Importance of Basic Research on the Causes of Feather Pecking in Relation to Welfare

Hybro chicks outperform Ross308 in a numerical-ordinal task. Cognitive and behavioral comparisons between 2 broiler strains of newborn domestic chicks (Gallus gallus)

Domestic chickens (Gallus gallus) are among those species subject to intensive selection for production. Among the most widely used broiler strains are the Ross308 and the Hybro. From the perspective of animal production, Ross308 were superior to Hybro in weight gain, final body mass, and feed conversion. Intensive selection is thought to also cause behavioral changes and to negatively affect cognitive abilities. Up to date, though, no evidence has been provided on broiler breeds. The aim of this study was to explore cognitive differences among Hybro and Ross308 chickens by assessing their ordinal-numerical abilities. Chicks learned learnt to find a food reward in the 4th container in a series of 10 identical and sagittally aligned containers. We designed a standard training procedure ensuring that all chicks received the same amount of training. The chicks underwent 2 tests: a sagittal and a fronto-parallel one. In the former test, the series was identical to that experienced during training. In the fronto-parallel test, the series was rotated by 90°, thus left-to-right oriented, to assess the capability of transferring the learnt rule with a novel spatial orientation. In the sagittal test, both chicken hybrids selected the 4th item above chance; interestingly the Hybro outperformed the Ross308 chicks. In the fronto-parallel test, both strains selected the 4th left and the 4th right container above chance; nevertheless, the Hybro chicks were more accurate. Our results support the hypothesis that intense selection for production can influence animal cognition and behavior, with implications on animal husbandry and welfare.

Reduction of wing area affects estimated stress in the primary flight muscles of chickens

In flying birds, the pectoralis (PECT) and supracoracoideus (SUPRA) generate most of the power required for flight, while the wing feathers create the aerodynamic forces. However, in domestic laying hens, little is known about the architectural properties of these muscles and the forces the wings produce. As housing space increases for commercial laying hens, understanding these properties is important for assuring safe locomotion. We tested the effects of wing area loss on mass, physiological cross-sectional area (PCSA), and estimated muscle stress (EMS) of the PECT and SUPRA in white-feathered laying hens. Treatments included Unclipped (N = 18), Half-Clipped with primaries removed (N = 18) and Fully-Clipped with the primaries and secondaries removed (N = 18). The mass and PCSA of the PECT and SUPRA did not vary significantly with treatment. Thus, laying hen muscle anatomy may be relatively resistant to changes in external wing morphology. We observed significant differences in EMS among treatments, as Unclipped birds exhibited the greatest EMS. This suggests that intact wings provide the greatest stimulus of external force for the primary flight muscles.

Malfunctioned inflammatory response and serotonin metabolism at the microbiota-gut-brain axis drive feather pecking behavior in laying hens

Feather pecking (FP) is a multifactorial abnormal behavior in laying hens where they display harmful pecks in conspecifics. FP has been associated with the altered functioning of the microbiome-gut-brain axis affecting host emotions and social behavior. The altered levels of serotonin (5-HT), a key monoaminergic neurotransmitter at both terminals of the gut-brain axis, affect the development of abnormal behavior, such as FP in laying hens. However, the underlying mechanism involving reciprocal interactions along the microbiota-gut-brain axis, particularly about the metabolism of 5-HT, remains unclear in FP phenotypes. This study examined the microbiota diversity, intestinal microbial metabolites, inflammatory responses, and 5-HT metabolism in divergently selected high (HFP; n = 8) and low (LFP; n = 8) FP hens to investigate the possible interconnections between FP behavior and the examined parameters. The 16S rRNA analysis revealed that compared to LFP birds, the gut microbiota of HFP birds exhibited a decrease in the abundance of phylum Firmicutes and genera Lactobacillus, while an increase in the abundance of phylum Proteobacteria and genera Escherichia Shigella and Desulfovibrio. Furthermore, the intestinal differential metabolites associated with FP phenotypes were mainly enriched in the tryptophan metabolic pathway. HFP birds had higher tryptophan metabolites and possibly a more responsive immune system compared to the LFP birds. This was indirectly supported by altered TNF-α levels in the serum and expression of inflammatory factor in the gut and brain. Moreover, HFP birds had lower serum levels of tryptophan and 5-HT compared to LFP birds, which was consistent with the downregulation of 5-HT metabolism-related genes in the brain of HFP birds. The correlation analysis revealed that genera Lactobacillus and Desulfovibrio were associated with differences in intestinal metabolites, 5-HT metabolism, and inflammatory response between the LFP and HFP birds. In conclusion, differences in the cecal microbiota profile, immune response and 5-HT metabolism drive FP phenotypes, which could be associated with the gut abundance of genera Lactobacillus and Desulfovibrio.

