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ABSTRACT This study aimed to determine the effect of three distinct cage densities (750 cm2/hen, 535 cm2/hen, and 375 cm2/hen) on the keel bone damage of brown (Hyline Brown, HB) and white (Isa Tinted, IT) laying hens by x-ray method. Moreover, osteocalcin (OC), calcitonin (CT), and parathormone (PTH) hormones were examined by taking blood from a total of 162 laying hens (54 laying hens from each period) at the 35th, 51st and 60th weeks. The research took place from laying hen ages of 20 to 60 weeks. A total of 396 laying hens (198 HB, 198 IT) were used in the research. Scoring was done at the end of the experiment, using the x-ray images of the chest area of the laying hens at the 35th, 51st, and 60th weeks (162 laying hens). A ‘0’ score was attributed to images with deviation and fracture; while those without them were attributed a score of ‘1’. The hormones examined were not affected by cage density. Only PTH hormone differed according to age (p HB) (p

Simple Summary: The objectives of this study were to determine if housing Bovan brown laying hens in conventional cages or enriched floor pens impacted novel physiological and behavioral markers for animal welfare and whether we can use these markers to assess animal welfare. We found that birds that were housed in conventional cages showed increased tonic immobility durations (indication of fearfulness), decreased fecal Immunoglobulin A (indicator of immune function), and increased feather corticosterone concentrations (indicator of chronic stress) compared to hens that were housed in enriched pens. These results indicate that caged birds are more stressed, have reduced immune function, and are more fearful than birds that are housed in pens. In contrast to expectations, we found that caged hens showed a shorter latency to feed during attention bias testing, indicating reduced anxiety compared to birds from pens. Overall, we found that conventional cages generally impacted animal welfare negatively, with the exception of anxiety. In addition, the results suggest that the chosen novel markers for animal welfare show appropriate contrast between long-term housing systems for laying hens. Yet, additional work needs to be done before these measures can be used more broadly. The scientific community needs objective measures to appropriately assess animal welfare. The study objective was to assess the impact of housing system on novel physiological and behavioral measurements of animal welfare for laying hens, including secretory and plasma Immunoglobulin (IgA; immune function), feather corticosterone (chronic stress), and attention bias testing (ABT; anxiety), in addition to the well-validated tonic immobility test (TI; fearfulness). To test this, 184 Bovan brown hens were housed in 28 conventional cages (3 birds/cage) and 4 enriched pens (25 birds/pen). Feces, blood, and feathers were collected 4 times between week 22 and 43 to quantify secretory and plasma IgA and feather corticosterone concentrations. TI tests and ABT were performed once. Hens that were from cages tended to show longer TI, had increased feather corticosterone, and decreased secretory IgA at 22 weeks of age. The caged hens fed quicker, and more hens fed during the ABT compared to the penned hens. Hens that were in conventional cages showed somewhat poorer welfare outcomes than the hens in enriched pens, as indicated by increased chronic stress, decreased immune function at 22 weeks of age but no other ages, somewhat increased fear, but reduced anxiety. Overall, these novel markers show some appropriate contrast between housing treatments and may be useful in an animal welfare assessment context for laying hens. More research is needed to confirm these findings. [ABSTRACT FROM AUTHOR]

With the majority of conventional cage (CC) laying facilities transitioning into cage-free (CF) systems in the near future, it is important to characterize biological markers of health in layers housed in commercial housings for sustainable production. The objectives of this study were to compare i) blood markers, that is heterophil:lymphocyte (H:L) ratios and susceptibility to avian pathogenic Escherichia coli (APEC) and ii) lung and ceca microbiome between hens at different maturity stages in commercial CC and CF farms. Laying hens at 3 maturity stages were randomly sampled (N = 20 per maturity and per farm). Blood was tested for H:L ratios and APEC killing ability using microscopy and in vitro assay, respectively. Microbiomes were assessed using 16S rRNA sequencing and QIIME2 analysis. Data show H:L ratios did not differ between maturities in both farms. Avian pathogenic Escherichia coli killing was only different in CC hens, where χ7122 level was higher (P

