The efficacy of three on-farm euthanasia methods for broiler chickens throughout the production cycle.

1. There is a need to humanely kill moribund or injured broiler birds on-farm with no reasonable chance of recovery. Two experiments evaluated the efficacy of three commercially applicable killing methods; manual cervical dislocation (CD), mechanical cervical dislocation with the Koechner Euthanising Device (KED) and a non-penetrative captive bolt device (Zephyr-EXL; ZEXL), at 7, 21 or 35 d of age, on their ability to induce insensibility (unconsciousness and loss of brain stem reflexes) and death.2. Experiment one assessed the damage to the cranial-cervical region resulting from the methods applied to cadavers of cull birds (n = 180) by radiography and gross pathology observation.3. Experiment two evaluated the latency to insensibility and death when cull broiler birds (n = 240) were killed by CD, KED or ZEXL, using behavioural and reflexive indicators. Insensibility and death were measured by the absence of pupillary light, palpebral blink and nictitating membrane reflexes and cessation of rhythmic breathing, cloacal winking and convulsions. Analysis of variance for the main effect of the method was performed to determine the differences.4. In experiment one, only the Zephyr resulted in skull fractures. A higher number of vertebral fractures occurred with KED application compared to CD, at 21 and 35 d.5. In experiment two, indicators of sensibility were absent earliest with the ZEXL (µ < 2 s); then,CD (µ = 28 s) and were longest with KED (µ = 47 s), at 21 and 35 d. Cloacal winking and convulsions ceased earlier after CD (88 s), compared to either KED (124 s) or Zephyr (118 s). Death after a single application occurred 100%, 100% and 98% of time for CD, KED and ZEXL, respectively.6. Overall, all methods were efficacious at inducing insensibility and death. Insensibility occurred earliest with ZEXL, whilst death occurred earliest with CD. KED resulted in the longest time to insensibility and death.

Short communication: limit feeding affects behavior patterns and feeding motivation of dairy heifers.

The study objective was to assess the effects of limit feeding dairy heifers on behavior patterns and feeding motivation. Ten Holstein heifers (291.6±39.2d of age, weighing 324.2±61.2kg; mean ± SD) were exposed to each of 2 dietary treatments, in a random order, over 2 successive 26-d treatment periods (14-d adaptation period and a 12-d data collection period) using a crossover design: (1) a high-forage total mixed ration (TMR), provided ad libitum (CON) and (2) a low-forage TMR, limit-fed at 2.05% body weight (LF). Heifers were fed daily at 1100h and motivation to access a low-nutritive feedstuff (straw) was assessed using a push-door apparatus at 2 time points: 3h after feed delivery (1400h) and 21h after feed delivery (0800h). The amount of weight pushed, weight pushed as percentage of body weight, and latency to access the push door were recorded on 3 different days for each heifer at each time point on each treatment. When fed CON, heifers had greater dry matter intake (12.9 vs. 7.2kg/d), greater feeding time (209.3 vs. 82.4min/d), greater ruminating time (452.2 vs. 318.3min/d), and slower rates of intake (0.06 vs. 0.09kg of dry matter/min) than when fed LF. Heifers fed LF pushed more weight as a percentage of body weight at 3h (4.5 vs. 1.9%) and 21h (9.3 vs. 2.8%) after feed delivery. At both 3 and 21h after feed delivery, latency to access the door was shorter for the LF heifers compared with the CON heifers (65 vs. 145 s). These results indicate that, in addition to decreasing feeding time, limit feeding increases motivation of heifers to access a low-nutritive feedstuff, possibly due to lack of satiety resulting from lack of physical fill or insufficient time spent foraging.

Short communication: effects of frequency of feed delivery and bunk space on the feeding behavior of limit-fed dairy heifers.