Environmental Enrichment as Part of the Improvement of the Welfare of Japanese Quails

Simple Summary

Nowadays, keeping animals in cage systems is controversial. Regulations and increased consumer awareness are causing cage systems to lose ground in many countries. In the case of Japanese quails bred for both egg and meat production, their maintenance in a non-cage system is very difficult and uneconomical; therefore, they are kept in cages, and, unlike egg-laying hens, the regulations only regulate the basic parameters, such as cage size and access to food and water. Taking this into account, studies have been conducted that indicate that keeping quails in enriched cages improves the birds’ welfare.

Abstract

The aim of this study was to evaluate the indicators of the behavioural and physiological welfare of Japanese quails (Coturnix japonica) as possible responses to the enrichment of the birds’ habitat. The study sample consisted of 280 Japanese quails (224 ♀ and 56 ♂, respectively). Birds of 5 weeks of age were randomly divided into seven equally sized groups and then divided into replication subgroups (four per group, 10 birds in each replication). Birds were maintained in 0.5 m² cages with unrestricted access to water and food. The experimental factor was the presence or absence of enrichment of the birds’ cages: the nest box, scratcher, plastic corrugated pipe (tunnel), limestone cubes, sandbathing box and feeder box with a drilled cover. Quails were subjected to behavioural tests (tonic immobility and open field tests) and, after 6 weeks, blood samples were taken from them to determine their biochemical indices as well as their cortisol and corticosterone levels. An additional element was the assessment of fertility indices. The presence of enrichment was shown to reduce behavioural disturbances in Japanese quails. This study also found that the colour and shape of an object were very important regarding the birds’ interest in it. Additionally, individuals kept in enriched cages, who were allowed to exhibit their natural behavioural patterns, had lower stress levels.

The Impact of Probiotic Bacillus subtilis on Injurious Behavior in Laying Hens

Simple Summary

Injurious behavior prevention is a critical issue in the poultry industry due to increasing social stress, leading to negative effects on bird production and survivability, consequently enhancing gut microbiota dysbiosis and neuroinflammation via the microbiota–gut–brain axis. Probiotics have been used as potential therapeutic psychobiotics to treat or improve neuropsychiatric disorders or symptoms by boosting cognitive and behavioral processes and reducing stress reactions in humans and various experimental animals. The current data will first report that probiotic Bacillus subtilis reduces stress-induced injurious behavior in laying hens via regulating microbiota–gut–brain function with the potential to be an alternative to beak trimming during poultry egg production.

Abstract

Intestinal microbiota functions such as an endocrine organ to regulate host physiological homeostasis and behavioral exhibition in stress responses via regulating the gut–brain axis in humans and other mammals. In humans, stress-induced dysbiosis of the gut microbiota leads to intestinal permeability, subsequently affecting the clinical course of neuropsychiatric disorders, increasing the frequency of aggression and related violent behaviors. Probiotics, as direct-fed microorganism, have been used as dietary supplements or functional foods to target gut microbiota (microbiome) for the prevention or therapeutic treatment of mental diseases including social stress-induced psychiatric disorders such as depression, anxiety, impulsivity, and schizophrenia. Similar function of the probiotics may present in laying hens due to the intestinal microbiota having a similar function between avian and mammals. In laying hens, some management practices such as hens reared in conventional cages or at a high stocking density may cause stress, leading to injurious behaviors such as aggressive pecking, severe feather pecking, and cannibalism, which is a critical issue facing the poultry industry due to negative effects on hen health and welfare with devastating economic consequences. We discuss the current development of using probiotic Bacillus subtilis to prevent or reduce injurious behavior in laying hens.