Abstract: Furnished cages for laying hens have advantages in allowing normal behaviors and maintaining productivity. As the cost of introduction is a barrier for farms, we developed furnished cages that re‐use conventional cages. To determine the minimum and functional cage design, we compared six designs, combinations of two floor designs (artificial turf or wire cage floor) and three screening designs in the integrated area (no screening, one entrance side or four sides). In total, 144 hens were used, and we measured behavior, physical condition and productivity. Comparing the floors, the percentages of hens performing dust‐bathing and laying eggs in the integrated area were higher in cages with turf than wire floor (P < 0.05 for both). Comparing the screening, dust‐bathing, litter‐exploring and active behavior tended to be more frequent in cages with the integrated area screened on one side than four sides. Feather damage was lower in cages with the integrated area screened on one side than with no screening (P < 0.05). These results suggest that the cage design with an integrated area with artificial turf floor, screened on one side, was effective for furnished cages that re‐use conventional cages. [ABSTRACT FROM AUTHOR]

The effect of three housing systems (conventional cages, enriched cages and litter) on egg quality parameters was evaluated in two experiments with four brown laying strains ISA Brown, Hisex Brown, Bovans Brown and Moravia BSL. During 40 weeks of lay the total number of 7200 eggs was produced and analysed for egg weight, egg component weight and eggshell quality indicators. In 60 eggs, pore density in the small-end, large-end and equatorial areas was determined. Significant interactions between genotype and housing were found out in egg weight (P ≤ 0.001), yolk and albumen weight (P ≤ 0.001) and yolk colour (P ≤ 0.001). Haugh units were the highest in eggs laid in cages and the lowest in the ISA Brown strain. Eggshell quality indicators were affected more by genotype than by housing. The interaction between genotype and housing was not significant for eggshell thickness but it was significant for eggshell weight and strength. Although eggshell thickness was lower in eggs produced in cages, eggshell strength was higher. A significant negative correlation was found out between pore density and housing system. Results of the study suggest that the ability of a strain to produce eggs of high quality in a particular housing system should be considered, even within brown strains.

The aim of this study was to investigate effects of conventional-cage (CC), enriched-cage (EC), and free-range (FR) systems and hen age on internal and external egg quality parameters of layers (Lohmann Brown). A total of 720 eggs were analyzed for egg weight (EW), shell weight (SW), yolk weight (YW), albumen weight (AW), shell thickness (ST), shell breaking strength (SBS), shape (SI), albumen (AI), yolk index (YI) of eggs, shell ratio of eggs (SR), albumen ratio of eggs (AR), yolk ratio of eggs (YR), yolk color (YC), and Haugh unit (HU). The highest EW, YW, AW, SW, AI, YI, HU (all P < 0.001), and SI values were found in FR system eggs compared with CC and EC system eggs (P = 0.045). The SBS, ST, YC, SR, YR, and AR were found similar in all housing systems. There was an interaction between the housing system and hen age for EW, SW, YW, AW, SBS, ST, AI, YC, HU, AR (all P < 0.001), SI (P = 0.003), SR (P = 0.001), and YR (P = 0.001) of eggs. It can be concluded that eggs in the FR system were better in overall quality than eggs from CC and EC systems. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare egg production performance and welfare traits of laying hens kept in conventional cage (CC), enriched cage (EC), and free range (FR). Lohmann Brown laying hens (n = 480 with 160 per housing type) were studied across a production cycle from placement at 17 wk until depopulation at 66 wk. The hens were randomly allocated into cages or pens of housing system groups; within each system there were four replicates with 40 hens in each pen or cage. The hen day egg production (P = 0.037), feed intake (FI) (P < 0.001), egg mass (EM) (P < 0.001), and dirty egg ratio of hens were higher in the FR system but similar in the CC and EC systems. The highest mortality ratio was found in EC system hens (P = 0.020). The best feather score was found in FR system hens (P < 0.001). The worse body wound score was found in EC system hens (P = 0.038). On the other hand, the worse bumble foot and footpad lesions were found in FR system hens (P < 0.001). The highest tibia breaking strength was found in FR system hens compared with in CC and EC system hens (P < 0.001). The highest Heterophil/Lymphocyte (H/L) ratio was found in CC system hens (P = 0.006) but the blood phosphorus (P) level was higher in FR system hens (P = 0.013). The tonic immobility, blood glucose, total cholesterol, triglyceride, and Ca values of hens were found to be similar in all systems (P > 0.05). The hens in the FR system had additional space for optimum comfort and better feather and bone traits, but the dirty egg ratio, feed consumption, and foot lesions were higher than in CC and EC systems. [ABSTRACT FROM AUTHOR]

