If dairy scientist Glen Broderick were a dairy producer, he might harvest red clover silage instead of alfalfa haylage.
"If the agronomic aspects of alfalfa and red clover were equal, I would plant red clover for silage," says Broderick, based at USDA's Dairy Forage Research Center in Madison, WI.
While alfalfa is more persistent and yields more than red clover in most areas, the latter forage showed some benefits in four feeding trials Broderick conducted.
"There's less protein breakdown in the silo when red clover is ensiled vs. alfalfa," he says.
When the proteins in alfalfa haylage break down in the silo, non-protein nitrogen (NPN) is formed.
"The more NPN you have in the diet, the less efficiently that protein equivalent will be utilized by the cow," he says. "More of the nitrogen will end up being excreted in the urine and less will be captured as milk protein."
Conversely, red clover has about 40% less NPN because it contains an enzyme, polyphenol oxidase, which reduces protein breakdown.
The crude protein of the alfalfa haylage that Broderick used in his studies was 21% on a dry matter basis vs. 18% for the red clover silage. But the haylage protein was 51% NPN vs. 34% NPN for the clover silage protein.
The crude protein levels varied because the red clover was harvested a few weeks later than the alfalfa.
"We harvested the alfalfa around May 25. If we would have harvested the red clover at that time, it would have been very immature with very little fiber and wouldn't be a good feed."
The ADF and NDF of the alfalfa and clover silages were similar.
In three of the trials, cows ate a total-mixed ration that contained either alfalfa haylage or red clover silage for one month and then were switched. On average, the cows ate 2.5 lbs of dry matter more of the rations with alfalfa haylage and produced 2.5 lbs more milk per day.
In the fourth trial, the protein percentages of the two rations were equal. The intake was still lower for cows eating red clover silage, but the production level was equal between the two groups.
While the results of his studies are complex, Broderick summarizes his main findings as follows:
* Cows fed red clover silage produced more milk per pound of dry matter consumed. "With red clover silage, they're more efficient at converting the dry matter into milk and milk protein," says Broderick. "The protein efficiency is also greater with the red clover silage."
* The fiber and dry matter digestibility of the red clover was greater than that of alfalfa haylage. "I think the cows ate less of the red clover silage partly because it's more digestible."
* The net energy value of the diets containing red clover silage was 10% higher than that of the alfalfa haylage diets.
In addition to its improved digestibility and protein utilization, red clover offers some agronomic benefits, notes Dick Smith, USDA-ARS red clover breeder at the research center.
Because red clover seed is cheaper than alfalfa seed, the crop's less expensive to establish. Smith recommends seeding red clover at 10-12 lbs/acre if it's being seeded alone or at 6-8 lbs/acre if it's seeded with grass.
Red clover also grows better than alfalfa in lower-pH soils. While a soil pH of 6.8 or more is needed for alfalfa, a pH around 6.0 works for red clover.
Of course, alfalfa stands generally last at least one to two years longer than stands of red clover. But newer, more-persistent red clover varieties are available and more will be released this year by USDA-ARS.
"The new varieties are 10-15% more persistent than earlier varieties," says Smith. "There's a greater assurance of them being persistent into the third and fourth years."