The importance of daylength and darkness exposure on the welfare and productivity of commercial broilers

The impact of daylength on commercial broilers was studied in two experiments, with birds exposed to one of four lighting programs (14L:10D (14L), 17L:7D (17L), 20L:4D (20L) and 23L:1D (23L)). The first experiment was repeated in a block formation four times, with each block containing two full-room replications and including a total of 16,128 broilers. In addition to daylength, other main effects studied in this experiment were genotype (Ross x Ross 308 and Ross x Ross 708) and gender, and these variables were randomly placed within each room. The second experiment included two replications of each of the four lighting programs described above in a format similar to a commercial situation. The total number of birds in this experiment was 7,552, equally distributed into one of eight rooms, with each room containing equal numbers of male and female Ross x Ross 308 broilers. Lighting programs used graded levels of daylength, which allowed the use of regression analysis as the primary statistical tool to define relationships between variables and daylength (SAS Proc Reg and Proc RSReg). For data involving light, genotype and gender (productivity, mortality, gait score, ocular weights), statistics included SAS General Linear Model to test for differences in genotype and gender, and interactions between the three main effects. In all cases, data not normally distributed were (log+1) transformed prior to analysis. In experiment 1, daylength and body weight were quadratically related at 32 and 39 d of age, with 20L producing the heaviest birds. Although not statistically significant, the data curve at 49d was of similar shape, with both 17L and 20L birds heavier than those raised under 23L. With less replication in experiment 2, differences only approached significance at 31 d of age (P=0.09), but once again, the regression curve was similar in shape. Birds raised under 20L consumed more feed at 39 and 49 d as compared to those under any other lighting program. 23L birds at 39 d ate as much as those raised on 17L, and less than the similar group at 49d. Feed efficiency was impacted quadratically, and birds given the longest dark period were most efficient. The latter birds exhibited the lowest mortality levels, which increased linearly with daylength. Both metabolic and skeletal mortality levels increased linearly with daylength in all periods, and infectious disorders in a quadratic fashion, with the peak found in birds raised under 20L. Average gait score was reduced either linearly or quadratically with increasing daylength, and footpad health at 28 and 35 d of age decreased as daylength lengthened. Eye weight was heavier under 23L only. The behaviour of 2 pens per lighting program of Ross x Ross 308 males was recorded with the use of infrared cameras within two of the experiment 1 trials (27/28d in trial 1 and 42/43 d in trial 2). Using scan sampling techniques at 10 min intervals, the average percentage of time performing various behaviours was calculated for the photophase, scotophase, and 24 h period (6 measurements x 24 h per d). Standing, walking, feeding preening, stretching, dustbathing and foraging decreased (linearly or quadratically) with increasing daylength at both ages in both the photophase and 24 h period. Running was reduced in a similar manner at 27/28 d, and was completely eliminated under 23L. These latter birds no longer performed dustbathing behaviour at 42/43 d of age. Percent of time of all behaviours was similar or only slightly different for birds raised under 14 and 17L. Reactivity was reduced in birds raised under 23L, was intermediate under 20L, and similar for 14L and 17L at 27d of age. To determine if melatonin within the flock was produced in diurnal rhythms, blood samples were collected either six (23L) or eight times (14, 17 and 20L) over the 24 h period (six per time). Samples were analyzed using radioimmunoassay. Diurnal melatonin production patterns were noted for flocks under 14, 17 and 20L, but were not found in 23L flocks. Frequent significant quadratic or linear relationships were noted between behaviour and time during the photophase under both 14 and 17L, and occasionally under 20L. No such relationships were noted under 23L, indicating sporadic timing of behavioural expression amongst the flock. The lack of flock synchronization under 23L may lead to repeated sleep disruption (fragmentation), which results in similar symptoms to total sleep deprivation, including poor productivity, a reduction in health, and poor reactivity leading to increased lethargy

Assessing the Effects of Stocking Density on Turkey Tom Health and Welfare to 16 Weeks of Age