On 1 January 2012, conventional cages for laying hens were banned in the European Union (EU); all egg farmers must now use alternative hen housing systems. In total, 218 Flemish egg farmers were surveyed in 2013 to 2014 regarding which housing systems they currently use, their degree of satisfaction with the system, and how they experienced the transition from conventional cages to an alternative system. The response rate was 58.3% (127 respondents). Of these, 43 (33.9%) were no longer active as an egg farmer, mainly due to the ban on conventional cages. The respondents who were active as egg farmers both before and after the transition (84, 66.1%) mainly judged the ban as negative for their own finances and for the competitive position of the Belgian egg industry, but were neutral or positive regarding the general consequences for their own business. Most respondents' hens were housed in either aviary systems (47.7%) or in alternative cage systems (38.2%). When choosing a new system, the fit into the farm and consumer demand were the most important factors. Consumer demand was the main reason for choosing a system with free-range access. In general, egg farmers were satisfied with the system they chose, although this differs between systems. When asked to compare the alternative systems to conventional cages, alternatives were judged to be better for hen welfare and consumer demand, but similar or worse for all other aspects, especially labor. Egg farmers previously using conventional cages judged alternative systems more negatively than those who had no prior experience with conventional cages. Farmers who had experience with free-range systems judged these more positively than those without this experience, e.g., for egg consumer demand, profitability, and hen welfare. These results can possibly be extrapolated to other EU countries in which conventional cages were the most common housing system until 2012, and lessons can be drawn from the farmers' experiences when implementing other animal welfare legislation that may require similar far-reaching adaptations for primary production. [ABSTRACT FROM AUTHOR]

As of 2012, the EU has banned the use of conventional cages (CC) for laying hens, causing a shift in housing systems. This study's aim was to gain insight into farmers' opinions on hen health and welfare in their current housing systems. A survey was sent to 218 Belgian egg farmers, of which 127 (58.3%) responded, with 84 still active as egg farmer. Hen welfare tended to be less important in choosing the housing system for farmers with cage than with non-cage systems. Respondents currently using cage systems were more satisfied with hen health than respondents with non-cage systems. Reported mortality increased with farm size and was higher in furnished cages than in floor housing. Feather pecking, cannibalism, smothering and mortality were perceived to be higher in current housing systems than in CC, but only by respondents who shifted to non-cage systems from previously having had CC. Health- and production-related parameters were scored to be more important for hen welfare as compared to behavior-related parameters. Those without CC in the past rated factors relating to natural behavior to be more important for welfare than those with CC. This difference in opinion based on farmer backgrounds should be taken into account in future research. [ABSTRACT FROM AUTHOR]

This paper is an integral part of the special publication series that arose from the multidisciplinary and multi-institutional project of the Coalition for Sustainable Egg Supply (CSES). The CSES project involves 3 housing systems for egg production at the same research farm site in the Midwest, USA, namely, a conventional cage (CC) house, an aviary (AV) house, and an enriched colony (EC) house. The CC house (141.4 m L × 26.6 m W × 6.1 m H) had a nominal capacity of 200,000 hens (6 hens in a cage at a stocking density of 516 cm2/hen), and the cages were arranged in 10 rows, 8 tiers per cage row, with a perforated aisle walkway at 4-tier height. The AV house (154.2 m L × 21.3 m W × 3.0 m H) and the EC house (154.2 m L × 13.7 m W × 4.0 m H) each had a nominal capacity of 50,000 hens. The AV house had 6 rows of aviary colonies, and the EC house had 5 rows of 4-tier enriched colonies containing perches, nestbox, and scratch pads (60 hens per colony at a stocking density of 752 cm2/hen). The overarching goal of the CSES project, as stated in the opening article of this series, was to comprehensively evaluate the 3 egg production systems from the standpoints of animal behavior and well-being, environmental impact, egg safety and quality, food affordability, and worker health. So that all the area-specific papers would not have to repeat a detailed description of the production systems and the management practices, this paper is written to provide such a description and to be used as a common reference for the companion papers. [ABSTRACT FROM PUBLISHER]

