New Zealand
November 19, 2010

Wide variation in the persistence and palatability of different ryegrass cultivars has become clearly evident on a South Canterbury farm where new grasses are compared each year.
Otaio dairy farmer and former seed consultant Roderick Hayman (photo), who converted a sheep and cattle property five years ago into a 220 hectare dairy farm, believes the importance of cultivar selection cannot be over-stated.

“We want to see for ourselves the amount of residual left behind after grazing and how well these different grasses are being grazed, their recovery after grazing and their quality,” said Roderick, who wintered 800 cows and is milking 770 this season.

While pasture persistence is an essential requirement, a grass’ taste or palatability to cows is also a top priority and in Roderick’s book a good measure is how much grass the cows leave behind after a 12-hour grazing break.

High sugar grasses that offer an elevated level of soluble carbohydrate are leading the way.

“They will go into AberMagic (photo) with a cover of 3,300 (kg drymatter per hectare) and just hoover through it. They graze it to the boards and are nearly eating the soil. I have yet to see that happen with another grass,” said Roderick.

As well as fully feeding the cows, such close grazing means a paddock’s regrowth is likely to be more dense, fresh and leafier than pasture that’s grazed half-heartedly and clumps being left behind.

A problem with not-so-tasty paddocks is they often have to be re-grazed, usually with dry cows, or topped with a mower – or even taken out of the round and shut for silage.

“I have never had to re-graze or mow the Aber grass. I haven’t cut it for silage yet because it doesn’t bolt and then go rank. It’s a very easy grass to manage,” said Roderick, who has 25 hectares in AberMagic and AberDart diploid perennial high sugar grasses and is about to plant more paddocks.

AberDart was sown at the start of the farm’s conversion, followed by the more recent cultivar AberMagic, because Roderick liked the concept of its extra carbohydrate boosting rumen activity in the cow and encouraging more grass consumption – and more milk production.

Last spring a different ryegrass marketed as offering “improved soluble carbohydrate levels” was sown in half a paddock with AberMagic sown in the other half as a test.

“There was no fence between those two grasses but you could clearly see the difference,” said Roderick.

During winter the other grass was frost damaged and had yellowed while the AberMagic stayed a deeper green and grew densely.

“It was like chalk and cheese. In spring they would not graze the (other grass) down,” said Roderick, who hosted a spring visit from CRT Seed consultants wanting to see how the grasses compared.

A shorter term tetraploid ryegrass that’s promoted as an alternative to high sugar grass is another having its turn in the sun, in a paddock close to the dairy so its persistence and ability to fully feed the cows can be closely watched.

Tetraploid plant tissue holds more water, which means a cow has to consumer more of this grass to match its drymatter intake from a diploid ryegrass like AberMagic.

Among trialled ryegrasses since sprayed out was one marketed as drought proof.

“Perhaps it looked drought proof because nothing would eat it. The cows would not graze the stuff,” said Roderick.

He has given up trying mixes of several grasses to extend a paddock’s year-round performance because their different heading (seeding) dates made quality maintenance difficult.

“I will keep going with one ryegrass, as we have decided with AberMagic and clover. This is a strong grass. It grows dense and despite an extremely wet winter has shown less pugging damage.”

After each grazing he applies a light “salt and pepper” spread of urea (nitrogen).

“These new grasses need feeding. If you don’t put it in the paddock, it won’t walk it out the gate,” said Roderick.
 

Website: http://www.germinalseeds.co.nz/

Published: November 19, 2010