Why conduct plantain research?

Dr Ina Pinxterhuis and Dr Elena Minnée are scientists working at DairyNZ. In this video, they explain their interests in plantain and the variety of paths their research has taken.

The video shows a GreenFeed unit that measures the emissions of methane and carbon dioxide exhaled and burped by cows when they visit the feeding hood.

Questions for discussion:

• What does Ina mean when she says, “In research, the more you know, the more you know what you didn’t know or don’t know”?

• Why is it important for Elena to research potential effects of plantain on milk composition?

Transcript

Dr Ina Pinxterhuis

Originally, the interest in plantain grew because of its summer growth. Plant breeders focused on that and that it was a plant that could really complement grass very well in our summer dry pastures. Plant breeders have bred plantain varieties that animals can eat and digest better. Their nutritional value is comparable to grass, but they’ve got a little bit more sugars – carbohydrates – so the nitrogen that the cows are eating can be utilised better. And that means that a little bit more of that nitrogen that the cows are eating goes to milk, and more of it than in grass goes to faeces. And that is beneficial because it means less will go to the urine patch.

Dr Elena Minnée

And what we noticed through that work was that the animals really took to the plantain – they found it quite palatable. They were producing the same or more amount of milk, and it was looking very, very promising. Then there was a series of work that was looking at integrating that into the pastures. And through that research, it was discovered that, when you add other species into the pasture, like plantain and chicory, we were noticing a decrease in the concentration of nitrogen coming from the cows in urine. There was also some modelling studies that were predicting that, if you include plantain in the diet, you would have lower amounts of nitrogen excreted in the urine.

Dr Ina Pinxterhuis

We were really focusing on nitrate leaching. Plantain can have a major effect on groundwater leaching. That is the drainage of water with the dissolved nitrates below their root zone so plants cannot reach it any more. The urine patch is really the big source of drainage of nitrogen. With plantain diluting the urine, there’s less nitrogen in surplus of what plants can take up. When we discovered that urine patch effect, we also realised that that should have a beneficial effect for greenhouse gas emission as well, because if we have urine patches with a lower nitrogen load – so less nitrogen per area – also the nitrous oxide and ammonia emission should be lower.

Dr Elena Minnée

I’ve been working in Ina’s programme of work to look at how much plantain do we need to feed a cow to reduce the amount of nitrogen she’s excreting in her urine to reduce that risk of nitrate leaching. So I have done several studies where I’ve been feeding cows different levels of plantain to try and find what that critical level of plantain in the diet is needed to cause a reduction in her urinary N. And we have determined that you do need at least 30% of plantain in the diet to induce that reduction in urinary N concentration.

Dr Ina Pinxterhuis

What we’ve noticed in our programme is really how many questions there actually are. You only start off with a few, but the more you know, the more you know that you didn’t know or don’t know. So there’s still a lot of research questions that are open for work.

Dr Elena Minnée

What I’ve been moving into more recently is looking at the milk composition. So if every farmer in New Zealand adopts plantain as a tool for reducing their nitrogen leaching risk, what’s that going to do to the milk that we are providing to our processors? It’s being sent all over the world. Is there any issues around product quality and integrity?

And the other pet area of interest of mine is looking at methane emissions, because we want to make sure that, while we’re addressing our freshwater quality issues, we’re not causing another problem elsewhere by creating a greenhouse gas problem. So most recently, we’ve been doing experiments where we have been feeding cows various levels of plantain and evaluating how much methane they’re producing. It is very early days, but the trends that we’re observing is that it looks like there is a reduction in methane emissions per unit of feed eaten when cows are fed plantain, and this is really exciting, because if we get two for one, then that is a really positive benefit.

Acknowledgements Dr Ina Pinxterhuis Dr Elena Minnée Grace Gibberd DairyNZ

Acknowledgement

This resource has been produced with the support of DairyNZ.