Nutritional approaches to reduce or prevent feather pecking in laying hens: any potential to intervene during rearing?

Effects of β-Mannanase Supplementation and Soyhull Inclusion on Production Performance, Economics, Egg Quality, Blood Biochemicals, Nutrient Digestibility, and Intestinal Morphology in Golden Brown Hens (RIR × Fayoumi) during Late Peak Production

This study investigated the effects of the β-mannanase enzyme and soyhulls on production performance, economics, egg quality, hematology and serum biochemistry, nutrient digestibility, gut morphology, digesta viscosity, and excreta consistency in laying hens during the late peak production phase (37 to 40 weeks of age). Golden brown hens (RIR × Fayoumi; n = 200) were fed a control diet (no soyhulls or enzymes) and diets containing four combinations, i.e., 3% soyhulls with 20 mg/kg β-mannanase (D1), 3% soyhulls with 30 mg/kg β-mannanase (D2), 9% soyhulls with 20 mg/kg β-mannanase (D3), and 9% soyhulls with 30 mg/kg β-mannanase (D4), for four weeks in four replicates of 10 birds each. Overall, a significantly higher (p < 0.05) feed intake, weight gain, feed conversion ratio, and water intake were calculated in the D2 group as compared to the control and remaining combinations of soyhulls and β-mannanase. No mortality was recorded during the entire experiment. Economically, the D1 and D2 groups showed the best results as compared to the D3 and D4 groups. Egg quality parameters like egg weight, shell weight and shell thickness, yolk weight, albumen weight and height, and the Haugh unit remained unchanged (p > 0.05). Similarly, the D2 group showed significantly lower total cholesterol, LDL, and VLDL levels and enhanced gut morphology with greater villus width, height, crypt depth, and surface area across intestinal segments. Crude protein (CP), crude fiber (CF), crude fat, and ash digestibility were higher (p < 0.05) in the D1 and D2 groups compared to the control. Digesta viscosity, excreta consistency, and other egg quality parameters remained unaffected. In conclusion, the dietary inclusion of a combination of 3% soyhulls and 30 mg/kg β-mannanase may have potential benefits for laying hens by improving some production performance and egg quality indicators and economics, lowering blood cholesterol, LDL, and VLDL levels, enhancing nutrient digestibility, and improving gut morphology without affecting egg quality.

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.

Restorative effects of Lactobacillus rhamnosus LR-32 on the gut microbiota, barrier integrity, and 5-HT metabolism in reducing feather-pecking behavior in laying hens with antibiotic-induced dysbiosis

The development of abnormal feather-pecking (FP) behavior, where laying hens display harmful pecks in conspecifics, is multifactorial and has been linked to the microbiota-gut-brain axis. Antibiotics affect the gut microbial composition, leading to gut-brain axis imbalance and behavior and physiology changes in many species. However, it is not clear whether intestinal dysbacteriosis can induce the development of damaging behavior, such as FP. The restorative effects of Lactobacillus rhamnosus LR-32 against intestinal dysbacteriosis-induced alternations need to be determined either. The current investigation aimed to induce intestinal dysbacteriosis in laying hens by supplementing their diet with the antibiotic lincomycin hydrochloride. The study revealed that antibiotic exposure resulted in decreased egg production performance and an increased tendency toward severe feather-pecking (SFP) behavior in laying hens. Moreover, intestinal and blood-brain barrier functions were impaired, and 5-HT metabolism was inhibited. However, treatment with Lactobacillus rhamnosus LR-32 following antibiotic exposure significantly alleviated the decline in egg production performance and reduced SFP behavior. Lactobacillus rhamnosus LR-32 supplementation restored the profile of the gut microbial community, and showed a strong positive effect by increasing the expression of tight junction proteins in the ileum and hypothalamus and promoting the expression of genes related to central 5-HT metabolism. The correlation analysis revealed that probiotic-enhanced bacteria were positively correlated, and probiotic-reduced bacteria were negatively correlated with tight junction-related gene expression, and 5-HT metabolism, and butyric acid levels. Overall, our findings indicate that dietary supplementation with Lactobacillus rhamnosus LR-32 can reduce antibiotic-induced FP in laying hens and is a promising treatment to improve the welfare of domestic birds.

