Evaluation of the Influences of New Sustainable Bedding Materials with Stacked Litter Management on Factors that Benefit Turkey Health and Environment

January 2022 Report:

We have measured the moisture absorbing properties of the bedding materials to be used and find that the Ag fiber, paper, and cardboard based materials have very high moisture holding compared to saw dust.  Also, the dry and moist bulk densities vary considerably and a baseline for these properties is being established.  A late March beginning of the pen trials is planned.

January 2023 report:

The bedding material trials with this crop of turkeys has been completed. There were six cohorts of poults totaling over 5,500 turkeys spread over the months of April to July. Densities were often times very high depending on the schedule of incoming poults, rapidly growing adolescents and final processed birds. Bedding was applied at the farmer's discretion and in four major events between poult cohorts while pen 1 was empty. The depth of bedding grew from 3" in early April to 30-36" in total depth by October. The farmer ran out of trial bedding in late July, perhaps due to over application, and finished the season with topdressings of sawdust as needed. Adjacent pens (2 &3) were added to data collection events to provide a comprehensive look at the farmer's usual operations of layering with sawdust.   Data and samples were collected from six sampling events of the project area and over ten visits to the farm.  All sampling events have associated lab work that is still being analyzed.  Many laboratory tests have been completed.  Four of the fourteen categories of measurements remain to be finished. An update of some of the findings is presented here.

 December 2023 Final Report

After extensive farm and lab work and following some health interruptions the project has finally been completed.  The repost has many sections that build to a final summary of findings.

INTRODUCTION:

The objective of this research is to evaluate the effectiveness of the materials when applied with stacked bedding management to improve conditions for bird growth and health.  Stacked litter management has been observed to provide the greatest benefit from the bedding materials by frequently applying thin layers of fresh absorbent bedding over the surface of tightly caked litter surfaces.  That allows for drying and absorbing the new excreta and for ammonia reduction and absorption.  This also improves foot pad, leg, and breast health. 

In this study we combine investigations of some trial bedding materials with the use of the stacked litter method to find ways of improving bird performance and health. In comparing these newer materials with a standard control of sawdust we learn more about ways to improve bird health.

The project was conducted in a turkey production facility in central Pennsylvania.  A brooder pen was divided into four equal quadrants with the four test bedding materials used in each quadrant. The fore materials included a control of sawdust and three more advanced bedding materials produced by PittMoss LLC from Ambridge Pennsylvania. Throughout the study the three materials are designated as A-PM, B-PM, and C-PM. All three materials are covered by a patent and are different renditions of absorbent materials manufactured from clean recycled industrial cardboard and paper waste. The cardboard and paper stock are fiberized and reformatted into particles engineered to optimize porosity and absorption for applications to poultry bedding.

IMPORTANCE OF PHYSICAL PROPERTIES:

Poultry bedding materials are used to promote health and cleanliness. The physical properties of the bedding must produce high absorbance and remain as dry as possible while protecting the birds from the effects of their own excreta. The density needs to be sufficient to stay in place and provide a structure that is not damaging to the bird’s feet and breast.  Material must have the ability to absorb and hold moisture to maintain dryness providing for disease reduction. Good physical properties impact the chemistry of the litter and helped to reduce ammonium emissions and avoid low oxygen conditions that can lead to increased disease development. Particle density, size, and form influence the ability to absorb excreta and hold moisture while still drying from the surface.

BULK DENSITY (WEIGHT/CUBIC FOOT):

The density of a material used for bedding must be light enough for easily handling, shipping, and application. It must be heavy enough when dry to stay in place with the movement of birds and air.  The particle that makes up the mass cannot be too dense and must readily absorb fluids and help to dry the feces. The accompanying figure ‘Average Bulk Density by Bedding Type” presents the density (weight per cubic foot) of the four trialed materials.  It also presents the wet sampled and oven dried densities as averaged over the five samplings. The samples were taken after each set of brood poults were removed and extracted from three locations in each of the trial sectors and down to the full depth of the litter (new and old).

