Effects of housing conditions during the rearing and laying period on adrenal reactivity, immune response and heterophil to lymphocyte (H/L) ratios in laying hens (original) (raw)
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Physiological Responses of Laying Hens to the Alternative Housing Systems
International Journal of Poultry Science, 2003
Measurements of differential leucocyte count, H/L (Heterophil to Lymphocyte) ratio and Ab (Antibody) titres to commercial used vaccines, ND (Newcastle Disease) and IB (Infectious Bronchitis) were employed to investigate whether the exposure of laying hens to different housing systems was associated with haematological-immunological changes. Layers were kept in three different housing systems: conventional battery cages, modified cages and an intensive free-range housing system. Differential leucocyte count and H/L ratio were used as indicators of stress response and sensitive biomarkers crucial to immune function, whereas the Ab levels to IB and ND vaccines were measured to assess humoralmediated immunity. This study indicated that in hens exposed to the three various housing conditions H/L ratio was found to be significantly different, 0.58, 0.43 and 0.38, respectively. The results show that in hens kept in battery cages heterophils were raised, while lymphocytes decreased. Although, differences in H/L ratio suggest that hens of different housing systems should have a reduced antibody response and several investigators have recommended that environmental stressors decrease Ab production this was not demonstrated in this survey. Ab titre presented as log was unaffected by any housing system. A slight 10 negative correlation between H/L ratios and antibody levels was also observed. The results would suggest that housing conditions and social stress might have a great effect on the stress response (H/L ratio) while humoral response seems unaltered.
The humoral immune response and the productivity of laying hens kept on the ground or in cages
Alternatives to laboratory animals : ATLA
The effects of two different keeping systems on the humoral immune response and productivity were compared for 80 laying hens, divided into four groups. Two groups each of 20 hens were kept on the ground and two were kept in cages. All the birds were immunised subcutaneously with human serum immunoglobulin G (IgG) at a dose of 100(microg per injection. The immunisations were performed twice at 4-week intervals. The lipopeptide Pam(3)Cys-Ser-(Lys)(4) was used as an adjuvant at a dose of 0.25mg per injection in one group from each housing system. In the second group from each housing system, the hens were immunised without any adjuvant (antigen control groups). The mean egg yield was significantly higher in both the antigen control group and the adjuvant group, when laying hens were kept in cages. Total egg weight remained constant in both of the housing systems. Keeping hens in cages resulted in higher mean specific antibody titres and mean immunoglobulin Y concentrations in the egg ...
Poultry Science, 2009
Measurements of the heterophil:lymphocyte (H/L) ratio (invasive technique) and corticosterone in yolk and 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 en-vironment and strain for the H/L ratio showed that in both environments, LB and CR hens had a higher H/L ratio than LW and HN layers. In 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 than LB hens. In cages but not floor pens, yolk corticosterone concentrations at wk 22 were significantly higher than at wk 45. In floor pens but not cages, albumen corticosterone 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 corticosterone 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.
Animals
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 ...
Stress (Amsterdam, Netherlands), 2015
This study evaluated whether phenotypic appearance (PA) alteration during two developmental phases in laying hens, reared in two different group sizes, affects stress and immune responses. After hatching, 750 chicks were randomly assigned to 30 pens at a group size of either 10 or 40 birds. Then, the appearance of 0, 30, 50, 70 or 100% of the chicks in each pen was altered by blackdyeing their head feathers (marked); remaining chicks were unmarked. At 32 weeks, basal and postacute stress plasma corticosterone concentration, leukocyte counts, phytohemagglutinin-p lymphoproliferative and primary antibody responses were measured in six birds/pen. Analysis of variances (ANOVAs) showed no differences among treatment combinations. In a second phase, birds within initially homogeneous pens were sequentially either marked or had dye bleached to alter PA of 70% of hens in each flock (= group in a pen). Hens within initially heterogeneous pens remained unaltered as controls. The above variabl...
Laying hen behavior 2. Cage type preference and heterophil to lymphocyte ratios
Poultry Science, 2000
Studies were conducted to determine hen preference for and stress response to cage type. By using a plywood (1.25 cm) test apparatus with open-and solidsided compartments and a plexiglass divider at the entrance for controlling passage, birds (n = 20) were evaluated as to their choice of compartment after training and acclimation. For each test, after training, an individual bird was placed in the start box and given 1 min to acclimate before making a choice. The experiment was repeated after rotating the apparatus 180°. In Experiment 1, the open-sided compartment was chosen by 45% of the hens, and the solid-sided compartment by 25% (P = 0.02); 30% chose neither. In Experiment 2, the compartment with open sides was chosen by 70% of the hens, and that with solid sides was chosen by 15% (P = 0.004); 15% (
Poultry Science, 2016
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.
Stress, 2011
Procedures in the commercial production of animals involve stressful situations which lessen the animal's welfare. This study on Japanese quail evaluated whether an environmental enrichment manipulation can affect avian immune responses and if combined with a chronic stressor exposure can help to counteract the negative effects of stress on the immune system. Potential gender effects were also considered. After hatch, half of the birds were housed in non-enriched boxes and half were housed in environmentally enriched boxes. From day 33 to 42 of age, all birds within half of the non-enriched and enriched boxes remained undisturbed while the other half were daily exposed to a 15 min restraint stressor (chronic stressor). The inflammatory response (lymphoproliferation after phytohemagglutinin-p), percentage of lymphocytes, heterophil/lymphocyte (H/L) ratio and primary antibody response against sheep red blood cells were assessed. The chronic stressor application and the enrichment procedure, respectively, either increased or reduced the four immunological parameters evaluated and always in opposite directions. Males consistently showed lower antibody titres than females and presented the highest H/L ratio in response to the stressor when reared in the non-enriched environment. The findings indicate that submitting these animals to an enriched environment can be effectively used to improve their immune response and to reduce the detrimental effects of a stressor exposure.