However, Rex and Audrey Stevenson, with DairyNZ, have proved two-day shifts can work without breakouts occurring and soil structure damaged.
The trial was at the Stevensons’ runoff near Te Anau, where this year they wintered 730 mixed-aged cows and in-calf heifers, 250 dairy yearlings and 100 beef steers on 47ha of crop, mainly Swedes and kale, with a small area of fodder beet. The soil type is mostly a silt loam, with some heavier soil, and 80-90mm of rain falls each month through winter.
Besides decreasing their workload, the Stevensons also wanted to minimise crop losses when hungry cows rushed on to a new break. Animals were divided into mobs of 150 and given breaks of 0.2-0.22ha (14m2 per cow), as well as four bales of grass balage, two bales of whole-crop balage and one bale of cereal straw.
Bales were placed about six metres apart so cows could get around them easily. Feeding levels were 60% crop, 40% supplement. Per cow per day this worked out to be 8.5kg drymatter (DM) crop, 2.5kg DM grass balage, 1.3kg DM whole-crop balage, and 2kg DM straw.
Breaks were square in shape instead of long faces.
The Stevensons found two to three hours after the cows were moved on to the new break in the morning they were sitting down.
By late afternoon they had eaten 80% of the crop, 25% of the grass balage and hadn’t touched the whole-crop balage or the straw.
By late afternoon on the second day the crop and the grass balage was mostly eaten, as well as 66% of the whole-crop silage and 33% of the straw. If a mob had eaten everything by the end of the second day it was moved, instead of waiting until the next morning.
It took four days at the start of the winter for cows to settle into the regime and when the weather forecast was bad another bale of straw was added to the current break, so they were full before the bad weather hit.
Although the system used more bale feeders – the Stevensons used 48 – it meant less tractor work, with the balage placed on the crop before winter and straw needing to be moved only every second day.
Another benefit was cows competed less for feed, resulting in a smaller range of body condition scores at the end of winter.
Cows on fodder beet were transitioned using on-off grazing for at least a week before the two-day system began.
DairyNZ said the system would not work when cows needed to be restricted to less than 12kg DM/cow/day because feed was tight, because breakouts could occur and cows would compete more for feed. Also, if crop yields were high – more than 18 tonnes DM/ha – cows might need to be given three-day breaks because otherwise they would be on too small an area and would cause damage to the uneaten crop.
It also advised the two-day system was unlikely to work for yearling mobs because yearlings tended to walk up and down instead of settling, which caused feed to be trampled.
