1 August 1997

Growth falling, but average OK

GRASS growth is slowing but still above average in most regions, ranging from 30 to 60kg DM/ha a day, reports New Zealand consultant Paul Bird.

Growth at 30kg DM/ha a day is enough to sustain a stocking rate of 2 cows/ha (0.8/acre); 60kg DM growth can sustain twice that rate.

If grass growth is slowing on your farm bring more area into grazing. Many silage aftermaths are, for example, ready to graze.

If milk production lifts significantly when cows are grazed on aftermaths, it is likely that not enough attention has been paid to maintaining quality grass on the rest of the grazing area. There should not be a significant difference in intakes and milk yield potential between the two areas. Remember that cows are capable of producing 20 litres plus from quality grass at this time of year.

Rotationally grazed farms should be lengthening rotations in line with grass growth decline. With grass growth at 60kg DM/ha a day a 25-day rotation is required to allow enough time for regrowth.

Example: Desired amount of grass just before grazing (pre-grazing) is 3000kg DM/ha; desired amount of grass left after grazing (residual) is 1500kg DM/ha. There-fore, grass eaten is 3000kg DM/ha pre-grazing, less the 1500kg DM/ha residual, which is 1500kg DM/ha. This will take 25 days to grow if growth is 60kg DM/ha a day. &#42