Day-old chicken quality and performance of broiler chickens from 3 different hatching systems

Effects of on-farm hatching versus hatchery hatching on growth performance, gut development, and intestinal health and function in broiler chickens

An alternative hatching system known as hatch on-farm (HOF) provides early access to feed compared to hatch in hatchery (HH) system. Early feeding may promote favorable gut development, potentially improving intestinal health and broiler performance. Previous studies have assessed the effects of HOF on chick quality, welfare and performance, its impacts on gut health remain inconclusive. A total of 560 Ross 308 male chicks were reared until d 38, hatched either in a hatchery (n = 280) or on-farm (n = 280), with 14 replicates per system and 20 birds per pen. Production parameters were periodically monitored. Digestive and immune organ characteristics, intestinal permeability and histomorphology were assessed on d 7, 14, and 38. High-throughput qPCR analyzed 79 ileal genes regarding barrier integrity, immune function, nutrient transporters, gut hormones, metabolism, and oxidation. HOF chicks had higher d1 body weights than HH chicks (P < 001), but this advantage disappeared within first week, with no subsequent performance differences. HOF chickens demonstrated increased duodenal villus width on d 7 and 14, and increased ileal crypt depth and submucosal thickness on d 7 (P < 0.05). Relative bursal weight was higher on d 14 (P = 0.018) and tended to be higher on d 38 in HOF chickens (P = 0.094). Intestinal permeability remained unaffected (P > 0.05), while HH chicks showed upregulation of gut barrier genes such as MUC5ac on d 7 and CLDN2 and MUC2 on d 14 (P < 0.05). HH chicks also showed upregulation of nutrient transports including VDR on d 7 and SLC30A1 and SLC5A9 on d 38, and decreased expression of the appetite-suppressing hormone CCK on d 7 (P < 0.05). HOF chicks upregulated immune-related genes, including IL-8 on d 7, IL-6, IFN-γ, AVBD9 on d 14, and NOS2 on d 38 (P < 0.05), and the oxidation gene HIF1A on d 38 (P = 0.039). In conclusion, although the HOF showed only transient growth advantages, it enhanced mucosal morphology and modulated immunity, indicating improved intestinal health.

Effects of breed and early feeding on intestinal microbiota, inflammation markers, and behavior of broiler chickens

Recently, the Netherlands has shifted toward more welfare-friendly broiler production systems using slower-growing broiler breeds. Early post-hatch feeding (EF) is a dietary strategy that is currently used in commercial broiler production to modulate the gut microbiota and improve performance and welfare. However, there is a knowledge gap in how both breed and EF and their interplay affect gut microbiota composition and diversity, inflammatory status, and broiler behavior. Therefore, the aim of this study was to investigate the effects of breed (fast vs. slower-growing), EF, and their interaction on jejunum microbiota, inflammation, and behavior of broiler chickens. The study included a total of 416 Ross 308 and 416 Hubbard JA757 day-old male broiler chickens, observed until they were 37 days and 51 days old, respectively. Within each breed, one-half of the chickens received EF and the other half did not. A total of two chickens per pen were euthanized at two time points, that is, target body weight (BW) of 200 g and 2.5 kg, and jejunum samples were collected. The jejunum content samples (N = 96) were analyzed for their microbiota, whereas the jejunum tissue (N = 96) was used for the detection of mRNA levels of cytokines (IL-17, IL-22, and IFNγ). Two behavioral tests were performed to assess fear responses: (1) a novel environment test at a target BW of 200 g and (2) a tonic immobility test at a target BW of 2.5 kg. Breed affected the microbiota at a target BW of 2.5 kg (p = 0.04). A breed × EF interaction (p = 0.02) was present for IFNγ at a target BW of 200 g. During the novel environment test, Ross 308 chickens exhibited a shorter latency to vocalize and a higher number of vocalizations compared to Hubbard JA757 chickens (p < 0.05). Early-fed broiler chickens vocalized less compared to not early-fed chickens (Δ = -27.8 on average; p < 0.01). During the tonic immobility test, Hubbard JA757 chickens exhibited a shorter latency to stand compared to Ross 308 chickens. In conclusion, using a slower-growing breed has beneficial effects on gut microbiota and fear responses of broilers, especially at slaughter age, whereas EF seems to have an impact only at an early stage of the life of broilers.

