Some nitrogen normally excreted in urine was diverted to milk production and feces.
His Agriculture and Agri-Food Canada research paper has just been published in the Journal of Dairy Science.
The researchers found that methane, expressed on dry matter intake basis, as a percentage of gross energy intake, or grams per pound of energy corrected milk declined as the amount of canola meal in the diet increased. This energy was captured in greater milk production, rather than lost to the atmosphere.
The researchers also found that more of the dietary nitrogen from canola meal was converted to milk protein, and less was lost in the urine with each incremental increase in dietary canola meal. Urine nitrogen contributes to atmospheric ammonia and nitrous oxide.
“It is really interesting that canola meal reduces methane emissions, shifts nitrogen excretion from urine to feces (i.e. less potential N emissions) and improves performance at the same time,” said Benchaar. “Thus, canola meal improves the environmental footprint of milk production.”
The diets contained 52 per cent forage and 48 per cent concentrate on dry matter basis. The diets were balanced to provide 16 per cent crude protein, with all the supplemental protein in the control diet provided by soybean meal.
The test diets contained (on dry matter basis), eight, 16 or 24 per cent canola meal.
Dry matter intake and energy corrected milk increased as canola meal in the diet increased, with no effect on feed efficiency (energy corrected milk/dry matter intake).
“To the best of my knowledge, the 24 per cent inclusion of canola meal is the highest ever tested in a controlled study,” Benchaar said.
“The all-canola meal diet resulted in five pounds more energy corrected milk than the all-soybean meal diet.”