Introduction

This fact sheet has been developed to support the implementation of the Natural Resources Conservation Service Feed Management 592 Practice Standard. The Feed Management 592 Practice Standard was adopted by NRCS in 2003 as another tool to assist with addressing resource concerns on livestock and poultry operations. Feed management can assist with reducing the import of nutrients to the farm and reduce the excretion of nutrients in manure.

The Natural Resources Conservation Service has adopted a practice standard called Feed Management (592) and is defined as “managing the quantity of available nutrients fed to livestock and poultry for their intended purpose”. The national version of the practice standard can be found in a companion fact sheet entitled “An Introduction to Natural Resources Feed Management Practice Standard 592”. Please check in your own state for a state-specific version of the standard.

Regardless of the size of a dairy operation, producers know problems can occur in every silage program. This fact sheet describes possible causes and solutions for nine potential problems in managing silage in bunker silos, drive-over piles, and bags.

The nine potential problems include:

• High ‘forage in’ versus ‘silage out’ loss in bunker silos, drive-over piles, and silage bags
• Large variation in DM content and/or nutritional quality of the ensiled forage
• Missing the optimum harvest window for whole-plant corn
• High levels of butyric acid and ammonia-nitrogen, particularly in ‘hay-crop’ silage
• High levels of acetic acid in wet corn silage
• Aerobically unstable corn silage during feedout
• Excessive surface-spoiled silage in bunker silos and drive-over piles
• Poorly managed bagged silage
• Safety issues for bunker silos and drive-over piles.

Dairy producers should discuss these problems and solutions with everyone on their silage team, including their nutritionist and custom operator, as a reminder to implement the best possible silage management practices.

Four Excel spreadsheets to help producers make decisions about bacterial inoculants, packing density, and sealing strategies for bunker silos and drive-over piles are discussed.

Please check this link first if you are interested in organic or specialty dairy production

High ‘Forage In’ versus ‘Silage Out’ Loss in Bunker Silos, Drive-over Piles, and Silage Bags

Solutions

• Select the right forage hybrid or variety.
• Harvest at the optimum stage of maturity and DM content.
• Use the correct size of bunker or pile, and do not over-fill bunkers or piles.
• Employ well-trained, experienced people, especially those who operate the forage harvester, pack tractor, or bagging machine. Provide training as needed.
• Apply the appropriate lactic acid bacterial (LAB) inoculant.
• Achieve a uniform packing density in bunkers and piles (a minimum of 15 lbs of DM per ft³).
• Provide an effective seal to the surface of bunkers and piles and consider using double polyethylene sheets or an oxygen barrier (OB) film.
• Follow proper face management practices during the entire feedout period.
• Schedule regular meetings with your forage team.

Large Variation in DM Content and/or Nutritional Quality of the Ensiled Forage

Causes

• Interseeded crops that are not at the optimum stage of maturity at harvest.
• Multiple cuttings or multiple forages ensiled in the same silo.
• Delays in harvest activities because of a breakdown or shortage of machinery and equipment.
• Seasonal or daily weather that affects crop maturing and field-wilting rates.
• Variation among corn hybrids.

Solutions

• Use multiple silos and smaller silos that improve forage inventory control.
• Ensile only one cutting and/or variety of ‘hay-crop’, field-wilted forage per silo.
• Minimize the number of corn and/or sorghum hybrids per silo.
• Shorten the filling-time, but do not compromise packing density.
• Harvest during stable weather, especially for ‘hay-crop’ forages.

Missing the Optimum Harvest Window for Whole-plant Corn

Causes

• Harvest equipment capacity is inadequate and/or the crop matures in a narrow harvest window.
• Warm, dry weather can speed the maturing process and dry-down rate of the crop.
• Wet weather can keep harvesting equipment out of the field.
• Sometimes it is difficult to schedule the silage contractor.

Solutions

• Plant multiple corn hybrids with different season lengths.
• Improve the communication between the dairy producer, crop grower, and silage contractor.
• Change harvest strategy, which might include kernel processing, shorter theoretical length of cut (TLC), or adding a pack tractor.

High Levels of Butyric Acid and Ammonia-nitrogen, particularly in ‘Hay-crop’ Silage

Causes

• The forage is ensiled too wet, and clostridia dominate the final fermentation process.
• Alfalfa and other legumes, which experience a rain event in the field after mowing, are at a higher risk because rain leaches soluble sugars from the forage.