Average Bulk Density Bedding Type

In the graphic we see that the sawdust Base Bedding material was considerably heavier than the three experimental blends.  After being successively spread in layers over the surface of the “floor” then trampled and absorbing deposits of excreta the dry density becomes much higher and more uniform between bedding types. This uniformity in dry weights after cropping indicates that the three research blends absorbed proportionately more excreta than the sawdust.  Additionally, the lower wet bulk density in the research materials indicates that the research materials are tending to dry more readily during cropping. From these observations it is clear that the research bedding materials work very favorably in the stacked bedding system

MOISTURE ABSORPTION AND DRYING:

The moisture absorbing and holding ability is the most significant part of this study. Absorption of fluids is critical to maintaining good bird health. Some bird houses do not have sufficient ventilation and the humidity and ammonium levels can become so high that  damage occurs in the birds, reducing feed conversion and growth rates as well as creating long lasting health problems.

The ability of bedding materials to absorb fluids can be easily measured by comparing weights of dry and wet bedding.  This is accomplished by soaking the bedding material and comparing wet and dry weights. The graphic on “Fluid Absorption Ability” presents the relative percent by weight and by volume of five different common bedding materials. The figure shows that sawdust and shavings have the lowest moisture holding ability while straw is higher but approximately the same as peat and the PittMoss base product used for the experimental blends (PM-Roost) had the highest absorption based on both weight and volume.

Fluid Absorption Ability

A graphic presentation of the comparisons of the bedding types in “Stacked Litter Moisture Content Over Successive Broods” from this research project is linked here. It shows the moisture levels on a weight basis beginning on May 4^th at the end of the first brood through to August 5^th at the end of the fifth brood.  It charts the moisture levels for each of the research materials and as the stacked bedding accumulated. Across the board the sawdust moisture level was the highest from the beginning until the end. Keep in mind that the moisture levels are a reading from the fully stacked top to bottom sampling. They all maintain the same general pattern but the three PittMoss research blends did not rise to the high moisture level of the sawdust blend at any time.  The moisture increased the most during the first and fifth broods. These three middle samplings on May 18^th, June 3^rd, and on June 29^th were lower. In this observation it is proposed that the lower mid-term moisture is

Stacked Litter Moisture Content Over Sucesive Broods

due to the more effective surface drying during those warmer times and the PittMoss blends with the good hydraulic conductivity draw moisture from the lower levels of the stacked litter more effectively. In all we clearly see that for stack litter management the treatments including the three PittMoss blends yielded a much lower over-all moisture than the sawdust bedding.

RELATIVE DRYING RATES:

Significant differences were observed in the relative drying rate of the trial bedding materials. This was demonstrated in an experiment that compared evaporation of the water from the surface of each fully saturated bedding material.  In the experiment we placed triplicate replications with one liter of fully saturated bedding layered one inch thick on plates that sat in ambient air for 10 days. The results are displayed in the graphic “Surface Drying Rates of Trial Bedding” In it we can see that the sawdust evaporation amount over the ten days was about 58% of the PM-A & PM-B formulations and 64% of the evaporation amount for the PM-C formulation.  All three of the PittMoss formulations had a significantly higher water evaporation than the sawdust.  The physical structure and the engineered particles in the PittMoss trial blends are believed to contribute to better drying.

Surface Drying Rates of Trial Bedding

PHYSICAL PROPERTIES & CHANGES FROM CROPPING:

The physical space distribution in the bedding materials influences the ability to absorb the bird excreta while maintaining good properties for holding urine and feces.  As the birds age and grow the pressures on the bedding (litter) become greater. Typically, the bedding material is most effective when first applied but in two to three weeks the bedding can  become caked-over with feces and has little effect on absorption of added moisture and feces. That then increases the possibilities of high surface moisture and toxic ammonia emissions.  This then presents the main argument for the stacked litter management system.  Regular and repeated applications of a thin layer (1 to 2 inches) provide for ready absorption of newly deposited excreta. The absorptivity of the bedding is a result of the physical properties of the bedding.  Particle sizes and density influence the rate and quantity of absorption.  Those particles create a physical environment for holding fluids while also allowing for sufficient air space thus allowing oxygen to penetrate the litter.

