Saturday, December 29, 2012

Reducing Hay and Silage Harvesting Losses

Hay and silage account for half the cost of most livestock farms. Too often, valuable feed is lost: 1) in the field, 2) during storage, and 3) at feeding. In years when feed supplies are tight, it is especially critical to minimize these losses. This blog entry is the first of a three-part series, and will focus on strategies to reduce the losses during the field operations of hay and silage making. Mowing, conditioning, drying, and harvesting operations all contribute to field losses of forage.  

Mowers and Conditioners

Work at Michigan State University and the University of Wisconsin have shown that rotary disc mowers tend to have 3-4% higher field losses than sickle cutterbar mowers. This is due to greater respiration (plant breakdown) losses for the rotary cutterbars (4.2-4.8%) compared to sickle bars (0.3%), Rotz and Sprott (1984). Additionally higher losses occur in the baler when rotary disc mowers (2.1-2.2%) are used compared to sickle cutterbars (1.5%), Koegel et al. (1985). Rotary disc mowers allow for faster harvest than sickle cutterbars which typically operate at 6-8 mph. Rotary disc mowers can more easily harvest lodged fields than sickle cutterbars, but more forage will be left in the field with rotary disc mowers. For more detailed discussion of adjustments to the both types of harvesters to minimize losses see Machinery Designs and Adjustments for Minimized Field Losses.

Figure 1: Rotary Disc and Sickle Cutterbar Mowers

Properly adjusting conditioners have a greater impact on field losses than the type of conditioner. Shattered leaves and over-conditioned (bruised) alfalfa stems are the primary sources of field losses from conditioners. When using a roll conditioner, the clearance between rolls and the pressure should be reduced for low-yielding harvests and the clearance and pressure should be increased for larger harvests. The timing of the inter-meshing rolls also needs to be adjusted to prevent over-conditioning (dark green discoloration on stems) and reduce leaf shatter. Impeller conditioners should only be used for making grass hay. Even if the impeller speed is reduced, alfalfa and clover crops will have high leaf losses. When trying to make silage there is no need for any conditioner in the mower provided the haylage is laid in a wide swath (>70% of cutterbar width) and properly tedded. Conditioning only helps to dry out the stems once the stomata on the leaves are closed. Spend the money instead on a wider mower and tedder/merger to increase the amount of haylage that can be cut and dried quickly. When making wide swaths for silage drying remove the deflector shields or place them all the way up with metal bars attached to spread the swath back out wide. For more discussion on drying hay and haylage see Reducing the Drying the Time of Hay and Silage in the Field
The hood height can be lowered to provide more aggressive conditioning or raised to reduce the conditioning action on impeller units for pure grass crops. Few, if any, differences in field DM losses have been shown between molded rubber (5.2%), tire cord (5.4%), rubber and steel (5.8%), and two steel conditioning rollers (5.9%), Shinners et al. (1990).

Figure 2: Flail Impeller Conditioner and Roll Conditioner

Rakes, Tedders, Mergers, and Inverters

Pickup height, tractor speed, and forage moisture are the most important factors influencing field losses during field operations of rakes, tedders, and mergers. Rake height needs to be adjusted to pick up the forage while minimizing the rocks and dirt that end up in the forage. Side rakes, tedders, and mergers do not have to touch the ground in order to turn the windrow/swath, but wheel rakes need to touch the ground in order to work properly. Faster tractor speeds increase the amount of leaves lost in alfalfa, but a compromise between working fast enough to get the job done and not losing valuable feed needs to be struck when doing these operations. Losses from tedding operations can be minimized by tedding when the forage crop is 60% moisture or greater, while raking, merging, and inverting should be done when the forage crop is at least 40% moisture.

Figure 3: Side Rake, Wheel Rake, Tedder, and Merger

Balers and Silage Harvesters

Similar to tedding, raking, merging, and inverting, the most important factors influencing field losses when making bales or silage are the crop moisture, pick-up height, and ground speed. Leaf losses increase as crop moisture goes down, Figure 4. 

Figure 4: Hay Leaf Losses Increase as Hay Moisture Decreases

Round bales should be made at a uniform density, about 10 pounds/ft3. Adjustments may be needed throughout the baling process and will vary depending the type of baler used. Making uniform bales will make for easier handling, storage, marketing, and cost calculation. When round baling narrow windrows (less than half the pick-up width), picking up on one side of the windrow for 10-12 seconds and then quickly crossing over to the other side of the windrow (pattern a) makes more uniform round bales than constantly swerving across the windrow (pattern b) or driving straight down the windrow (pattern c), Figure 5. 

