Research

Lincoln University PhD student Cameron Marshall has been researching how cow diet affects the environment for his thesis.

A different perspective

By Samantha Tennent

A Lincoln University PhD student has found proof that dairy cows could be part of the solution when it comes to mitigating the environmental impact of farming.

Dairy cows are typically seen as the problem when it comes to environmental impact, but a PhD student at Lincoln University has uncovered how the cow can be used as a solution.

As part of his doctoral thesis, Cameron Marshall has identifi ed two promising tools that dairy farmers can use to reduce nitrogen (N) losses and relieve the negative impact on the environment.

“Animals tend to be seen as a problem that needs changing and there’s often no consideration that perhaps the system is wrong for the animal,” Marshall, who was studying with the Lincoln University Pastoral Livestock Production Lab, says.

“We try to change the system and strategies to try to fi x the animal but now we can look at the animal as a solution.

“And if we use it in conjunction with other solutions, such as dietary and system management options, we could reduce the overall environmental impact from the dairy sector.”

His work has explored the milk urea nitrogen breeding value (MUNBV) and how it relates to nitrate leaching and nitrous oxide emissions from cows.

“We found with cows that are phenotypically lower for milk urea nitrogen, what they eat and how they eat is important to reducing their environmental impact,” he says.

“And that helps us understand how to get the maximum benefi t from cows predisposed to urinating lower concentrations of N, resulting in less leaching to waterways.”

Milk urea (MU) is a byproduct of the breakdown of dietary protein. It is formed from the normal daily metabolism of N and protein and although most urea is excreted in the urine, some passes into the milk. Dairy cows with differing MUNBVs have been shown to have differences in milk composition, rumen function and urination behaviour.

Marshall used MUNBV information for the herd on the Lincoln University Dairy Farm, which was identifi ed through herd testing from CRV. He noted when they were fed a diet of plantain rather than ryegrass, cows with low MUN phenotypes excreted signifi cantly less N each time they urinated, which reduces the potential N leaching into waterways.

He also found cows with differing MUNBV displayed different grazing and ruminating behaviour. They chew their pasture differently, which determines their rumen function and e ciency of N digestion and use in the rumen, and this leads to altering the N excretion patterns to the environment.

In previous research, he had demonstrated that cows selected for low MUNBV had a 28% reduction in the urinary urea N loading rate per urine patch than cows with higher MUNBV. The ‘better cows’ also produced a higher milk protein percentage.

“With the milk urea nitrogen breeding value we have identifi ed a trait we can breed for that will reduce the

“We try to change the system and strategies to try to fix the animal but now we can look at the animal as a solution.”

Cameron Marshall

environmental impact of dairy cows,” he says.

“There is natural variation among cows and if farmers categorise their cows for the milk urea nitrogen they could build it into their breeding programme. For example, mating a low MUNBV cow with a LowN sire will likely produce progeny with less environmental impact.

“And then if we feed them plantain in their diet the impact is likely reduced further.”

His research indicates that both the use of cows with low MUNBVs and the use of a plantain diet are tools that temperate pastoral dairy production systems can use to reduce nitrogen losses. This is good news for the dairy sector, having further tools in the toolbox to support sustainability and reduce the impact on the environment.

Marshall grew up on a lifestyle block near Lincoln and spent four years completing a Bachelor in Agricultural Science with First Class Honors before moving into his PhD. He has just finished the work towards his PhD, including publishing scientific articles explaining his findings.

He is now on the hunt for a role that will allow him to continue contributing to developing solutions for the problems New Zealand agriculture faces.

“I like this space, especially in New Zealand, there’s a lot of demand and potential to support our rural communities and I love being able to contribute,” he says.

A Lincoln University study has found proof that dairy cows could be part of the solution when it comes to mitigating the environmental impact of farming.

Chap’s Pond Was Too Thick To Stir!

It’s no wonder Chap Zwiers’ 520 cow dairy farm has such luscious green grass…just take a look at his effluent pond!

To describe the nutrients in Chap’s effluent pond as rich would be an understatement. His cows have the luxury of a large covered feedpad looking out to green pastures on one side, and the effluent pond on the other. With just a short journey from feedpad to pond, the slurry is very thick. So thick that Chap thought he might need to install a solid separator.

‘With all the effluent from the feedpad, the pond was just too thick and the stirrer was struggling. I’d been thinking solid separation might be the answer, but I didn’t want to deal with 2 products if I didn’t have to.’

Chap’s brother-in-law, Thomas Scheres, had used Nevada before and was more than pleased with the results, so Chap picked up the phone to ask for some advice.

‘The slurry was thick alright, but nothing a good stirrer in the right location couldn’t handle.’

