Improving lamb growth rates using new ryegrass and endophyte technology

Preliminary data on the evaluation of two distinct perennial ryegrass varieties for prime lamb production in a high rainfall environment conducted at Ballarat, Victoria.


  • The two grass treatments were Victorian perennial ryegrass (-10 days to Nui) diploid and Halo AR37 (+25 days to Nui) tetraploid perennial ryegrass. These were sown as pure swards at a rate of 25 kg/ha. Each treatment was replicated three times and were all rotationally grazed and spelled at similar times
  • The trial commenced in autumn 2015 using second cross lambs and will continue over a number of years to account for seasonal differences
  • Liveweight gain, stocking rate and return /ha were the main performance criteria and these were determined by averaging the results from the three replicates
  • Persistence scores on both ryegrasses will be conducted at the conclusion of the trial

Trial results to date

  • From the inception of the trial in autumn 2015 to spring 2016, Halo perennial ryegrass has produced 179kg more carcass weight/ha than Victorian perennial ryegrass. This equates to an extra $895/ha based on a $5/kg carcass price
  • Most of this gain can be attributed to the genetic origin of this modern ryegrass. Halo is of North West Spanish origin which has been extensively trialed under Australian conditions. These grasses have the ability to produce more feed than Victorian rye over that critical autumn/winter period. This is reflected in our results resulting in higher stocking rates (Figure 2) and a larger gross return (Figure 4) over this period
  • The other important aspect of Halo, particularly in higher rainfall areas, is that it is a late maturing ryegrass. In October Victorian ryegrass started sending up seed heads and consequently the feed quality deteriorates quite rapidly. At the same time Halo remains in a green vegetative state still supporting high lamb liveweight gains in mid/late spring (Figure 1).
  • Halo perennial ryegrass also contains the new and much improved endophyte AR37. This endophyte provides very good plant protection against insects and has less animal health impacts on stock than the wild type endophyte found in Victorian ryegrass. The standard endophyte found in Victorian ryegrass can cause animal staggers and heat stress along with lower liveweight gains and reduced milk yields. For more information on AR37 endophyte, including animal health and production information visit
  • The trial is still running and more data and analysis is required (e.g. feed quality tests, more seasons, statistical analysis etc.)

- (2015/16) in the figures refers to the average of that season over those 2 years. E.g. if the live weight gain for Halo in autumn 2015 was 300g/ha/day while in Autumn 2016 it was 200g then the average used in the figures would be 250g/hd/day.
-(2015) in the figures refers to only one year's data since 2016 data is still to be collected

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