Choose your pasture sowing dates for best results

“Pasture renewal strategies which provide high-quality feed production from spring through into late summer begin even before the seed is sown,” he said.

Rob Brazendale, DairyNZ’s development team leader of productivity, agrees, said late-flowering ryegrass varieties have the potential to lift feed quality as dairy farms move into the summer months.
“Having quality feed throughout the lactation is critical to achieving high production and profitability.” October and November were the most critical months for pasture management, as growth rates were high and any drop in energy levels affected pasture quality and animal production.

Kerr said many recent dairy conversions have chosen to plant about 50:50 in early and late-heading varieties to ensure a balanced feed supply from August through into December. Careful choice of varieties with early-heading dates have a key position in dairy farms, because of their better yield through August and September, a critical time in dairy systems covering calving and into the second grazing round. However, they are liable to go to seed and lose quality earlier.

Reduced MJ ME

These grasses have a reduction in their megajoules of metabolisable energy (MJ ME) as the spring progresses, from a high level of over 12MJ ME in early October, down to 11-12MJ ME late in November, under an efficient grazing management regime.

Brazendale said early-heading grasses had been the backbone of New Zealand’s agricultural system for decades and would continue to be.

“By comparison, lateheading varieties will not begin reducing in ME levels until early November and slowly lose quality through into mid- or late December. Sowing these varieties has the potential to maintain continued high quality animal intake and performance during November well after the early heading varieties have peaked.”

Generally, all late-heading varieties produce less seedhead overall and, as a result, it’s easier for farmers to maintain ME through their grazing.

DairyNZ supports forage options that better match the feed demands of highproducing dairy farm systems. That includes increasing the supply of homegrown feed when it’s most limited, and where the introduction of laterheading pasture varieties can help out.

When silage is typically made through November and December, the later-heading varieties are in full production to maintain a feed supply that is both high quality and quantity, and so ideal for high animal production.

“We make our money getting as much ME as possible directly into cows,” Kerr said. While silage needed to be made out of excess pasture growth through late spring, farmers should feed the best quality pasture, paddocks of late-heading varieties, to their cows to maximise their intakes.

Quality silage is vital for cows to thrive through the winter months, and early-heading grasses make excellent silage at over 11.5MJ ME if cut at a 3500kg dry matter (DM)/ha herbage mass.

The three vital questions

Farmers considering pasture renewal need to answer three key questions:

  • Which paddock to renew?
  • Which endophyte to choose?
  • What cultivar to select?

Farmers are advised to identify their poorest performing paddocks, understand why they are below standard and correct these problems before renewing the pasture species. Problems may include poor fertility and drainage.

Generally, protection from insect attack becomes increasingly important moving north. Most of the South Island has little insect challenge and therefore introducing a novel endophtye is less of a priority. For lower North Island farmers, protection against Argentine stem weevil is essential. From Taupo north, pastures need protection from both that weevil and black beetle.

Choosing the right endophtye for a particular farming environment is not a simple task and farmers are advised to seek advice before deciding.

Different cultivars have different growth-rate characteristics. Farmers must match these characteristics with their requirement to maximise the return from renewed pastures.

Published courtesy of Dairy Exporter November 2009