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Harvesting Forage Dr. Dan Undersander University of Wisconsin Topics Quality loss with advancing maturity Wide swath system Cost of ash in forage Wheel traffic on alfalfa Alfalfa Quality Loss with Advancing Maturity Days without rain at La Crosse Wide swath benefits Faster drying
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Harvesting Forage Dr. Dan Undersander University of Wisconsin
Topics • Quality loss with advancing maturity • Wide swath system • Cost of ash in forage • Wheel traffic on alfalfa
Wide swath benefits • Faster drying • Higher forage quality
Sequence of Drying Forages • Phase I • moisture moves along stem • Primary moisture loss is through stomata • Phase II • Primary moisture loss from the stem surface • Phase III • Removes tightly held water below 45%
Sequence of Drying Forages 80% Stomatal openings 70% Conditioning Moisture Weather regulated Osmotic & Cell forces 20% Time
Stomata Openings • Sunlight – more they get the more they stay open • Shading closes Stomata • 20 – 30% of water removed before stomata close • Removes 30% of the water from the stem (grass)
Respiration continues after cutting until lose some water Breakdown of starch and sugars Carbon dioxide 2 – 8% of Dry Matter loss
Mower-conditioner Swath Width Study (Windrow 33% and Swath 65% of Cutting Width)
Alfalfa Moisture Content after 6 Hours Conditioned? Herzmann, 2004, Univ of Wisconsin
Alfalfa Moisture Content after 6 Hours • Conditioned increased drying rate • Wide swath increased drying more Conditioned? Herzmann, 2004, Univ of Wisconsin
Maximum swath width versus cutting width Maximum Swath Width Cutting Width
Moisture content of alfalfa 5.5 hours after cutting with various windrow width to cut width ratios, WI Farm Technology Days, 2002
Mower Conditioner Options • Sickle Cutterbar - roll conditioner • Disk Cutterbar - roll conditioner • Disk Cutterbar - impeller conditioner
Conditioner types Flail/impellers Rubber Rolls
Roll and Impeller Comparison • Roll creates a crushing action • Impeller creates a stripping action • Impeller tends to have higher losses • Roll with rotary mower will leave strips in light crops (Limited air through rear of machine)
Drying Rate Comparisons CutterbarConditioner Drying Rate Rotary Roll 0 Sickle Roll +.2 hr Rotary Impeller +1.8 hr
Conditioner drying rates Alfalfa Grass
Conditioner field losses Flail conditioners have 2 to 3 % higher field losses with alfalfa. The loss is all leaves so forage quality is significantly reduced. Stems Leaves
Adjust conditioner properly • Tension on rollers • Spacing of rollers
Adjust conditioner roller spacing Measure clearance where “Crimp” or smallest clearance occurs
What is ash? • In forages, 2 sources. • Internal sources (e.g. minerals like calcium, magnesium, potassium, phosphorous). • External sources(e.g. dirt, sand, bedding).
Why should % ash be a concern? • Ash provides minerals to the diet, but no calories (i.e. energy). • Takes the place of nutrients on almost a 1:1 basis.
What about research looking directly at the effect of % ash in the forage in milk production? “While there have been few dairy research trials in this area, it is highly likely that cows do not milk well when fed dirt.” Pat Hoffman, Dairy Scientist,Marshfield ARS, 2002
Ash Content of Forage Samples • Raking increases ash content of forage
Lodged Alfalfa Possible Causes ofHigher Levels of Ash in Forages
Possible Causes ofHigher Levels of Ash in Forages Disk Cutterbar Cutting height
Mower knife type Those knives that “pick up hay” better, also pick up more ash
Percent Ash in First Cutting Growth of Alfalfa Hoffman and Others, Marshfield Agricultural Research Station, 1991
What can you do? • Cut hay onto layer of stubble • Keep hay off ground • Wide swath • Set rake not touch soil • Merge rather than rake
Typical Forage Harvesting Losses Field curing -26% 29% Fed 71% Lost Harvesting -14% Storage -35% Feeding -30%
Optimum Management Field curing -12% 71% Fed 29% Lost Harvesting -8% Storage -5% Feeding -8%
Reducing the cost of a ton of forage If forage costs $50 / ton to produce Cost of fed forage is $172/ton Cost of fed forage is $70/ton