Solutions

• Chop and ensile all forages at the correct DM content for the type and size of silo.
• Proper packing to achieve a minimum density of 15 lb of DM per ft³ excludes oxygen and limits the loss of plant sugars during the aerobic phase (Visser, 2005; Holmes, 2006).
• Apply a homolactic LAB inoculant to all forages to ensure an efficient conversion of plant sugars to lactic acid.
• Do not contaminate the forage with soil or manure at harvest, and put the forage on a concrete or asphalt base.
• If it is not possible to control the DM content by wilting in the field, the addition of dry molasses, beet pulp, or ground grain can reduce the chance of a clostridial fermentation and the problems associated with butyric acid silages.

High Levels of Acetic Acid, particularly in wet Corn Silage

Causes and symptoms

• If the whole-plant has a low DM content, it is predisposed to a long, heterolactic fermentation.
• This silage has a strong ‘vinegar’ smell, and there will be a 1- to 2-foot layer of bright yellow, sour smelling silage near the floor of a bunker silo or drive-over pile.

Solutions

• Ensile all forages at the correct DM content, and especially not too wet.
• Apply a homolactic LAB inoculant to ensure an efficient conversion of plant sugar to lactic acid.

Aerobically Unstable Corn Silage during Feedout

Research has not explained why corn silages differ in their susceptibility to aerobic deterioration. Microbes, primarily lactate utilizing yeast, as well as forage and silage management practices contribute to aerobic stability of an individual corn silage. Nevertheless, there are several practical steps dairy producers need to be aware of, which can help minimize feedout problems.

Solutions: At harvest and filling time.

• Harvest at the correct stage of kernel maturity, and especially not too mature.
• Ensile at the correct DM content, and especially not too dry.
• In normal conditions, do not chop longer than ¾-inch TLC if the crop is processed or ½-inch, if not processed.
• Achieve a uniform packing density of at least 15 lbs of DM per ft³.
• If aerobic stability continues to be a problem, consider using a LAB inoculant that contains the heterolactic bacteria, Lactobacillus buchneri (Kung et al., 2003).

Solutions: At feedout.

• Maintain a rapid progression through the silage during the entire feedout period.
• The feedout face should be a smooth surface that is perpendicular to the floor and sides in bunker or pile.
• Proper unloading technique includes shaving silage down the feedout face and never ‘digging’ the bucket into the bottom of the silage feedout face.
• Remove 6 to 12 inches per day in cold weather months; 12 to 18 inches per day in warm months.
  • Feed from ‘larger feedout faces’ in cold weather months.
  • Feed from ‘smaller feedout faces’ in warm weather months.
• Minimize the time corn silage stays in the commodity area before it is added to the ration.
• It might be necessary to remove silage from a bunker or pile and move it the commodity area two times per day.
• When building new silos, size them correctly to allow adequate feedout rates.
• Consider using a silage facer as an alternative to a front-end loader.

A ‘Facer Cost Analysis’ Excel spreadsheet by Holmes (2003) calculates the breakeven cost of a facer for silage removal compared to a front-end loader.

The breakeven cost of the facer, when converted to an annual cost, equals the sum of improvement in DM recovery value and additional labor, equipment, and fuel use costs. The labor, equipment, and fuel use could actually be savings if the facer operates at a faster rate than the front-end loader. The spreadsheet and a complete discussion of the topic are available on the UW-Extension Team Forage web site.

Excessive Surface-spoiled Silage in Bunker Silos and Drive-over Piles

Solutions

• Achieve a uniform density (minimum of 12 to 14 lbs of DM per ft³) within the top 3 ft of the silage surface.
• Shape all surfaces so water drains off the bunker or pile, and the back, front, and side slopes should not exceed a 3 to 1 slope.
• Seal the forage surface immediately after filling is finished.
• Two sheets of polyethylene or a single sheet of OB film is preferred to a single sheet of plastic (Berger and Bolsen, 2006; Bolsen and Bolsen, 2006b).
• Overlap the sheets that cover the forage surface by a minimum of 3 to 4 feet.
• Arrange plastic sheets so runoff water does not contact the silage.
• Sheets should reach 4 to 6 feet off the forage surface on the perimeter of a drive-over pile.
• Put uniform weight on the sheets over the entire surface of a bunker or pile, and double the weight placed on overlapping sheets.
  • Bias-ply truck sidewall disks are the most common alternative to full-casing tires.
  • Sandbags, filled with pea gravel, are an effective way to anchor the overlapping sheets, and sandbags provide a heavy, uniform weight at the interface of the sheets and bunker wall.
  • Sidewall disks and sandbags can be stacked, and if placed on pallets, they can be moved easily and lifted to the top of a bunker wall when the silo is being sealed and lifted to the top of the feedout face when the cover is removed.
  • A 6- to 12-inch layer of sand or soil or sandbags is an effective way to anchor sheets around the perimeter of drive-over piles.
• Prevent damage to the sheet or film during the entire storage period.
  • Mow the area surrounding a bunker or pile and put up temporary fencing as safe guards against domesticated and wild animals.
  • Store waste polyethylene and cover weighting material so it does not harbor vermin.
  • Regular inspection and repair is recommended because extensive spoilage can develop quickly if air and water penetrate the silage mass.
• Discard all surface-spoiled silage because it has a significant negative effect on DM intake and nutrient digestibility (Whitlock et al., 2000; Bolsen, 2002).
• Full casing discarded tires were the standard for many years to anchor polyethylene sheets on bunker silos. These waste tires are cumbersome to handle, messy, and standing water in full casing tires can spread the West Nile virus, which is another reason to avoid using full casing tires on beef and dairy operations (Jones et al., 2004).