The US egg industry is exploring alternative housing systems for laying hens. However, limited published research related to cage-free aviary systems and enriched colony cages exists related to production, egg quality, and hen nutrition. The laying hen's nutritional requirements and resulting productivity are well established with the conventional cage system, but diminutive research is available in regards to alternative housing systems. The restrictions exist with limited availability of alternative housing systems in research settings and the considerable expense for increased bird numbers in a replicate due to alternative housing system design. Therefore, the objective of the current study was to evaluate the impact of nutrient and energy intake on production and egg quality parameters from laying hens housed at a commercial facility. Lohmann LSL laying hens were housed in three systems: enriched colony cage, cage-free aviary, and conventional cage at a single commercial facility. Daily production records were collected along with dietary changes during 15 production periods (28-d each). Eggs were analyzed for shell strength, shell thickness, Haugh unit, vitelline membrane properties, and egg solids each period. An analysis of covariance (ANCOVA) coupled with a principal components analysis (PCA) approach was utilized to assess the impact of nutritional changes on production parameters and monitored egg quality factors. The traits of hen-day production and mortality had a response only in the PCA 2 direction. This finds that as house temperature and Met intake increases, there is an inflection point at which hen-day egg production is negatively effected. Dietary changes more directly influenced shell parameters, vitelline membrane parameters, and egg total solids as opposed to laying hen housing system. Therefore, further research needs to be conducted in controlled research settings on laying hen nutrient and energy intake in the alternative housing systems and resulting impact on egg quality measures. [ABSTRACT FROM PUBLISHER]

The majority of human illnesses caused by Salmonella Enteritidis are attributed to contaminated eggs, and the prevalence of this pathogen in commercial laying flocks has been identified as a leading epidemiologic risk factor. Flock housing and management systems can affect opportunities for the introduction, transmission, and persistence of foodborne pathogens in poultry. The animal welfare implications of different types of housing for laying hens have been widely discussed in recent years, but the food safety consequences of these production systems remain incompletely understood. The present study assessed the effects of 2 different housing systems (conventional cages and colony cages enriched with perching and nesting areas) on the horizontal transmission of experimentally introduced Salmonella Enteritidis infection within groups of laying hens. In each of 2 trials, 136 hens were distributed among cages of both housing systems and approximately one-third of the hens in each cage were orally inoculated with doses of 108 cfu of Salmonella Enteritidis (phage type 13a in one trial and phage type 4 in the other). At regular intervals through 23 d postinoculation, cloacal swabs were collected from all hens (inoculated and uninoculated) and cultured for Salmonella Enteritidis. Horizontal contact transmission of infection was observed for both Salmonella Enteritidis strains, reaching peak prevalence values of 27.1% of uninoculated hens in conventional cages and 22.7% in enriched cages. However, no significant differences (P > 0.05) in the overall frequencies of horizontal Salmonella Enteritidis transmission were evident between the 2 types of housing. These results suggest that opportunities for Salmonella Enteritidis infection to spread horizontally throughout laying flocks may be similar in conventional and enriched cage-based production systems. [ABSTRACT FROM AUTHOR]