By defining the physical properties provided when the bedding is laid down, we can quantify the physical space distributions in the bedding materials. Testing the materials by saturating each with water, then draining each, we can determine the air space at saturation. This is accomplished by measuring the quantity of the water drained. Then by measuring the weight change in drying we can obtain the capacity of the material to hold fluids (from fully dry to fully saturated). Finally, the remaining weight represents the solids that take up space. The linked graphic “Physical Space Distribution” presents the measurements of the percentages of space that is occupied by solids, liquids, and air when fully saturated. This provides a measure of the theoretical capacity for holding gases and liquids.

Physical Space Distribution

In this graphic we see that in the fresh unused bedding materials the quantity of theoretical air space, which provides for gas exchange, is approximately identical for all three PittMoss research materials and the sawdust can provide greater air space.  The space represented as solids is the percentage of space occupied in the bedding material that cannot absorb fluids or provide gas exchange. In comparing the solids present in each of the bedding types we see that sawdust has approximately 7% more of the space occupied by solids therefore it has 7% lower total absorptive capacity compared to the three PittMoss experimental versions.  The percentage of space that can hold liquids, or be filled with excreta, ranges from approximately 15 to 17 percent higher in the PittMoss trial blends than in the sawdust.

ACCUMULATED SOLIDS:

 As anticipated for the project the solids accumulated at approximately the same rate for all tested substrates in each sector of the communal trial room.  The linked graphic “Increase in Space Occupied by Solids” charts the accumulation of solids. It shows that there is very little difference in the rate of accumulation for different bedding types.  

Increase in Space Occupied by Solids

In representation it is apparent that over the sequence of five different settings of brooding poults, the solids increase averaged approximately 20% in each material.  That further indicates that the young poults spent  approximately equal residence time over each of the experimental quadrants. This increase in solids is due to increased  feces deposits and compaction from bird traffic. Together they impact the ability to absorb additional solids and fluids while reducing air space.

  CAPACITY TO HOLD FLUIDS:

The capacity to absorb moisture was measured over successive broods of poults.  Those changes are depicted in the attached graphic showing the “Capacity to Hold Fluids”. Note that the potential fluid absorbing capacity appears to have substantially increased after the first set of poults (for reasons not explained) and then tended to remain the same with the added bedding layers through to the end of the fifth set of poults. Keep in mind that this represents the capacity for holding fluids if totally saturated and not the content of fluids in the sampled litter.

Capacity to Hold Floids

TRENDS IN AIR SPACE:

The accumulation of fluids and the increase in accumulation of solids reduced the airspace over the series of successive broods of poults. The linked graphic shows the “Trends in Airspace” for all four trial materials.  The changes in solids within the composite of stacked litter appear to be approximately the same for all the materials The airspace was reduced in each at about the same rate consistent with the litter accumulation of more excreta.  This reduction in air space also reduces the possibility of gas exchange, which is not necessarily a problem, to a point but can develop conditions that limit oxygen penetration into the litter and intern can increase ammonia gases.

Trends in Airspace

CHEMICAL PROPERTIES & ANALYSES:

Total mineral analyses were performed on the initial bedding materials and  litter produced  from the stacked litter method after five cycles of brooding turkey poults. Both soluble mineral measurements, using the saturated media extract method (J.R. Peters Lab, Allentown PA), and total digested mineral content from compost analyses, (MMI Labs, Athens GA) were performed.  Differences in water soluble (mobile) mineral levels and total content can be distinguished by comparing the two analyses. Differences in pH and total soluble salts (EC) as measured by the two outside lab measurements are discussed further below. Information on the nitrogen and phosphate levels, comparing soluble and total levels, is presented in detail in the respective sections below.  A table listing other significant minerals is also included with a discussion of the impacts associated with the different materials used in this stacked bedding trial.