Poorly Managed Bagged Silage

The bag silo has become a popular storage system on many farms in the USA. While bagged silage requires specialized equipment, bagging machines can be rented or many silage custom operations provide them. Bags are also used to store extra silage when forage yields exceed the capacity of existing silo structures. Nevertheless, bagged silage is not trouble-free. Bolsen and Bolsen (2006a) surveyed 15 nutritionists, dairy producers, and silage contractors and asked, ‘better bagged silage: what is important?’. Selected responses from participants are presented here.

Better bagged silage: what is important?

• Bags should be located on a well-drained, firm surface and preferably on concrete or asphalt.
  • Keep bags out of the mud.
  • Provide feeders easy access to all bags.
• Low silage DM densities are a problem in bags (Visser, 2005). A skilled bagging machine operator is essential to insure a consistent, uniform fill and achieve an acceptable density.
• Mark (paint) bags with a number, date, crop, farm/field, use description (i.e., which cattle to feed).
• Record the DM content of all forage going into a bag, especially field-wilted, hay-crop silage, and mark the location of potentially ‘problematic silage’ (i.e., too wet, too dry, too mature, etc.).
• Do not bag alfalfa ‘too wet’. The DM target should always be 35 to 45 percent.
• Check all bags at least three times per week and mend/patch the punctures and holes.
• The silage removal rate at feedout must be sufficient to prevent the exposed silage from heating and spoiling, especially if multiple bags are open at same time.
  • Caution: The first bags used in the 1970s had diameters of 8 to 9 feet, but some :*Remove only enough plastic for silage needed daily.
• Monitor the DM content of all silages and make appropriate changes in the ration when DM content changes more than two percentage units.
• Remember: Good bagged silage is no accident; it takes sound management and attention to detail!

Safety Issues for Bunker Silos and Drive-over Piles: Major Hazards and Preventive Measures

Consistently protecting workers, livestock, equipment, and property at harvest, filling, and feeding does not occur without thought, preparation, and training (Murphy and Harshman, 2006).

Tractor roll-over

• Roll-over protective structures (ROPS) create a zone of protection around the tractor operator. When used with a seat belt, ROPS prevent the operator from being thrown from the protective zone and crushed by the tractor or equipment mounted on or drawn by the tractor.
• Install sighting rails on above ground walls. These rails indicate the location of the wall to the pack tractor operator but are not to hold an over-turning tractor.
• Form a progressive wedge of forage when filling bunkers or piles. The wedge provides a slope for packing, and a minimum slope of 3 to 1 reduces the risk of a tractor roll-over.
• Use low-clearance, wide front end tractors and add weights to the front and back of the tractors to improve stability.
• When two or more pack tractors are used, establish a driving procedure to prevent collisions.
• Raise the dump body only while the truck is on a rigid floor to prevent turnovers.

Entangled in machinery

• Keep machine guards and shields in place to protect the operator from an assortment of rotating shafts, chain and v-belt drives, gears and pulley wheels, and rotating knives on tractors, pull-type and self-propelled harvesters, unloading wagons, and feeding equipment.

Run-over by machinery

• Never allow people (especially children) in or near a bunker or pile during filling.
• Properly adjust rear view mirrors on all tractors and trucks.

Fall from height

• It is easy to slip on plastic when covering a bunker, especially in wet weather, so install guard rails on all above ground level walls.
• Use caution when removing plastic and tires, especially near the edge of the feeding face.
• Never stand on top of a silage overhang in bunkers and piles, as a person’s weight can cause it to collapse.