Fatty liver is a common energy metabolic disorder in caged laying hens. Considering that the egg industry is shifting from conventional cages to alternative housing systems such as enriched cages, the objective of this study was to determine the effects of perches on fat deposition and liver health in laying hens. Three hundred twenty-four 17-wk-old White Leghorn hens were housed in 1 of 4 treatments with 9 hens per cage. Treatment 1 hens never had access to perches during their life cycle. Treatment 2 hens had access to perches during the pullet phase only. Treatment 3 hens had access to perches during the laying phase only. Treatment 4 hens always had access to perches. Liver weight, abdominal fat pad weight, BW, liver fat, and circulating alanine transaminase, aspartate transaminase, and adiponectin were determined. Provision of perches during either the rearing or laying phase did not affect liver health in 71-wk-old hens. However, perch access compared with no perch access during the egg laying phase reduced relative fat pad weight. These results suggest that providing perches as a means of stimulating activity reduced abdominal fat deposition in caged hens during the laying period. However, perch access in caged hens was ineffective in reducing fat deposition in the liver and altering enzyme activities related to improved liver function. [ABSTRACT FROM AUTHOR]

The shell of the egg is essential in providing shape to the egg and ensuring safe packaging of the internal contents; however, shell defects have been shown to increase the risk of microbial contamination of eggs. Eggs were collected from commercial cage and free-range flocks at the ages of 25, 35, 45, 55, 65, and 75 wk. From each collection per flock, 30 eggs were processed for the eggshell and egg internal quality determination, 30 eggs for cuticle estimation, 30 eggs for mammillary layer ultrastructural features scoring, and 60 eggs for egg microbial enumeration. Translucency score and shell reflectivity were significantly higher in free-range eggs and increased with flock age in both production systems. Egg weight, shell weight, percentage shell, shell thickness, albumen height, Haugh unit, and yolk color were higher for cage eggs. The amount of cuticle was higher in cage eggs and fluctuated with flock age in both production systems. For the mammillary layer ultrastructural variables, a significant effect of production system and flock age was observed for early fusion, Type A bodies, and Type B bodies, whereas aragonite, depression, erosion, and hole were rarely observed. Variability of mammillary cap size, the incidence of poor mammillary cap quality, incidence of late fusion, alignment, Type A bodies, Type B bodies, and cubic cone formation were greater in the free-range versus cage system and increased with flock age in both production systems. The incidence of confluence and early fusion were greater in cage eggs and decreased with age in both production systems. Significantly lower total microbial load was observed for cage compared with free-range eggs, but the overall bacterial load recorded in this study was low. It can be concluded that cage eggs were better in overall quality when directly compared with free-range eggs. [ABSTRACT FROM PUBLISHER]

Both epidemiologic analyses and active disease surveillance confirm an ongoing strong association between human salmonellosis and the prevalence of Salmonella enterica subspecies enterica serovar Enteritidis in commercial egg flocks. The majority of human illnesses caused by this pathogen are attributed to the consumption of contaminated eggs. Animal welfare concerns have increasingly influenced commercial poultry production practices in recent years, but the food safety implications of different housing systems for egg-laying hens are not definitively understood. The present study assessed the effects of 2 different housing systems (conventional cages and colony cages enriched with perching and nesting areas) on the frequency of Salmonella Enteritidis contamination inside eggs laid by experimentally infected laying hens. In each of 2 trials, groups of laying hens housed in each cage system were orally inoculated with doses of 1.0 × 108 cfu of Salmonella Enteritidis. All eggs laid between 5 and 25 d postinoculation were collected and cultured to detect internal contamination with Salmonella Enteritidis. For both trials combined, Salmonella Enteritidis was recovered from 3.97% of eggs laid by hens in conventional cages and 3.58% of eggs laid by hens in enriched cages. No significant differences (P > 0.05) in the frequency of egg contamination were observed between the 2 housing systems. [ABSTRACT FROM PUBLISHER]