Figure 5: Round Baler Pick-Up Strategies Effect Bale Shape in Narrow Windrows

Making wide windrows or swaths that are equal to the baler pick-up width will also result in more uniform bales, and enables driving directly down the windrow. Matching the ground speed to PTO speed will result in quickly formed bales which minimizes leaf loss. If harvesting full windrows that are equal to the pick-up width, ground speeds of 4-6 mph usually result in uniform bales. Using a round baler with a variable or expanding chamber instead of a fixed chamber will also result in more uniform bales and lower leaf loss (3.75-4.25% vs. 3.5-8.0%), Prairie Agricultural Machinery Institute.

Silage losses in the field are most often due to leaf loss of alfalfa, exposure to rain, improperly adjusted equipment, and delayed harvest operations. Similar to baling hay, silage harvester ground speed should be adjusted to match pick-up with PTO speed, but minimize leaf losses. Silage bleaching occurs when rain falls on the silage, which reduces many of the digestible nutrients and results in white windrows. Field DM losses of 22%-44% of silage can occur with only 1 to 1.6 inches of rainfall a day or two after cutting, Rankin and Undersander (2000).

Bottom Line
1. Properly adjusted and maintained equipment go a long way to reducing field losses of hay and silage.

2. Optimizing the speed of field operations and conducting these operations at the appropriate crop moisture levels reduce field losses of forage. 


Drying Rates, Losses and Fuel Requirements for Mowing and Conditioning Alfalfa
Rotz, C. A. and D. J. Sprott, Michigan State University, 1984. Transactions of the ASAE, 27(3)715-720.

Forage Growers Guide to Round Baling
Prairie Agricultural Machinery Institute.

Machinery Designs and Adjustments for Minimized Field Losses
Ronald T. Schuler, Extension Agricultural Engineer, Biological Systems Engineering Department, University of Wisconsin-Madison.

Management Tips for Round Bale Hay Harvesting, Moving, and Storage 

Robert Grisso, Extension Engineer, Biological Systems Engineering, Virginia Tech
Ray Smith, Forage Specialist, Crop and Soil Environmental Sciences, Virginia Tech
John Cundiff, Professor, Biological Systems Engineering, Virginia Tech

Quantification of Mechanical Losses
Koegel, R. G., R. J. Straub and R. P. Walgenbach, University of Wisconsin, 1985. Transactions of the ASAE, 28(4)1047-1051.

Rain Damage to Forage During Hay and Silage Making
Mike Rankin and Dan Undersander, University of Wisconsin, 2000. Focus on Forage.Vol. 2: No. 4.

Leaf Loss and Drying Rate of Alfalfa as Affected by Conditioning Roll Type
Shinners, K. J., R. G. Koegel and R. J. Straub, University of Wisconsin,  1990. ASAE aper 901048. St. Joseph, MI, 14 pp.

Tuesday, November 20, 2012

Reducing the Drying Time of Hay and Silage in the Field

Harvesting high quality hay and hay silage has been a challenge in a number of hay growing regions because of the unpredictability of rainfall. Rain falling on hay that is laying down in the field causes a number of problems. Soluble nutrients are lost, reducing feeding value and fermentation potential. Wet hay may also undergo spontaneously combustion. Forages can be ensiled or baled at a wide range of moisture contents (Figure 1). Whether making silage, hay, or baleage, some field drying will be necessary.  A number of practices can reduce the amount of time that cut forages are exposed in the field.

Figure 1: Forage Harvesting Methods and Associated Field and Storage Losses

Adapted from Grass Silage Jerry Cherney & Debbie J.R. Cherney, Cornell University

Wide Swaths
Cutting implements that lay hay down in windrows that are 70% or more of the cutting width dramatically reduce drying time. The wide rows maximize the amount of area hay exposed to the sun and allow air to move underneath the swath. This maximizes the drying rate in Phase I (Figure 2) of the dry-down process. This is very important because the plants will continue to respire and use nutrients while the stomata (holes in the leaves) stay open. The outer 0.75 inch of the swath/windrow dries quickly, and having wide, shallow swaths essentially allows all of the forage to dry rapidly compared to a small percentage on the outside of a traditional deeper windrow.

Figure 2: Sequence of Drying Forages

Field experiments in the Midwest and Northeast have shown that alfalfa cut in the morning and laid down in wide rows dries down to about 65% moisture about 5-7 hours later and is ready to be chopped for silage that same day during good drying conditions (warm, windy, sunny day). Adjustments can usually be made to the mower to increase the swath width. If swath width cannot be increased to at least 70% of the cut width farmers can use a tedder immediately after cutting, weld metal bars or bolt metal deflectors (Figure 3) to the back of the mower to spread out the feed, or find a neighbor or custom operator who has the equipment to spread the forage out. Cutting with a simple sicklebar mower (without conditioning attachments) also lays the silage or hay out wide to allow for quick drying. 