Crushed by an avalanche/collapsing silage

• The number one factor contributing to injuries or deaths from silage avalanches is overfilled bunkers and drive-over piles!
• Do not fill higher than the unloading equipment can reach safely, and typically, an unloader can reach a height of 12 to 14 feet.
• Use proper unloading technique that includes shaving silage down the feeding face and never ‘dig’ the bucket into the bottom of the silage. Undercutting, a situation that is quite common when the unloader bucket cannot reach the top of an over-filled bunker or pile, creates an overhang of silage that can loosen and tumble to the floor.
• Never allow people to stand near the feeding face, and a rule-of-thumb is never being closer to the feeding face than three times its height.
• Fence the perimeter of bunkers and piles and post a sign, “Danger: Do Not Enter. Authorized Personnel Only”.

Complacency

• Think safety first! Even the best employee can become frustrated with malfunctioning equipment and poor weather conditions and take a hazardous shortcut, or misjudge a situation and take a risky action (Murphy, 1994).

Achieving a Higher Silage DM Density in Bunker Silos and Drive-over Piles

A high DM density in the ensiled forage is important (Holmes, 2006). Why? First, density determines the porosity of the silage, which affects the rate at which air can enter the silage mass during the feedout phase. Second, achieving a higher density increases the storage capacity of a silo.

Thus, a higher DM density typically decreases the annual storage cost per ton of crop by increasing the tons of crop that can be put in a given silo volume and decreasing the ‘forage in’ vs. ‘silage out’ loss that occurs during the fermentation, storage, and feedout periods.

Case Study Dairy

The Holmes-Muck Excel spreadsheet calculations for the average silage density in a drive-over pile of corn silage at a case study dairy are in Table 1. The actual 2003 pile of corn silage had a DM density of 11.5 lbs per ft³ and an estimated silage DM recovery of 77.5% (i.e., a 22.5% ‘shrink’ loss).

The following changes were made for the 2004 corn silage: 1) the maximum pile height was lowered from 16 to 14 feet, 2) the forage delivery rate increased from 75 to 90 tons per hour, 3) the average forage DM content increased from 32 to 34%, 4) a second tractor was added to assist in packing, and 5) the estimated forage layer thickness decreased from 8 to 5 inches. These changes resulted in a predicted silage DM density of 15.8 lbs per ft³. The estimated silage DM recovery was 85.0% (i.e., a 15.0% ‘shrink’ loss) for the 2004 silage, which was based on the data by Ruppel (1992).

Profitability of LAB inoculated Corn Silage for Lactating Dairy Cows

Dairy producers, dairy nutritionists, and custom silage operators are sometimes concerned about whether it is economical to use an LAB inoculant when making whole-plant corn silage. Presented in Table 2 is an example from an Excel spreadsheet, which shows the profitability of inoculating whole-plant corn silage with LAB for lactating dairy cows. The dairy herd in this example had an average milk production of 75 lbs per cow per day and a ration DM intake of 52 lbs. The increase in net income with LAB-treated corn silage, calculated on a per cow per day and per cow per year basis, comes from improvements in both forage preservation and silage utilization. The additional ‘cow days’ per ton of crop ensiled from an increased silage recovery (1.5 percentage units) and an in¬creased milk per cow per day (0.25 lbs) gave an added net income of 13.0¢ per cow per day and $39.53 per cow per year. The increase in net return per ton of whole-plant corn ensiled with an LAB inoculant was $5.73. The Excel spreadsheet is on the Kansas State University silage web site.

Profitability of LAB inoculated Corn Silage for Growing Cattle

Presented in Table 3 is an example from an Excel spreadsheet, which shows the profitability of inoculating corn silage with LAB for growing cattle.

The cattle in this example had an average weight of 650 lbs, a DM intake of 2.62% of body weight, a ration DM intake to gain ratio of 7.1, and an average daily gain of 2.39 lbs. The cattle performance responses to LAB-treated corn silage were a 0.06 lb increase in avg. daily gain (2.39 vs. 2.45 lbs) and an improved ration DM to gain ratio of 0.15 (6.95 vs. 7.1). The DM recovery response was 1.5 percentage units for LAB-treated silage compared to the untreated silage (84.0 vs. 82.5). The gain per ton of ‘as-fed’ whole-plant corn ensiled was 92.0 lbs for the LAB-treated vs. 88.45 lbs for untreated corn silage, which was an increase of 3.55 lbs. With a cattle price of $1.20 per lb and a LAB cost of $0.75 per ton of crop ensiled, the net benefit per ton of crop ensiled was $3.51. The Excel spreadsheet is on the Kansas State University silage web site.

Spreadsheet: Profitability of Sealing Bunker Silos and Drive-over Pile

An Excel spreadsheet to calculate the profitability of sealing corn silage and alfalfa haylage in bunker silos and drive-over piles was developed from research conducted at Kansas State University between 1990 to 1995 and equations published by Huck et al. (1997). The authors noted that about 75% of the total tons of corn and sorghum silage made in Kansas from 1994 to 1996 were not sealed, and the value of silage lost to surface spoilage was between 7 and 9 million dollars annually.

