Explore the vast range of titles available.

Interspecific avian brood parasites, like cuckoos and cowbirds, lay their eggs in nests of other species, the hosts, which take over the entire parental care of the parasite's eggs and chicks. This breeding strategy requires decisions that may affect the parasite's reproductive success. During the breeding season, cowbirds search for host nests and revisit them to monitor its progress and parasitize at the time host laying begins. When visiting hosts nests, they repeatedly peck the nest contents trying to destroy one or more eggs. This behaviour favours parasite's offspring by reducing the competition for food with nestmates. We evaluated if the egg-pecking behaviour of female shiny ( Molothrus bonariensis ) and screaming ( M. rufoaxillaris ) cowbirds is affected by the strength and the size of the eggs they find in the nest. We presented to wild-caught females artificial clutches with two natural eggs that differ in size and shell strength. We found that female shiny and screaming cowbirds adjusted egg-pecking behaviour based on the strength but not on the size of the eggs. When differences in strength between eggs were high, both cowbird species pecked more frequently the egg with the weaker shell, increasing the probability of a successful puncture. Our results indicate that female cowbirds can discriminate eggs through the strength of the shell, and by choosing the weaker egg to peck, they increase the probability of puncturing.

Aggressive pecking is an important welfare and production efficiency issue in poultry farming. The precise mechanisms underlying the occurrence of aggressive pecking remain poorly understood. In this study, we selected Sansui ducks that performed aggressive pecking and ducks that did not perform aggressive pecking from video recordings. Transcriptomic and metabolomic analyses of the whole brains of aggressive pecking ducks and normal ducks revealed 504 differentially expressed genes and 5 differentially altered metabolites (adenosine, guanidinopropionic acid, Met-Leu, Glu-Ile and 5,6,8-trihydroxy-2-methylbenzo[g]chromen-4-one). By jointly analysing the transcriptomics and metabolomics results, we discovered 8 candidate genes ( ADCYAP1 , GAL , EDN2 , EDN1 , MC5R , S1PR4 , LOC113843450 , and IAPP ) and one candidate metabolite (adenosine) that regulates aggressive pecking behaviour in ducks. The candidate genes and metabolites may be involved in regulating aggressive pecking behaviour by inducing neurodegeneration and disrupting neural excitatory-inhibitory homeostasis, which in turn affects central nervous system function in aggressive pecking and normal ducks. Our findings provide a new reference for revealing the underlying mechanism of aggressive pecking behaviour in ducks.

The current study was conducted to compare the effect of beak trimming and feather spraying with bitter taste compound (almond oil) on feather pecking behavior and duck welfare. A total of 63 healthy male 2-weeks-old Muscovy ducklings were randomly allocated to 3 groups. The first group was the control group (no beak trimming and no feather spraying), ducks in the second group were trimmed by scissors at 3 weeks of age, and birds in the third group were sprayed with bitter almond oil weekly from the age of 3 weeks. Growth performance parameters were evaluated. Some behavioral patterns were recorded by using focal sampling. Feather condition score and serum cortisol level were evaluated. At the end of the experiment, bills were collected for histopathological examination. The results showed that beak trimming with scissors had no negative effects on Muscovy ducks’ growth performance and significantly lowered feather pecking bouts resulting in good feather conditions. Feather spraying with bitter almond oil had adverse effects on growth performance, obviously increased feather pecking resulted in deterioration of feather quality and markedly increased the level of cortisol (p < 0.001) . Bill morphological analysis with hematoxylin and eosin (H&E) and S100 stains illustrated that the trimmed beak had an increase in the amount of connective tissue (scar tissue formation), numerous blood vessels, fewer nerve bundles, and no neuroma formation. In the Muscovy ducks’ sector, beak trimming with scissors at 3 weeks of age is good practice to control feather pecking and cannibalism without adverse effect on the welfare of ducks.

Feather pecking (FP) is a repetitive behaviour in chickens, influenced by genetic, epigenetic, and environmental factors, similar to behaviours seen in human developmental disorders (e.g., hyperactivity, autism). This study examines genetic and neuro-epigenetic factors in the thalamus of chickens from lines selected for seven generations for high or low FP behaviour (HFP or LFP). We integrate data on Differentially Methylated Regions (DMRs), Single Nucleotide Polymorphisms (SNPs), and Copy Number Variations (CNVs) in this controlled artificial selection process. Significant differences in behaviour, immunology, and neurology have been reported in these lines. We identified 710 SNPs in these lines that indicate new potentially important genes for FP such as TMPRSS6 (implicated in autism), and SST and ARNT2 (somatostatin function). CNV were the omic level most affected during selection. The largest CNVs found were in RIC3 (gain in HFP) and SH3RF2 (gain in LFP) genes, linked to nicotinic acetylcholine receptor regulation and human oncogenesis, respectively. Our study also suggests that promoters and introns are hotspots for CpG depletion. The overlapping of the omic levels investigated here with data from a public FP Quantitative Trait Loci (QTL) database revealed novel candidate genes for understanding repetitive behaviours, such as RTKN2 , associated with Alzheimer’s disease in humans. This study suggests CNVs as a crucial initial step for genomic diversification, potentially more impactful than SNPs.

