Diverse pastures increase production

Diverse pastures increase production

Diverse pastures with herbs and legumes added to traditional ryegrass and clover mixtures might increase milk production and reduce environmental impact, Lincoln University PhD student Frisco Nobilly says.

He presented a study to the Grassland Conference at Tauranga in November which focused on the productivity of simple and diverse pastures grazed by dairy cows under irrigation in Canterbury during a two-year period. It used two-species mixtures of perennial ryegrass (standard and high sugar) and tall fescue sown with white clover compared with more diverse mixtures where additional herbs (chicory and plantain), legumes (lucerne or red clover) and grasses (prairie grass) were added.

The results showed the diverse pastures produced more herbage drymatter than the simple pastures because of the extra yield grown during summer from the herbs including chicory and plantain.

The annual herbage production was 1.62 tonnes drymatter (DM)/ha greater in the diverse pastures. They averaged 16.77t DM/ha compared with the simple pastures which averaged 15.15t DM/ha.

The simple pastures had slightly higher metabolisable energy (ME) content than diverse pastures, but the diverse pastures had an overall higher ME/ha average during the two years. The diverse pastures measured 202 gigajoules (GJ) ME/ha compared with 185 GJ ME/ha in the simple pastures. The higher herbage drymatter and higher ME/ha production indicates that diverse pastures could increase milksolid production per cow and per hectare, Nobilly said.

A lower nitrogen excretion recorded during the study from cows grazing the diverse pastures indicated diverse pastures containing additional herbs and legumes might reduce the environmental impact. The diverse pastures also had lower natural detergent fibre (301g/kg DM) than the simple pastures (368g/kg DM).