Research Note: Effects of on-farm and hatchery hatching on broiler performance, intestinal lesions, and immune response during a subclinical necrotic enteritis challenge

The effects of traditional and on-farm hatching systems on broiler performance and health under a subclinical necrotic enteritis (NE) challenge were evaluated in this study. A 2×2 factorial study explored the effects of place of hatch (on-farm hatched [OFH] vs. hatchery hatched [HH]) and NE challenge (nonchallenged vs. challenged) on broilers. Cobb 500 eggs (∼E19) were acquired from a commercial hatchery; 840 eggs were placed in pens on clean shavings in prewarmed floor pens and allowed to hatch out, while 927 eggs were placed in a hatcher set under standard practices. On day (d) of hatch, all chicks were weighed and randomly distributed to 4 treatments (8 replicate pens each and 30 birds/pen). The OFH birds were placed immediately after sorting while HH birds were placed back in the hatcher overnight to simulate commercial hatchery procedures. After placing HH birds, feed and litter in the challenge group pens were sprayed with a live oocyst coccidia vaccine as a predisposing factor to NE. The small intestines of 3 male chicks per pen were scored for NE lesions (n = 24) on d 8 (peak NE challenge) and jejunal samples were collected from 1 bird per pen for RNA extraction and qPCR on d 8 and d 14. Data were analyzed using JMP Pro17 and significance between treatments was identified by LSD (P ≤ 0.05). Regardless of the hatching system, the subclinical NE challenge caused a significant reduction in average daily gain (ADG) and average daily feed intake (ADFI), and increased feed conversion ratio (FCR) until d 28 (P ≤ 0.05). Moreover, OFH birds exhibited significantly better growth (P ≤ 0.05) through d 28 but had similar performance to HH birds by d 42. There were no significant differences in NE lesion scores between HH and OFH groups. In conclusion, OFH system resulted in better broiler performance compared to HH system under both no-challenge and challenge conditions during the starter and grower periods. This practice may hold potential for further exploration by the industry as an alternative to traditional hatching, aiming to improve the welfare and productivity of broilers.

Health, welfare and lifetime performance implications of alternative hatching and early life management systems for broiler chickens

Broiler chicks are typically hatched in a hatchery, exposing them to handling and transportation before being placed on the farm where (dry) feed and water is offered. This study compared different early life systems, including: (1) typical practice (control), (2) typical practice with wet feed offered upon placement, (3) access to water at the hatchery, (4) access to feed and water at the hatchery, (5) hatching on the farm. Birds were placed in groups of approximately 500 (day 0), with six replicates per treatment. Measures were taken between placement and slaughter (day 39) and included chick quality (navel and red hock scores), body weight, feed conversion ratio (FCR), mortality, gait and litter conditions scores, and behavioral and post-mortem assessments. There were no apparent treatment effects on gait score, play behaviour or novel object test measures, and no consistent effects on litter quality. Chick quality was only evaluated in Treatments 1 and 5 and was numerically worse in Treatment 5. Body weight at slaughter was lowest in Treatment 2, and did not differ between other treatments. Overall FCR was lowest (best) in Treatment 1, and did not differ between other treatments. There was higher overall mortality in Treatments 3 and 4 than in other treatments apart from Treatment 5. Treatment 4 appeared to promote feeding behaviour upon placement, and Treatment 5 birds rested the most, significantly more than in Treatment 2. Treatment 5 birds had the greatest bursa weights, and tibial dyschondroplasia appeared worse in Treatment 4. There were no consistent effects of early access to feed and water on gastrointestinal tract weight measures at slaughter. Compared to the control, there were few benefits in providing feed and/or water in the hatchery, or wet feed. Some benefits of in-house hatching were found, but negative effects were also apparent.

