Surprising agricultural research results prompt academics to consider further study

• Research from Charles Sturt University shows that changing the type of pasture offered to ewes and lambs does not reduce their survival rates
• The research was conducted by a professor and honorary student of Charles Sturt
• The aim of the research was to assess the impact of grazing forage oats during late gestation on lamb survival.

Research by a Charles Sturt University lecturer and her undergraduate student shows no significant impact on ewe and lamb survival from grazing oats rather than pasture.

Dr Susan Robertson (pictured, inset, main image) is a senior research fellow at the Gulbali Institute for Agriculture, Water and the Environment and a lecturer in ruminant production at the Charles Sturt School of Agricultural, Environmental and Veterinary Sciences in Wagga Wagga and led the research with honorary student Mr Walter Morton.

Mr Morton (pictured, second image) was completing a Bachelor of Animal Science (Honours) at Wagga Wagga.

The aim of the research was to compare pasture types in late gestation to determine their impact on lamb survival.

The research involved comparing oats or pasture grains with alfalfa during late gestation and lambing.

Pasture cereals can be used in autumn and winter for lambing ewes, but some producers avoid grazing pregnant ewes on wheat, oats and barley because of concerns about increased rates of lambing difficulty and ewe and lamb mortality.

This is because grazed cereals are low in calcium and magnesium. Supplementation of these minerals is recommended when grazing pregnant or lactating ewes to minimise the risk of disease.

The research team conducted the study to compare the survival of lambs from alfalfa and forage oat pastures. All ewes were also given calcium and magnesium supplements. Lamb survival was recorded at the end of the lambing period.

Ewe mortality was low and ewe attendance at lambing was low, not increased by oats.

No metabolic diseases were observed and blood samples did not detect any magnesium or calcium deficiency.

Lamb survival was similar for ewes grazing alfalfa (84%) or oats (79%); however, lamb survival decreased for ewes grazing oats only during lambing (71%), which was associated with greater loss of condition during lambing.

Lambs grazing oats weighed two kilograms less than lambs grazing alfalfa at the time of branding.

Dr Robertson and Mr Morton concluded that when supplemented with calcium, magnesium and sodium, cereal oats can be grazed by late gestation and lambing ewes without increased risk to their survival.

Dr Robertson said some of the study’s results were surprising.

She thought that feeding oats to ewes in late pregnancy might lead to greater weight gain in ewes and higher birth weights in lambs, but that was not the case. She added that there were also some other unexpected effects.

“The lower lamb survival rate when ewes switched from legumes to oats for lambing was unexpected,” she said.

“This was probably due to greater nutritional restriction, but further studies are needed to assess whether this is a random finding or occurs consistently.

“I also didn’t expect to see lower weight gain in lambs grazing oats, but this may be due to more limited intake or the fact that in August the oats were becoming stalkier. If lambing had taken place earlier, when the oats are of better quality, this may not have happened.”

Mr Morton said completing the study was an “extremely informative and valuable experience” that gave him unique skills to launch his career in agriculture.

“Learning how to identify a knowledge gap and begin to fill that gap is a skill that is definitely being translated into the agricultural sector,” he said.

“Developing the ability to synthesize raw data to convey the meaning behind it succinctly and clearly has also been an extremely valuable experience for me.”

Dr Robertson said the surprising results and the lack of other published studies prompted the team to repeat the study to better understand the response and improve information for producers.