Southeast Manitoba sees considerable winterkill in alfalfa

Manitoba Forage & Grassland Association Green Gold Report for May 18, 2017

Fields throughout the Southeast have experienced considerable winter kill due in part to the mild conditions this past winter and rains that may have reduced the insulating effect of the snow and/or caused icing that suffocated the alfalfa.

Winter Kill

Hopefully most of you have walked your alfalfa fields and assessed if you have any significant winterkill concerns. From the fields that I have visited in the South-East winterkill looks to be a concern. Hopefully your fields look like photo at the top of this page rather than the photo below. For more information on assessing alfalfa winter kill, read this article from the MFGA May newsletter.

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What is Relative Feed Value?

Over the years we often get the question about RFV. Relative Feed Value is an excellent measure of alfalfa quality because it reflects the digestibility (per cent ADF) and the intake potential (per cent NDF) of alfalfa. The guideline was 20-30-40. That was based on forage testing 30 per cent ADF (acid detergent fiber) and 40 per cent NDF (neutral detergent fiber) would be 150 RFV with 20 per cent crude protein. Producers use it when buying alfalfa and on the alfalfa they grow to determine quality.

Obviously the more mature the alfalfa at harvest the higher the percent ADF and NDF (lower Relative Feed Value). However, rain damaged hay will also be higher in ADF and NDF because the soluble sugars and carbohydrates can be leached out. Rain damaged hay is also less palatable. Notice that Relative Feed Value does not include the protein percent of the alfalfa!!

Astute dairy producers who purchase alfalfa not only utilize the chemical analysis and relative feed value, they also buy small quantities and feed some of it free choice to see if the cows readily consume it before purchasing larger quantities. Although the Green Gold program targets a RFV of 150 as the optimum time to cut alfalfa, many producers want higher quality hay for their livestock or the hay market. Through MFGA’s program you can follow the decline in RFV and time your harvest based on the quality of hay you are targeting. Is 150 RFV Good Enough Today? Read this University of Minnesota Extension article to learn more.

Relative Feed Values we developed some 30 years ago. Today we have herds producing 50 per cent more milk per cow per year than 30 years ago. Relative Feed Value was changed to Relative Forage Quality or RFQ. The question in 2017 is: Is 150 RFV high enough for high producing dairy cows today?

Click here to read the full Green Gold Report for May 18 as a pdf!

For more information contact John McGregor, MFGA Green Gold Coordinator, by email [email protected], or visit the MFGA website or follow @MBForages on Twitter.

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