Effects of litter substrate and genotype on layers' use of litter, exterior appearance, and heterophil:lymphocyte ratios in furnished cages

Flock-level risk factors of litter condition for the occurrence of plumage damage and skin lesions in commercial laying hen farms

Plumage damage (PD) as a result of severe feather pecking (SFP) and skin lesions (SL) due to cannibalism (CA) is serious welfare, performance, and economic problems in commercial layer farms. Genetics, nutrition, and housing conditions are central complexes that contribute to the multifactorial causes of these behavioral disorders. Practical recommendations consider the quality of litter as an important criterion for the prevention of SFP, although systematic longitudinal studies providing evidence-based findings are lacking. Therefore, the aim of this study was to investigate the effects of litter condition on the occurrence of PD and SL in the field using a longitudinal design. Integument scoring (PD and SL; 7 times), litter scoring (structure, cake formation, litter quality, and litter height; 12 times), and laboratory litter analysis (dry matter (DM), nitrogen (N), phosphorus (P) and pH value; 12 times) were performed in 28 laying hen flocks with a median flock size of 12,357 birds, in barn (n = 21) or free-range systems (n = 7), during the first laying period. Binary logistic regression (BLR) models showed the association of housing type and animal age on PD and SL (P < 0.001), and of the hybrid type on PD (P < 0.001). Furthermore, a significant association with PD and SL was observed for several litter traits. An increase in litter height, DM, and P was associated with lower PD (P ≤ 0.022) and SL (P < 0.001). In contrast, a higher N content of the litter was associated with an increase in SL (P = 0.007). Cake formation (P < 0.001) and a low structure (P = 0.025) of the litter showed an association with higher PD. In conclusion, this study identified caked litter with less structure, low height, and low contents of DM and P as risk factors for behavioral disorders in commercial laying flocks.

Edible Environmental Enrichments in Littered Housing Systems: Do Their Effects on Integument Condition Differ Between Commercial Laying Hen Strains?

The aim of this study was to investigate the effect of additional enrichment materials (EMs; pecking stones and alfalfa bales) on the occurrence of plumage damage, skin injuries, and toe injuries, with an emphasis on the possible differences between commercial hybrid strains of laying hens. During rearing (weeks 1-18, 16 compartments, 4000 pullets) and laying periods (weeks 21-72, 24 compartments, 2808 hens) in a littered housing system, EMs were permanently provided to the study groups (EXP), while control groups (CON) did not receive additional EM. In a two-factorial study design (two groups with four strains) with 351 hens per variant, the brown egg-laying Lohmann Brown classic (LB) and Bovans Brown (BB) strains as well as the white egg-laying Lohmann Selected Leghorn classic (LSL) and Dekalb White (DW) strains were investigated. Compared to the CON, the EXP showed reduced body mass during rearing (p < 0.001) and reduced albumen consistency in the laying period (p < 0.001). Regarding integument condition, the LSL in the EXP showed more toe injuries than in the CON (p = 0.018). Remarkably, genotype-environment interactions between strains and groups were evident (p < 0.001). In groups with an EM supply, plumage damage decreased in LB (p ≤ 0.033) and LSL (p ≤ 0.005) but increased in BB (p ≤ 0.003). Moreover, there were fewer skin injuries in LSL (p = 0.001) but more in BB (p = 0.001) in groups with access to EM. In view of the diverging effects between strains, future practical recommendations for laying hen husbandry should be strain-specific.

Effects of different litter substrates and induced molt on production performance and welfare quality parameters of white Leghorn hens housed in multi-tiered aviary system

