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Litter Management

by 5m Editor
20 June 2008, at 12:00am

By Dr Ken Macklin, Assistant Professor and Extension Specialist Department of Poultry Science, Auburn University and presented at the 2008 North Carolina Broiler Supervisors Short Course, North Carolina State University.

The cost of pine shavings for broiler chicken bedding has risen considerably over the past few years. Several factors have contributed to this; the most notable is its usage as a source of energy. There are several alternatives available; however they may have faults that prevent them from being commonly used. Two commonly used alternatives are rice hulls and peanut hulls. Both of these waste products are regional based and in the case of peanut hulls, becoming harder to obtain. So there is a need for a good quality alternative bedding material. Before examining bedding alternatives there must be some guidelines as to what makes up a good quality bedding material. Guidelines for ideal bedding material should include that it is inexpensive, absorbent, non-toxic, manageable and easily obtainable. Over the years many alternatives have been studied, some are suitable alternatives (peanut/rice hulls), while others have some potentially serious drawbacks (hardwood shavings, straw).

Research was conducted at Auburn University (AU) to compare some possible alternatives to pine shavings. This work was performed this past year in which eight different bedding materials were compared over three grow outs. The results were that there was no significant difference between the eight materials concerning bird performance; however some of the material caked quite a bit more than others. Those that were deemed suitable alternatives were sand, door filler, pine bark, and ground hardwood pallets.

Typically, on a commercial broiler farm, litter is used for six or more consecutive grow-outs. Each grow-out generally lasts 6+ weeks; this translates to the same litter being utilized for at least one year. Throughout this time, pathogenic organisms may become established as part of the built-up litter’s microflora. These organisms may present problems for subsequent flocks or to people exposed to the litter or infected birds. As mentioned, the cost of new shavings and its general lack of availability, as well as the cost of full cleanout and restrictions on land application, make finding ways to prolong litters useful lifespan imperative. There are several methods to prolong litters lifespan, some of which are mentioned below.

The first and most commonly used method is using litter amendments. The majority of those commercially sold work by acidifying the litter, which will kill many microorganisms and reduce ammonia emissions. Several university and non-university researchers have talked and written reports about the various types of acidifying litter treatments. So they will not be discussed in any great detail in this paper. Another method that has been looked into by researchers at LSU and at AU is in-house windrow composting.

One of the most common questions commonly asked by people thinking about doing in-house composting is all the bugs (microorganisms) killed, because not all of them are undesirable. Considering that in-house compositing is typically performed for 5 days and it is not turned there are a lot of microorganisms that survive. A better term to describe what is going on is pasteurization of the litter. Why use the term pasteurization instead of composting? Simply put, pasteurization is technically the correct name, since the process kills most of the microorganisms, but not all. This differs from traditional composting, which effectively kills almost all microorganisms; however it is performed for several weeks or even months.

Research studies conducted at Auburn University (AU) have shown that in-house windrowing eliminates almost all of the pathogens that are present in litter. Why does this process selectively kill these pathogens? The answer is fairly simple. Most pathogens that affect chickens (or for that matter people, too) grow most effectively at a certain temperature. In the case of chickens this is in the range of their body temperature, which is 105-107oF. If the temperature goes up just a few degrees the pathogen’s growth will be inhibited, and if it is higher by 20-30 degrees the microorganism will be killed. The target temperature inside these windrow compost piles is 135oF; however, we have seen them as high as 170oF. At these temperatures there are few pathogens that can survive. Even at fairly low internal temperatures of 130oF, there is substantial pathogen reduction. Besides heat, windrow composting kills pathogens in two other ways. The other two methods are ammonia and other microorganisms, these being chiefly bacteria.

As mentioned, research performed at AU has shown that the simple act of windrow composting can effectively reduce pathogens. In some trials performed at AU it has been shown that making a static windrow pile (one that isn’t turned) for five days can significantly reduce overall bacterial numbers even when the internal temperature achieves only 130oF. A surprising finding from this research is that the bacteria Clostridium perfringens was affected. Why was the destruction of this organism so surprising? Simply put, this bacterium is known as a spore former. Typically when a spore former detects that the environment is unfavorable it will form a spore. This is extremely resistant to virtually all disinfectants, extreme temperature changes and desiccation. From these studies it was shown that this particular bacterium is reduced by more than 99.99% compared to litter that was not windrow composted.

In addition to bacteria, in-house windrow composting affects viruses as well. One such virus that has had a significant impact on poultry production is infectious laryngotracheitis virus (ILTV). Work performed at AU as well as in field trials has shown that windrow composting effectively eliminates ILTV in contaminated litter after 5 days. ILTV, like many viruses, is very susceptible to high temperatures. Using built up litter; a typical windrow compost pile will reach an internal temperature of 140oF by 24 hours, which is hot enough to destroy this virus.

Using good litter management to reduce microorganisms as well as sound biosecurity practices should minimize the likelihood of a serious disease outbreak.

May 2008