UK egg production has a value of £1bn, but is afflicted with urgent economic and welfare problems, limiting the sustainability of this growing market. Injurious pecking is a severe welfare and economic problem, affecting 65–86% of free-range flocks[1,2]. On top of this, the prevalence of keelbone fractures in free-range hens is 60-90%[3,4]. Efforts to understand these problems have focussed on the birds themselves, with limited success. However, parental effects are recognised as a major influence in determining life trajectory in birds. Birds pass information to offspring via hormone transfer to the egg and/or epigenetic pathways. This “predictive adaptive response” prepares offspring to cope with environmental conditions, but becomes maladaptive when offspring conditions differ to that of their parents, as is the case with commercial chickens.
Our recent pilot data showed that hens with healed keelbone fractures produced eggs with less eggshell membrane than those from intact hens. This semipermeable structure allows exchange of gases and water and acts as a physical and chemical barrier to bacteria8. We predict that a reduction in eggshell membrane will have detrimental effects on hatch rates and mortality.
This PhD project will confirm and extend these findings to examine parental effects on offspring sustainability.
Aims and objectives
To determine the influence of parental keel bone damage (KDB) and injurious pecking (IP) on offspring sustainability.
1) Does parental KBD influence egg quality? Hypothesis: KBD hens produce eggs with KBD have mortality.
3) Do parental (i)KBD and (ii)IP influence chick welfare and production during a) rearing and b) laying periods? Hypothesis: Chicks from breeder farms with >KBD and >FP have >mortality, slower to reach point of lay, lay fewer eggs and of lower quality.
For objective 1, KBD and control hens will be obtained from a commercial farm and housed in UoB’s CIEL poultry unit according to their fracture status. Eggs produced by both groups will be compared using measures of egg quality (weight, strength, calcification, eggshell membrane). Objective 1 requires further funding (~£6K). There is also scope to breed from the birds to examine effects of KBD on chick outcome measures (+4K) but is not essential to the project.
Objectives 2-4 will involve initially visiting breeder farms to obtain measures on breed, production (Weight, feed and water consumption, feed conversion ratio, plumage score, egg quality, quantity and age at point of lay, mortality) and welfare measures (Keel fracture status, Feather score, Fear and stress reactivity, injurious pecking and aggression). Objective 2 will then utilise commercial hatchery data on hatch rates, weights and mortality.
Objectives 3 and 4 will involve collection of data from commercial egg systems (rearing (1 day – 16 weeks) and laying (16 - ~70weeks) farms)
The student will be trained in KBD palpation, behavioural observation and statistical techniques, including multilevel modelling, to examine associations between variables during the breeding, and subsequent rearing and laying periods.
How to apply for this project
This project will be based in Bristol Veterinary School in the Faculty of Health Sciences at the University of Bristol.
Please visit the Faculty of Health Sciences website for details of how to apply