Every year, billions of egg layer chicks around the world are hatched under highly stressful, industrial circumstances. Here, it is investigated how the stressful procedure in the commercial hatchery, including incubation, hatching, processing, and transport affects the chicks with regards to traits relevant for the egg production industry. These traits were compared to those of a control group hatched in a small incubator and handled gently och quietly in a quiet room without any processing and transport. The chicks were weighed at hatch and at eight additional time points: 4 days, 1 week (w), 2 w, 3 w, 5 w, 8 w, 20 w and 25 w of age. Feather pecking was studied at 15 w of age and damages to the feathers and injuries on the comb and wattle were assessed at 25 w of age. From 19 w of age, eggs were collected on three days per week, counted and weighed. Chicks from a commercial hatchery had a lower hatch weight than control chicks (p<0.001). At 20 w of age, the weight of the commercial hatched chicks was still numerically lower, although this did not reach statistical significance. Commercially hatched chicks tended to show more feather pecking behaviour at 15 w of age compared to control chicks (p<0.1), although feather condition at 25 w of age showed the opposite pattern. Regarding production, commercially hatched chickens laid fewer (p<0.05) and smaller (p<0.05) eggs than chicks hatched and handled under calm circumstances. From this experiment, it is concluded that the stressful experience in the commercial hatchery has an overall negative effect on traits relevant for the industry.

Impacts of environmental complexity on affective states in slow-growing broiler chickens ( Gallus gallus domesticus ) are unknown. Chickens’ performance in judgment bias tests (JBT) can be limited as they are tested individually, causing fear and anxiety. The objectives were to apply a social-pair JBT to assess the effect of environmental complexity on slow-growing broiler chickens` affective states, and assess the impact of fearfulness, anxiety, and chronic stress on JBT performance. Six-hundred Hubbard Redbro broilers were housed in six low-complexity (similar to commercial) or six high-complexity (permanent and temporary enrichments) pens. Twelve chicken pairs were trained (1 pair/pen, n = 24 chickens) using a multimodal approach (visual and spatial cues), with reward and neutral cues of opposing color and location. Three ambiguous cues were tested: near-positive, middle, and near-neutral cues. Approach and pecking behavior were recorded. Eighty-three percent of chickens (20/24) were successfully trained in 13 days. Fearfulness, anxiety, and chronic stress did not impact chickens’ performance. Chickens successfully discriminated between cues. Low-complexity chickens approached the middle cue faster than high-complexity chickens, indicating that they were in a more positive affective state. The environmental complexity provided in this study did not improve affective states in slow-growing broiler chickens compared to a control. A social-pair JBT resulted in excellent learning and testing outcomes in slow-growing broilers.

This study was conducted to compare conventional hatchery-hatching and on-farm-hatching systems in terms of hatching success and first-week chick performance for commercial Cobb 500, Ross 308, and local Anadolu-T genotypes. Eggs in both the conventional and on-farm-hatching groups were subjected to standard hatchery procedures until the end of 18 d of hatching. Subsequently, the eggs in the on-farm-hatching group were transported and placed in pens, while the eggs in the conventional-hatching group were transferred to the hatcher. Data on the length of the hatch window, hatching time, and other hatchery traits were collected for all groups during the hatching process. Post-hatch body weight and chick length were measured 24 h after the end of the hatch window for all groups. Chick feeding behaviour was evaluated through direct observation. There were no significant differences in terms of the hatchability of fertile eggs and total embryonic mortality between the hatching or genotype groups. However, on-farm hatching resulted in a higher chick body length at day zero (P<0.001). Hatching time was significantly influenced by the hatching system (P<0.004) and genotype (P<0.001). The hatching system and genotype had significant effects on feed pecking behaviour at the feeder (P<0.009 and P<0.03, respectively). Based on these findings, it can be concluded that the on-farm-hatching system appears to be competitive with conventional-hatching systems. Despite some limitations of this study, the local broiler genotype could play a crucial role in local sustainable broiler meat production. Further study is required to evaluate growth performance and other relevant parameters under commercial conditions and in large-scale populations.