Presented in Table 4 are examples from the spreadsheet. The profitability of properly sealing bunkers and piles with standard 5- or 6-mil plastic or an improved oxygen barrier film makes it clear that producers should pay close attention to the details of this ‘highly troublesome’ task. Further information about the improved OB film is at http://www.silostop.com.

References

Berger, L.L. and K.K. Bolsen. 2006. Sealing strategies for bunker silos and drive-over piles. In: Proc. Silage for Dairy Farms: Growing, Harvesting, Storing, and Feeding. NRAES Publ.181. Ithaca. NY.

Bolsen, K. K. 2002. Bunker silo management: four important practices. Pg. 160-164. In: Proc. Tri-State Dairy Nutrition Conference. Ft. Wayne, IN. The Ohio State University, Columbus.

Bolsen, K.K., R.N. Sonon, B. Dalke, R. Pope, J.G. Riley, and A. Laytimi. 1992. Evaluation of inoculant and NPN additives: a summary of 26 trials and 65 farm-scale silages. Kansas Agric. Exp. Sta. Rpt. of Prog. 651:102.

Bolsen, K.K. and R.E. Bolsen. 2006a. Better bagged silage: what is important? Presentation at the Penn State Dairy Nutrition Workshop. http://www.das.psu.edu/research-extension/dairy/nutrition/pdf/bolsen-bag-silageppt.pdf/

Bolsen, K.K. and R.E. Bolsen. 2006b. Common silage pitfalls. Pg. 5-13. In: Proc. of the Penn State Dairy Nutrition Workshop: http://www.das.psu.edu/research-extension/dairy/nutrition/pdf/bolsen-silage-pitfalls.pdf/

Holmes, B.J. 2003. Bunker silo facer: why invest? UW-Extension Team Forage web site: http://www.uwex.edu/ces/crops/uwforage/storage.htm

Holmes, B.J. 2006. Density in silage storage. Pg. 214-238. In: Proc. of Silage for Dairy Farms: Growing, Harvesting, Storing, and Feeding. NRAES Publ. 181. Ithaca, NY.

Huck, G.L., J.E. Turner, M.K. Siefers, M.A. Young, R.V. Pope, B. E. Brent, K.K. Bolsen. 1997. Economics of sealing horizontal silos. Kansas Agric. Exp. Sta. Rpt. of Prog. 783:84.

Jones, C.M., A.J. Heinrichs, G.W. Roth, and V.A. Isher. 2004. From harvest to feed: understanding silage management. Publ. Distribution Center, The Pennsylvania State University, 112 Agric. Admin. Bldg, University Park, PA 16802.

Kung, L., Jr., M.R. Stokes, C.J. Lin. 2003. Silage additives. Pg. 305-360. In: Silage Science and Technology. D. Buxton, R. Muck, and J. Harrison, eds. ASA, CSSA, and SSSA Publ., Madison.

Murphy, D.J. 1994. Silo filling safety. Fact sheet E-22. Agric. and Biol. Engineering Dept, The Pennsylvania State University, University Park, PA.

Murphy, D.J. and W.C. Harshman. 2006. Harvest and storage safety. Pg. 171-187. In: Proc. of Silage for Dairy Farms: Growing, Harvesting, Storing, and Feeding. NRAES Publ. 181. Ithaca, NY.

Ruppel, K.A. 1992. Effect of bunker silo management on hay crop nutrient management. M.S. Thesis, Cornell University, Ithaca, NY.

Visser, B. 2005. Forage density and fermentation variation: a survey of bunker, piles and bags across Minnesota and Wisconsin dairy farms. Four-state Dairy Nutrition and Management Conference. MWPS-4SD18. Ames, IA.

Whitlock, L.A., T. Wistuba, M.K. Siefers, R. Pope, B.E. Brent, and K.K. Bolsen. 2000. Effect of level of surface-spoiled silage on the nutritive value of corn silage-based rations Kansas Agric. Exp. Sta. Rpt. of Prog. 850:22.

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Introduction

This fact sheet has been developed to support the implementation of the Natural Resources Conservation Service Feed Management 592 Practice Standard. The Feed Management 592 Practice Standard was adopted by NRCS in 2003 as another tool to assist with addressing resource concerns on livestock and poultry operations. Feed management can assist with reducing the import of nutrients to the farm and reduce the excretion of nutrients in manure.

