Research/Optimising methods for multiple batch litter use by broilers
From Poultry Hub
Title: Optimising methods for multiple batch litter use by broilers
Project Leader: Walkden-Brown at UNE funded by Poultry CRC (Project 06-15)
Duration of Project: 1 July 2007 to 31 December 2009
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Project overview
The Australian broiler industry has a well-recognised problem with both the supply of bedding material in some regions, and with the disposal of spent litter. An estimated 81% of chickens are reared on fresh litter materials following complete shed cleanout between batches. Some other countries such as the USA make more extensive use of multiple batch litter and employ a wider range of treatments of litter between batches (antimicrobials, acidifiers, drying agents). The preference for single use litter in Australia is driven primarily by concerns about chicken pathogen carryover leading to reductions in chicken health and performance, and excess ammonia production on reused litter. Nevertheless at least one company has a high level of litter reuse and reports good performance on multiple batch litter following partial composting. This project will systematically investigate litter reuse for multiple batches in Australia, risks associated with it, and means of evaluating and ameliorating those risks. The ultimate potential benefit is a higher level of litter reuse without some of the risks associated with it, leading to lower costs of production and a smaller ecological footprint for the industry.
Project objectives
- Determine survival times of key viral poultry pathogens in litter under a variety of litter management practices; and
- Develop methods for litter treatment and management to enable litter to be safely re-used by broilers taking into account the geographical, breed, nutrition and litter type variation that exists within the Australian meat chicken industry.
Project progress
The project is making good progress. Initial experiments at the University of New England showed that a simulated 24 hr transportation of litter in cloth bags in cooled eskies did not influence the infectivity of viral pathogens in litter compared relative to fresh litter. Using infected litter generated at UNE and late batch litter submitted from 3 major poultry companies we were able to develop a bioassay system for litter infectivity using SPF chickens placed on infective litter at day old. Specific pathogen free (SPF) chickens proved superior to commercial broilers which contain maternal antibody, and challenge at day old proved superior to challenge at 7 days of age. The end point was serological evidence of infection at day 35 post challenge. Results showed that chicken anaemia virus, infectious bursal disease virus and fowl adenovirus serotype 8 infections were readily transmitted in litter but infectious bronchitis virus and Newcastle disease virus were poorly transmitted via litter. It is likely that Marek’s disease virus would have been transmitted if it was present but no chickens exposed to commercial litters showed evidence of MDV infection. Differences in infectivity of different litter samples were demonstrable using the method and we are confident that it is a viable bioassay of litter infectivity. A literature review and risk assessment on the re-use of litter by broilers has also been drafted and is undergoing revision. The next phase of the project involves working with our commercial partners to test the effects of various litter management methods on viral pathogen survival in litter, and on other important measures, such as ammonia concentrations.