More than 90% of the commercial egg production in the United States is pledged to be in cage-free systems by 2025. Management practices like induced molting and litter area management have come under scrutiny because of the housing system change. The aim of this study was to determine the welfare and production implications of different litter substrates and also evaluate induced molting of hens in a cage-free system. Bovan White hens were housed in a multi-tier aviary system with daily access to open litter area of either Astroturf (AT), wood shavings (SH), or straw (ST) and bare concrete floor (CO) serving as control. At 68 wk of age, molt was induced in half of the hens whereas the other half continued without molting to 116 wk. Production and welfare parameters were measured periodically throughout first and second cycles. Litter substrate did not influence hen-day production and case-weight measurements. However, CO had the lowest total number of eggs produced during the first cycle (P < 0.05). Hen-day percentage was approximately 14% greater in molted hens during the second cycle with egg case weight being heavier in non-molt hens toward the end of second cycle (P < 0.05). The only welfare parameter influenced by litter substrate during the first cycle was a greater crop feather loss in AT than ST at mid-lay (P < 0.05). Keel deformations increased with age irrespective of the litter substrate with 91.5% of palpated hens having keel deformations at the end of first cycle (P < 0.05). Molting did not influence the keel palpation and footpad scores whereas frequency of moderate comb wound was greater in molt hens during molt (P < 0.05). Severe feather loss was seen in non-molt hens during the second cycle (P < 0.05). Litter substrate does not affect production and physical parameters of welfare of hens in a multi-tier aviary system. Additionally, induced molting can be successfully carried out in the multi-tier cage-free system.

The effects of environmental enrichment and transport stress on the weights of lymphoid organs, cell-mediated immune response, heterophil functions and antibody production in laying hens

The effects of environmental enrichment and transport stress on the immune system were investigated in laying hens. A total of 48 1-day-old chickens were used, half of the chickens were reared in conventional cages (RCC) and the rest in enriched cages (REC). Transport stress was applied in the 17th week. Liver weight decreased, spleen and bursa of Fabricius weights, white blood cell count, CD4+ and CD8+ cell proportions increased due to the transport. Environmental enrichment significantly increased antibody production and tended to increase monocyte percentage and CD8+ cell proportion. The effect of transport on, heterophil (H) and lymphocyte (L) percentages was not significant in RCC chickens. While heterophil percentage and H:L ratio increased, lymphocyte percentage decreased in REC chickens subjected to transport. Transport stress increased heterophil functions both in REC and RCC chickens, but the increase was higher in REC hens than in RCC hens. In conclusion, although environmental enrichment did not neutralize the effect of transport on lymphoid organs, it activated the non-specific immune system, cellular and the humoral branches of the specific immune system by increasing heterophil functions, CD8+ cells and antibody production, respectively. Therefore, environmental enrichment suggested for improving animal welfare may also be beneficial to improve the immune system of birds exposed to stress.

Effects of Furnished Cage Type on Behavior and Welfare of Laying Hens

This study was conducted to compare the effects of layout of furniture (a perch, nest, and sandbox) in cages on behavior and welfare of hens. Two hundred and sixteen Hyline Brown laying hens were divided into five groups (treatments) with four replicates per group: small furnished cages (SFC), medium furnished cages type I (MFC-I), medium furnished cages type II (MFC-II), and medium furnished cages type III (MFC-III) and conventional cages (CC). The experiment started at 18 week of age and finished at 52 week of age. Hens’ behaviors were filmed during the following periods: 8:00 to 10:00; 13:00 to 14:00; 16:00 to 17:00 on three separate days and two hens from each cage were measured for welfare parameters at 50 wk of age. The results showed that feeding and laying of all hens showed no effect by cage type (p>0.05), and the hens in the furnished cages had significantly lower standing and higher walking than CC hens (p<0.05). The birds in MFC-III had significant higher preening, scratching and feather-pecking behavior than in the other cages (p<0.05). No difference in nesting behavior was found in the hens between the furnished cages (p>0.05). The hens in MFC-I, −II, and −III showed a significant higher socializing behavior than SFC and CC (p<0.05). The lowest perching was for the hens in SFC and the highest perching found for the hens in MFC-III. Overall, the hens in CC showed poorer welfare conditions than the furnished cages, in which the feather condition score, gait score and tonic immobility duration of the hens in CC was significantly higher than SFC, MFC-I, MFC-II, and MFC-III (p<0.05). In conclusion, the furnished cage design affected both behavior and welfare states of hens. Overall, MFC-III cage design was better than SFC, MFC-I, and MFC-II cage designs.

