Article By: Country Wide-Magazine. Source: Country-Wide

Studying sheep grazing patterns is helping scientists find out how to maximise performance.
"Looking at intake rates and patterns of grazing throughout the day on clover and ryegrass has shown us that sheep prefer about 70% clover and 30% grass in their diet. They rarely get this in a traditional mixed sward pasture, because the proportion of clover is too low," says AgResearch scientist Gerald Cosgrove.

The four-year trial, carried out by AgResearch, has tested a novel grazing method that allows sheep to chose the diet they prefer. The work was contracted to Meat New Zealand and the Foundation for Research, Science and Technology, and presented at the June Society of Animal Production Conference by Danielle Marotti. The concept involves offering pure swards of clover and ryegrass side-by-side, so that the sheep's nutritional demands for high clover intake can be met. "By providing both clover and ryegrass, sheep can really perform well because they get a high daily intake and the clover provides quality," explains Cosgrove.

"We found that lambs did around 80% better on clover and ryegrass side-by-side, than on pure ryegrass swards."

The result will hit-home to farmers the benefit of legume in a sheep's diet. Most importantly it's also demonstrated that you can get similar performance off clover/ryegrass side-by-side as on 100% clover. This is good news for farmers trying to maximise efficiency by limiting feed costs while still boosting performance. "As sheep did just as well on the side-by-side option as they did on 100% clover, this means that farmers can keep feed costs low by including ryegrass in their diet. It reduces the need to plant large areas of clover, which can be more expensive," comments Cosgrove.

"Most importantly, the side-by-side method is a far more practical way of ensuring the proportion of clover in the diet is kept high."

"Imagine the cost of trying to create and maintain a mixed sward that has 50% white clover and 50% ryegrass. It would be difficult and damned expensive."

The trials involved grazing newly weaned lambs, lactating cross-bred ewes with twin lambs at foot, and ewe hoggets on three different options - pure ryegrass, pure white clover, or pure swards of clover and ryegrass side-by-side. Liveweight gain was measured over a 21-35 day period, depending on the class of stock. These classes of stock were chosen as they are either more responsive to higher nutrient intake than others, or suffer from restricted intake during crunch periods of the year.

The trials were run on three-year-old Yatsyn perennial ryegrass or white clover pastures at AgResearch Grassland (Manawatu) and Meridian perennial ryegrass or Pitau white clover pastures at Poukawa Research Station. A trial of weaned lamb performance on typical mixed ryegrass/clover pasture (containing 90% ryegrass and 10% white clover) was also included. When grass and clover were grazing side-by-side, each species comprised 50% by area. Herbage samples, weight changes and daily grazing patterns were used to calculate intake.
Lambs grew 150g/day faster on the pure clover and side-by-side treatments than on ryegrass alone. This was despite the fact that the ryegrass in the trial was a dense leafy high quality sward. Over the 29 days of the trial, the higher liveweight gain resulted in an extra 4.3 kilograms of liveweight per lamb. At $4.40/kgCW, this equates to $8.80/lamb.
"Alternatively, this 150g/day advantage could be used to put more lambs through a finishing block," suggests Cosgrove.

It would take lambs 27 days to gain five kilograms of liveweight if they grazed the ryegrass alone option. However, it would take only 15 days on a clover dominated diet (either 100% clover or ryegrass and clover side-by-side) to make the same gains. Almost double the number of lambs could be finished to the same target weight, although they would consume only the same total amount of feed.

The problem of low clover content in mixed swards was clearly demonstrated with the LWG of lambs on a mixed sward (10% clover) being similar to those offered grass alone.
The trial of ewes with lambs at foot showed that the combined weight advantage on ryegrass/clover side-by-side was 50% above ryegrass alone. WoolPro-funded work at Lincoln University is also looking at the benefits of this novel grazing concept, in their on-going designer-sward project. AgResearch scientist Gerald Cosgrove would like to take the work further, to look at the potential for chicory, brassica or lucerne side-by-side with ryegrass.