The Effect of Hard Pecking Enrichment during Rear on Feather Cover, Feather Pecking Behaviour and Beak Length in Beak-Trimmed and Intact-Beak Laying Hen Pullets

Injurious pecking, commonly controlled by beak trimming (BT), is a widespread issue in laying hens associated with thwarted foraging. This controlled study compared the effect in intact and beak-trimmed pullets of providing pecking pans to eight treatment flocks from six weeks of age. Flocks (mean size 6843) comprised eight British Blacktail, six Lohmann Brown and two Bovans Brown. All young birds (6−7 weeks) pecked more frequently at the pecking pans (mean 40.4) than older pullets (mean 26.0, 23.3 pecks/bird/min at 10−11 weeks and 14−15 weeks, respectively) (p < 0.005). There was no effect on feather pecking or plumage cover. Mean side-beak length and mean top-beak lengths were shorter in treatment flocks at 6−7 weeks and 10−11 weeks (p < 0.001). Intact-beak treatment flocks had shorter mean side-beak length at 10−11 weeks (p < 0.001) and at 14−15 weeks (p < 0.05) and mean top-beak length at 6−7 weeks (p < 0.05) and at 10−11 weeks (p < 0.05). BT treatment flocks had shorter side-beak and top-beak lengths at 6−7 weeks and at 10−11 weeks (p < 0.001). Beak lengths showed linear growth, with individual bird variation indicating a potential for genetic selection. The study demonstrated that abrasive material can reduce beak length in pullets.

Working for food is related to range use in free-range broiler chickens

When animals prefer to make efforts to obtain food instead of acquiring it from freely available sources, they exhibit what is called contrafreeloading. Recently, individual differences in behavior, such as exploration, were shown to be linked to how prone an individual may be to contrafreeload. In this work, our main objective was to test whether and how individual differences in range use of free-range broiler chickens (Gallus gallus domesticus) were related to the individual motivation to contrafreeload. We also verified whether other behavioral variations could relate to range use. To that aim, over three different periods (before range access, first weeks of range access, and last weeks of range access), chickens with different ranging levels (low and high rangers) were submitted to a contrafreeloading test and had different behaviors recorded (such as foraging, resting, locomotion) in their home environment. During the contrafreeloading test, chickens were conditioned to one chamber presenting a foraging substrate and mealworms, while in the other chamber, mealworms were freely available on the floor. During testing trials, chickens had access to both empty chambers, and the time spent in each chamber was quantified. On average, low rangers preferred the chamber where mealworms were easily accessible (without the foraging substrate), while high rangers preferred the chamber where mealworms were accessible with difficulty, showing greater contrafreeloading. Out of ten behaviors recorded in chickens' home environment, foraging was the only one that differed significantly between our two ranging groups, with low rangers foraging, on average, significantly less than high rangers. These results corroborate previous experiences suggesting that range use is probably linked to chickens' exploratory trait and suggest that individual differences in free-range broiler chickens are present even before range access. Increasing our knowledge of individual particularities is a necessary step to improve free-range chicken welfare on the farm.

Effects of poor plumage conditions on egg production, antioxidant status and gene expression in laying hens

The objective of this study was to investigate the effects of poor plumage conditions on production performance, antioxidant status and gene expression in laying hens. Two hundred ten 54-week-old laying hens with similar body weights were assigned into two groups based on plumage conditions (the poor plumage conditions (PPC) group and the control group). All the birds had free access to water and crumbled feed, and received the same management in step cages. Compared with hens in the control group, the hens in the PPC group consumed more feed and produced lighter eggs (P < 0.05). Hens in the PPC group showed lower serum concentrations of glutathione peroxidase and total antioxidant capacity and higher malondialdehyde content than those in the control group. The eggshell breaking strength was lower in the PPC group than in the control group (P < 0.05). The eggshell shape index and yolk colour in the PPC group were significantly higher than those in the control group. The mRNA expression level of HTR2C in the neck skin and that of IL-2 in the liver and breast muscle were higher in the PPC group than in the control group (P < 0.05). The results indicated that PPC may increase feed consumption and influence egg quality, antioxidant status and gene expression in laying hens.