Four levels of turkey tom stocking density (SD) (30, 40, 50, 60 kg/m2) were evaluated in two 16 week trials (n = 2,868 Nicholas Select). Poults were allocated to one of eight independently ventilated rooms per trial (6.71 × 10.06 m) based on final predicted body weight (two replicates per SD per trial). Room temperature, humidity, carbon dioxide and ammonia concentration were recorded throughout the trial; ventilation was adjusted to equalize air quality across treatments. Mobility (gait score, scale 0–5) was recorded at 12 and 16 weeks (20 birds per replicate). Footpad lesion score (scale 0–4), feather condition (scale 1–4), and cleanliness scores (scale 1–4) were recorded at 10 (Trial 2), 12, and 16 weeks of age (20 birds per replicate). Aggressive injury incidence was recorded daily for Trial 2. Stress (heterophil/lymphocyte ratio) was evaluated at 4, 12, and 16 weeks of age (15 birds per replicate). Behavior was recorded and scan sampled (field of view) at 12 (Trial 1), 14, and 16 weeks. Data were analyzed using regression analysis (linear, Proc Reg; quadratic, Proc RSReg) for relationships between the variables and SD. Differences were considered significant when p ≤ 0.05. Mobility and footpad lesions were negatively affected by increasing SD (linear) at 16 weeks only. Feather condition and cleanliness decreased linearly as SD increased at week 10, 12, and 16. The incidence of aggressive damage was higher as SD increased during week 4–8 (quadratic). Heterophil/lymphocyte ratios increased linearly at 4 weeks (similar trend at 12 weeks). Behavior was impacted at 12 weeks of age with standing behavior showing a quadratic response, and walking and total disturbance showing a linear decrease as SD increased. Resting, preening, and comfort behaviors increased linearly (14 weeks), while walking and strutting decreased linearly with increasing SD. Finally, at 16 weeks of age resting, standing, walking, feeding, and total disturbance responded quadratically while preening behavior increased linearly with increasing SD. Results suggest that increasing SD negatively impacts bird health and wellbeing through decreased mobility, increased footpad lesions, poorer feather condition and cleanliness, and behavioral changes, but that very low SD (30 kg/m2) may result in increased aggressive damage

Assessing a Method of Mechanical Cervical Dislocation as a Humane Option for On-Farm Killing Using Anesthetized Poults and Young Turkeys

Our objective was to determine the efficacy of manual cervical dislocation vs. a mechanical cervical dislocation device for on-farm killing of poults and young turkeys. Forty-two 1- and 3-week old turkeys were randomly assigned to one of three experimental groups: awake manual cervical dislocation (CD), anesthetized manual cervical dislocation (aCD), or anesthetized mechanical cervical dislocation (MCD). Anesthetized birds received an intramuscular dose of 0.3 mg/kg medetomidine and 30 mg/kg of ketamine to achieve a light plane of anesthesia. A comparison of CD vs. aCD responses indicated that the anesthetic plane did not affect jaw tone or pupillary light reflex, indicators of loss of sensibility and brain death, respectively. MCD was unsuccessful for killing 1-week old poults as indicated by the ongoing presence of the pupillary eye reflex as well as failure to achieve cardiac arrest within 5 min in 5 of 5 birds. Radiographs also indicated no vertebral dislocation or fracture. Pupillary light reflex was present in 98% and jaw tone was present in 73% of turkeys, respectively, for all groups combined, but retention of the pupillary light reflex (P < 0.001) and jaw tone (P = 0.001) was longer for birds killed by MCD. Time to last movement (P = 0.797) and cardiac arrest (P = 0.057) did not differ between method. Survey radiographs demonstrated an effect of method for the average displacement distance at the site of vertebral dislocation, with a greater distance observed in birds killed by CD compared to MCD (P = 0.003). A method by age interaction was observed between CD and MCD for the number of birds with fractures; more vertebral fractures were observed in 3-week old turkeys killed with MCD compared to CD (P = 0.047). Upon gross examination, the majority of birds killed by either method had minimal to no hemorrhage within the brain and spinal cord. However, turkeys killed using CD had more microscopic subdural brain hemorrhage (P = 0.020). Ante-mortem and post-mortem measures suggest that neither manual CD nor the MCD tool used in this study caused immediate insensibility, but CD resulted in a shorter latency to brain death and fewer fractures compared to MCD

Anatomical Pathology, Behavioral, and Physiological Responses Induced by Application of Non-penetrating Captive Bolt Devices in Layer Chickens

We evaluated three models of non-penetrating captive bolt devices, Zephyr-E, Zephyr- EXL, and Turkey euthanasia device (TED) for time to loss of sensibility and degree of brain damage during euthanasia in four age groups of male and female layer chickens (10–11, 20–21, 30–35, 60–70 weeks respectively). Latencies to onset of insensibility and cardiac arrest were assessed to detect whether killing birds via these devices was humane and effective. Both gross and microscopic pathology evaluations were conducted to score skull and brain trauma post mortem. All three NPCB devices induced loss of breathing, pupillary reflex and nictitating membrane reflex within 5 s after application in most chickens. Latencies to loss of jaw tone and neck muscle tone were longer in 60–70 weeks old roosters (p < 0.05). Younger birds (10–21 week-old) demonstrated the longest time (p < 0.0001) to onset of tonic convulsions, time at last movement, cloacal relaxation and cessation of heart beat. A positive correlation (p < 0.0001) was found for all three devices between time of cardiac arrest and times to onset of tonic convulsions, last movement, and cloacal relaxation. More than 80% of birds had skin lacerations with external bleeding following application of all 3 devices. Device type did not affect the incidence of skull fractures but higher skull fracture scores were noted in 10–11 week-old birds compared to other ages. Regardless of device type and age, microscopic SDH was most apparent in the brain and proximal spinal cord of all birds. In summary, all three devices caused significant trauma to the midbrain and spinal cord. Results demonstrated that all three devices induce rapid insensibility after application and can be used as a single-step method that results in a humane death in all age groups of layer chickens