In ovo probiotic supplementation supports hatchability and improves hatchling quality in broilers

In modern broilers, the period of embryonic development constitutes a greater proportion of a broiler's productive life. Hence, optimum embryonic development can exert a significant influence not only on chick hatchability and hatchling quality but also on overall broiler growth and performance. Further healthy and active hatchlings are correlated with improved posthatch performance. In this regard, probiotics are good candidates to mediate early-life programming. Therefore, we evaluated the effect of In ovo probiotic spray application on broiler hatchability and hatchling quality. The experiment was set out as a completely randomized study with 2 independent trials. In each trial, 540 eggs (Ross 308) were either sprayed with phosphate buffered saline (PBS; control) or probiotics [∼9 log CFU/egg of Lactobacillus rhamnosus NRRL B-442(LR) or Lactobacillus paracasei DUP 13076 (LP)] during incubation. On day 18, eggs were transferred to the hatcher and set up for hatching. Starting on day 19, eggs were observed for hatching to determine the spread of hatch and hatchability. Hatched chicks were then assessed for quality using the Tona and Pasgar score and morphometric measurements including hatchling weight, yolk-free-body-mass and hatchling length were measured. Further, chicks were reared in floor pens for 3 wk to assess posthatch growth. Overall, In ovo probiotic supplementation improved hatchability and hatchling quality. Specifically, the spray application of LP improved hatchability by ∼ 5% without affecting the spread of hatch. Further, both LR and LP significantly improved Pasgar and Tona score, indicating an improvement in hatchling quality. Also, LP and LR significantly improved hatchling weight, yolk-free-body-mass, and posthatch growth in chicks. LR significantly improved hatchling weight and hatchling length (P < 0.05). Moreover, this increase in posthatch growth was positively correlated with hatchling weight in the probiotic groups. Overall, our study demonstrates that In ovo probiotic application exerts a positive effect on hatchability, hatchling quality, and subsequent posthatch growth.

Impact of early posthatch feeding on the immune system and selected hematological, biochemical, and hormonal parameters in broiler chickens

Under commercial conditions, chicks hatch within a 24 to 48 h window, a period known as the hatching window. Subsequently, they undergo various treatments before finally being transported to the broiler farm. These procedures may delay the chicks' access to food and water, sometimes receiving them as late as 72 h after hatching. Previous studies have indicated that fasting during this initial period is detrimental, leading to impaired body growth, compromised immune system response, and hindered muscle development. The objective of this study was to assess the impact of early posthatch feeding on immune system organs and selected hematological, biochemical, and hormonal parameters. The experiment utilized Ross 308 broiler eggs incubated under typical commercial hatchery conditions. The experimental group's eggs were hatched in HatchCare hatchers (HC) with immediate access to feed and water, while the control group's eggs were hatched under standard conditions (ST). Thirty chickens from each group were assessed on the 1st (D1), 7th (D7), 21st (D21), and 35th (D35) day after hatching. On D1, the HC group exhibited lower hemoglobin, hematocrit, and total serum protein values, suggesting that early access to water prevents initial dehydration in newborn chicks. Conversely, the ST group showed a stress reaction on D1 due to feed deprivation, leading to an almost 2-fold higher serum corticosterone concentration compared to the HC group. However, this increase did not result in a significant change in the heterophil/lymphocyte ratio. Furthermore, the HC group displayed an increase in triglyceride concentration and a decrease in HDL concentration on D1. On D7, the HC group exhibited an increased relative weight of the bursa and a higher CD4+ cell number in the cecal tonsil (CT), indicating a more rapid development of these organs resulting from early stimulation of the gastrointestinal tract. However, early feeding did not influence the numbers of Bu-1+, CD4+, and CD8+ cells or the germinal center (GC) areas in the spleen. In conclusion, early feeding contributes to the welfare of newborn chicks by reducing dehydration and stress levels and stimulating the development of gut-associated lymphoid tissue.

Group level and individual activity of broiler chickens hatched in 3 different systems

Information on the behavior of chickens hatched in different systems is limited and inconsistent across different studies. Changes in broiler activity can be measured automatically and continuously. The aim of this study was to assess the effects of 3 hatching systems on flock activity using a commercial tracking system, and to compare these findings to individual activity measured under experimental conditions. As this experiment was part of a larger study, it was possible to investigate the effects of vaccination on individual activity. In study 1, flock activity was measured in chickens that hatched either conventionally in the hatchery (HH), in a system which provided nutrition in the hatcher (HF), or on-farm (OH). Chickens were reared in 2 batches, in 12 pens/batch (1,155 animals/pen). One camera recorded top-view images of each pen. A daily activity index (moved pixels/total pixels × 100) was calculated by automated image analysis. In study 2, individual activity was measured under experimental conditions using an ultra-wideband (UWB) system. Chickens from the 3 hatching systems were reared in 3 pens (1 pen/treatment, 30 animals/pen). At d14, UWB-tags were attached to 5 chickens/pen, which tracked the distances moved (DM). In study 1, group level activity showed a significant age × hatching system interaction (F8,752= 5.83, P < 0.001). HH and HF chickens showed higher activity levels than OH chickens in wk 1, 4, and 5. In wk 3, higher activity levels were measured in HH compared to HF, and in HF compared to OH pens. In contrast, HH chickens in small groups in study 2 showed lower DM than HF and OH chickens in wk 3 (P < 0.001). DM did not differ between treatments before vaccination, however, thereafter, HH chickens showed longer DM, whereas HF and OH chickens moved less. The results indicate that hatching system affected broiler activity at specific ages. Effects found at flock level could not be reproduced by individual measurements in study 2, although stocking density was comparable.