Air Quality in Alternative Housing Systems May Have an Impact on Laying Hen Welfare. Part I-Dust

The new legislation for laying hens in the European Union put a ban on conventional cages. Production systems must now provide the hens with access to a nest, a perch, and material for dust bathing. These requirements will improve the behavioral aspects of animal welfare. However, when hens are kept with access to litter, it is a concern that polluted air may become an increased threat to health and therefore also a welfare problem. This article reviews the literature regarding the health and welfare effects birds experience when exposed to barn dust. Dust is composed of inorganic and organic compounds, from the birds themselves as well as from feed, litter, and building materials. Dust may be a vector for microorganisms and toxins. In general, studies indicate that housing systems where laying hens have access to litter as aviaries and floor systems consistently have higher concentrations of suspended dust than caged hens with little (furnished cages) or no access to litter (conventional cages). The higher dust levels in aviaries and floor housing are also caused by increased bird activity in the non-cage systems. There are gaps in both the basic and applied knowledge of how birds react to dust and aerosol contaminants, i.e., what levels they find aversive and/or impair health. Nevertheless, high dust levels may compromise the health and welfare of both birds and their caretakers and the poor air quality often found in new poultry housing systems needs to be addressed. It is necessary to develop prophylactic measures and to refine the production systems in order to achieve the full welfare benefits of the cage ban.

Effect of substrate provision on performance and behaviour of laying hens in the pecking and scratching area of furnished cages

1. An experiment was set up to study the effects of substrate provision on performance and behaviour in the pecking and scratching area (PSA) of non-beak-trimmed hens housed in large furnished cages (60 hens/cage). 2. Three layer hybrids (two brown and one white, ISA-Hendrix Genetics, France) and two substrate conditions (with or without wheat bran automatically distributed on the PSA) were compared in a 3 × 2 experimental design with 12 cages per treatment. 3. Substrate distribution improved laying rate with no impact on the frequency of dirty or cracked eggs. 4. Substrate distribution improved the viability and body integrity of hens, which were not beak-trimmed. 5. Distribution of substrate tended to increase the number of hens in the PSA and enhanced their pecking and scratching behaviours but had a negative impact on the number of dust bath bouts per cage and encouraged dust bathing on the wire floor close to the feeder. 6. The white hens laid more eggs in the nest than the brown birds and used the PSA more for pecking, scratching and dust bathing at the end of the day than the brown hens, underlining the necessity to adapt cage furnishing and rearing management to specific behaviours of each layer genotype.

Food, wood, or plastic as substrates for dustbathing and foraging in laying hens: A preference test

The provision for dustbathing material will be a legal requirement in cage-housing systems for laying hens within the European Union beginning in 2012. At present, food particles are widely used and typically offered in small amounts on Astroturf mats one or more times per day to facilitate dustbathing, pecking, and scratching. In the present study, we compared layers' preference for food and 3 other (nonnutritive) substrates for foraging and dustbathing. In each of 2 identical trials, 72 hens of 2 genotypes (Lohmann Selected Leghorn and Lohmann Brown) were kept in 12 compartments (6 hens each). Compartments were equipped with a plastic grid floor and additionally contained 4 different dustbathing trays (each 1,000 cm(2)/hen) holding either wood shavings (WS), lignocellulose (LN, soft wood fiber, pelleted), Astroturf mat without substrate (AT), or food particles (FP). Hens were housed from 18 wk of age and video recordings were done at wk 21, 24, and 27. Time spent and frequency of dustbathing, duration of a single dustbath (DB), frequency of foraging behavior, and relative frequency and duration of behavioral patterns within a single DB were recorded during the light period over 2 d in each observation week. The FP treatment was preferred for foraging over WS, LN, and AT. Time spent dustbathing and number of DB were higher in LN compared with WS, FP, and AT, whereas average duration of a single DB was longer in FP compared with LN and WS. More vertical wing shakes and scratching bouts within a single DB were observed in LN compared with AT. Bill raking occurred more frequently in WS and LN in comparison to FP and AT. No differences in the relative durations of behavioral patterns within a single DB were found. In conclusion, FP were preferred for foraging but not for dustbathing, indicating that FP may not be an optimal dustbathing substrate for laying hens.