Figure 3: Farmer Mower Modifications to Increase Swath Width

In the past there was a large concern about driving on windrows because of the risk of leaf loss. While this would be a concern on very dry hay, few leaves are lost when a wide swath is driven on during the initial drying stages (Phase I and Phase II, Figure 2) unless extremely wet and muddy field conditions exist at the time of harvest. No detectable difference in forage quality has been found in the areas driven over compared to the other parts of the swath.

There are two types of conditioners available to farmers:  roller crimpers and flail impellers.
Roller crimpers are made out of rubber or steel. They are used to crush the stems of alfalfa to increase the dry down rate in Phases II and III (Figure 2). If alfalfa is being made into hay then it should be conditioned with a roller crimper. If the alfalfa is made into silage it does not need to be conditioned if laid down in a wide row. Narrow windrows (less than 70% cut width) should be conditioned whether the alfalfa is made into silage or hay if the windrows are not spread out soon after cutting. Before harvesting, the rollers must be properly adjusted in order to crush the stems. Check your machine's owner's manual or refer to Mower-conditioner Adjustments for Rapid Forage Drying in the Field for more information. Various crimper designs are available, but no consistent differences have been shown between the various designs in the dry down time.

Flail impellers are used primarily for grass hay or entangled forages. The deflector must be properly adjusted to ensure that the grass surfaces are cut by the flails. Impellers are not very effective tools to condition alfalfa.

Tedding, Raking, Inverting, & Merging
Raking and tedding are two of the most well known practices to increase the dry down rate of hay in the field. They can, however greatly increase the ash content and leaf loss of the hay if done improperly. Lower leaf loss occurs if the hay is tedded or raked between 40-65% moisture (i.e. with the morning dew on). If a farmer lays down a wide swath when making hay they could ted/rake the next morning, while a farmer with narrow windrows would typically have to wait an additional day or two to reach this moisture content. Tedders and rakes should also be adjusted to minimize the amount of ash (dirt) they pick up off the ground. Inverters and mergers are used to flip and merge swaths and windrows. Inverters tend to pick up less ash than rakes or tedders. Mergers are used before chopping or bailing to merge multiple windrows (swaths) into one bigger windrow. Some drying occurs when the windrows are flipped, but not as much as wide swathing or conditioning operations.

Dessiccants are drying agents that can be sprayed on forages which can reduce the time needed for hay to dry. They are most often applied at cutting. The most effective products have potassium or sodium-carbonate based solutions. These treatments are most effective on alfalfa cut in the summer months. The major drawback to using desiccants is the large volume of water required to apply the products to the hay.

Preservatives are applied at baling to ensure the quality of hay, often at a slightly higher moisture content (20-25%). When rain is coming, applying a preservative can allow baling at these higher moisture contents.  The most effective preservatives on the market are made from proprionic acid. Other organic acids (acetic acid, etc.) can work as well, but proprionic acid-based products are the most reliable. They are generally applied at 1-2% of hay weight.

Many products are available to inoculate silage and baleage. These products do not increase the drying rate of forages or make up for poor field handling, but can preserve or increase forage quality if applied correctly. Many products on the market have not been independently tested so farmers should take some time before the season to evaluate which of the available products have truly shown consistent results outside of company trials.  Most of the products contain at least one of three types of bacteria: homolactic, heterolactic, or propionibacteria. 

Homolactic bacteria ferment sugars to lactic acid which improves initial fermentation by quickly dropping pH. Enterococcus faecium and several Pediococci species have been shown to be effective in modifying initial fermentation. 

Heterolactic bacteria convert moderate amounts of lactic acid to acetic acid after initial fermentation and improve aerobic stability during feedout. Lactobacillus plantarum (once thought to be a homolactic bacterium) and Lactobacillus buchneri are the only heterolactic bacteria consistently shown to increase the aerobic stability of silage during feed out. 

Propionibacteria theoretically convert lactic acid to acetic and proprionic acids in the bunk, but currently no species or strains have been shown to actually increase aerobic stability in the field.  For a more in depth discussion of silage inoculants and situations in which to use them refer to, Help in Choosing an Effective Silage Inoculant.

Bottom Line
1. Drying forages occurs much more quickly in wide, thin swaths than thick, narrow windrows. Silage can be made the same day as cutting if the forage is spread wide. Inoculants can enhance, but not save silage

2. Hay and silage making often require using multiple management practices (wide swaths, conditioning, raking, tedding, desiccants, preservatives, inoculants, etc.) and a little bit of luck in the humid regions of the U.S. in order to make high quality hay and silage.

