Peter John Groves

Cage-free egg production is now the predominant system in Australia. However, the occurrence of floor eggs (FE), which are eggs laid outside designated nest boxes, presents a major challenge for these producers. To understand factors that may be associated with the laying of FE, a national scoping survey of cage-free egg-laying flocks was undertaken. Forty-three flocks across multiple farms were surveyed via a phone-based interview using predetermined questions. Floor egg levels ranged from 0.01–17%. There was no difference in floor egg levels between the breeds of brown-egg-laying hens. Age at peak lay did not alter the level of FE, but higher rate of peak lay had a weak association with fewer FE (r = −0.31, p = 0.049). Larger flocks had a lower percentage of FE (r = −0.5, p = 0.002), and farmers of larger sized flocks considered a lower level of floor eggs to be acceptable. Farms with tunnel-ventilated sheds reported fewer FE compared to those using other ventilation systems (p = 0.013). Higher floor egg levels were associated with increased labor costs (p = 0.023). These findings suggest that shed design and environmental management may be leveraged to reduce floor egg occurrence and improve operational efficiency in cage-free systems.

Nontyphoidal serovars of Salmonella enterica subsp enterica frequently colonize the intestinal tracts of chickens, creating risks of contamination of meat and egg food products. These serovars seldom cause disease in chickens over 3 weeks of age. Colonization is generally transient but can continue to circulate in a flock for many months. Vaccination of breeders and layers is the most effective method of control of infections with serovars Enteritidis and Typhimurium and development of these vaccines or other preventative treatments require challenge studies to demonstrate efficacy. However, establishing a successful challenge model where the control birds are colonized to a sufficient extent to be able to demonstrate a statistically significant reduction from the vaccine or treatment is problematic. A meta-analysis of published S. Enteritidis challenge studies was performed to pursue the best challenge model conditions that provides consistent control colonization outcomes. Challenge at sexual maturity was significantly more effective in achieving at least 80% colonization of control hens.

As hen body weight (BW) impacts egg weight (EW) and feed efficiency, egg producers prefer pullets of a specific size to enter the egg-laying cycle. Lighting and feeding programs were tested to achieve target Hy-Line Brown pullet BW. Three feeding programs were implemented: ad libitum (ad lib); feeding to achieve breed standard weight for age (BSW); and feeding to achieve 88% BSW (managed). The feeding programs were used with either control lighting (CL: 10 h light/d from 7 weeks of age (WOA)) or reduced lighting (RL: 9 h light/d from 4 WOA). One-hundred and fifty pullets were assigned to each feeding program by lighting treatment during rearing. At 16 WOA, 70 pullets from each treatment during rearing were moved to cages and onto ad libitum feeding under a step-up photoperiod reaching 16 h light/d at 33 WOA. The age and weight of the first egg, hen BW, feed intake (FI), egg production (EP), and EW were measured until 36 WOA. At 16 WOA, pullets reared with ad lib feeding under CL had higher BW and cumulative FI (CFI) compared to ad lib feeding under RL. The latter were the earliest to lay, and the managed pullets under CL were the last to lay. Control lighting and BSW independently generated the heaviest first eggs. At 36 WOA, BW, EW, CFI, and cumulative egg production (CEP) were highest following ad lib feeding during rearing, while rearing under CL generated higher BW and EW but lower CEP than RL. Hence, lighting and feeding programs throughout rearing can regulate pullet growth, FI, and hen performance throughout early lay.

