Egg Industry Articles

Uzelac Rotary Drying Systems to Process Layer Manure


Application of Uzelac Manure Drying Systems.


Uzelac Industries based in Greendale, WI. has developed considerable expertise in the design and installation of rotary drum dryers capable of reducing the moisture content of manure from high-rise houses with 65 percent water or belt systems with 45 percent water down to 15 percent. Manure handling and drying installations convert a waste product into a valuable pathogen-free fertilizer in a commercially acceptable form for domestic and institutional applications.


Direct application of raw manure to farmland will be subject to increasing restriction as nitrogen percolating through soil contaminates ground water and hence wells. Runoff entering streams and waterways will come under heightened scrutiny from state and federal regulators.

 A Uzelac rotary dryer installations reduces odor, obviating complaints and lawsuits and when used with belt manure collection, effectively eliminates fly problems without expenditure on insecticides. In the future environmental regulations may necessitate on-farm or remote processing of manure before application.


A typical Uzelac on-farm or remote installation comprises:-

  • Hoppers to accumulate raw material conveyed from houses or delivered from farms
  • A mixer to ensure that raw material is uniform in composition before processing
  • An air-heater assembly to fire the rotary drum dryer configured to the volume of input
  • A product collector to receive processed, dried material
  • A dust cyclone to limit air contamination
  • An optional pellet mill and pellet cooler to convert processed material into a saleable form
  • Packaging systems for either pelleted or granular products or a storage and delivery system for bulk product


Current Uzelac customers in the U.S. poultry industry include Herbruck’s Poultry Ranch, Giroux’s Poultry Farm, Michael Foods, Foster Farms and Tyson Foods among others.


Financial Evaluation of Uzelac Manure Drying Installations

Calculating the return from an investment in a manure drying installation is dependent on a number of factors including:-

  • Housing system such as high-rise, belt battery or aviary that will influence the moisture content of raw manure.
  • Prevailing power, gas and labor costs.
  • Single or two-shift operation to process manure from a complex or combination of smaller operations.
  • Seasonal climatic conditions with hot weather increasing water consumption of a flock, leading to manure with a higher moisture content
  • Size of supply flock influencing initial capital cost and utilization. Some installations are sited remotely to receive manure from a number of farms or complexes.
  • Form of product sold, whether bulk or bagged, granular or pelleted, will determine unit revenue.
  • State or local grants to offset capital cost.
  • Prevailing interest rates.


In order to calculate the return on investment from a manure-drying installation the following boiler-plate examples are provided. The first model assumes single shift operation, 40 hours/week; processing manure from one million hens in aviaries. The format allows insertion of specific values relating to a complex:- 

Capital cost of a Uzelac manure drying installation.

Buildings and installations


Mechanical equipment


Total Capital cost


Annual Fixed Cost of Operation :

Depreciation, Buildings @ 7% pa

$ 74,200

Depreciation, Equipment @ 15% pa

$ 441,750

Interest on capital @ 3% pa

$ 120,150

Overhead provision

$ 10,000

Annual Fixed Cost

$ 646,100

Annual Variable Cost of Single-shift Operation


$ 150,000

Maintenance provision

$ 50,000

Power Estimate

$ 250,000

Annual Variable Cost

$ 450,000

Annual Cost of Operation



In assessing the return on investment it is assumed that 1,000,000 hens in aviary houses produce 35,000 tons raw manure each year with 45 percent moisture content dried to 15 percent resulting in 24,500 tons of saleable product.


Revenue from dry product @ $145 per ton


Less value of wet manure @ $10 per ton

$ 350,000

Differential in revenue

$ 3,202,500

Add saving on fly and rodent control

$ 10,000

Annual Revenue

$ 3,212,500

Less Annual Fixed and Variable Costs

$ 1,096,100

Annual Contribution

$ 2,116,400


Discounted Cash Flow Calculation

In order to evaluate the capital cost of the manure drying installation the annual contribution over a five-year period would be:-


Year 1 2 3 4 5

5% discount factor

0.95 0.91 0.86 0.82 0.78

Annual Revenue ($ mil.)

