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Litter Conditioning for a Healthy Flock

by 5m Editor
1 January 2008, at 12:00am

Susan E. Watkins, Extension Poultry Specialist at University of Arkansas offers advice on treatments when litter is reused for several consecutive flocks in the Summer 2001 issue of the University's <em>Avian Advice</em>.

The high cost of clean out, litter disposal and new bedding makes it economical for broiler producers to re-utilize bedding material for one, two, three or even more years of production. However, this practice makes proper litter conditioning an essential tool of good management for keeping flocks healthy and profitable. Conditioning litter between flocks addresses where the birds live, which is the most crucial aspect of the poultry house environment. Litter quality impacts bird health, skin and footpad quality and even the bacteria levels on the final product. While occasionally a good flock is produced on poor litter, the odds are far more likely that a flock will have a lower average weight, poor feed conversion, higher condemnation rates with a loss in profit when litter quality is allowed to deteriorate.

Critical Factors in Litter Quality: Moisture, Temperature and pH

Moisture is the key factor which influences litter quality. Litter moisture is linked to the survival of harmful organisms (pathogens) such as Salmonella, E. coli, Clostridium, viruses, coccidiosis and mold that can impact both bird and human health. The wetter litter is, the more likely bacteria will survive for extended periods of time. Bacteria can survive for weeks in wet litter versus days or hours in dry litter. It has recently been documented that by lowering the moisture level of litter through increased air flow, it is possible to reduce the litter Salmonella levels, which can help to reduce the contamination entering the processing plant. The key was dry litter. Friability is a physical property of litter that directly impacts litter available water. Friability is a measure of how easily the litter will crumble or break up. Practically speaking the more friable the litter, the easier it is to break up and less likely to mat and hold water on the surface.

In addition, litter moisture helps support the bacteria which converts litter nitrogen or uric acid (a key component of bird's manure) into ammonia. High levels of ammonia cause blindness, damage trachea or lungs and depress appetite. Once the bird’s trachea is damaged, dust, bacteria and viruses can easily enter the birds system making it very susceptible to air sacculitis infections.

Temperature will also contribute to ammonia production. The warmer the litter, the more active the bacteria will be in converting uric acid to ammonia. Thus, while raising the temperature is critical for brooding young birds, it results in a release of ammonia from the litter.

Litter pH is another critical factor affecting quality. The pH of litter is alkaline or basic and typically ranges from 7.5-8.5. Within three flocks litter pH can be well above 8.0. Most bacteria, including the ammonia-producing bacteria, grow best at pH values above 7.0, while few grow below 4.0. Also yeast and mold growth is slowed at low pHs. Reducing litter pH as a means to control microorganisms requires reducing and maintaining the litter pH at 4.0 or below.

Ideal Litter Conditions

In order to understand how litter can be managed to provide an optimum environment, it is first important to have litter quality goals. Ideal litter has the following characteristics:

  • Loose and not caked over
  • Not too dry or too wet (20-30 % moisture is ideal)
  • Low level of ammonia (less than 20 parts per million)
  • Uniform particle size (No large clumps)
  • Minimum insect load.

Addressing Litter Quality

The best time to address litter quality is immediately after the last flock has been removed. Litter should be decaked by removing or pulverizing the material that has become saturated with moisture and is severely clumped together. Allowing litter cake to remain in a facility can create a protective seal keeping moisture trapped in the litter. Litter cake creates a microenvironment where bacteria can remain living even when birds are absent and the house temperature is cold. The moisture trapped in caked litter will also contribute to a substantial ammonia release once the house is closed and rewarmed for the next flock.

After decaking, when possible, stirring litter or raking the litter will help the release of moisture. Many turkey producers deep stacking litter down the center of the house and allow it to go through a heat cycle for 10 to 14 days to destroy bacteria and lose moisture. The litter is then re-spread in the house.

Litter Amendments and How to Use Them

An additional way to enhance litter quality is through the use of litter amendments. The three most commonly used amendments are all chemicals that acidify the litter. These contain either sulphate or sulphuric acid. The sulphate when combined with air or litter moisture converts to sulphuric acid, which as a strong acid that will acidify the litter. When used at the manufacturers recommendations of 50 to 100 pounds per 1000 square feet, the treatments will drop the litter surface pH to below 4 and in some cases, such as newer litter, as low as 2. The low litter pH then results in an unfavourable environment for most bacterial growth including the bacteria responsible for creating ammonia. Properly adding litter treatments prior to the placement of a new flock will reduce ammonia during the brooding cycle, which allows producers to run fans for minimum ventilation instead of over ventilating to remove high atmospheric ammonia levels. Litter treatments also reduce bacterial exposure for young birds. Yet as new manure and moisture are added to the litter, the litter treatments will become neutralized and lose their ability to control ammonia production and bacteria growth. Litter treatments usually control ammonia for two to three weeks. The less treatment used, the shorter the time of ammonia control.


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"Choosing the right litter treatment should include information on cost, availability and other factors such as nutrient best management practices."