Quantifying Acute Behavioral Reactions of Bali Mynas (Leucopsar rothschildi) to Environmental and Progressively Challenging Enrichment

Animals use specific behaviors and skills to overcome challenges and access resources. Environmental enrichment is provided to animals in human care to both promote species-appropriate behaviors and reduce undesired behaviors. Feather pecking in birds is an undesired behavior without a clear cause. The Saint Louis Zoo houses three pairs of young Bali mynas (Leucopsar rothschildi) who pluck neck feathers from conspecifics. To reduce this behavior, animal care staff presented the birds with seven enrichment items from four categories, presenting each item twice. The enrichment included a modifiable, progressively challenging bamboo tube device at multiple levels of difficulty. While plucking was not affected by any enrichment item, we observed significant increases in locomotion and decreases in autopreening, allogrooming, and head bobbing. Leafy greens produced the greatest changes when compared to other enrichment types. Overall engagement with the progressively challenging enrichment increased with the change from the first to the second level of difficulty, and interaction with the device was highest for the third and most difficult version. These increases suggest that no habituation to the progressively challenging device occurred, while a possible neophobic effect declined with multiple uses and increased familiarity.

Welfare issues and potential solutions for laying hens in free range and organic production systems: A review based on literature and interviews

In free-range and organic production systems, hens can make choices according to their needs and desires, which is in accordance with welfare definitions. Nonetheless, health and behavioral problems are also encountered in these systems. The aim of this article was to identify welfare challenges observed in these production systems in the EU and the most promising solutions to overcome these challenges. It is based on a review of published literature and research projects complemented by interviews with experts. We selected EU specific information for welfare problems, however, the selected literature regarding solutions is global. Free range use may increase the risk of infection by some bacteria, viruses and parasites. Preventive methods include avoiding contamination thanks to biosecurity measures and strengthening animals' natural defenses against these diseases which can be based on nutritional means with new diet components such as insect-derived products, probiotics and prebiotics. Phytotherapy and aromatherapy can be used as preventive and curative medicine and vaccines as alternatives to antibiotics and pesticides. Bone quality in pullets and hens prevents keel deviations and is favored by exercise in the outdoor range. Free range use also lead to higher exposure to variable weather conditions and predators, therefore shadow, fences and guard animals can be used to prevent heat stress and predation respectively. Granting a free range provides opportunities for the expression of many behaviors and yet many hens usually stay close to the house. Providing the birds with trees, shelters or attractive plants can increase range use. Small flock sizes, early experiences of enrichment and personality traits have also been found to enhance range use. Severe feather pecking can occur in free range production systems, although flocks using the outdoor area have better plumage than indoors. While many prevention strategies are facilitated in free range systems, the influence of genetics, prenatal and nutritional factors in free range hens still need to be investigated. This review provides information about practices that have been tested or still need to be explored and this information can be used by stakeholders and researchers to help them evaluate the applicability of these solutions for welfare improvement.

Effect of beak trimming at hatch and the inclusion of oat hulls in the diet on growth performance, feed preference, exploratory pecking behavior, and gastrointestinal tract traits of brown-egg pullets from hatch to 15 weeks of age

The influence of infrared beak trimming at hatch (IRBT) and the inclusion of oat hulls (OH) in the diet on growth performance, feed preference, exploratory pecking behavior, and gastrointestinal tract (GIT) development, was studied in brown-egg pullets from 0 to 15 wk of age. The experimental design was completely randomized with 4 treatments arranged as a 2 × 2 factorial with IRBT (sham vs. treated) and OH inclusion (0 vs. 3%) as main effects. Each treatment was replicated 20 times and the experimental unit was a cage with 10 pullets. Feed intake (FI), BW gain, feed conversion ratio (FCR), energy intake (EI, kcal AMEn/d), and energy conversion ratio (ECR, kcal AMEn/g of BW gain) were determined by feeding period (0 to 6, 7 to 10, and 11 to 15 wk of age) and cumulatively. Particle size preference was measured at 7 wk and exploratory pecking behavior of the pullets and at 8 to 14 wk of age. From 0 to 6 wk of age, beak trimming decreased FI (P < 0.01) and increased pullet mortality (P < 0.001) but did not affect BW gain. From 0 to 15 wk of age, OH inclusion improved BW uniformity (P = 0.090) but impaired FCR (P < 0.05) without showing any effect on BW gain or ECR. Preference for coarse particles was greater for the sham than for the treated pullets. Beak trimming and OH feeding reduced (P < 0.05) the exploratory pecking behavior of the pullets from 8 to 12 wk of age but not thereafter. Oat hulls increased the relative weights of the full gizzard and intestines at all ages (P < 0.05). In summary, beak trimming did not affect pullet performance at 15 wk of age or GIT development at any age. Oat hulls improved GIT development at all ages but did not affect BW or ECR. Both beak treatment and OH inclusion affected particle size preference and reduced the exploratory pecking behavior of the birds.

