Plantain Trials Yield Promising Results In Reducing Dairy Nitrogen Excretion

“Promising” results have emerged from Teagasc plantain research trials where a 25pc reduction in urinary nitrogen excretion from dairy cows was observed.

Teagasc has previously found that urine patches from cattle at pasture can be responsible for as much as 62pc of nitrate leached

“This €riN model currently estimates a nitrate loss rate of approximately 28pc for urine N, which could be potentially overestimating the impact of the urine patch,” lead Teagasc researcher Dr Michael Dineen said.

“Further experiments are underway to strengthen this estimate.”

The plantain trials come as part of a Department of Agriculture-funded project entitled ‘Pasture-Nue’, which has also been working across 28 commercial farms to understand factors affecting nitrogen emissions.

“It is important to note that we had 50pc plantain in our three-species swards of grass, white clover and plantain. The swards were reseeded in July 2022 and then we started harvesting for the experiment in August 2023,” Dr Dineen told the Farming Independent.

​“In practice, a more realistic target would be 30pc plantain and the challenge then is to try maintain that proportion of plantain over time. When there was 50pc plantain, the cows reduced their urinary nitrogen excretion by 25pc.”

The researchers found similar milk yield and milk protein, but observed a “slight reduction” in milk fat concentration.

“There might have been too much plantain at 50pc and you’re potentially losing a little bit of milk fat. Looking at a larger grazing study in Moorepark, there were no differences in milk-solids yield over the grazing season between grass-white clover and grass-white clover-plantain,” he said.

“Some of the New Zealand work would suggest improved milk solids, the majority have demonstrated no impact on milk solids, and then a couple of studies have observed slightly lower milk fat. Researchers in UCD that are collaborating on the Pasture-Nue project would have seen similar, with no significant differences in milk-solids yield over a grazing season.”

Part of the nitrogen reduction found in the trial is attributable to less nitrogen intake, where the crude protein of the plantain sward was lower.

“The cows seemed to also partition nitrogen away from their urine and into their faeces. That’s a positive outcome because it’s more organically bound, less likely to be leached and more likely to be recycled back up into the sward and retained in the system.

“Whereas with urine, it’s more soluble and more likely to be leached from free-draining soils.”

“The cows consuming plantain produced about 20 litres more urine per day and urinated 4 more times.

“The urine was much more dilute, with about a 40pc reduction in the concentration of nitrogen in the urine.

“This would result in the cow spreading urine, that is less concentrated in nitrogen, more frequently around the paddock through more urination events.”

“One of the most important questions to answer now is whether plantain can persist in our swards under Irish conditions and if it can maintain the profitability of pasture-based systems.”

(Source – Irish Independent – Farming Independent – Niall Hurson – 19/11/2024)