Each litter treatment is unique in the way that it works. The aluminium sulphate- (or alum-) based treatment, commonly called Al+ Clear must be worked or tilled into the litter to be most effective. While this litter treatment will give some ammonia control if not worked into the litter, the producer will not get the most effective use from the product. The AL+ Clear product works best if applied 7 days before chick placement if the litter is dry and 3 days before chick placement if the litter is moist. The other two commonly used amendments, sodium bisulphate (PLT) and a clay product acidified with sulphuric acid (Poultry Guard) work best when top-dressed on the surface of the litter. The sodium bisulphate product (PLT) works best when applied as close to chick placement as possible. This product will actually pull moisture from the air and combine with ammonia. Poultry Guard works best if applied 3 days or less before chick placement. A trend that has recently started is the use of two treatments in a facility. For example, blending the Al+ Clear with one of the other products. One suggestion is to apply 50 pounds/1000 square feet of Al+ Clear and then apply 50 pounds/1000 square feet of a second product.

All of the common litter treatment products can easily be applied with standard equipment such as a rotary disk spreader. However, before amendments are applied, it is crucial that the litter be properly prepared through decaking, tilling or pulverizing. The longer litter is maintained in a house, the more important good decaking or litter pulverizing is before amendment applications. It is also important to level the litter surface as a final step before application to ensure uniformity of application so that ammonia and bacteria can be controlled through out the house. Since litter treatments are acids, they will corrode metal over time, so it is important to keep them away from footings and equipment.. Remember to follow all listed safety precautions when handling the products. Protective eye gear is especially important.

Another amazing benefit from the use of litter treatments is a reduction in darkling beetle population. Since beetles will eat anything, they also consume these products. The products turn into strong acids in their digestive tracts and the beetle is destroyed. Facilities which consistently use litter treatments have fewer beetles. In addition, insecticides last longer under acid conditions versus alkaline conditions. Thus, litter treatments may increase the residual killing power of insecticides. Therefore, by applying liquid insecticides before litter treatment application and dry insecticides after litter treatment application, extended effectiveness of the insecticide can be obtained. Make sure that liquid insecticides have had time to dry before litter treatment application.

Choosing the right litter treatment should include information on cost, availability and other factors such as nutrient best management practices. The aluminium sulphate product will tie up the phosphorus in litter and prevent it from becoming a run-off hazard when the litter is spread on pasture or crop land. This has become an accepted tool by the Arkansas Natural Resource Conservation Service, which might allow producers who regularly use alum to spread litter on soil that has a high phosphorus level. To get optimum phosphorus binding, it is necessary to use the higher levels of alum (200 pounds/1000 ft2) and to use it every flock. See your local conservation district water quality technician to obtain more details on how this practice could be utilized in your operation.

The utilization of the aluminium sulphate product for extended periods does make the litter less desirable as a feedstuff for cattle. The key reason is the aluminium imparts a bitter, metallic taste to the litter. It is recommended that if litter is fed to cattle, it should not be treated with aluminium sulphate. Remember that cattle have a maximum recommended sulphur intake of 0.4%. The sulphur content of poultry litter ranges from 0.2 to 0.8% sulphur without added litter treatments. The use of any of the litter treatments could raise the litter sulphur to levels that are toxic for cattle. One symptom of sulphur toxicity in cattle is reduced feed consumption. Check with your county extension agent for information on use of litter for cattle feed.

A final word of caution, follow the manufacturers' recommendations when using litter treatments. Utilizing levels below recommendations may drop litter pH to a level that is close to 7. This reduced amount of litter treatment can enhance bacterial growth instead of depressing it.

Table 1 shows results of a trial where three-flock old litter was autoclaved and inoculated with known levels of Salmonella. Litter was then treated with either Poultry Guard or PLT (Poultry Litter Treatment) at different levels and sterile drag swabs were used to collect Salmonella samples. The results showed that using low levels such as 25 pounds of treatment/1000 square feet of litter resulted in higher levels of Salmonella as compared to the untreated litter. The pH of the low level application litter was high enough to support the growth of the Salmonella. It took utilizing 100 pounds/1000 square feet to drop the Salmonella to levels which were much lower than what was found in the untreated litter.



Table 1. Effects of litter amendments on autoclaved litter inoculated with Salmonella
Litter treatment Application rate
(pounds/1000 ft2)
Salmonella count/sponge Litter pH Litter moisture
(%)
Untreated litter 0 589abc 8.300a 23.60
Poultry Guard 25 2723a 5.825bc 25.40
50 697abc 4.425d 24.30
75 191bcd 3.550e 23.75
100 53d 2.675f 23.80
PLT 25 1026ab 6.233b 23.27
50 123cdb 5.475c 23.33
75 146cd 4.425d 25.60
100 30d 3.475e 24.98
SEM 2.29 .272 .813
P-value .0075 .0001 .7610
1 Means followed by a different letter in the same column are significantly different

Conclusion

In conclusion, managing litter is a crucial step in promoting flock health and well being. Conditioning litter between flocks can help keep the environment productive and the operation profitable. Controlling litter moisture and utilizing litter amendments at the proper rates can maintain litter quality maintained for extended periods of time.

November 2008