Basing Turkey Lighting Programs on Broiler Research: A Good Idea? A Comparison of 18 Daylength Effects on Broiler and Turkey Welfare

Daylength used as a management tool has powerful implications on the welfare of both broilers and turkeys. Near-constant light results in many detrimental impacts, including lack of behavioural rhythms and circadian melatonin rhythms. Both are suggestive that sleep fragmentation could result in birds reared on long photoperiods, which can lead to the same negative health and physiological responses as total sleep deprivation. An indirect comparison of the welfare implications of graded levels of daylength on broilers and turkeys clearly indicate that long daylengths depress welfare by increasing mortality, reducing mobility, increasing ocular pathologies and changing behaviour in both species. Furthermore, long daylengths change melatonin secretion patterns and eliminate behavioural and melatonin circadian rhythms, which were measured in broilers in these works. However, feather pecking in turkeys was reduced when birds were exposed to long daylengths. Exactly how much darkness should be included in a management program to maximize welfare will depend on the species, the age of marketing, and in turkeys, bird gender

Basing Turkey Lighting Programs on Broiler Research: A Good Idea? A Comparison of 18 Daylength Effects on Broiler and Turkey Welfare

Daylength used as a management tool has powerful implications on the welfare of both broilers and turkeys. Near-constant light results in many detrimental impacts, including lack of behavioural rhythms and circadian melatonin rhythms. Both are suggestive that sleep fragmentation could result in birds reared on long photoperiods, which can lead to the same negative health and physiological responses as total sleep deprivation. An indirect comparison of the welfare implications of graded levels of daylength on broilers and turkeys clearly indicate that long daylengths depress welfare by increasing mortality, reducing mobility, increasing ocular pathologies and changing behaviour in both species. Furthermore, long daylengths change melatonin secretion patterns and eliminate behavioural and melatonin circadian rhythms, which were measured in broilers in these works. However, feather pecking in turkeys was reduced when birds were exposed to long daylengths. Exactly how much darkness should be included in a management program to maximize welfare will depend on the species, the age of marketing, and in turkeys, bird gender

Understanding How Infrared Beak Treatment Affects the Beak Tissue and the Healing Response of Brown and White Feathered Layer Pullets

Infrared beak treatment has less of a negative impact on laying hen welfare compared to other methods of beak treatment; however, it is still not fully understood how infrared beak treatment affects the beak tissue during the first few days post treatment. The objective of this study was to examine the histology of infrared beak treated vs. untreated beaks of 2 strains of layer chicks during early life. One-hundred Lohmann Brown-Lite (LB) and 100 Lohmann LSL-Lite (LW) chicks were obtained; 50 chicks per strain were infrared beak treated post hatch (IR) with the remainder being sham untreated controls (C). Data collected included presence of beak sloughing, length, and histology. Histology slides were analyzed and scored on a scale of 0 to 4, with 0 indicating no lesions and 4 indicating severe inflammation. Sloughing of the treated beak tissue began at 10 days and was complete by 20 days. IR pullets had shorter beak lengths once sloughing was initiated and less overall beak growth. No differences in healing scores were found between treated LB and LW beaks; all treated LB beaks were healed by 21 days while some LW beaks still showed inflammation. Overall, infrared beak treatment was effective at reducing beak growth post treatment. Healing occurred post treatment in both strains as evident by complete regeneration of the epithelium and a reduction in inflammation

Assessing the effect of starch digestion characteristics on ileal brake activation in broiler chickens.