2.01 1.93 1.82 1.74 1.65


Net Present value over 5 years attains $9.15 million


This exceeds Present Value applying 5% annual discount factor


Discounted payback of 25 months

In evaluating the effect of selling price as the major variable influencing ROI a series of DCF calculations were performed yielding the following results:-


Selling Price per ton Net present Value of Investment over 5 years


$ 75 $1.74 million
$ 85 $2.79 million
$105 $4.91 million
$125 $7.03 million
$145 $9.15 million


The return on investment is extremely sensitive to unit selling price. At $105 per ton the project would require 47 months to achieve a breakeven net present value of $4 million, corresponding to the original capital investment.


In demonstrating the influence of volume and price on the return on investment the manure-drying installation was evaluated with the theoretical output of 2 million hens, operating the Uzelac plant on a double-shift schedule 80 hours per week, corresponding to five, 16-hour working days. In this approach in the interests of simplicity, fixed costs of $646,100 would remain unaltered but variable costs would double to $900,000.


Annual Cost of Operation $1,546,100


In assessing the return on investment it is assumed that 2,000,000 hens produce

70,000 tons wet manure each year at 45 percent moisture content dried to 15 percent resulting in

49,000 tons of saleable product.

Revenue from dry product @ $145 per ton $7,105,000
Less value of wet manure @ $10 per ton $ 700,000
Differential in revenue $ 6,405,000
Add saving on fly and rodent control $ 20,000
Annual Revenue $ 6,425,000
Less Annual Fixed and Variable Costs $ 1,546,100
Annual Contribution $ 4,878,900

Discounted Cash Flow Calculation


In order to evaluate the capital cost of the manure drying installation the annual contribution over a five-year period would be:-

Year 1 2 3 4 5
5% discount 0.95 0.91 0.86 0.82 0.78
Annual Revenue ($ mil) 4.63 4.44 4.20 4.00 3.81

Net Present value over 5 years attains $21.08 million


Exceeds Present Value by a factor of 5 applying a 5% annual discount factor

Discounted payback period of 10 months

In evaluating the effect of selling price as the major variable influencing return, a series of DCF calculations were performed yielding the following results:-

Selling Price per ton Net present Value of Investment over 5 years

$ 75 $ 6.27 million
$ 85 $ 8.37 million
$105 $12.61 million
$125 $16.84 million
$145 $21.08 million


The return on investment is extremely sensitive to unit selling price. At $75 per ton the project would require 37 months to achieve a breakeven net present value of $4 million, corresponding to the original capital investment.


The calculations provided assume manure from an aviary house with 45 percent moisture. Manure from high-rise complexes with moisture content of 65 percent would require a higher drying capacity with proportional increases in capital and operating costs to reduce moisture content to 15 percent.


Uzelac manufactures components for rotary drying systems that can be adapted in capacity and layout to suit specific applications. Uzelac engineers are available to review specifications and to design custom installations.


Additional information on Uzelac installations can be accessed by clicking on to the Uzelac logo on the right side of the welcome page or on or (414) 529 0240 - contact Mike Terry.


What Does the Latest Study on Eggs and Cholesterol Mean?


Mickey Rubin, PhD, Executive Director, Egg Nutrition Center


Many of you may have seen the headline this morning touting another study on eggs and cardiovascular disease, with the headline “Are eggs good or bad for you? The truth may be somewhere in between.” This is one where your readers, followers or patients may have questions. I would encourage you to read past the headline because there are some important points made by experts, including Dr. Walter Willett from the Harvard School of Public Health.


“The study results are problematic because they only asked people once about their egg consumption, then followed them for many years without checking to see if their diet had changed” according to Dr. Willett, while other experts in the same article stated that "The conclusions of this study are overblown.”


What does the latest study on eggs and cholesterol mean? See below for a brief summary of the results and the broader context:


  • This new study reported an increased risk for all-cause mortality, cardiovascular mortality, and cancer mortality.


  • However, this study was limited by the fact it only assessed diet once at the start of the study 25 years ago and then never again.
    • In contrast, a stronger study from the Harvard School of Public Health assessed diet multiple times over decades and found no link between egg intake and cardiovascular risk.


  • Several studies published just in the last year on the topic of eggs, dietary cholesterol, and cardiovascular risk contradict the findings from this new study, including the Harvard study linked above, a meta-analysis of 23 studies that found egg intake reduced the risk of coronary artery disease, as well as a global analysis across 50 countries that found no link between eggs and cardiovascular disease.