Host genotype affects endotoxin release in excreta of broilers at slaughter age

Host genotype, early post-hatch feeding, and pre- and probiotics are factors known to modulate the gut microbiome. However, there is a knowledge gap on the effect of both chicken genotype and these dietary strategies and their interplay on fecal microbiome composition and diversity, which, in turn, can affect the release of endotoxins in the excreta of broilers. Endotoxins are a major concern as they can be harmful to both animal and human health. The main goal of the current study was to investigate whether it was possible to modulate the fecal microbiome, thereby reducing endotoxin concentrations in the excreta of broiler chickens. An experiment was carried out with a 2 × 2 × 2 factorial arrangement including the following three factors: 1) genetic strain (fast-growing Ross 308 vs. slower growing Hubbard JA757); 2) no vs. combined use of probiotics and prebiotics in the diet and drinking water; and 3) early feeding at the hatchery vs. non-early feeding. A total of 624 Ross 308 and 624 Hubbard JA757 day-old male broiler chickens were included until d 37 and d 51 of age, respectively. Broilers (N = 26 chicks/pen) were housed in a total of 48 pens, and there were six replicate pens/treatment groups. Pooled cloacal swabs (N = 10 chickens/pen) for microbiome and endotoxin analyses were collected at a target body weight (BW) of 200 g, 1 kg, and 2.5 kg. Endotoxin concentration significantly increased with age (p = 0.01). At a target BW of 2.5 kg, Ross 308 chickens produced a considerably higher amount of endotoxins (Δ = 552.5 EU/mL) than the Hubbard JA757 chickens (p < 0.01). A significant difference in the Shannon index was observed for the interaction between the use of prebiotics and probiotics, and host genotype (p = 0.02), where Ross 308 chickens with pre-/probiotics had lower diversity than Hubbard JA757 chickens with pre-/probiotics. Early feeding did not affect both the fecal microbiome and endotoxin release. Overall, the results suggest that the chicken genetic strain may be an important factor to take into account regarding fecal endotoxin release, although this needs to be further investigated under commercial conditions.

Effects of hatching system on chick quality, welfare and health of young breeder flock offspring

Alternative hatching systems have been developed for broiler chickens to provide immediately feed and water after hatch and reduce the number or severity of early life stressors. Besides beneficial effects of these alternative hatching systems on chick quality and performance, broiler health and welfare may be positively affected as well. Especially offspring from young broiler breeder flocks may benefit, as they have been shown to be more sensitive to preturbations than offspring from older breeder flocks. This study evaluated effects of hatching systems on chick quality, health and welfare of young breeder flock offspring, using 3 different hatching systems: conventional hatchery-hatched (HH), hatchery-fed (HF), and on-farm hatching (OH). A total of 24 pens were used in a completely randomized block design, with 8 pens per hatching system and 30 chickens per pen. Chick quality at hatch and performance until 35 d of age was improved in the HF and OH compared to HH treatment, but only minor effects were found on the welfare indicators: footpad dermatitis, hock burn, cleanliness, skin lesion and gait score. No effect was observed on the dynamics of a humoral immune response after NCD vaccination, given at d 0 and 14 of age, as no differences between NCD titers were found at d 18. Animals were vaccinated with a live attenuated infectious bronchitis vaccine virus (IBV) at d 28 to address treatment related differences to disease resilience. The expressions of inflammation and epithelial integrity related genes in the trachea and histo-pathological changes in the trachea were examined at 3 d after vaccine administration. No differences between treatment groups were observed. Although beneficial effects of HF and OH systems were found for young breeder flock offspring on chick quality at hatch and body weight posthatch, only one effect of alternative hatching systems on welfare and health indicators were found. No effect of hatching system on humoral immune response or disease resilience was found.