The objective of this research was to evaluate activation of the ileal brake in broiler chickens using diets containing semi-purified wheat (WS; rapidly and highly digested) and pea (PS; slowly and poorly digested) starch. Diets were formulated to contain six WS:PS ratios (100:0, 80:20, 60:40, 40:60, 20:80, 0:100) and each starch ratio was fed to 236 Ross 308 male broilers housed in 4 litter floor pens. At 28 d of age, the effect of PS concentration was assessed on starch digestion, digestive tract morphology, and digesta pH and short-chain fatty acid (SCFA) concentration. Glucagon-like peptide-1 (GLP-1) and peptide tyrosine-tyrosine (PYY) status were assessed in serum (ELISA) and via gene expression in jejunal and ileal tissue (proglucagon for GLP-1). Data were analyzed using regression analyses, and significance was accepted at P ≤ 0.05. Increasing dietary PS resulted in reduced starch digestibility in the small intestine, but had no effect in the colon. Crop content pH responded quadratically to PS level with an estimated minimum at 55% PS. Total SCFA increased linearly in the crop with PS level, but changed in a quadratic fashion in the ileum (estimated maximum at 62% PS). Ceacal SCFA concentrations were highest for the 80 and 100% PS levels. The relative empty weight (crop, small intestine, colon), length (small intestine) and content (crop jejunum, Ileum) of digestive tract sections increased linearly with increasing PS concentration. Dietary treatment did not affect serum GLP-1 or PYY or small intestine transcript abundance. In conclusion, feeding PS increased the presence of L-cell activators (starch, SCFA) and increased trophic development and content of the digestive tract, suggestive of L-cell activation. However, no direct evidence of ileal brake activation was found by measuring venous blood levels of GLP-1 or PYY or corresponding gene expression in small intestine tissue

Electroencephalographic, physiologic and behavioural responses during cervical dislocation euthanasia in turkeys

Abstract Background There is a critical need to develop appropriate on-farm euthanasia methods for poultry species. Euthanasia methods should affect the brain first causing insensibility, followed by cardiorespiratory arrest. Neck or cervical dislocation methods, either manual (CD) or mechanical (MCD), are reported to cause a prolonged time to loss of sensibility and death with inconsistent results upon application, especially MCD methods. However, there is limited information on cervical dislocation in turkeys. The overall objective of this study was to assess the welfare implications of CD and a newly developed MCD device for euthanasia of cull turkeys in comparison with intravenous (IV) pentobarbital sodium (1 mL/4.5 kg), the gold standard euthanasia method. Time to death using electroencephalographic (EEG) and behavioural responses were monitored in eight and eighteen week-old turkeys for five minutes after each euthanasia method application. Spectral analyses of EEG responses and onset of isoelectric EEGs were compared to baseline EEG recordings of birds under anesthesia and behavioural responses were studied among euthanasia treatments. A significant decrease in brain activity frequencies analysis and isoelectric EEG were recorded as time of brain death. Results All turkeys euthanized with IV pentobarbital sodium presented a rapid and irreversible decrease in the EEG activity at approximately 30s post-injection with minimal behavioural responses. CD and MCD methods caused EEG responses consistent with brain death at approximately 120 s and 300 s, respectively. Additionally, isoelectric EEGs resulted in all pentobarbital sodium and CD groups, but only in 54 and 88% of the eight and eighteen week-old turkeys in the MCD groups, respectively. There were few clear patterns of behavioural responses after CD and MCD application. However, cessation of body movement and time to isoelectric EEG after CD application were positively correlated. Conclusions Use of CD and MCD resulted in a prolonged time to death in both age groups of turkeys. MCD application presents a number of welfare risks based on electroencephalographic and behavioural findings. Intravenous pentobarbital sodium induced rapid brain death, but possesses several on-farm limitations. To develop improvements in cervical dislocation methods, further investigations into combined or alternative methods are required to reduce the prolonged time to insensibility and death

Evaluation of Two Models of Non-Penetrating Captive Bolt Devices for On-Farm Euthanasia of Turkeys

On-farm euthanasia is a critical welfare issue in the poultry industry and can be particularly difficult to perform on mature turkeys due to their size. We evaluated the efficacy of two commercially available non-penetrating captive bolt devices, the Zephyr-EXL and the Turkey Euthanasia Device (TED), on 253 turkeys at three stages of production: 4–5, 10, and 15–20 weeks of age. Effectiveness of each device was measured using both ante- and post-mortem measures. Application of the Zephyr-EXL resulted in a greater success rate (immediate abolishment of brainstem reflexes) compared to the TED (97.6% vs. 89.3%, p = 0.0145). Times to last movement (p = 0.102) and cardiac arrest (p = 0.164) did not differ between devices. Ante- and post-mortem measures of trauma and hemorrhage were highly correlated. Skull fractures and gross subdural hemorrhage (SDH) were present in 100% of birds euthanized with both the Zephyr-EXL and TED devices. Gross SDH scores were greater in birds killed with the Zephyr-EXL than the TED (p < 0.001). Microscopic SDH scores indicated moderate to severe hemorrhage in 92% of turkeys for the Zephyr-EXL and 96% of turkeys for the TED, with no difference between devices (p = 0.844). Overall, both devices were highly effective inducing immediate insensibility through traumatic brain injury and are reliable, single-step methods for on-farm euthanasia of turkeys