The trend over the past 15 years has been to feed a single total mixed ration to the dairy herd. Higher producing cows have a greater dry matter intake and, therefore, receive more nutrients daily. Unfortunately, most feeding systems consequently over-feed lower producers to assure that higher producers receive enough feed of the correct concentration of nutrients. Feeds are usually inexpensive compared to the return generated by milk sales, and the results of this feeding practice were higher production at a moderate cost.

Surveys of milk production versus nutrient consumption done regionally around the United States have shown significant over-feeding of protein and phosphorus on dairy farms. In some cases, rations provided as much as 50% more phosphorus than needed for the herd’s production level. Certainly, these high levels can be reduced through the choice of feed ingredients and more precise mineral feeding, however producers want assurance their cows have adequate nutrients for optimum milk production. There is a middle ground where producers can feed for optimum performance while meeting the demands of changing environmental constraints.

Dividing the herd into two or three feeding groups allows tailoring rations more closely to the production level and nutrient requirements of the group. By feeding more cows more closely to their requirements, a producer can reduce waste and the excretion of excess nitrogen and phosphorus.

Please check this link first if you are interested in organic or specialty dairy production

The Basics of Grouping Cows

Obviously, a dairy farm must have facilities so cows can be divided into multiple groups. The size of the groups are influenced by the size of the milking parlor, the barns or corrals available for housing the cows, other grouping currently done (dry cows, heifers), and the ability to deliver different rations to different groups of cows. Furthermore, the average age of the herd, average days in milk, and reproductive goals (AI, bull bred, etc.) are all factors that must be considered.

There are many schemes for deciding which cows to group together. Some producers group cows by days in milk or where they are in the production curve. This method is roughly equal to grouping by daily milk production, but some cows produce twice as much daily milk as other cows at the same point in the lactation cycle. Other farms group according to the cows’ reproductive status. Higher producing, early lactation cows are usually not bred so putting them together in a group allows feeding for the higher production and for more efficient heat detection and artificial insemination. However, not all early lactation cows produce at the same level. The most successful way to group cows has been shown to be selecting cows based on the nutrients required per pound of feed; for example nutrients such as crude protein, starch, sugar, fiber, fat, vitamins, and minerals. While directly related to daily milk production, it is a more precise way to feed cows what they need without waste and over-excretion of nutrients (Williams, 1992).

It appears that feeding in three groups produces higher income over feed costs than feeding two groups and group feeding in two groups results are better than one group feeding (Williams, 2002). A California survey showed feeding three groups reduced nitrogen excretion by 15% over herds feeding a one-group TMR (Castillo, 2000).

Why not then?

There are some important considerations when grouping cows for more efficient use of feed nutrients. It takes professional help to formulate rations for and to monitor the performance of different production groups. A nutritionist can also help monitor the quality of feed ingredients used in rations.

All feeds vary in nutrient content load to load and throughout storage. Table 1 shows the mean content of protein and net energy-lactation of common feeds in the northeastern U.S. It also shows the standard deviation derived from the group of feed samples. Adding and subtracting the standard deviation from the mean shows the range in nutrient content for two-thirds of the samples. The other third of the samples tested outside of this range. For example, the mean corn silage contained 7.9% crude protein, and had a standard deviation of 1.3%. This means that two-thirds of the samples tested between 6.6% and 9.2% CP, so one-third tested either greater or less than that range. A ration formulated to supply 6.1 pounds of protein to support the average milk production of the group could be as low as 5.5 pounds and this would result in a loss of almost 7 pounds of milk per day.

How can the risk of nutrient variation be controlled? Nutrients can be over-fed, but that defeats the point of grouping for more efficiency and results in more nutrients excreted. Formulating rations with multiple sources of protein and energy can reduce the risk because it is unlikely that all sources would vary on the low side at one time. Blending single commodities can help as well. One truck load of corn taken from storage containing multiple loads of corn will vary less than a single source. (St. Pierre, 1999). Therefore, receiving larger quantities (train car load vs. truck load) of a single ingredient is best if inventory control, purchasing, and transportation will allow.

Testing all feeds is important in managing the variation of feedstuffs. Notice that forages vary the most so they must be monitored closely. Experienced managers and researchers suggest the following testing schedule (St. Pierre, 1999):

All feeds – Protein, fat, fiber, minerals at purchase or harvest
Forages – weekly for moisture, monthly for protein, fiber (more often if fed quickly)
TMRs – monthly for particle size before and after eating
All feeds – four times a year for macrominerals
Silages – twice a year for VFAs and pH

One obvious way to control variation in the quality of feedstuffs is to reduce or eliminate the use of the feeds most prone to large variations.