Michael Prestidge – Nevada Effluent Management Specialist

The problem wasn’t the slurry, it was that the original stirrer had been placed in the wrong location and didn’t have enough power to churn through the amount of solids entering the pond. Given the size and shape of the pond, Mike recommended a 9m Nevada electric stirrer be placed on the adjacent side of the pond to the inlet.

Chap had been expecting to need solids separation and given his last stirrer from another supplier hadn’t worked out, he was naturally sceptical of Mike’s advice.

‘I didn’t want to go to the efforts of getting a new one [stirrer] installed in a new spot, only to

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‘Well she’s still in there! The advice was spot on. I was a bit surprised how much of a difference a good stirrer in the right location can make. It’s definitely worth consulting with specialists with a proven record.’

find it didn’t work out either and I should have just gone for the solid separator.’

Chap asked Mike if he’d be prepared to guarantee the stirrer would work and take it out if it didn’t. Mike was confident in his advice, and so the stirrer was installed. The results?

‘Well she’s still in there! The advice was spot on. I was a bit surprised how much of a difference a good stirrer in the right location can make. It’s definitely worth consulting with specialists with a proven record.’

NZ’s Leading Dairy Effluent Management Specialists nevadagroup.co.nz 0800 464 393

AgResearch scientist Caroline Thum has discovered an ingredient found in a natural oil that could make infant formulas more digestible for babies and improve their brain development.

A winning formula?

By Tony Benny

An exciting new discovery by an AgResearch scientist will change the composition of infant formulas and has the potential to be a financial boom.

Asecret ingredient identified by AgResearch scientist Caroline Thum could improve both the digestibility of infant formula and its contribution to babies’ brain development, a discovery that could be worth billions of dollars to New Zealand’s dairy industry.

Though she can’t disclose exactly what the ingredient is, it’s found in a nutritional oil soon to be available in NZ. Thum discovered it when researching ways to improve infant formula.

“It was funny because it was not in an area I would be looking at. I was reading papers when I found it and we have some companies in New Zealand that could produce that for us and I think in New Zealand we can build an industry around that,” Thum says.

At present, during manufacture of formula, milk fat, which babies are unable to digest properly, is removed and replaced with a blend of vegetable oil which more closely matches the profile of fatty acids in human milk. But that can cause constipation in babies.

“The poo gets really hard and causes discomfort in the baby and they lose energy and calcium,” she says.

Formula makers add prebiotics to help with constipation but the scientist isn’t convinced that’s the best solution.

“Instead of solving the problem they add something else to solve the problem, so it was like, ‘Okay, can we have a different blend or a different source of fat to add to the formula to solve that?’,” she says.

“I started doing some research and I found an oil that is surprisingly similar to the fat in breast milk – it’s from a

“We aim to show improved fat and calcium absorption, in addition to the positive effect of the phospholipids for brain development.” Caroline Thum

natural source that I can’t disclose – that potentially solves this problem.”

With funding over three years recently announced from the Government’s 2021 Endeavour Fund, Thum and fellow AgResearch scientist Simon Loveday, along with collaborators from Massey and Monash universities, are aiming to enhance the “humanness” of infant formula produced from NZ ingredients.

Thum also wants to add an element found in milk fat back into the formula. Phospholipids are removed along with other fats during manufacture, but they have an important role in the development of babies’ brains as well as immunity.

“What we want to do is use this special oil and encapsulate that with the phospholipids that the dairy industry produces to create a formula much closer to what we find in human milk, with the right fat profile for the baby, as well as a source of phospholipids to better develop the brain,” she says.

Over the next three years the nextgeneration formula ingredient will be tested in the laboratory using equipment that simulates the conditions inside a baby’s digestive system.

“This will tell us how well the new combination is digested, compared to conventional infant formula. We aim to show improved fat and calcium absorption, in addition to the positive effect of the phospholipids for brain development,” she says.

With the global markets for infant formula and baby foods expected to continue their strong growth, new products that provide a health advantage are in high demand.

Further down the track she can see the oil being used to develop product for the elderly as their digestive systems slow down and produce fewer enzymes to aid digestion.

“It’s very similar to what we find in babies so we could tailor this special oil to give the right lipid profile for the elderly too,” she says. n Researchers are aiming to enhance the humanness of infant formulas produced from New Zealand ingredients and the discovery of a new ingredient will help with this.

I struggle to think about going back to wintering cows on pasture now for a variety of reasons. The cows are warm and happy, we can feed them much more “ economically and we’ve got beautiful compost to put on our pastures and boost the nutrients.

Jeff Rea, Readale West Otago

Increased milk production, benefits in cow comfort and pasture yield SmartShelters clear spans provide industry leading airflow and natural light Reduce mastitis levels and eliminate lameness