Welfare of broilers on farm

This Scientific Opinion considers the welfare of domestic fowl (Gallus gallus) related to the production of meat (broilers) and includes the keeping of day-old chicks, broiler breeders, and broiler chickens. Currently used husbandry systems in the EU are described. Overall, 19 highly relevant welfare consequences (WCs) were identified based on severity, duration and frequency of occurrence: 'bone lesions', 'cold stress', 'gastro-enteric disorders', 'group stress', 'handling stress', 'heat stress', 'isolation stress', 'inability to perform comfort behaviour', 'inability to perform exploratory or foraging behaviour', 'inability to avoid unwanted sexual behaviour', 'locomotory disorders', 'prolonged hunger', 'prolonged thirst', 'predation stress', 'restriction of movement', 'resting problems', 'sensory under- and overstimulation', 'soft tissue and integument damage' and 'umbilical disorders'. These WCs and their animal-based measures (ABMs) that can identify them are described in detail. A variety of hazards related to the different husbandry systems were identified as well as ABMs for assessing the different WCs. Measures to prevent or correct the hazards and/or mitigate each of the WCs are listed. Recommendations are provided on quantitative or qualitative criteria to answer specific questions on the welfare of broilers and related to genetic selection, temperature, feed and water restriction, use of cages, light, air quality and mutilations in breeders such as beak trimming, de-toeing and comb dubbing. In addition, minimal requirements (e.g. stocking density, group size, nests, provision of litter, perches and platforms, drinkers and feeders, of covered veranda and outdoor range) for an enclosure for keeping broiler chickens (fast-growing, slower-growing and broiler breeders) are recommended. Finally, 'total mortality', 'wounds', 'carcass condemnation' and 'footpad dermatitis' are proposed as indicators for monitoring at slaughter the welfare of broilers on-farm.

Thermal manipulation modifies embryonic growth, hepatic free amino acid concentrations, and hatching performance in layer-type chicks

Thermal manipulation (TM) of incubation temperature has been demonstrated to alter metabolism and post-hatch thermotolerance in broiler strains (meat-type chickens). Fewer reports were focused on layer-type chickens and there was no report on amino acid metabolism during TM in layer-type embryos. In this study, we investigated the effects of TM on embryonic development, hepatic amino acid metabolism, and hatching performance in layer-type chickens. Fertilized eggs were incubated under control thermoneutral temperature (CT, 37.6°C) and TM with high temperature (TMH, 39°C, 8 h/day) or low temperature (TML, 20°C, 1 h/day) from embryonic day (ED) 8 to ED 15. The embryonic weight and relative embryonic weight (yolk-free embryonic weight to the initial egg weight) significantly declined in the TML group at ED 13 (P < 0.01) and ED 16 (P < 0.0001), and were significantly increased (P < 0.001) in the TMH group at ED 16, in comparison with the embryos in the CT group. The concentrations of all hepatic free amino acids were significantly increased (P < 0.01) with embryonic development. Interestingly, TMH and TML caused similar effects on hepatic amino acid metabolism, in which most of the essential and non-essential amino acids were significantly declined (P < 0.05) under TM treatments at ED 13 but not affected at ED 16. Until hatching, TML, but not TMH, caused a significant (P < 0.05) delay (31-38 min/day from ED 8) in incubation duration. The hatchability in the TML group was lower than the other two groups, which indicated that 20°C as cold stimulation was not suitable for layer embryos. The body weight, yolk weight, yolk-free body mass, and chick quality were not affected by TM treatments. However, the relative weight of the liver, but not the heart, was significantly reduced (P < 0.05) at hatching by TML treatment. In conclusion, TML, but not TMH, caused to delay in embryogenesis and affected the internal organ of chicks at hatch. Similar changes in amino acid metabolism under TMH and TML indicated that thermal stress induced by both high and low extreme ambient temperatures influences embryonic amino acid metabolism in a similar fashion in layer-type embryos.

