Water deprivation in poultry in connection with transport to slaughter-a review

Poultry are deprived of water when transported to slaughter, beginning shortly prior to catching of the first bird and lasting through catching and loading, the journey on the vehicle, time spent in lairage, and up until time of death. Our aim was to review existing knowledge on variables which may be useful in determining the length of time that poultry may go without water in connection with transport before their welfare begins to deteriorate. During transport, it is likely that birds experience a motivation to drink, which may transition into the negative emotional state of thirst if water is unavailable. Determining when drinking motivation reaches a threshold where welfare is negatively impacted is challenging. In the absence of water, birds may over time experience dehydration which may be detected through physiological indicators as their body attempts to maintain homeostasis. In poultry, plasma osmolality, arginine vasotocin, and chloride have been suggested as being most suitable for assessing dehydration resulting from periods of water deprivation that correspond with typical transport durations, due to their particular sensitivity during this period. While initial dehydration may not be associated with negative emotional states, it is likely that it eventually leads to discomfort, but additional behavioral and motivational studies are necessary to infer when this begins. Impacts of thermal conditions, genetics, and the condition of the individual bird on the development of a dehydrated state were also assessed, though more information is needed to fully understand these interactions. With the available literature, this review concludes that total transport (i.e., from the initial deprivation from water until time of slaughter) durations of longer than 6 h are likely associated with measurable physiological indicators of dehydration and may potentially be associated with negative emotional states, although more research is needed to clarify this. Current available knowledge and assessment tools are not sufficient to detect the degradation of welfare derived from thirst itself, which should be further examined to protect poultry welfare during transport.

Water scarcity can be a critical limitation for the poultry industry

Water is essential for various physiological functions and the productive performance of animals. However, with climatic uncertainties exacerbated by climatic changes, water could become a scarce nutrient shortly. This is already the case in one-third of the world's countries, which are under medium to high levels of water stress. Accordingly, with the growth of poultry production, the availability of water at ad libitum level may not be guaranteed, and birds can be under water restriction for variable periods. Thus, this article aims at attracting the attention of animal scientists to the freshwater shortage challenge, as well as shedding light on (1) the effects of climate change on the freshwater resources; (2) the effects of limited access to water, either by water restriction (WR) or water deprivation (WD), on the growth, feed efficiency, and meat quality of broilers; (3) the effects of different levels of WR or WD on egg production and egg quality traits; (4) the effects of limited access to water on the health, behavior, and welfare status of chickens; and (5) suggested solutions to overcome future water shortage challenges. In conclusion, severe water shortage/restriction might negatively influence the productivity, behavior, and welfare status of the chickens. Genetic background and environmental conditions may interact with the WR effects. The tolerance level of indigenous chicken breeds to limited water access could provide the knowhow to potential solutions to overcome water shortage problems. Selection of chicken strains with high tolerance capacity to thirst and limited water access regimens may be a sustainable solution for solving water scarcity problems.

Heterophil/lymphocyte response of local Spanish breeds of laying hens to cold stress, heat stress, and water restriction

Environmental challenges may adversely affect poultry production. Autochthonous breeds are particularly valuable in a climate change context because of adaptation to the local environment. The objective of the present study was to determine the impact of cold stress, water restriction, and heat stress on the stress response quantified by the heterophil to lymphocyte ratio (H/L) of ten local Spanish breeds of laying hens. Hens of these local breeds were consecutively subjected to three treatments: natural cold stress (2, 4, 6, 7, 9, and 13 °C), water restriction (with a duration of 2.5, 4.5, 7, 10, and 12 h, respectively), and natural heat stress (23, 26, 28, 30, 34, 38, 40, and 42 °C). During cold stress, H/L was higher at 9 and 13 °C than at 2, 4, and 6 °C, and higher at 9 °C than at 7 °C (P < 0.05). H/L values were similar during all water restriction levels. During heat stress, H/L was particularly elevated at temperatures higher than 40 °C (P < 0.05). Overall, Andaluza Azul, Andaluza Perdiz and Prat Codorniz showed lowest resilience to stress based on their H/L response, whereas Pardo de Leon, Villafranquina Roja, and Prat Leonada showed highest resilience.

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.

