New Thinking

Dietary diversity brings benefits

A set of trials treating research sheep to a four-course meal of varying forages served throughout the day has provided valuable insights for farmers wanting to improve stock productivity and animal welfare while reducing their environmental footprint. Richard Rennie reports.

THE prospect of eating the same meal for breakfast, lunch and dinner day in, day out holds little appeal for humans. But work by Lincoln University Pastoral Livestock Production Lab PhD student Konagh Garrett indicates sheep feel the same way and a more varied diet will see them repay farmers as happier, higher-producing and more environmentally-friendly livestock.

She says given New Zealand’s reliance upon pastoral systems it is surprising more work has not been done on how different pasture plant species and more functional dietary combinations could improve animal productivity, while reducing environmental impact and enhancing animal welfare.

She is just finishing up her work on that very subject, completing her PhD in animal science with results on dietary combinations that offer practical solutions that could be applied relatively easily to existing commercial pasture systems.

“We were working on the hypothesis that dietary diversity, when functional, will improve animal production and welfare while reducing the environmental impact of agricultural practices, compared to monotonous diets,” Garrett said.

While including indoor cutcarry regimes, the main focus of her work was on feeding ewes and lambs outdoors with grazeable forages.

These comprised plantain, chicory, ryegrass and lucerne, fed either in mixed swards, or individually, while compared to conventional and monotonous diets of either ryegrass or lucerne.

The outcomes supported the hypothesis, with 20% greater dry matter intake of feed compared to conventional ryegrass pastures when it was offered separately in four ‘serves’ and 10% greater when offered as all four in a pasture mix.

The weight gains for the lambs on all four offered in a mixture were 296g a day but when offered separately it was an impressive 378g a day, compared to 227g a day on lucerne, so often considered the gold-standard feed for weight gain.

“We would feed them rye and plantain in the morning and then chicory and lucerne in the afternoon,” she said.

Researchers suspect the animals, just like humans, prefer to have a rotating variety of feeds and even when that variety is incorporated into a single mixture they tend to get bored with it.

Another aspect of Garrett’s work that puts it at the leading edge of dietary study is examining the trans-generational effects of grazing diverse pastures.

She followed twin-bearing ewes and then their lambs grazing each diet. One lamb was removed from the mother at birth to determine the effects of each in-utero and early life dietary experience and the influence on preference and performance in later life.

The results have been promising, providing evidence supporting improved production and welfare compared to those on conventional monoculture diets.

The work has some parallels with the world-leading research conducted by Sir Peter Gluckman and his team who examined the links between maternal diets and the ongoing health of offspring, including links to childhood obesity and diabetes.

Garrett’s work also has relevance to the current attention regenerative agriculture is receiving.

“This provides some insights to pasture mixes and proves how spatially separating species gives farmers another option if you cannot plant all species together,” she said.

Her work is also leading to a better understanding of animal “wellness” and whether a varied dietary offering is contributing to happier animals that are more productive and releasing fewer nitrates.

“The diverse diet appeared to show improved wellness in that happier animals tend to be more productive. But we also found that the ewes on the diverse diets had higher antioxidant status and lower non-esterified fatty acid levels 24 hours after lambing, indicating lower oxidative stress levels,” she said.

Meanwhile, a diet that included alternatives to high protein, high nitrate-generating ryegrass has also proven to have significantly (30%) lower nitrate losses and up to 90% greater daily weight gains.

Garrett has just been awarded sponsorship from farmer cooperative Ruralco to continue with further research while her PhD is being graded. Longer-term, she would like to see her work extended to study an even wider range of pasture species and to apply the different dietary regimes to commercial farming situations.

“There has been a lot of interest, including 10 publications in peer reviewed journals, and it is work that could be applied to farms relatively easily,” she said.

We would feed them rye and plantain in the morning and then chicory and lucerne in the afternoon.

Konagh Garrett Lincoln University

OPTIONS: Lincoln PhD student Konagh Garrett says sheep display a preference for a variety of pasture types.

Keep an eye out

The latest issue of Dairy Farmer will hit letterboxes on August 30.

Our OnFarmStory this month features a Taranaki couple who are passionate about caring for the land. We also catch up with the Canterbury farmers who bought a restaurant to showcase their Red Devon meat, the two South Island farmers behind the Meat the Need and Feed Out charities and take a look at some beef breeds to use over the dairy herd.

SEPTEMBER 2021 | $8.95

Caring for the land

Taranaki farmers on an environmental journey

PLUS: Paddock to plate

➜ Red Devon on the menu ➜ Helping those in need ➜ Better bulls better calves