Transmission of antimicrobial resistance (AMR) during animal transport

The transmission of antimicrobial resistance (AMR) between food-producing animals (poultry, cattle and pigs) during short journeys (< 8 h) and long journeys (> 8 h) directed to other farms or to the slaughterhouse lairage (directly or with intermediate stops at assembly centres or control posts, mainly transported by road) was assessed. Among the identified risk factors contributing to the probability of transmission of antimicrobial-resistant bacteria (ARB) and antimicrobial resistance genes (ARGs), the ones considered more important are the resistance status (presence of ARB/ARGs) of the animals pre-transport, increased faecal shedding, hygiene of the areas and vehicles, exposure to other animals carrying and/or shedding ARB/ARGs (especially between animals of different AMR loads and/or ARB/ARG types), exposure to contaminated lairage areas and duration of transport. There are nevertheless no data whereby differences between journeys shorter or longer than 8 h can be assessed. Strategies that would reduce the probability of AMR transmission, for all animal categories include minimising the duration of transport, proper cleaning and disinfection, appropriate transport planning, organising the transport in relation to AMR criteria (transport logistics), improving animal health and welfare and/or biosecurity immediately prior to and during transport, ensuring the thermal comfort of the animals and animal segregation. Most of the aforementioned measures have similar validity if applied at lairage, assembly centres and control posts. Data gaps relating to the risk factors and the effectiveness of mitigation measures have been identified, with consequent research needs in both the short and longer term listed. Quantification of the impact of animal transportation compared to the contribution of other stages of the food-production chain, and the interplay of duration with all risk factors on the transmission of ARB/ARGs during transport and journey breaks, were identified as urgent research needs.

Early life environment affects behavior, welfare, gut microbiome composition, and diversity in broiler chickens

This study aimed to identify whether early-life conditions in broiler chickens could affect their behavior and welfare, and whether or not this was associated with an altered gut microbiome composition or diversity. Broilers were tested in a 2 x 2 factorial design with hatching conditions [home pen (OH) or at the hatchery (HH)] and enrichment (dark brooder (EE) or no brooder (NE) until 14 days of age) as factors (N = 6 per treatment combination). Microbiota composition was measured in the jejunum on days (d) 7, 14, and 35 and in pooled fecal samples on day 14. A novel environment test (NET) was performed on days 1 and 11, and the behavior was observed on days 6, 13, and 33. On day 35, composite asymmetry was determined and footpad dermatitis and hock burn were scored. In their home pen, HH showed more locomotion than OH (P = 0.05), and NE were sitting more and showed more comfort behavior than EE at all ages (P <0.001 and P = 0.001, respectively). On days 6 and 13 NE showed more eating and litter pecking while sitting, but on day 33 the opposite was found (age^*enrichment: P = 0.05 and P <0.01, respectively). On days 1 and 11, HH showed more social reinstatement in the NET than OH, and EE showed more social reinstatement than NE (P <0.05). Composite asymmetry scores were lower for EE than NE (P <0.05). EE also had less footpad dermatitis and hock burn than NE (P <0.001). Within OH, NE had a more diverse fecal and jejunal microbiome compared to EE on day 14 (feces: observed richness: P = 0.052; jejunum: observed richness and Shannon: P <0.05); the principal component analysis (PCA) showed differences between NE and EE within both HH and OH in fecal samples on day 14, as well as significant differences in bacterial genera such as Lactobacillus and Lachnospiraceae (P <0.05). On day 35, PCA in jejunal samples only showed a trend (P = 0.068) for differences between NE vs. EE within the OH. In conclusion, these results suggest that especially the dark brooder affected the behavior and had a positive effect on welfare as well as affected the composition and diversity of the microbiome. Whether or not the behavior was modulated by the microbiome or vice versa remains to be investigated.