INFLUENCES ON PH:

 Wide variations in pH are observed from the impacts of the bedding materials. This is significant because acidic pH levels in the litter help to significantly reduce the ammonia gas emissions that are damaging to the birds and severely impact growth rate. There were differences in the pH between the alternate bedding materials (A-PM, B-PM, C-PM) and the  control (sawdust). As a snapshot of changes in pH  the data in the graphic “Final pH of Litter Compost Analysis” presents the starting and finished pH with changes noted. In the  stacked litter trials of sawdust and the grow out pens which had sawdust bedding the pH levels increased in all three applications by up to 2.1 full units,  while the pH levels in the three PM formulations decreased during cropping by up to 1.7 units. While these observations are limited there is a clear indication that the pH can be maintained more effectively using the PittMoss trial formulations than with sawdust.  Those lower pH levels likely contributed to the lower ambient ammonia levels measured over the various PittMoss trial blends.

Final pH of Litter Compost Analysis

TOTAL SOLUBLE SALT:

The soluble salt level of the litter is an indication of the minerals that can be dissolved and leached out.  The minerals increase as the excreta from the birds accumulates.  With the stacked litter method, the layering of the added bedding absorbs the urine and feces to help reduce the surface accumulations of waste.  Keeping the soluble salts levels lower contributes to foot pad and breast health. In the graphic “Bedding Soluble Salts” we see that all bedding treatments increased substantially in soluble salts levels but not high enough to create observed problems. No clear and significant differences are displayed but it appears that the B-PM and C-PM formulations absorbed the minerals a little more effectively and had lower increases in soluble salts. Note that the soluble levels of nitrogen and phosphate can be important when considering possibilities of increasing pollution from manure field applications. Nitrogen and phosphorus are discussed in detail below.

Bedding Soluble Salts

NITROGEN BALANCE:

A primary part of this research was to determine the impact of the bedding type on the forms of nitrogen that are in the litter. These forms include organically, nitrate, and urea nitrogen. To obtain the total quantity of nitrogen a total digestion analysis provides the total percent nitrogen and the parts per million of ammonium and nitrate present in the litter. In addition, we get a carbon:nitrogen ratio which indicates the ability of the bedding to sequester nitrogen into organic complexes. Table 1 presents data on the total nitrogen content.  It provides reference to the bedding base material before use and the results from a composite sample from the full depth of the stacked litter after the fifth brood of poults.

In the listings we see that the Carbon:Nitrogen ratio varies widely depending upon the base bedding material. The total nitrogen was low in all materials in the beginning and rose to a range from 3.6 to 4.5% after cropping. Most significant was the difference in the ammonium (NH4) nitrogen content after cropping. The sawdust was the highest at 1580 ppm N from ammonia, while the lowest was 861 ppm for the B-PM. The A-PM and C-PM formulations were better than the sawdust. Nitrate (NO3) levels were hardly detected. What is most important about nitrogen is the portion which can be released as ammonia gas creating problems in bird health and environmental pollution. To further understand the nature of the nitrogen components we examine the water-soluble nitrogen present in the litter. Table 2 presents the water-soluble nitrogen components before and after cropping for each of the trial bedding materials.

 The total volume water soluble nitrogen measured in the sawdust was 1,338.5 PPM with 1,300.2 PPM of nitrogen in the ammonium form. Therefore 97% of the ammonium in the sawdust litter is labile and can escape as ammonia gas when conditions are right. The level of water dissolved ammonium is significantly lower in the A-PM litter.  At 552.8 PPM the soluble portion is down to 45% of the total measured ammonium.  Similarly, B-PM, and C-PM had lower water dissolved ammonium levels of 552.4 and 1005.7 with respective percentages of the total ammonium at 64% and 69%.  These data are very significant in that they demonstrate that the PittMoss formulations clearly are sequestering the nitrogen in a less soluble form compared to the sawdust. Additionally, considering that they all contained approximately the same amount of total nitrogen after cropping it appears that the nitrogen is complexed within the organic material of the various PittMoss formulations. The complexed nitrogen then remains in the litter and provides opportunities to use that litter in manuring fields while greatly reducing the potential for nitrogen solubilization and runoff.  Also important, as seen in the data, the nitrate nitrogen levels were so low in the litter from all these bedding materials that the ready leaching of nitrate is not expected when direct applying manure from the stacked litter system.

