When you have 1,600 acres of hay to cut and bale, quality is a tradeoff between the perfect time to harvest and the realities of weather and equipment capacity.
“We’ve got so many acres that maybe we maybe have to start too soon and finish too late,” said Dave Grajczyk, who farms and raises cattle near Mortlach, Sask.
He starts cutting when the alfalfa is in early bud. He uses a disk cutter with impellers for quick drying and, for the first time this year, a double-V rake to double the swath and allow quicker baling.
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The system has been successful, with Grajczyk selling hay locally and in Alberta and the Pacific Rim.
Don Green, Manitoba Agriculture forage specialist, said many producers consider alfalfa’s bud stage when determining the right time to cut.
The late bud stage is “a good general indicator that alfalfa will be of reasonable high quality,” he said. But researchers have been developing more precise methods.
One of the yardsticks is Relative Feed Value. RFV is a figure calculated from a laboratory analysis of two types of plant fibre levels that determine how much an animal will eat and how much it can digest.
Producers who need exact quality information, such as dairy farmers or alfalfa exporters, might want to try RFV tests.
One way is to take clippings and send them to a laboratory.
For quicker assessments, researchers have developed ways to estimate RFV based on plant height and maturity.
Tables give RFV based on plant height and the farmer’s estimate of plant development.
Another method is called PEAQ, or predictive equation for alfalfa quality, developed by agronomists at the University of Wisconsin in Madison.
PEAQ uses a measuring stick that shows the RFV number associated with the height and maturity of the plant.
“Both methods are very useful in terms of predicting the relative feed value of the standing forage,” said Green.
Zero in on feed value
Manitoba Agriculture and the Manitoba Forage Council are working on a predictive model based on growing degree days, Green added.
“Preliminary information shows growing degree days could be a good indicator of relative feed value of alfalfa stands,” he said.
This year, researchers will monitor alfalfa stands at several Manitoba sites to gather data for the project. Green hopes the researchers will be able to deliver a usable model for farmers by 2002.
The ideal RFV number is 150. That will provide alfalfa feed quality appropriate for lactating dairy cows. Beef cattle require lower RFV numbers depending on their energy needs. Stocker cattle need an RFV of about 130, younger heifers about 120 and dry cows about 100 to 110.
“If a producer has a specific relative feed value goal in their final forage, they should be cutting at approximately 20 RFV points higher than their goal,” Green said.
“The reason for that is that as the hay dries in the swath, it is going to respire and continue to use up those photosynthates that have been produced, and mature.”
Once standing alfalfa reaches the late bud stage, it loses about five RFV points per day, he said.
Cutting at the perfect time is not the goal of every producer. Some might want the higher yield available at mid bloom.
So, a harvest that lasts a while can produce a mix of quality.
“That can be a benefit because it will produce a range of quality and they can use those different quality hays to feed their livestock at different times through the winter, putting the feed quality in sync with the nutritional requirements of the livestock,” said Green.