  • One point not discussed extensively in this new study or the news article is the finding that consumption of eggs was linked to a reduced risk of Alzheimer’s disease. While this should be viewed in the context of the limitations of the study described above, this is consistent with other studies on choline – a nutrient for which eggs are an excellent source - that have shown favorable results for cognitive outcomes and reducing risk for dementia.


  • Finally, recent guidance from the American Heart Association (AHA) as well as the Dietary Guidelines for Americans 2020-2025 that have assessed the totality of evidence on the topic state that eggs can be a part of heart-healthy diet patterns.
    • The AHA stated in 2019 that healthy individuals can include up to a whole egg daily in heart-healthy dietary patterns, older healthy individuals can include up to 2 eggs per day in heart-healthy diets, and vegetarians who do not consume meat-based cholesterol-containing foods may include more eggs in their diets within the context of moderation.
    • The Dietary Guidelines for Americans 2020-2025 include eggs in all recommended healthy eating patterns starting from when children are first introduced to solid foods.


As always, there are often competing headlines in nutrition science, with one study showing one thing, and another study showing the opposite. Rather than getting caught with nutrition science whiplash, it is important not to focus too much on any one study, but rather view the research in totality. As is reflected in the latest nutrition guidance, nutrient-rich eggs are an important part of healthy dietary patterns across the lifespan.


Reducing feed cost during times of high feed-ingredient prices


Kristjan Bregendahl, Ph.D.; Poultry Nutritionist, Devenish Nutrition, Fairmont MN


The cost of feed accounts for 65 percent or more of the cost of egg production. Minimizing feed cost and optimizing feed utilization and production therefore becomes paramount for ensuring profitability. The following considerations are options for lowering feed costs without compromising performance.


Diet density

The three most expensive parts of laying-hen diets are energy, protein, and phosphorus (in that order), so it is tempting to lower the dietary concentration of one or more of these in an effort to lower feed cost. This could be done by re-formulating the diets, or—if the diet program includes different diets based on feed intake—switching to a higher-intake diet (e.g., from a diet designed for 25 lb/day feed intake to 26 lb/day, which lowers diet density and feed price. However, switching to such lower-density diets is only possible if the flock is ‘overfed’ to begin with. Otherwise, lowering diet density likely backfires, because the birds need the same amount of energy (calories) and nutrients regardless of feed-ingredient prices—the birds will either increase feed consumption in an attempt to obtain the needed calories and nutrients, or the smallest birds will reduce egg-production due to the now marginally deficient diet. The loss of income from either of these consequences will offset the decreased feed cost of the lower-density diet, and may even increase feeding cost (Table 1). Even if a small loss in production is accepted as a consequence of the lower-density diet, there is a very fine balance between lowering production slightly and crashing the flock.


Table 1. Lowering the feed price by reducing energy and/or nutrients often leads to an increase in feed consumption and thus feeding cost.

Energy and/or nutrient density  Feed price         Feed consumption             Feeding cost

                                                           $/ton                        lb/day                  $/day per 1,000 birds

Original                                               300           ×             0.25               =              37.50

Reduced                                              290           ×             0.26               =              37.70


To minimize feed cost and maintaining the desired production, it is important to work closely with the feed mill and nutritionist to ensure that the diet currently fed is formulated to supply the birds with only what they require and with no excesses or deficiencies. Be prepared to share with the nutritionist information about current and desired production performance, including feed intake, egg weight, percentage egg production, and body weight. The nutritionist, in turn, will have to evaluate the dietary nutrient content, including the amino acid concentration and balance.

Using the correct rounding or minimum production amounts in diet formulation is helpful to avoid deficiencies or overages. Perhaps the diet-formulation program optimizes a given diet by using 52.435 lb/ton meat and bone meal, but the mill’s major scale needs 5-lb/ton increments and instead adds only 50 lb/ton—or, 22 lb/ton of a major ingredient is suggested, but the mill’s scales need at least 50 lb/ton inclusion rate without having to manually override a system error. So, set your diet-formulating program to use appropriate minimum production amounts and round the ingredients to match the scales’ capabilities. Also, most mixers cannot adequality mix (distribute) ingredients from the micro-bins when added at less than 1.0 lb/ton with amounts between 0.50 and 1.0 lb/ton being borderline. Even if the diet-formulation program can balance a diet using, form example, 0.35 lb/ton (0.0175%) l-threonine, most hens in the flock will likely be fed a marginally threonine-deficient diet, because the too-small amount of l-threonine cannot be adequately dispersed in the diet.