The paper discusses the relations between some physical indicators of market eggs of laying hens housed in conventional and enriched cage batteries. The measured results were evaluated by the multiple regression dependence method. They show that in the case of both the conventional as well as the enriched cages a statistically significant dependence exists between the eggshell deflection (dependent variable) and thickness, or the force needed for the eggshell destruction (independent variable). The respective P values are given in brackets (0.002 < 0.05; 0.03 < 0.05; 1.16 × 10-10 < 0.05; 8.31 × 10-4 < 0.05); in the case of the conventional cage and enriched cage also a statistically significant dependence existed (3.81 × 10-91 < 0.05; 3.86 × 10-81; 1.27 × 10-97 < 0.05; 3.46 × 10-57 < 0.05) between the shell weight (dependent variable) and shell thickness, or egg weight (independent variable); in the conventional cage, statistical dependence also occurred between the eggshell weight and egg shape index, (1.07 × 10-6 < 0.05), in the enriched cage this was on the verge of statistical significance (0.062 > 0.05); if in the conventional cage the eggshell thickness was increased by 1 mm, the shell deflection decreased by 0.08 mm,and if the force necessary for the eggshell destruction was increased by 1 N, the shell deflection decreased by 0.0003 mm; if in the conventional cage the shell thickness was increased by 1 mm, the shell weight increasee by 15.509 g and if the egg weight was increased by 1 g, the shell weight increased by 0.061 g. Our work brings further knowledge concerning the monitored characteristics and their mutual relations.

More human illnesses caused by Salmonella entérica subspecies entérica serovar Enteritidis throughout the world have been linked to the consumption of contaminated eggs than to any other food vehicle. Deposition of this pathogen in the edible contents of eggs occurs when systemic infections of laying hens involve colonization of reproductive organs. In recent years, the consequences of different housing systems for laying ñocks have become the focus of international attention from both animal welfare and public health perspectives. Nevertheless, many questions remain unresolved regarding the food safety implications of various laying hen production systems. The present study assessed the effects of 2 different housing types (conventional cages and colony cages enriched with perching, nesting, and scratching areas) on the invasion of internal organs by Salmonella Enteritidis in experimentally infected laying hens. In 2 trials, groups of laying hens housed in each cage system were orally inoculated with doses of 1.0 x 107 cfu of Salmonella Enteritidis. At 5 to 6 d postinoculation, hens were euthanized and samples of internal organs were removed for bactériologie cul-turing. For both trials combined, Salmonella Enteritidis was recovered from 95.3% of cecal samples, with no significant differences observed between housing systems. However, Salmonella Enteritidis was detected at significantly (P < 0.05) higher frequencies from hens in conventional cages than from hens in enriched cages for samples of livers (96.9 vs. 75.0%), spleens (93.8 vs. 53.1%), ovaries (25.0 vs. 10.4%), and oviducts (19.8 vs. 2.1%). These results demonstrate that differences in housing systems for egg-laying flocks can affect the susceptibility of hens to colonization of internal organs by Salmonella Enteritidis. [ABSTRACT FROM AUTHOR]

Eggs from alternative production practices are a growing niche in the market. Meeting consumer requests for greater diversity in retail egg options has resulted in some unique challenges such as understanding the food safety implications of eggs from alternative production practices. A study was conducted to determine what, if any, differences exist between nest run conventional cage-produced eggs and free range-produced eggs. A sister flock of brown egg layers was maintained in conventional cage and free-range production with egg and environmental sampling every 6 wk from 20 to 79 wk of age. Aerobic, coliform, and yeast and mold populations were monitored. Environmental microbial levels were not always indicative of egg contamination levels. When significant differences (P < 0.05 and P < 0.0001, dependent on season) were observed among treatments for coliforms, shell contamination levels of free-range nest box eggs and free-range floor eggs were always greater than those of conventional cage eggs, which remained low throughout the study (0.42-0.02 log cfu/mL). Shell yeast and mold levels were significantly greater in free-range floor eggs than in free-range nest box eggs and conventional cage eggs throughout the entire study. Egg contents contamination levels were extremely low for all monitored populations and treatments. Season of the year played a role in both environmental and egg microbial levels. Winter had the lowest levels of all populations monitored for all treatments, except for aerobic free-range floor egg shell emulsions, which were increased (3.6 log cfu/mL). Understanding the differences in microbial populations present on conventional cage-produced and free range-produced eggs can lead to the development of effective cleaning procedures, enhancing food safety. [ABSTRACT FROM AUTHOR]