Group Feeding Strategies

When feeding groups of cows, nutrients are provided to the average daily production of the group. The average cow in each of three groups is closer in production to her group-mates than the average cow is to the entire herd. However, by feeding the average cow in the group, rations will be inadequate for the higher producing cows in the group. Higher dry matter intake will make up for some of the shortage, but most managers will “lead feed” the group to supply necessary nutrients to the top half of the group. Lead feeding factors have been developed through trial and error and by research using commercial dairy herds. One rule of thumb to lead feeding was to feed the average cow plus one standard deviation of the variation in the group. If the average for a group is 70 pounds/cow-day and the standard deviation in the group is 5 pounds; the herd would be fed for 75 pounds per day. This works when production variation is small due to many production groups. When feeding two or three groups, researchers in Virginia and Ohio have developed lead factors as shown in Table 2.

Notice two things: 1.) Lead factors are different for protein and energy in the Ohio work, 2.) The level of lead feeding over the entire herd can be reduced when feeding more production groups. In a three group dairy, the top string would be fed 115% of the average nutrient requirement based on energy in the Ohio system or 114% of average in the VPI system.

In summary, grouping cows can be part of a total feed management program to reduce waste and the excretion of unused nutrients. Grouping cows by production level or stage of lactation is most common. In addition, grouping cows is beneficial for dairy producers because it helps control feed costs. It promotes feeding valuable nutrients to benefit cows at different stages of lactation and results in optimum efficiency, productivity, and profitability.

References

Castillo A.R., E. Kebreab , D.E.Beever and J. France. 2000. A review of efficiency of nitrogen utilization in dairy cows and its relationship with the environmental pollution. J. Anim. and Feed Sci. 9:1-32.

Castillo. A.R., E. Kebreab, D.E. Beever, J.H. Barbi, J.D. Sutton, H.C. Kirby and J. France. 2001. The effect of protein supplementation on nitrogen utilization in lactating dairy cows fed grass silage diets. J. Anim. Sci. 79:247-253.

Dou, Z., R.A. Kohn, J.D. Ferguson, R.C. Boston, and J.D. Newbold. 1996.Managing nitrogen on dairy farms: an integrated approach I. Model description. J. Dairy Sci. 79:2071-2080.

Grant, R.J. and J.L. Albright. 2001. Effect of Animal Grouping on Feeding Behavior and Intake of Dairy Cattle. J. Dairy Sci. 84(E.Suppl.):E156-E163. McGilliard, M.L, J.M. Swisher, and R.E. James. 1983. Grouping lactating cows by nutritional requirements for feeding. J.Dairy Sci. 66:1084-1093.

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“Extension programs and policies are consistent with federal and state laws and regulations on nondiscrimination regarding race, sex, religion, age, color, creed, national or ethnic origin; physical, mental or sensory disability; marital status, sexual orientation, or status as a Vietnam-era or disabled veteran. Evidence of noncompliance may be reported through your local Extension office.”

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Introduction

This fact sheet has been developed to support the implementation of the Natural Resources Conservation Service Feed Management 592 Practice Standard. The Feed Management 592 Practice Standard was adopted by NRCS in 2003 as another tool to assist with addressing resource concerns on livestock and poultry operations. Feed management can assist with reducing the import of nutrients to the farm and reduce the excretion of nutrients in manure.

The concept of Direct Fed Microbial (DFM) involves the feeding of beneficial microbes to dairy cattle when they are under periods of stress (disease, ration changes, environmental, or production challenges). Probiotics is another term for this category of feed additives. Probiotics or DFM have been shown to improve animal performance in controlled studies. In this section, we will evaluate bacterial additives (not fungal or yeast-based products).

Please check this link first if you are interested in organic or specialty dairy production

Role of Direct Fed Microbials

The proposed mechanisms for improvement in dairy cattle performance when feeding DFM are outlined below.

• Produce of anti-bacterial compounds (acids, bacteriocins, or antibiotics)
• Compete against undesirable (pathogenic) organisms for nutrients and/or colonization of the digestive tract (competitive exclusion)
• Produce nutrients or other growth factors
• Stimulate production of enzymes and/or stimulate growth of natural bacteria
• Metabolize or detoxify undesirable compounds (such lactic acid, mycotoxins, etc.)
• Stimulate the immune system

Several studies the have reported positive animal performance when using a combination of several microbial species listed in Table 1.