AMMONIA GAS EMISSIONS:

Emissions of ammonia gas arise from anaerobic conditions and higher pH levels in the litter. Over the course of this research ammonia gas levels in the air at about one foot above the litter surface were measured using a Forensics Lab Ammonia Detection Meter. At each sampling ten measurements were taken above each treatment sector.  The measurements ranged from 0 to 25.5 PPM ammonia. Note that at or above 25 PPM ammonia can severely damage the birds.  Levels consistently above 10 ppm are considered to do some harm while slowing the growth of the birds, especially very young birds. A graphic presentation of the “Average Ambient Ammonia Gas Levels” is presented in the attached link.  Presented in it are the studied treatments along with observations of grow out Pens 2 and 3 which had sawdust bedding. The sawdust bedding consistently had higher ammonia.  Note that the grow out pens were populated with larger birds producing more excreta and had much higher moisture levels. The sawdust treatment in the trial room was not as moist and employed the stacked litter method with freshly applied sawdust layers with each new set of poults.  In the communal room trial the three PittMoss trial blends had consistently lower ammonia emissions. 

Average Ambient Ammonia

PHOSPHORUS BALANCE:

One primary focus of this research is the impact of bedding type on the level of soluble phosphorus. Every advancement to reduce phosphorus pollution is urgently needed. Data on the total and soluble phosphorus levels in the bedding and litter are presented in Table 3. While the base bedding  materials started with very low soluble phosphorus levels, after the five sets of brood poults were completed on the stacked litter, the total phosphorus level increased to a range from 218 to 303 PPM of elemental phosphorus and the soluble phosphorus ranged from174.6 to 223.2 ppm and only slightly varied among the litter types.  The PittMoss blends tended to complex or sequester

a portion of the phosphorus which was apparently held in a  non-soluble form.  From 27 to 29 percent of the total phosphorus level was held as insoluble in the PittMoss formulations as observed in these analyses.  This apparent sequestration is extremely meaningful for manure management and field applications and may serve to greatly reduce the nutrient runoff from farm fields where poultry manure is surface applied.

OTHER MINERALS:

Several other minerals present in the litter have nutrient value. The total mineral analyses were performed in both the total digested analyses and the water-soluble saturated media extract analyses (SME). The SME analyses was the most representative for reporting the other minerals.  Table 4 lists seven of the most significant minerals when using the litter for crop growth.  The base levels in the bedding provide a reference for the materials applied in the stacked litter and the levels after 5 sets of brood poults provide a picture of the changes over the twelve weeks. 

Potassium registered the greatest concentration of nutrients for all minerals evaluated. Sawdust had the highest density of potassium at 4001 PPM. The lowest density was in the A-PM  formulation registering  2124 PPM in the SME.  The concern over sodium and its potential to contaminate soils is always great. The sawdust registered the highest sodium concentration at 535 PPM. Likewise, chloride levels are a concern in some agricultural applications, however chloride is readily leached from most soils. Again, the sawdust had the highest chloride level at 1,295 PPM. The graphic differences in iron levels from 9.1 PPM in A-PM to 20 PPM in sawdust presents a suggestion that sequestration of ions is occurring in the PittMoss formulations.  That is similar to what we see in nitrogen, phosphorus, potassium, sodium, and chloride. Manganese was the highest in the A-PM blend.  Boron reached levels of concern over toxic buildup if repeated manure applications occurred at 5.3 PPM.