Ryegrass choice dilemma for farmers

With the lack of truely independent trials for farmers to evaluate in ryegrass cultivar selection, and the seed companies advertising selective, choosing the correct seed mix can be confusing for farmers.

This article in Country-wide summarizing a paper given at the Grassland conference will be useful reading to many.

Lack of profits in farming is often driven by increased cost, and sowing the incorrect ryegrass can shorten the renewal cycle and lower profits.

New grass breeding has brought many advantages in production and palatability, but the longievity of a pasture is often disappointing, adding greater costs to pastoral farming.

Tom Fraser from Ag Research, with Professor Grant Edwards from Lincoln University, ran a farmer workshop session at the recent Grassland Conference to discuss the issue of ryegrass selection. Edwards explained that ryegrasses sit on spectrum from annual, Italian and short-rotation ryegrasses through to the long rotation perennial ryegrasses. As a rule of thumb, annual grasses produce a high volume of high-quality feed, have some cool season activity but have decreased persistence, while long-rotation ryegrasses tend to have better persistence, less feed quality than the annual varieties and little winter growth.

Selecting the best variety comes down to key factors which include flowering dates, endophyte, ploidy (tetraploid or diploid) and sugar levels. The flowering date does affect the growth pattern. Mid-flowering varieties will generally have more early spring growth than later flowering varieties and for this reason late-flowering varieties may not be ideally suited to a summer dry environment. As perennial ryegrasses lose quality with the development of a seed head, the feed quality with early flowering varieties will drop off earlier in the season than that of late flowering.

Sugar levels are another consideration. High-sugar grasses were developed 25 years ago in Europe and some are available in NZ. Some NZ-bred standard perennial ryegrasses are available that have high sugar content, but they are not marketed as such. Edwards says there is not a lot of evidence to suggest that these grasses give better animal performance. There is also no evidence to suggest they are worse than standard ryegrasses. High-sugar grasses may have some environmental benefits in that they improve the utilisation of nitrogen (N) in the rumen which reduces losses to the environment. They make a contribution to reducing the amount of N secreted by livestock, but this may require higher sugar levels than are expressed at present.

Endophyte selection is determined by the pests in any given situation. Several endophytes on the market offer differing degrees of protection against a variety of pests. AR37 ryegrasses are more persistent but possibly less palatable than AR1, but AR1 ryegrasses are easier to over-graze as the deterrents for over-grazing are just not there.