Disc Mowers vs Sicklebar Mowers
No difference in drying rate is noticeable between disc and sicklebar/cutterbar mowers. 
Tom Kilcer, Advanced Ag Systems, Kinderhook, New York

Drying Forage for Hay and Haylage

C. Alan Rotz, Agricultural Engineer USDA-ARS, Penn State University

Jerry Cherney & Debbie J.R. Cherney, Cornell University

Help in Choosing an Effective Silage Inoculant

Limin Kung, Jr, University of Delaware

Mower-conditioner Adjustments for Rapid Forage Drying in the Field
Ronald T. Schuler, Agricultural Engineer, Wisconsin Extension

Jimmy C. Henning and Howell N. Wheaton, University of Missouri Extension

Jerry Cherney, Tom Kilcer, Debbie J.R. Cherney, Cornell University

Friday, October 26, 2012

The Value of Increasing Pasture Numbers

Historically pastures have been seen as low yielding land and little, if anything, was done to increase their productivity. In recent years management intensive rotational grazing has done much to change this perspective and high yielding, high quality pastures now form the backbone of many profitable livestock farms. This blog entry will describe one of the management practices that has greatly increased pasture yields--managing a larger number of pastures.

Increasing Harvest Efficiency

Farmers that practice rotational grazing manage many paddocks (small pastures 2-5 acres in size) instead of a smaller number of large pastures. This practice results in very large increases in harvest efficiency.  The traditional pasture typically had cows continuously grazing throughout the whole growing season. Under this system only 30% of the potentially available feed is harvested by the cows. However, as graziers add pastures, cow harvest efficiency greatly increases up to 75% of available feed when at least 24 pastures/paddocks are grazed in rotation. Figure 1 demonstrates this by using 5 tons DM of available feed per acre for a single growing season multiplied by the appropriate harvest efficiency as pasture numbers increase. Harvest efficiency data was taken from the USDA grazing stick. For more information about the USDA grazing stick see the instructional video and availability.

Figure 1: Increasing Pasture Number Increases Feed Grazed

Generally once a pasture is grazed, farmers wait 25-40 days before returning their cows to that pasture. This rest period allows enough regrowth in order for the grass and legume root carbohydrate reserves to be resupplied. Additionally rotational graziers don't graze their pastures until the soil is bare, but rather they tend to "take half and leave half" . Leaving at least 4 inches of grass is necessary in most cases to maintain desired  species in the pasture. Clipping the pastures once a year helps maintain an even stand without unpalatable clumps of dead plants. In many areas graziers will harvest a number of their pastures for hay or silage in the spring because often there is more feed than can be grazed. They then feed the spring harvests during the summer or winter in order to supplement or replace the pastures.

Increasing Feed Quality

Increasing pasture numbers not only increases the quantity of pasture that cows eat, but it also increases the quality of the pasture. In management intensive rotational grazing, grasses and legumes are grazed when they are in the vegetative growth stage. Pastures grazed at this time are more palatable, higher in protein, higher in fiber digestibility, higher in starch and sugar content, and lower in fiber content. Figure 2 outlines generally how forage quality declines with increasing plant maturity.  As pasture plants age they lose leaves and gain more stems resulting in lower forage quality.

Figure 2: Declining Forage Quality with Increasing Plant Maturity
From page 4 in Understanding Forage Quality

Grazing generally begins when the pastures are at least 8 to 12 inches tall. If pastures are grazed too soon in the spring cattle will often get diarrhea and will need supplemental fiber from low quality hay.  Having many pastures allows for staggered plant maturity across the farm. This allows cows to continuously graze high quality feed. Grass heading date determines how long grass will be in the high quality vegetative growth stage in the spring. Different grass species and different grass varieties have heading dates from a week to a month apart. By planting different grass species and/or varieties with different heading dates in separate pastures graziers can more effectively maintain pastures constantly in the vegetative growth stage. When using rotational grazing beef producers will generally move their animals every one or two days, while dairy farmers will move their animals to new pasture after every milking during the growing season. Maintaining high levels of pasture fertility, selecting proper plant species and varieties, building appropriate fences, supplying adequate water, sheltering animals from extreme weather conditions, and other factors are also necessary in order have a well managed, profitable rotational grazing farm.

Bottom Line

1. Dividing one large pasture into two dozen or more paddocks can double the amount of feed that cows will be able to graze over the course of growing season.

2. Having many pastures enables grazers to have the highest feeding quality through the growing season, because plants are constantly in the vegetative growth stage.

Understanding Forage Quality
Don Ball, Mike Collins, Garry Lacefield, Neal Martin, David Mertens, Ken Olson, Dan Putnam, Dan Undersander, and Mike Wolf

USDA Grazing Stick Availability
Debra Heleba, University of Vermont Extension

USDA Grazing Stick Instructional Video 
Sarah Flack, Sarah Flack Consulting & Amanda Gervais, University of Vermont Extension