What are they?
A tetraploid plant has 4 sets of chromosomes per cell, compared
with a normal diploid plant (2 sets). The tetraploid plant cells are
therefore bigger than diploid plants and have a higher ratio of
cell contents (soluble carbohydrates) to cell wall (fibre). The result
is a plant that tastes better and is more palatable to animals and
this can improve intake and increase animal production.
Wrightson Seeds currently has six tetraploids available:
- QUARTET , a tetraploid perennial ryegrass,
- BANQUET ® a tetraploid long rotation ryegrass,
- FEAST II ™ a tetraploid italian ryegrass,
- WINTER STAR , a tetraploid annual ryegrass
- WINTER STAR II , a new tetraploid annual ryegrass
- SUNGRAZER T , a new tetraploid annual ryegrass
These cultivars have been carefully bred and tested before
release to ensure both good persistence and good production
levels.
Animal Performance Benefits
The animal performance benefits of tetraploid ryegrasses are:
- improved palatability and therefore intake - greater
intake can lead to increased milk production and/or
improved body condition.
- More efficient rumen function - tetraploid ryegrasses
can be broken down more quickly and completely
in the rumen due to the high ratio of cell contents to
cell wall.
- More clover - tetraploid ryegrass allows about 10% more
clover in the pasture and this further increases pasture
quality and nitrogen fixation.
Farm Management Benefits
The farm management benefits of using tetraploid ryegrasses
are:
- Improved utilization of pasture - because of the improved
palatability more of the grass is utilized. This can lead to
easier pasture management by reducing the need to top,
or by having less seed head development.
- Reduced stocking rates - with the improved palatability
and greater intake per cow, the opportunity exists to
reduce stocking rate and improve per cow production and
farm profitability. Fewer cows means fewer replacements
reared or purchased and reduced farm costs, including
labour, mating and vet costs.
Grazing Management Tips
The following tips for getting the best out of your Wrightson bred
tetraploid ryegrasses have been sourced from researchers and
farmers.
These are:
- Avoid overgrazing - because of their excellent palatability
animals can overgraze tetraploid ryegrasses. If you graze
to a lower residual than with your diploid ryegrasses you
may compromise persistence although tetraploid
ryegrasses we market have demonstrated better
persistence than most diploids.
- Apply nitrogen - tetraploid ryegrasses are naturally darker
in colour than diploid ryegrasses, however they require
similar amounts of nitrogen to diploids.
Camden dairy trial
A trial was undertaken during 2002 by The University of Sydney
at “Mayfarm”, Camden, which compared tetraploids against
diploids from the same genetic base, for both perennial and
short-term ryegrasses. The trial results below compare Impact
(diploid perennial ryegrass) and Banquet (a tetraploid based on
Impact).
The results show that the tetraploid Banquet produced 10%
more milk volume , 17% more milk fat and 16% more
protein per hectare than control cultivar Impact, for an
improved return of $223 per ha . (See Banquet page 13).
- The trial was conducted at the University of Sydney’s ‘Mayfarm’, at
Camden, New South Wales.
- The trial commenced in April 2002, when the pastures were sown.
- The animal production aspect of the trial concluded after 8 months
in December 2002; final plant density measurements were made
on 15 March 2003.
- All economic calculations are based on a milk price of $0.30 per
litre, being the milk price applying in the Camden region during the
period of the trial in 2002.
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