Comparisons of management practices and farm design on Australian commercial layer and meat chicken farms: Cage, barn and free range

<div><p>There are few published studies describing the unique management practices, farm design and housing characteristics of commercial meat chicken and layer farms in Australia. In particular, there has been a large expansion of free range poultry production in Australia in recent years, but limited information about this enterprise exists. This study aimed to describe features of Australian commercial chicken farms, with particular interest in free range farms, by conducting on-farm interviews of 25 free range layer farms, nine cage layer farms, nine barn layer farms, six free range meat chicken farms and 15 barn meat chicken farms in the Sydney basin bioregion and South East Queensland. Comparisons between the different enterprises (cage, barn and free range) were explored, including stocking densities, depopulation procedures, environmental control methods and sources of information for farmers. Additional information collected for free range farms include range size, range characteristics and range access. The median number of chickens per shed was greatest in free range meat chicken farms (31,058), followed by barn meat chicken (20,817), free range layer (10,713), barn layer (9,300) and cage layer farms (9,000). Sheds had cooling pads and tunnel ventilation in just over half of both barn and free range meat chicken farms (53%, n = 8) and was least common in free range layer farms (16%, n = 4). Range access in free range meat chicken farms was from sunrise to dark in the majority (93%, n = 14) of free range meat chicken farms. Over half of free range layer farms (56%, n = 14) granted range access at a set time each morning; most commonly between 9:00 to 10.00am (86%, n = 12), and chickens were placed back inside sheds when it was dusk.</p></div

Overall perceived importance of biosecurity practices per farm type (most biosecurity practices rated as ‘very important’ including those not depicted).

<p>Overall perceived importance of biosecurity practices per farm type (most biosecurity practices rated as ‘very important’ including those not depicted).</p

The five most common unusual signs^a perceived by farmers as most significant and the number and percentage of chickens in a shed affected by unusual signs that would prompt the farmer to contact someone on commercial layer and meat chicken farms in the Sydney basin and South East Queensland during 2015–2016.

<p>The five most common unusual signs<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0195582#t003fn001" target="_blank">^a</a> perceived by farmers as most significant and the number and percentage of chickens in a shed affected by unusual signs that would prompt the farmer to contact someone on commercial layer and meat chicken farms in the Sydney basin and South East Queensland during 2015–2016.</p

Assessing the probability of introduction and spread of avian influenza (AI) virus in commercial Australian poultry operations using an expert opinion elicitation

<div><p>The objective of this study was to elicit experts’ opinions and gather estimates on the perceived probability of introduction and spread of avian influenza (AI) virus in the Australian broiler and layer industry. Using a modified Delphi method and a 4-step elicitation process, 11 experts were asked to give initial individual estimates for the various pathways and practices in the presented scenarios using a questionnaire. Following this, a workshop was conducted to present group averages of estimates and discussion was facilitated to obtain final individual estimates. For each question, estimates for all experts were combined using a discrete distribution, with weights allocated representing the level of expertise. Indirect contact with wild birds either via a contaminated water source or fomites was considered the most likely pathway of introduction of low pathogenic avian influenza (LPAI) on poultry farms. Presence of a water body near the poultry farm was considered a potential pathway for introduction only when the operation type was free range and the water body was within 500m distance from the shed. The probability that LPAI will mutate to highly pathogenic avian influenza (HPAI) was considered to be higher in layer farms. Shared personnel, equipment and aerosol dispersion were the most likely pathways of shed to shed spread of the virus. For LPAI and HPAI spread from farm to farm, shared pick-up trucks for broiler and shared egg trays and egg pallets for layer farms were considered the most likely pathways. Findings from this study provide an insight on most influential practices on the introduction and spread of AI virus among commercial poultry farms in Australia, as elicited from opinions of experts. These findings will be used to support parameterization of a modelling study assessing the risk of AI introduction and spread among commercial poultry farms in Australia.</p></div

Combined probability estimates for spread of LPAI infection to at least one other shed on the property via different pathways.

<p>The plot shows the median, the lower and upper quartiles (25% and 75%) (enclosed by shaded boxes) and the lower (5%) and upper (95%) values as whiskers in each production type (broiler barn (BB), broiler free-range (BFR), layer cage (LC), layer barn (LB) and layer free-range (LFR)) for each of the pathways.</p

The median and range for the numbers of chicken and shed attributes for barn and free range meat chicken farms, and for cage, barn and free range layer farms in the Sydney basin bioregion and South East Queensland, Australia, June 2015 until February 2016.

<p>The median and range for the numbers of chicken and shed attributes for barn and free range meat chicken farms, and for cage, barn and free range layer farms in the Sydney basin bioregion and South East Queensland, Australia, June 2015 until February 2016.</p

Biosecurity information related to farm layout, water sources, shed/vehicle/equipment sanitation and personnel practices on commercial layer and meat chicken farms in the Sydney basin and South East Queensland during 2015–2016.

<p>Biosecurity information related to farm layout, water sources, shed/vehicle/equipment sanitation and personnel practices on commercial layer and meat chicken farms in the Sydney basin and South East Queensland during 2015–2016.</p

The median and range number of stocking density on the range area and range-related attributes for free range meat chicken and layer farms in the Sydney basin bioregion and South East Queensland, Australia, June 2015 until February 2016.

<p>The median and range number of stocking density on the range area and range-related attributes for free range meat chicken and layer farms in the Sydney basin bioregion and South East Queensland, Australia, June 2015 until February 2016.</p

Combined probability estimates (Median (5% and 95% estimate interval)) for spread of LPAI and HPAI infection from one farm to another.

<p>Combined probability estimates (Median (5% and 95% estimate interval)) for spread of LPAI and HPAI infection from one farm to another.</p

Combined probability estimates for probability of LPAI mutating to HPAI in a shed.

<p>The plot shows the median, the lower and upper quartiles (25% and 75%) (enclosed by shaded boxes) and the lower (5%) and upper (95%) values as whiskers in each production type (broiler barn (BB), broiler free-range (BFR), layer cage (LC), layer barn (LB) and layer free-range (LFR)).</p