 51 to 71 kg DM/ha per day last week. Sward white clover content in August so far has been 23% and 22% on the grass-clover 150 and grass-clover 250 treatments, respectively. So far this year we have grown 10.9, 9.9, 10.3 and 11.6 t DM/ha on the grass-only 250, grass-only 150, grass-clover 250 and grass-clover 150 treatments.

In terms of milk production, the cows grazing grass-clover swards are producing more milk solids than cows grazing the grass-only swards, with no real effect of nitrogen fertiliser rate being observed currently. The cows grazing grass-clover swards are currently milking 18.7 kg at 4.88% fat and 3.90% protein giving 1.63 kg milk solids per cow per day. The cows grazing grass-only swards are currently milking 17.5 kg at 4.73% fat and 3.88% protein giving 1.50 kg milk solids per cow per day. In terms of cumulative milk solids production to date, the grass-clover cows have produced 398 kg compared to 376 kg for the grass-only cows.