LINDELL BEA CH, B.C. – Researchers have found that up to 35 percent of accumulated nitrogen on high density dairy farms can be reduced with a balanced protein diet without compromising milk production.
Sixty-four commercial farms were involved in the study led by biologist Haritz Arriaga of the Basque Institute for Agricultural Development and Research, Neiker-Tecnalia in Barcelona, Spain.
One part of the study analyzed feed and found that 70 percent of the diet of lactating cows was excessively rich in proteins. The quantity of protein ingested was directly related to the volume of nitrogen excreted in the feces and urine and therefore into the environment.
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Arriaga said this was because 6.25 percent of the protein was formed by the nitrogen chemical element. The research indicated that with a better balance of protein in the diet, nitrogen can be reduced by 35 percent.
The results also showed nutritional strategies can reduce accumulation of nitrogen on high-density dairy farms and the concentration per acre of soil can be reduced by 4.5 percent.
Another part of the study researched the efficient use of nitrogen by cattle through the use of commercial concentrates.
It compared diets with low forage content and high concentrates typically used on commercial dairy farms with diets that had greater forage and less concentrate content. The resulting manure from the different diets was applied to grasslands to evaluate the effects of the nitrogen-based gases and ammonia on the environment.
The research showed that the diet with higher forage content reduced the animals’ urge to eat because the volume of fibre provided a greater sense of satisfaction.
The nitrogen intake in this high forage, low consumption diet was lower, as was the amount of nitrogen in the manure, but it also caused a loss in milk production.
“The best option is to balance nitrogen intake with an accurate forage-concentrate ratio,” Arriaga said.
“It is estimated that nitrogen intakes of around 650 grams per day and a forage-concentrate ratio of 50:50 are able to produce high milk yields (above 40 kilograms milk per day). These nitrogen intakes should not compromise milk yields. Nevertheless, it is extremely important to fit nitrogen intakes to the milk yield level of each herd. In our study there were some herds which produced 25 kg of milk per day. I think that you can use the above data as an approach to diets which do not compromise milk yields, but the importance of (matching) nitrogen intake to production level should be highlighted.”
Another part of the study looked at how the concentration of protein in the ration affects the amount of ammonia and nitrous oxide concentration in the dairy barn. Both gases are harmful to humans, cattle and the environment.
The study showed that concentrations of the gases in the soil ranged between 7.1 milligrams of ammonia per cubic metre in low protein diets to 10.8 mg of ammonia per cubic metre in higher protein feeds.
In contrast, the amount of nitrous oxide was similar with an average of 1.1 mg per cubic metre but was still greater than the atmospheric concentration of 0.5 mg per cubic metre.