Welfare of domestic birds and rabbits transported in containers

This opinion, produced upon a request from the European Commission, focuses on transport of domestic birds and rabbits in containers (e.g. any crate, box, receptacle or other rigid structure used for the transport of animals, but not the means of transport itself). It describes and assesses current transport practices in the EU, based on data from literature, Member States and expert opinion. The species and categories of domestic birds assessed were mainly chickens for meat (broilers), end-of-lay hens and day-old chicks. They included to a lesser extent pullets, turkeys, ducks, geese, quails and game birds, due to limited scientific evidence. The opinion focuses on road transport to slaughterhouses or to production sites. For day-old chicks, air transport is also addressed. The relevant stages of transport considered are preparation, loading, journey, arrival and uncrating. Welfare consequences associated with current transport practices were identified for each stage. For loading and uncrating, the highly relevant welfare consequences identified are handling stress, injuries, restriction of movement and sensory overstimulation. For the journey and arrival, injuries, restriction of movement, sensory overstimulation, motion stress, heat stress, cold stress, prolonged hunger and prolonged thirst are identified as highly relevant. For each welfare consequence, animal-based measures (ABMs) and hazards were identified and assessed, and both preventive and corrective or mitigative measures proposed. Recommendations on quantitative criteria to prevent or mitigate welfare consequences are provided for microclimatic conditions, space allowances and journey times for all categories of animals, where scientific evidence and expert opinion support such outcomes.

Differences and variation in welfare performance of broiler flocks in three production systems

There is a trend toward broiler production systems with higher welfare requirements, that use slower growing broiler strains, apply a reduced stocking density and provide environmental enrichment. Although these separate factors each contribute to increased broiler welfare, there is little information on their combined effect on broiler welfare under commercial conditions, and on the variation in welfare performance of flocks within production systems. The aim of this study was to compare the welfare performance and the between-flock variation in welfare of 3 Dutch commercial broiler production systems differing in welfare requirements: Conventional (C), Dutch Retail Broiler (DRB) and Better Life one star (BLS). We applied a welfare assessment method based on the Welfare Quality broiler assessment protocol, in which we used 5 animal-based welfare measures collected by slaughterhouses and hatcheries (mortality, footpad dermatitis, hock burn, breast irritation, scratches), and 3 resource- or management-based measures (stocking density, early feeding, environmental enrichment). Data were collected for at least 1889 flocks per production system over a 2-year period. To compare the different measures and to generate an overall flock welfare score, we calculated a score on a scale from 0 to 100 (bad-good) for each measure based on expert opinion. The overall flock score was the sum of the scores of the different welfare measures. The results showed that with increasing welfare requirements, a higher total welfare score was found across production systems (BLS > DRB > C; P < 0.0001). Regarding individual measures, C generally had lower (worse) scores than BLS and DRB (P < 0.05), except for scratches where C had highest (best) score (P < 0.001). Both welfare measure scores and the total welfare score of flocks showed large variation within and overlap between systems, and the latter especially when only the animal-based measures were included in the total flock score. Total flock score ranges including animal-based measures only were: 112.1 to 488.3 for C, 113.0 to 486.9 for DRB, 151.3 to 490.0 for BLS (on a scale from 0 [bad]–500 [good]), with median values of 330.8 for C, 370.9 for DRB, and 396.1 for BLS respectively. This indicates that factors such as farm management and day-old chick quality can have a major effect on the welfare performance of a flock and that there is room for welfare improvement in all production systems.

In ovo Feeding of L-Leucine Improves Antioxidative Capacity and Spleen Weight and Changes Amino Acid Concentrations in Broilers After Chronic Thermal Stress

L-Leucine (L-Leu) was demonstrated to confer thermotolerance by in ovo feeding in broiler chicks and chickens in our previous studies. However, the L-Leu-mediated roles in recovering from the detrimental effects of heat stress in broilers are still unknown. This study aimed to investigate the effects of L-Leu in ovo feeding on the growth performance, relative weight of organs, serum metabolites and antioxidant parameters, and gene expression profiles in broiler chickens after chronic heat stress. Fertilized broiler eggs (Ross 308) were subjected to in ovo feeding of sterile water (0.5 mL/egg) or L-Leu (69 μmol/0.5 mL/egg) on embryonic day 7. After hatching, the male chicks were separated and used for the current study. All chickens were subjected to thermal stress exposure from 21 to 39 days of age and 1 week of recovery from 40 to 46 days of age. The results showed that in ovo feeding of L-Leu did not affect the body weight gain or relative weight of organs under chronic heat stress; however, the serum glutathione peroxidase was significantly increased and serum malondialdehyde was significantly decreased by L-Leu at 39 days of age. After 1 week of recovery, in ovo feeding of L-Leu significantly improved the relative spleen weight at 46 days of age. Subsequent RNA-seq analysis in the spleen showed that a total of 77 significant differentially expressed genes (DEGs) were identified, including 62 upregulated DEGs and 15 downregulated DEGs. Aspartic-type endopeptidase and peptidase activities were upregulated after recovery in the L-Leu group. The expression of genes related to B cell homeostatic proliferation and vestibular receptor cell differentiation, morphogenesis and development was downregulated in the L-Leu group. Moreover, the concentrations of serum catalase, total antioxidative capacity, isoleucine and ammonia were significantly decreased by L-Leu in ovo feeding after recovery. These results suggested that L-Leu in ovo feeding promoted the recovery of antioxidative status after chronic heat stress in broiler chickens.