Alternative and byproduct ingredients

Most poultry diets in the USA are based on corn and soybean meal, but using other ‘alternative’ ingredients (e.g., wheat grain, sorghum, canola meal, linseed meal) and byproduct ingredients (e.g., corn DDGS, meat and bone meal, bakery meal, corn gluten meal, wheat midds) may lower feed cost without impacting performance. A word of caution, though: The prices of these ingredient often follow those of corn and soybean meal, and the energy and nutrient contents of these ingredients are lower than those in corn and soybean meal, so the alternative or byproduct ingredients may not always ‘price in’ and lower feed cost while maintaining the desired energy and nutrient concentrations.  


Feed-grade amino acids

The diet’s protein is mainly supplied by corn and soybean meal; however, birds do not need protein per se, but rather the 20 amino acids that make up protein. When all the amino acids in the diet are supplied by corn and soybean meal, there are excesses of some amino acids. These excesses can be reduced by not formulating with a crude protein minimum and instead using digestible amino acids while allowing feed-grade amino acids to replace some of the soybean meal. Because protein is the second-most expensive part of the diet, reducing soybean meal—yet still meeting the birds’ amino acid requirements through the use of feed-grade amino acids—can be very cost effective. In organic production, only feed-grade methionine (dl-methionine and MHA-type products) is allowed, but the feed cost of conventional and non-GMO diets frequently benefits from including l-lysine•HCl, l-threonine, and possibly l-tryptophan l-isoleucine, and l-valine.


Feed enzymes

Feed enzymes improve the digestibilities of energy and nutrients in the feed ingredients. NSP enzymes work on the fiber fraction of feed ingredients and increase the digestibility of energy; these enzymes can therefore replace at least some of the added oil in the feed, or help maintain adequate energy concentration when high-fiber, low-energy byproducts are used. Phytase enzymes increase the digestibility of phosphorus in corn and soybean meal, and will therefore reduce the amount of expensive mono- or dicalcium phosphate in the diet. Feed enzymes are well studied and have been used for many years with good results, and organic-approved versions are available. Although the enzymes add cost to the feed, they easily pay for themselves in energy and phosphorus savings. That said, there are differences in both price and efficacy of the enzymes, so the choice of enzyme (brand name) should be re-evaluated on a regular basis in an effort to save on feed cost. 


Feed additives

So far, discussion has centered on the diet’s energy and nutrient contents and how to best meet the hens’ requirements. Another, sometimes substantial, cost in the diet is feed additives. Yeast, probiotics, and essential oils are often added to improve the birds’ production or feed utilization through increased health or improved food safety. Many, but not all, of these feed additives are well-researched, their mode of action known and shared with customers, and confer significant benefits to the flock. However, multiple, similar feed additives with overlapping effects are sometimes added to poultry diets with minimal or no additional benefit to bird health and only increase cost to the producer. In these cases—or when unproven feed additives are used—all feed additives should be reviewed to determine if one or more can be eliminated or if less expensive, but equally effective, versions (i.e., different brand names) can be used.

Sometimes, feed additives are added to control parasites (e.g., intestinal worms or coccidia), but these additives are often expensive per treated ton of feed, and their effectiveness variable. While there certainly may be benefits of using these feed additives to prevent parasites, there are cost advantages in using them only when necessary, rather than continuously. Work with the nutritionist and veterinarian to choose the best option for your particular circumstances.

Mycotoxin binders can be useful when there are high concentrations of mycotoxins present in the feed ingredients or when the risk of mycotoxins in feed ingredients is high, but they are too expensive to add routinely. In addition, some mycotoxin binders are more effective than others against certain mycotoxins, so work closely with the feed mill to determine the mycotoxin risks and with the nutritionist to select the most appropriate and cost-effective binder for your situation.


Take-home message

When feed-ingredient prices are high, the first step in attempting to save on feed cost is to make sure the current diet’s energy and nutrient concentrations closely match the need of the specific flock with no excesses or deficiencies. Additionally, alternative feed ingredients can be considered, the feed utilization optimized using enzymes and feed-grade amino acids, and the use and choice of feed additives re-evaluated.


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