Feather pecking (FP) is a damaging nonaggressive behavior in laying hens with a heritable component. Its occurrence has been linked to the immune system, the circadian clock, and foraging behavior. Furthermore, dysregulation of miRNA biogenesis, disturbance of the gamma-aminobutyric acid (GABAergic) system, as well as neurodevelopmental deficiencies are currently under debate as factors influencing the propensity for FP behavior. Past studies, which focused on the dissection of the genetic factors involved in FP, relied on single nucleotide polymorphisms (SNPs) and short insertions and deletions < 50 bp (InDels). These variant classes only represent a certain fraction of the genetic variation of an organism. Hence, we reanalyzed whole-genome sequencing data from two experimental populations, which have been divergently selected for FP behavior for over more than 15 generations, performed variant calling for structural variants (SVs) as well as tandem repeats (TRs), and jointly analyzed the data with SNPs and InDels. Genotype imputation and subsequent genome-wide association studies, in combination with expression quantitative trait loci analysis, led to the discovery of multiple variants influencing the GABAergic system. These include a significantly associated TR downstream of the GABA receptor subunit beta-3 (GABRB3) gene, two microRNAs targeting several GABA receptor genes, and dystrophin (DMD), a direct regulator of GABA receptor clustering. Furthermore, we found the transcription factor ETV1 to be associated with the differential expression of 23 genes, which points toward a role of ETV1, together with SMAD4 and KLF14, in the disturbed neurodevelopment of high-feather pecking chickens.

Feather pecking (FP) is a serious economic and welfare problem in the domestic fowl. It has recently been shown that the distribution of FP bouts within groups is heterogeneous and contains a sub-population of extreme feather peckers (EFP). The present study proposed a novel model to detect EFP hens. A mixture of two negative binomial distributions was fitted to FP data of a F2 cross of about 960 hens, and, based on the results, a calculation of the posterior probability for each hen belonging to the EFP subgroup (pEFP) was done. The fit of the mixture distribution revealed that the EFP subgroup made up a proportion of one third of the F2 cross. The EFP birds came more frequently into pecking mood and showed higher pecking intensities compared to the remaining birds. Tonic immobility and emerge box tests were conducted at juvenile and adult age of the hens to relate fearfulness to EFP. After dichotomization, all traits were analyzed in a multivariate threshold model and a genomewide association study was performed. The new trait pEFP has a medium heritability of 0.35 and is positively correlated with the fear traits. Breeding for this new trait could be an interesting option to reduce the proportion of extreme feather peckers. An index of fear related traits might serve as a proxy to breed indirectly for pEFP. GWAS revealed that all traits are typical quantitative traits with many genes and small effects contributing to the genetic variance.

In mammals, early-life probiotic supplementation is a promising tool for preventing unfavourable, gut microbiome-related behavioural, immunological, and aromatic amino acid alterations later in life. In laying hens, feather-pecking behaviour is proposed to be a consequence of gut-brain axis dysregulation. Lactobacillus rhamnosus decreases stress-induced severe feather pecking in adult hens, but whether its effect in pullets is more robust is unknown. Consequently, we investigated whether early-life, oral supplementation with a single Lactobacillus rhamnosus strain can prevent stress-induced feather-pecking behaviour in chickens. To this end, we monitored both the short- and long-term effects of the probiotic supplement on behaviour and related physiological parameters. We hypothesized that L. rhamnosus would reduce pecking behaviour by modulating the biological pathways associated with this detrimental behaviour, namely aromatic amino acid turnover linked to neurotransmitter production and stress-related immune responses. We report that stress decreased the proportion of cytotoxic T cells in the tonsils (P = 0.047). Counteracting this T cell depression, birds receiving the L. rhamnosus supplementation significantly increased all T lymphocyte subset proportions (P < 0.05). Both phenotypic and genotypic feather peckers had lower plasma tryptophan concentrations compared to their non-pecking counterparts. The probiotic supplement caused a short-term increase in plasma tryptophan (P < 0.001) and the TRP:(PHE + TYR) ratio (P < 0.001). The administration of stressors did not significantly increase feather pecking in pullets, an observation consistent with the age-dependent onset of pecking behaviour. Despite minimal changes to behaviour, our data demonstrate the impact of L. rhamnosus supplementation on the immune system and the turnover of the serotonin precursor tryptophan. Our findings indicate that L. rhamnosus exerts a transient, beneficial effect on the immune response and tryptophan catabolism in pullets.