As hen body weight (BW) impacts egg weight (EW) and feed efficiency, egg producers prefer pullets of a specific size to enter the egg-laying cycle. Lighting and feeding programs were tested to achieve target pullet BW. Three feeding programs: Ad libitum (Ad lib); feeding to achieve breed standard weight for age (BSW); feeding to achieve 88% BSW (managed) were used with either control lighting, (CL: 10h light/d from 7 weeks of age (WOA)) or reduced lighting (RL: 9h light/d from 4 WOA). At 16 WOA pullets moved to cages and ad libitum feeding under a step-up photoperiod reaching 16h at 33 WOA. The age and weight of first egg, BW, feed intake (FI), egg production (EP) and EW were measured until 36 WOA. At 16 WOA, pullets reared with Ad lib feeding under CL had higher BW and cumulative FI (CFI) compared to Ad lib feeding under RL. The latter were the earliest and managed pullets under CL the latest, to lay. Control lighting and BSW independently generated the heaviest first eggs. At 36 WOA, BW, EW, CFI and CEP were highest following Ad lib feeding during rearing while CL generated higher BW and EW but lower CEP than RL. Hence lighting and feeding programs throughout rearing can regulate pullet growth and, hen performance throughout early lay.

Campylobacter hepaticus, the causative agent of Spotty Liver Disease (SLD) is an important disease in cage-free egg producing chickens causing mortality and production drops. C. hepaticus is a slow growing Campylobacter easily overgrown by fecal bacteria. It is currently only reliably isolatable from bile samples. A selective media for isolation from feces or environment would assist diagnosis and impact assessment. Growth of five Australian C. hepaticus isolates was studied using Horse blood agar (HBA), sheep blood agar (SBA), Bolton, Preston and Brain Heart Infusion (BHI) base media. Blood and/or bile were added to Bolton, Preston and BHI medias. C. jejuni was used as a positive control. Plates were incubated in duplicate under microaerophilic conditions at 42°C for 10 days and examined at days 3–5 and 7–10 of incubation. Each isolate was examined for sensitivity to 14 antimicrobials using HBA sensitivity plates. Growth was inhibited by BHI and by added bile, while blood improved growth. Further replicates using SBA, HBA, Bolton and Preston media showed best growth on Bolton agar with blood. All five C. hepaticus isolates were resistant to trimethoprim and vancomycin, while four were also resistant to rifampicin and bacitracin. Media based upon Bolton plus blood supplemented with vancomycin and trimethoprim might be used as the most appropriate media for selective growth of C. hepaticus. The addition of bile to media for C. hepaticus isolation and growth will inhibit growth and is not advised.

This study was to assess the impact of permanent or temporary restricted feeding on laying hen production traits, physiology, and egg quality. Two hundred and forty individually housed ISA Brown hens were monitored across 2 phases, assigned to 3 treatments: ad libitum feeding (ALF), temporary restricted feeding (TRF) and permanent restricted feeding (PRF), n = 80 hens per treatment. In Phase 1 (P1), 22 to 40 weeks, the TRF and PRF hens were offered 115 g of feed daily. In Phase 2 (P2), 41 to 46 weeks, the TRF hens were transitioned to ALF status while the ALF and PRF hens remained as in P1. From 35 to 40 weeks, eggs were collected once weekly from 15 hens per treatment and assessed for differences in albumen, yolk, and shell variables. At 45 weeks, 10 hens each from the ALF and PRF groups were euthanized and differences in organ characteristics were assessed. In P1, feed intake, feed to egg conversion ratio and body weight (BW) change were lower (P < 0.01), while albumen height and Haugh unit were higher (P < 0.01) in both PRF and TRF hen treatments compared to hens allocated the ALF treatment. In P2, TRF and ALF hens had a higher egg production and egg mass than PRF (P < 0.01) than ALF. Body weight change in P2 was higher in TRF and similar in both ALF and PRF, while feed intake and feed conversion ratio were higher in TRF followed by ALF and least in the PRF treatment group (P < 0.01). At 45 weeks ALF hens had a greater abdominal fat pad weight and fatty liver haemorrhagic syndrome lesion score compared to PRF. Restricting hens to 115 g of feed per day from point of lay restrained BW, improved feed conversion ratio and albumen quality and reduced abdominal fat pad deposition and clinical signs of fatty liver haemorrhagic syndrome in individually housed laying hens.