Wendy Muir

I. INTRODUCTIONSpotty Liver Disease (SLD) is a major problem in free-range layer farming (Courtice et al., 2018). The causative agent of SLD has been identified as Campylobacter hepaticus (Van et al., 2017). The epidemiology of SLD in cage-free layers is poorly understood. Three analytical epidemiological studies have been conducted in this series. The studies surveyed cage-free layer houses acros ...

I. INTRODUCTIONThe mineralisation of calciferous eggshells is an extremely physiologically demanding process, having immense calcium requirements. As a result, laying hens have highly efficient, closely managed calcium homeostatic mechanisms involving a complex series of feedback loops primarily regulated by parathyroid hormone, calcitonin, and calcitriol (de Matos, 2008; Sinclair-Black et al., 20 ...

I. INTRODUCTIONThe physiological patterns of hen FI and BW trajectory are established by early lay (Muir et al. 2023a). Careful management of lighting and feeding patterns during rearing can regulate bird size and feeding habits by the end of rearing (Muir et al. 2023b). Whether this influences persistency of lay, efficiency of production and egg quality during an extended laying period is un ...

While the breeding programs of commercial meat chickens select birds with robust legs (Davis, 2015), poor leg strength and reduced locomotion are frequently observed in late stages of growth. We have previously reported that lower egg shell temperatures during early incubation, which delays chick hatch time, increases bone ash (BA) (Muir and Groves, 2017). Observations from our research and the li ...

I. INTRODUCTIONProduction improvements in commercial meat chickens via genetic selection and improved husbandry have resulted in rapid growing birds. These birds have endemically reduced locomotor ability; a conservative estimate is that 30% of birds in a flock are likely to have poor mobility (Knowles et al, 2008). Leg weakness has a direct impact on production due to lower bird quality, which ma ...

I. INTRODUCTIONA hen’s physiological patterns including FI and BW trajectory are established by early lay (Muir et al. 2022). Therefore, management tools such as lighting and feeding programs during rearing may offer opportunities to regulate bird size and establish feeding habits by the end of rearing. This may also influence persistency of lay, egg quality and hen health during an extended ...

I. INTRODUCTIONWith ongoing genetic selection for improved persistency of lay and feed efficiency (FE) in laying hens, the egg industry is pursuing the opportunity to extend layer hen lifespan until they are 100 weeks of age (WOA), with an aim for each hen to produce up to 500 eggs. This presents some challenges for the hen as during this longer laying cycle she will be producing more than 31 kg o ...

I. IntroductionPullet body weight (BW) has significant impact on hen sexual maturity, egg productivity and flock uniformity (Lacin et al. 2009). Australian layer flocks are frequently 100-300 grams heavier than breed standard weight (BSW) (Parkinson et al. 2015). These birds typically lay larger eggs than LW hens and higher BW is symptomatic of bird obesity which can result in the production of ex ...