As a result of welfare considerations, conventional cage systems will be banned in the European Union from 2012 onward. Currently, there is limited information on the level of contamination with zoonotic pathogens related to the laying hen housing system. Therefore, 2 studies were designed to investigate the effect of the housing system on colonization of layers with Salmonella. In both studies, layers were housed in 3 different housing systems: a conventional cage system, a furnished cage, and an aviary. At 18 wk of age, all birds were orally inoculated with Salmonella Enteritidis. Shedding and colonization were measured at regular time points. The results did not show an increased risk for alternative housing systems compared with the conventional battery cage system. In contrast, in one study, a faster decline in shedding was noted for layers housed in the alternative cage systems in comparison with the conventional cage system. This study does not give indications that housing layers in alternative systems will yield a risk for increased Salmonella contamination. [ABSTRACT FROM AUTHOR]

ABSTRACT Measurernents ofthe heterophil:lymphocyte (H/L) ratio (invasive technique) and corticosterone in yolk arid albumen (noninvasive techniques) were used to measure stress in 3 commercial laying strains, Lohmann White (LW), H&N White (HN), Lohmann Brown (LB), and a noncommercial cross (CR) between Rhode Island Red (male) and Barred Plymouth Rock (female), kept in conventional cages or floor pens. All chicks were reared in their respective environments, and 450 and 432 pullets were placed at 18 and 7 wk of age in cages and floor pens, respectively. Blood from 12 hens per strain was taken at 19, 35, and 45 wk of age in each housing system. A total of 100 heterophils and lymphocytes were counted and their ratio (H/L ratio) was calculated. Corticosterone was measured in yolk and albumen from 12 hens per strain in each housing system at 22 and 45 wk of age. The H/L ratio was within the normal range. The interaction between environment and strain for the H/L ratio showed that in both environments. LB and CR hen's had a higher H/L ratio than LW and 1-IN layers. ln cages, there were significant differences in H/L ratios between LW and HN hens that were likely due to genetic differences. The LW hens had significantly lower corticosterone concentrations in yolk thali LB hens. In cages but not floor pens, yolk corticostCrone concentrations at wk 22 were significanUy higher than at wk 45. In floor pens but not cages, albumen corti:costerone at wk 22 was higher than at wk 45. The H/L ratios suggest that none of the hens were unduly stressed, and corticosterone levels in yolk and albumen support the suggestion that hens adapted to their environments with age. Although measurement of yolk corticosteroiie and the H/L ratio may be comparable, the measurement of corticosterone level in the albumen may differ because it is secreted over a short time. [ABSTRACT FROM AUTHOR]

Production performance and egg quality were compared between 4 strains of beak-trimmed layers: 3 commercial strains—Lohmann White (LW), H&N White (HN), Lohmann Brown (LB)—and a non-commercial cross between Rhode Island Red (male) and Barred Plymouth Rock (female) in conventional cages and in floor pens. All chicks were reared and 857 pullets were housed at 18 wk of age in their respective environments. Body weight, hen-day egg production, feed consumption and efficiency, and egg quality were measured at wk 20, 30, 40, and 50. In floor pens, the location of eggs was recorded for 4 consecutive days at 4-wk intervals between 20 and 50 wk of age. Eggs from cages, nest-boxes, and the floor were tested for Escheri- chia coli and coliform contamination at 38 and 42 wk of age. Mortality was recorded during the rearing and laying periods. Housing systems significantly influenced BW and mortality but not feed consumption or feed efficiency. The interaction between environment and strain was significant for hen-day egg production at wk 20 to 30 and for BW at wk 30, 40, and 50. Hens in floor pens had greater BW, egg and yolk weights, and yolk color than those in cages. Commercial hens produced more eggs than the cross hens. Overall, HN hens had the best production performance, whereas cross hens had better egg quality. In floor pens, LW and HN hens laid most of their eggs in nest boxes, whereas LB and cross hens laid half of their eggs on the floor. Eggs from cages had lower E. coli and coliform contamination than those from nest-boxes and the floor, and E. coli contamination was greater for LB eggs than for LW eggs. Significant strain differences were found for the use of nest-boxes, with a high percentage of floor eggs for brown egg strains. This study suggests that genotype x environment interactions should be considered when alternative housing systems are proposed. [ABSTRACT FROM AUTHOR]