The influence on behavior and physiology of white-feathered end-of-cycle hens during simulated transport

Transportation is a stressful procedure that can alter end-of-cycle hen (EOCH) behavior and physiology. This study (5 × 3 × 2 factorial arrangement) aimed to assess the effects of temperature (T)/relative humidity (RH) (-10°C uncontrolled RH (-10), +21°C 30%RH (21/30), +21°C 80%RH (21/80), +30°C 30%RH (30/30), +30°C 80%RH (30/80)), duration (4, 8, 12 h), and feather cover [well (WF) and poorly-feathered (PF)] on white-feathered EOCH (65-70 wk) behavior and physiology. EOCH (n = 630) from 3 commercial farms were housed for adaptation (3-5 d), fasted (6 h), crated (53 kg/m2), and placed in a climate-controlled chamber. Data collected included chamber and crate conditions, feather condition score, mortality, core body temperature (CBT), behavior, and delta (∆) blood physiology. Analyses were conducted via ANOVA in a randomized complete block design (farm of origin) with significance declared at P ≤ 0.05. PF EOCH had higher mortality than WF hens during cold exposure (-10). EOCH ∆CBT demonstrated a greater (positive) change at 12 h for all T/RH compared to 4 h at 21/30, 21/80, and -10 (negative). Cold exposure (-10) resulted in a higher percentage of time spent shivering and motionless, while heat exposure resulted in a higher percentage of time spent panting for WF EOCH exposed to 30/30 and WF and PF hens exposed to 30/80. Hen ∆glucose had a greater (negative) change at 4 and 12 h for -10 compared to 4 h at 21/30, and all durations for 21/80, 30/30, and 30/80. PF hens exposed to -10 had a greater (positive) change in ∆sodium, ∆hemoglobin, and ∆hematocrit compared to WF birds (negative). The development of metabolic alkalosis was supported by the increase in ∆blood pH over time and the increase in ∆partial pressure of carbon dioxide, ∆bicarbonate, and ∆base excess extracellular fluid during cold exposure (-10). These results indicated that EOCH exposed to heat endured thermal stress while PF hens exposed to cold were unable to cope with cold stress.

Assessing the effect of water deprivation on the efficacy of on-farm euthanasia methods for broiler chickens

1. Moribund or diseased poultry requiring euthanasia are often dehydrated. To understand how dehydration influences the efficacy of various killing methods, this experiment investigated the effect of water deprivation (WD) on times to unconsciousness and death.2. Broiler chickens (n = 179) were water-deprived for 0, 24, 48 or 72 hours to mimic dehydration, then killed via manual cervical dislocation, mechanical cervical dislocation (Koechner Euthanising Device (KED)), or non-penetrating captive bolt (Zephyr-EXL), at 8, 22, 36 or 50 d of age. Degree of WD was confirmed by skin turgor, packed cell volume and body weight loss. Method efficacy was evaluated by the time to unconsciousness and death using pupillary light (PUP), palpebral blink (PAL) and nictitating membrane (NIC) reflexes, feather erection (FE), cloacal winking (CW) and convulsions (CN). The extent of damage caused by each method was examined via radiography, gross pathology and histopathology. The main effects of WD time and euthanasia method were analysed by two-way analyses of variance (CRD, PROC MIXED, SAS 9.4) with a-priori contrasts to compare water-deprived versus non-water-deprived (NON) birds.3. Skin turgor, packed cell volume and body weight loss had a quadratic relationship with WD, with highest values for those birds which were water-deprived for 72 h. WD level did not affect time to unconsciousness. Time to death was longer for WD birds than NON, with longer latencies to FE, CW and CN for water-deprived birds. WD only affected radiography or gross pathology scores on d 8, with the extent of subcutaneous haemorrhage within the neck decreasing as WD increased.4. The shortest latency to PUP loss, at all ages, and to PAL and NIC loss, at 22 d, was with the Zephyr-EXL. KED had the longest time to unconsciousness (PUP, PAL and NIC), at all ages, and to death, at 36 and 50 d.5. Overall, WD increased time to death, but did not affect the onset of unconsciousness, with no interaction between methods and WD level.

Nutrition, feeding and laying hen welfare

The relationship between nutrition and welfare is usually considered to be a direct result of supplying the hen with adequate quantities of feed and water. This simple notion of freedom from hunger and thirst belies the fact that nutrients play a pivotal role in the body’s response to challenges whether they relate to ambient temperature, gastrointestinal health, pathogen exposure, metabolic disorders, or social and mental stress. In all instances, maintaining homeostasis and allowing for physiologic response is dependent on an adequate and balanced nutrient supply. It is accepted that most laying hens are fed a complete diet, formulated commercially to provide the required nutrients for optimal health, egg production and welfare. In other words, the laying hen, irrespective of her housing, does not experience hunger or thirst. However, despite adequate nutrient and water supply, certain senarios can significantly affect and alter the nutrient requirements of the hen. Furthermore, the chemical composition and also the physical form of feed can significantly contribute to prevent or treat welfare and health conditions and is, therefore, a highly relevant tool to ensure and maintain an adequate welfare status. Therefore, this review takes a broader perspective of nutritional welfare and considers the nutrition of hens managed in different production systems in relation to nutritional physiology, gut microbiota, stress, metabolic disorders and feeding management.

