A slightly earlier harvest schedule may be one way to get more nutritional value from a red clover crop.
Early and average cutting times for the legume were compared in research at the U.S. Dairy Forage Research Center in Madison, WI. The results from two years of harvesting a first-year crop showed that taking cuttings a week earlier can improve seasonal distribution of yield, favorably decrease NDF and rumen undegradable protein (RUP) and increase crude protein and rumen degradable protein (RDP).
“We worked with the red clover variety Marathon and compared two three-cut systems, varying the cuttings of each by one week,” explains research agronomist John Grabber.
“For the earlier schedule, we took the first cutting on June 7, allowing for 40 days of regrowth between each of the next two cuttings. Our later schedule began with the first cutting on June 14, and followed with two more cuttings, each about 40 days apart. All cuttings were ensiled at 37% dry matter and stored for 90 days.”
The earlier harvest schedule shifted some dry matter production from the first to the third cutting, but overall seasonal dry matter yields and stand persistence were similar for the two harvest schedules, says Grabber. “But notable differences were seen in the levels of NDF, crude protein and protein fractions.”
With adequate soil moisture, red clover can produce dry matter yields and forage quality that are equal to or better than alfalfa, but feed intake and milk production from cows fed red clover is often not as good, he says.
“Red clover contains o-quinones that protect proteins during ensiling and increase RUP, but this could somewhat hamper amino acid absorption or utilization by dairy cows.”
Another factor that can reduce milk production is that red clover may not contain enough readily degraded protein to support rapid growth of microbes in the rumen, which are a major source of dietary protein, explains Grabber.
“We found that an earlier cutting schedule in the spring favorably increased the amount of RDP and slightly decreased the amount of RUP protected by o-quinones.”
First cutting was taken at the late-vegetative growth stage, the second when most plants were at bud stage, and the third when about one-third of plants were in bloom. That earlier harvest schedule produced a dairy-quality clover crop with more desirable dry matter concentrations of NDF (40%), crude protein (20%) and RDP (15%), he says.
“Even with early cuttings, the degradable protein in red clover was much lower than that found in a relatively mature alfalfa crop,” he says. “Degradable protein supplements may still be needed to help dairy cattle maximize rumen microbial protein synthesis.”
Grabber offers one caution to earlier harvest. “If you've got a clover variety that is marginal in winter persistence, an earlier first cutting could cause more stress and stand loss. The flip side is that having extra time for regrowth in the fall may improve the crop's persistence going into winter.
“Our findings, particularly those related to yield and stand persistence, must be confirmed by agronomists in other regions of the country before earlier cutting is widely adopted by farmers outside of south-central Wisconsin,” he says. “Feeding trials to confirm the benefits of an earlier first cutting would be a logical next step, as well.”