Effects of hatching on-farm on performance and welfare of organic broilers

As an alternative to traditional hatching in the hatchery, fertilized incubated eggs can be placed in the rearing barn on embryonic d 18 for hatching to occur on-farm, omitting several hatchery procedures, and transport of day-old chicks. In addition, this practice further allows newly hatched chicks access to feed and water immediately post-hatch. The aim of the present study was to examine welfare implications of hatching slower-growing organic broilers on-farm (OF) using the One2Born system (One2Born, Uden, the Netherlands). Hatchery-hatched chicks (HC) transported to the farm were used as control. Six flocks of both treatments, each comprising approximately 3,600 mixed-sex Hubbard JA57 ColorYield broilers, housed with veranda and outdoor access were included in the study. Compared to HC, the hatchability was higher in OF chicks (95.3% vs. 94.8%; P = 0.0097), whereas the number of second grade chicks was lower (11.6% vs. 16.1%; P < 0.0001). The chick quality was lower for OF than HC (odds ratio: 1.79; P = 0.0009), but this was not reflected in the first week mortality (OF: 0.41%, HC: 0.99%; P < 0.0001) or total mortality (OF: 1.51%, HC: 2.20%; P < 0.0001). No difference was found between treatments for the live body weight at slaughter age (P = 0.73). Breast blisters were more common in HC males than in OF males and in females from both treatments (P = 0.038), whereas OF males and females from the 2 treatments did not differ (P = 0.91). There was no effect of treatment on litter quality, footpad dermatitis, gait, skin injuries, and rejection rates at slaughter (P ≥ 0.35). In conclusion, OF hatching appears to be a viable concept, resulting in reduced mortality and increased hatchability, though knowledge on the topic is sparse. Therefore, more research should be addressed to the welfare implications of hatching OF, specifically to impacts on litter quality, footpad dermatitis, and how chick quality impacts other animal welfare indicators.

Effects of hatch window and nutrient access in the hatcher on performance and processing yield of broiler chicks reared according to time of hatch

The effects of hatch window and hatching basket nutrient availability on organ weights, performance, and processing yield of broilers were investigated. Eggs were hatched in illuminated hatchers. At the end of each hatch window period (HWP), hatched chicks were placed into control (CTL) hatching baskets with no nutrients or baskets providing access to feed and water (FAW). This resulted in 6 treatments in a factorial arrangement of 3 HWP (early, middle, or late) and 2 basket types (CTL or FAW). Chicks remained in experimental baskets until 504 h and were then subjected to a 4 h holding period at the hatchery without nutrient access. Subsequently, 1,500 hatched chicks were reared in floor pens for 42 d with 5 replicate pens per treatment. Common diets and water were provided ad libitum. Bird weights and feed consumption were recorded weekly. Individual bird weights were taken at 21 and 42 d. At 43 d, 14 males from each pen were processed. There was an interaction between HWP and basket type on placement BW (P = 0.028) and BW change in the hatcher (P < 0.001). The HWP influenced BW at hatch (P = 0.007), 7 d (P < 0.001), and 14 d (P < 0.001) and FI at 7 d (P < 0.001) and 14 d (P = 0.002). Chicks from FAW baskets were heavier (P < 0.001) than those from CTL baskets at 7 d; afterward, they were similar (P > 0.05) in BW. Yolk and liver weights were similar (P > 0.05) between basket treatments at 3 d posthatch. No differences (P > 0.05) in FCR, mortality, or processing were observed between basket treatments. Interestingly, early hatching chicks were lightest at hatch but subsequently had higher FI and BWG. These findings indicate that hatcher nutrient access may reduce weight loss in the hatcher, especially for early hatching chicks, but had no influence on subsequent performance or processing yields beyond 7 d.