The mode action and dosages of many bacterial species are given in Table 2. For example, Lactobacillus acidophilis produces lactic acid that may lower the pH in the small intestine thereby inhibiting the growth of undesirable microbes (pathogens). Calves that have been stressed (i.e. weaning, scouring, and shipping challenges) have responded quite favorability to large doses of Bifidobacterium, Enterococcus, Bacillus, and Lactobacillus. Megasphaera elsdenii is a major lactate utilizing organism found in the rumen of cattle fed high grain diets. Feedlot producers have used DFM when adapting cattle to high energy diets thereby reducing lactic acidosis. Applications in high producing cows are being explored in the field. Propionibacteria have the ability to convert lactic acid and glucose to acetic and propionic acid thereby potentially improving the energy status of early lactation cows. Similar results have been demonstrated in beef cattle through improved feed efficiency. Certain species of bacteria can reduce/detoxify nitrates in the ration.

Practical Considerations

The bacteria in DFM products must be alive to impact ruminal fermentation or lower gut responses. Thus, the viability and number of organisms fed must be ensured at the time of feeding to ensure performance responses. The use of DNA figure printing offers an approach to select the optimal strain(s) of bacteria to ensure optimal animal performance. Some products have guaranteed levels (i.e. 1 x 10^{6 – 10} CFU/g) of micro-organisms in the product to achieve animal performance.

The method of delivery of these products can vary from powders, pastes, boluses, to capsules using feed or water as carriers. If water is used, chlorination, temperature, minerals, flow rates, ionophores, and antibiotics must be considered to avoid killing or reducing the effectiveness of the DFM product. For example, the approval of monensin, which targets gram positive bacteria in the rumen, may result in certain DFM products being less effective due to the microbials being affected by monensin. Producers and nutritionists need to ask for controlled studies demonstrating the use of a particular DFM product in combination with monensin. Some DFM products may require a higher feeding rate or dosage to “seed down” the digestive tract for several days to out compete pathogenic bacteria followed by reducing the feeding rate to achieve a maintenance rate.

The ability of DFM to survive feed processing, especially pelleting, should be requested for each product. In addition, viability data during prolonged feed storage and stability when mixed with low pH silages in the bunk for several hours should be requested. The viability of DFM products in the market place has improved over the years, but follow manufacturers directions concerning heat, oxygen exposure, and moisture to ensure product performance and ultimately animal performance.

Summary

At this time, most nutritionists are “cautious” when adding DFM. However, the success in controlled and field studies has demonstrated improvements in animal performance. The use of DFM’s in milk fed calves seems to warrant the inclusion of a DFM product until dry matter intake of starter is over two pounds per calf per day. The inclusion of DFM products in drench products administered to off-feed cows, cows treated with high levels of antibiotics for various diseases, and those cows under stress would appear to be warranted. At this point, ask for data on animal performance responses to DFM products, evaluate the type and number of microbes added, and follow handling guidelines to ensure product performance and ultimately animal performance.

Selected References

• Hutjens, M.F. 2005. Feed additives in dairy nutrition, an industry and farm perspective. New England Nutrition Conf. Proc. p. 82-88.
• Hutjens, M. F. 1991. Feed additives. Vet Clinics North Am.: Food Animal Practice. 7:2:525.
• Krehbiel, C.R., S.R. Rust, G.Zhand, and S.E. Gilliand. 2003. Bacterial direct-fed microbials in ruminant diets: Performance response and mode of action. J. Anim Sci (E.Suppl.2):E120-E132.
• Kung, L. Jr. 2001. Direct-fed microbials for dairy cows and enzymes for lactating dairy cows: New theories and applications. Penn State Dairy Cattle Workshop Proc. Pp. 86-102.
• National Research Council. 2001. Nutrient Requirement of Dairy Cattle, 7th edition. National Academy Press. Washington, D.C. p. 192.
• Yoon, I.K. and M.D. Stern. 1995. Influence of direct-fed microbials on rumenal microbial fermentation and performance of ruminants: A review. J. Animal Sci. 8:6:533

“Extension programs and policies are consistent with federal and state laws and regulations on nondiscrimination regarding race, sex, religion, age, color, creed, national or ethnic origin; physical, mental or sensory disability; marital status, sexual orientation, or status as a Vietnam-era or disabled veteran. Evidence of noncompliance may be reported through your local Extension office.”

Disclaimer

This fact sheet reflects the best available information on the topic as of the publication date. Date 5-27-2007

This Feed Management Education Project was funded by the USDA NRCS CIG program. Additional information can be found at Feed Management Publications.

This project is affiliated with the Livestock and Poultry Environmental Learning Center.

Project Information

Detailed information about training and certification in Feed Management can be obtained from Joe Harrison, Project Leader, jhharrison@wsu.edu, or Becca White, Project Manager, rawhite@wsu.edu.

Author Information

Michael F. Hutjens
Department of Animal Sciences
University of Illinois, Urbana
hutjensm@uiuc.edu

Reviewer Information

Dave Casper – Agri-King, Inc.
Jim Drackley – University of Illinois

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