Simulated transport of well- and poor-feathered brown-strain end-of-cycle hens and the impact on stress physiology, behavior, and meat quality

Transportation of poultry is stressful, especially for end-of-cycle hens (EOCH) experiencing metabolic stress. The aim of this study was to evaluate the effects of simulated transport on well- and poor-feathered brown-strain EOCH. The study (5 × 3 × 2 factorial arrangement) consisted of 5 temperature and relative humidity (RH) combinations applied directly at crate level (−10°C uncontrolled RH [−10], +21°C 30%RH [21/30], +21°C 80%RH [21/80], +30°C 30%RH [30/30], or +30°C 80%RH [30/80]), 3 durations (4, 8, or 12 h), and 2 feather covers (well [WF] or poor [PF]). Hens (n = 540) from 3 commercial farms were housed for a 3- to 5-d adaptation period, then feed was withdrawn before treatment exposure (crate density 54.5 kg/m²). Data collected included chamber conditions, feather condition score, behavior, blood physiology, core body temperature, mortality, and meat quality. Data were analyzed (randomized complete block design) using ANOVA; significance declared at P ≤ 0.05. Time spent performing thermoregulatory behaviors increased for hot (30/30 and 30/80) and cold (−10) treatments. Mortality only occurred in hens exposed to −10 and increased with longer duration. Cold exposure impacted meat quality, resulting in higher thigh pH and lower L∗ (lightness) and b∗ (yellowness). Prolonged exposure duration resulted in dehydration, indicated by blood physiology (hematocrit and hemoglobin) and live shrink. PF hens struggled with thermoregulation in −10, while WF hens struggled in 30/30 and 30/80. These results demonstrate that EOCH exposed at crate level to hot (+30) conditions experience thermal stress, while hens exposed to cold (−10) are unable to cope, compromising welfare and meat quality.

Acceptability, growth performance and nutritional status of chickens fed cassava leaf meal (CLM)-based diets

This study evaluated the effect of feeding cassava leaf meal-based diets on feeding behavioural patterns, growth performance parameters and nutritional status of chickens. A total of 200 Cobb-500 female chickens (initial weight 0.53 ± 0.098 kg) were used in the experiment. The chickens were subjected to treatment diets with cassava leaf meal (CLM) included in diets at 0, 100, 200 and 300 g/kg. Number of visits to the feeder/drinker, duration of each visit on the feeder/drinker, average daily feed intake (ADFI), average daily gain (ADG) and feed efficiency (gain:feed ratio), total protein (TP), albumin, globulin and creatine kinase (CK) were the response variables that were measured of interest. Effects of inclusion level of CLM in diets of chickens on number of visits to the feeder and drinker was significant (P < 0.05). Duration of each visit on the feeder increased (P < 0.05) with inclusion level of CLM in diets of chickens. Conversely, time spent by chickens on the drinker decreased with inclusion level of CLM in diets (P < 0.05). Average daily gain and G:F decreased linearly (P < 0.05) with inclusion level of CLM in diets of chickens. Albumin, globulin and total protein in blood of chickens increased linearly (P < 0.05) with inclusion level of CLM in diets of chickens. From the study, it can be concluded that acceptability of diets with inclusion of CLM during the growing-finishing phase of the chickens was not affected. However, weight gain was compromised at higher inclusion levels of CLM in diets of chickens.

Mutilating Procedures, Management Practices, and Housing Conditions That May Affect the Welfare of Farm Animals: Implications for Welfare Research

A number of mutilating procedures, such as dehorning in cattle and goats and beak trimming in laying hens, are common in farm animal husbandry systems in an attempt to prevent or solve problems, such as injuries from horns or feather pecking. These procedures and other practices, such as early maternal separation, overcrowding, and barren housing conditions, raise concerns about animal welfare. Efforts to ensure or improve animal welfare involve adapting the animal to its environment, i.e., by selective breeding (e.g., by selecting "robust" animals) adapting the environment to the animal (e.g., by developing social housing systems in which aggressive encounters are reduced to a minimum), or both. We propose adapting the environment to the animals by improving management practices and housing conditions, and by abandoning mutilating procedures. This approach requires the active involvement of all stakeholders: veterinarians and animal scientists, the industrial farming sector, the food processing and supply chain, and consumers of animal-derived products. Although scientific evidence about the welfare effects of current practices in farming such as mutilating procedures, management practices, and housing conditions is steadily growing, the gain in knowledge needs a boost through more scientific research. Considering the huge number of animals whose welfare is affected, all possible effort must be made to improve their welfare as quickly as possible in order to ban welfare-compromising procedures and practices as soon as possible.