Influence of different dietary fibre contents in the diet on feather pecking, locomotor activity and performance of laying hens

1. This trial investigated the effects of three diets with increasing proportions of insoluble dietary fibre (3%, 6% and 9%) but with similar metabolisable energy on behaviour, plumage condition and laying performance of Lohmann Tradition hens.2. At 21 weeks of age, four groups of 20 hens each (= four replicates/treatment) were randomly assigned to one of the three feeding treatments and exclusively fed with their assigned feed until the end of the laying period.3. Severe feather pecking decreased with increasing fibre content (3%: 0.78 pecks/30min/hen, 6%: 0.31, 9%: 0.12; P<0.0001). In contrast, no effect of fibre was seen for gentle feather pecking (P=0.19) and aggressive pecking (P=0.84). The number of free feathers in the littered area increased with increasing fibre content (3%: 0.06 feathers/625cm²/hen, 6%: 0.09, 9%: 0.16; P=0.0074). Over time plumage quality worsened in all hens, but was consistently better with increasing fibre content (fibre content x sampling period; P<0.0001). Locomotor activity was similar across all treatments, except for a slight decrease in hens fed the 3% fibre diet at the end of the experimental period. No effect of fibre content on hens' weight (P=0.75) was detectable. Similarly, performance did not differ between hens fed varying dietary fibre.4. The results supported the assumption that increasing dietary fibre helps to reduce the risk for the occurrence of feather pecking in laying hens, i.e., improve well-being, while having no negative effects on performance.

Effects of Key Farm Management Practices on Pullets Welfare—A Review

Simple Summary

Studies on animal behavior and welfare have reported that improving the management practices of pullets can enhance their growth, as well as their physical and mental condition, thus benefiting the productivity of laying hens. Therefore, in this review, we elaborated on the key effective farm management measures, including housing type and matching, flock status, and environmental management and enrichment, to provide the necessary information to incorporate welfare into chicken rearing and its importance in production, with the aim of improving the quantity and quality of chicken products.

Abstract

Studies on animal behavior and welfare have reported that improving the management practices of pullets can enhance their growth, as well as their physical and mental condition, thus benefiting the productivity of laying hens. There is growing confidence in the international community to abandon the conventional practices of “cage-rearing and beak-trimming” to improve the welfare of chickens. Therefore, in this review, we summarized some of the effective poultry management practices that have provided welfare benefits for pullets. The results are as follows: 1. Maintaining similar housing conditions at different periods alleviates fear and discomfort among pullets; 2. Pullets reared under cage-free systems have better physical conditions and temperaments than those reared in cage systems, and they are more suitable to be transferred to similar housing to lay eggs; 3. Improving flock uniformity in appearance and body size has reduced the risk of pecking and injury; 4. Maintaining an appropriate population (40–500 birds) has reduced flock aggressiveness; 5. A combination of 8–10 h of darkness and 5–30 lux of light-intensity exposure via natural or warm white LED light has achieved a welfare–performance balance in pullets. (This varies by age, strain, and activities.); 6. Dark brooders (mimicking mother hens) have alleviated fear and pecking behaviors in pullets; 7. The air quality of the chicken house has been effectively improved by optimizing feed formulation and ventilation, and by reducing fecal accumulation and fermentation; 8. Complex environments (with litter, perches, straw bales, slopes, platforms, outdoor access, etc.) have stimulated the activities of chickens and have produced good welfare effects. In conclusion, the application of comprehensive management strategies has improved the physical and mental health of pullets, which has, in turn, improved the quantity and quality of poultry products.