Egg producer perception of floor egg problems: contributing factors

I. INTRODUCTION

During recent years, Australian supermarkets have changed from a predominant supply of eggs sourced from hens housed in conventional caged systems to an increasing number of eggs sourced from cage-free housing (Australian Eggs 2022). This move reflects the increasing demand for eggs produced by hens housed in systems other than cages (Edwards and Hemsworth 2021), where they have greater freedom of movement and more opportunity to express natural behaviour including scratching and dust bathing (Lay Jr et al. 2011). With recent updates to the Australian Animal Welfare Standards and Guidelines for Poultry, including a proposed phasing out of conventional layer hen cages (Department of Agriculture, Fisheries & Forestry 2022), and limited local adoption of furnished cages (Edwards and Hemsworth 2021), cage-free egg production is likely to increase. Within cage-free systems, hens may not lay their eggs in the designated nest boxes but in areas outside the nest box (Bécot et al. 2023), referred to as floor eggs, ground eggs, floor laying or mislaid eggs.

Compared to nest laid eggs, floor eggs have a greater risk of contamination due to their contact with faecal matter, moisture, dirt and dust, greater risk of cracks or fractures of the eggshell and requires staff to frequently walk the sheds to collect floor eggs and to move the birds around (O’Flaherty 2019). Floor eggs cannot be sold as first grade eggs, but as second grade eggs destined to produce pasteurised products, generating significantly reduced revenue (Australian Eggs 2023). As an initial investigation into the variables that may contribute to the incidence of floor eggs, some questions about them were included in surveys of producers of cage-free systems within an Australian Eggs funded project “Epidemiological risk factors for Spotty Liver Disease”. While the larger survey was not specifically designed to evaluate floor eggs, it gathered information about each farm, flock and housing environment. This information was aligned with the producer’s concern about their level of floor eggs and provided some initial indicators of factors that may be involved with floor eggs.

II. MATERIALS AND METHODS

A cross-sectional survey of cage-free egg laying systems within Australia was conducted during 2020-2022. Sixty-nine flocks housed in either barn or free-range systems from all Australian states except Tasmania were enrolled in the study. Initial survey interviews were conducted on farm (n = 43), but, with travel restrictions due to Covid-19, later interviews were undertaken by telephone (n = 26). Survey questions included whether the producer was concerned with the flock’s level of floor eggs and the percent floor eggs. Categorial variables including the Australian state in which the farm was located, strain of laying hen, farming system and indoor shed structure during lay, whether perches and platforms were present during lay, lighting colour in the shed, and the incidence of feather pecking during lay. Information was collected about continuous variables, including flock age at transfer to the laying shed, number of birds transferred, total shed floor area, total stocking density, total nest space, nest density, age at first access to nest boxes and, for free range systems the age, when hens were first given access to the range. The responses to each question were entered into REDCap® and then downloaded into Excel, cleaned, and prepared for analysis. Categorical variables were analysed using contingency tables and Pearson χ2 or, when an expected value was < 5, Fisher’s exact two tailed test was used. Continuous variables were analysed using a Student’s T-test with the dependent variable being whether the producer was concerned about the level of floor eggs.

III. RESULTS AND DISCUSSION

Of the 69 flocks included in the survey, the producers of 17 flocks (25%) had concerns about the level of floor eggs. For these flocks, floor egg production ranged from 2-28% with an average 7% and median 4%. In contrast, 52 flocks (75%) had floor egg levels between 1-3%, which the producer did not perceive to be a concern. Across these flocks, 1% floor eggs was both the average and median. In comparison, a recent qualitative enquiry about floor eggs with Australian cage-free egg producers found 4 of 10 producers (40%) were not concerned with floor eggs and the remaining 60% were concerned, experienced 1-15% floor egg (Campbell 2023).

The statistical assessment of categorical factors in the context of producer concern about the level of floor eggs is presented in Table 1. Most of the flocks were included in the analysis for light colour (n = 63, as 6 flocks housed with mixed lighting were removed from the analysis), layer strain, indoor shed structure and for continuous factors (Table 2), although some were not included due to missing information.

For flocks where the producer perceived a problem with floor eggs, the categorical factors of Australian state in which the flock was located, the type of cage free production system, the style of indoor housing, perch availability, platform availability and strain of bird did not contribute to floor eggs (P > 0.05; table 1). However, the use of cool white lighting within the shed increased the perceived problem of floor eggs (P = 0.017) relative to farmer perception with flocks with warm white lighting. The role of lighting of nest boxes and light intensity has been explored with floor egg production (Abbleby et al. 1984; Pillan et al. 2023) but lighting colour has not considered. In flocks where feather pecking had occurred, the producer perceived the level of floor eggs to be concerning (P = 0.008). In comparison, Gunnarsson et al. (1999) found no correlation between floor eggs and feather pecking.

Table 1 - Univariate analysis of categorical variables during lay with producer concerns of floor eggs.

Table 2 - Student T-test analysis of continuous variables during lay with producer concerns of floor eggs.

None of the continuous variables significantly contributed to the producer’s perspective of a concerning level of floor eggs (Table 2). There are very few reports on floor eggs that have addressed these types of continuous variables apart from nest density. In this regard, Williams (2021) recommends 100-120 hens/m2 nest box. This range includes the nest densities for flocks where floor eggs were both a concern and not a concern for producers in this study.

It should be reiterated that this survey was not specifically designed to explore variables that may be involved in the production of floor eggs but was an opportunistic early investigation into potential risk factors, many of which have not been previously explored for floor eggs. This provides evidence and rationale for more targeted exploration of factors that may predispose flocks to the laying of floor eggs in Australian cage-free systems.

ACKNOWLEDGMENT: Thank you to Australian Eggs for funding the Spotty liver disease epidemiological study, Yuanshuo K. Gao & Mini Singh for undertaking the surveys, and the egg producers for their involvement.

Presented at the 35th Annual Australian Poultry Science Symposium 2024. For information on the latest and future editions, click here.