The objective of this experiment was to determine the interaction between feed bunk space and frequency of feed provision on the feeding behavior patterns and growth of growing dairy heifers fed a limited amount. Sixteen Holstein dairy heifers (183.4 ± 9.1 d of age, mean ± standard deviation) were divided into 4 groups of 4. The groups were exposed to each of 4 treatments, using a 4 × 4 Latin square design with a 2 × 2 factorial arrangement of treatments, over 21-d periods (14-d adaptation period, 7-d data collection periods). The treatments were arranged in 2 feed delivery frequencies (once per day at 1200 h: 1 ×/d, and twice per day at 1200 and 1400 h: 2 ×/d) and 2 levels of feed bunk space (adequate feed bunk space: 0.40 m/heifer, and reduced feed bunk space: 0.29 m/heifer). Pen dry matter intake (DMI) was recorded daily, average daily gain (ADG) was recorded weekly, and variability in ADG was calculated from the standard deviation of ADG. Feeding, unrewarded behavior (time at feed bunk without feed present), and competitive behavior were recorded using time-lapse video. Feeding and unrewarded behavior were measured for the last 7 d of each period, whereas competitive behavior was recorded on d 16, 18, and 20 of each period. Lying time was recorded for the last 7 d of each period. A tendency for interaction between feed bunk space and frequency of feed delivery on the feed efficiency of limit-fed dairy heifers was noted. Heifers provided restricted bunk space were reported as being less efficient when fed 2 ×/d; however, no other interactions were found. Although DMI and variability in ADG were similar between treatments, ADG was higher (1.0 vs. 0.9 kg/d) when heifers were provided with 0.40 m of feed bunk space and tended to be higher when fed 1 ×/d compared with that of heifers given restricted bunk space or fed 2 ×/d. Heifers fed 1 ×/d spent more time feeding throughout the day (70.5 vs. 58.9 min/d) than heifers fed 2 ×/d. Heifers fed at a restricted bunk space or fed 1 ×/d were approximately 25% more variable in feeding time than heifers fed 2 ×/d or with adequate bunk space. Heifers spent a similar amount of time in unrewarded visits to the feed bunk (28.9 min/d). Although feed bunk space did not affect competition (3.6 displacements/d), heifers fed 1 ×/d were displaced twice as frequently than heifers fed 2 ×/d. Regardless of treatment, heifers spent a similar amount of time lying down and standing without eating. Overall, providing sufficient feed bunk space to allow all limit-fed heifers to feed simultaneously improves feed efficiency and ADG and reduces variability in feeding time. Additionally, although delivering feed 1 ×/d resulted in increased competition, it also enabled heifers to gain adequate weight and spend more time feeding each day.

Growing dairy heifers prefer supplementary long straw when fed a nutrient-dense ration in a limited amount.

The objective of this study was to determine whether limit-fed heifers will choose to consume long particles, rather than short, of a low-nutritive feedstuff to ameliorate rumen function and meet foraging needs. Ten Holstein heifers 261.6 ± 39.2 (mean ± SD) d of age were exposed to each of 2 dietary treatments, in a random order, over 2 successive 7-d treatment periods (4-d adaptation period and a 3-d data collection period) using a crossover design. The treatments were (1) a provision of long particle oat straw (85% of particles>8mm; LS) and (2) provision of short particle oat straw (45% of particles >8mm; SS). Both treatments were offered following consumption of a limit-fed, nutrient-dense total mixed ration fed at 2.05% of body weight. Following each 7-d period, heifers were given access to both types of straw during an additional 2-d preference period; individual intakes were recorded daily. Feeding and lying behavior were recorded during the last 3d of each treatment period. Ruminal temperature was recorded during the last 3d of each treatment period using a telemetric acquisition system and rumen boluses. Dry matter intake of both the total mixed ration (6.3 kg/d) and straw (0.36 kg/d) was similar between treatments. Heifers fed LS spent more time feeding (197.7 vs. 175.2 min/d) throughout the day than heifers fed SS due to the increase in time required to consume long particles in the LS (59.8 vs. 34.2 min/d). Daily lying time (974.7 min/d) and time spent standing without eating (278.9 min/d) was similar between treatments. The preference period showed a strong preference ratio for LS rather than SS (preference ratio=0.83), with heifers consuming 0.43 ± 0.2 kg/d of LS and 0.07 ± 0.1 kg/d of SS (mean ± SD). Heifers maintained similar mean (38.3°C), minimum (35.1°C), and maximum (38.9°C) rumen temperature across treatments. The amount of time that rumen temperature was elevated over 38.6°C, 39.0°C, and 39.4°C was similar between treatments. In conclusion, heifers will consume similar amounts of supplementary long or short straw if provided to them alongside of a limit-fed TMR. Limit-fed heifers do, however, show a clear preference for LS when offered the choice, suggesting that they find LS to be more satisfactory for achieving rumen fill or meeting their behavioral foraging needs.

Efficacy of three different cervical dislocation methods for on-farm killing of layer chicks.

Unfit chicks with low viability are often euthanized in the layer industry. An effective euthanasia protocol is characterized by rapid, irreversible insensibility, followed by prompt death. This study was conducted to evaluate the efficacy of three cervical dislocation methods for killing layer chicks (2-3-day-old, avg BW ± SD; 44 ± 3 g, n = 40): manual cervical dislocation (CD), assisted manual cervical dislocation (ACD; the bird's ventral neck is placed on a blunt table edge and the back of the neck pressed firmly), and mechanical cervical dislocation by Koechner Euthanizing Device (KED-model-S). All three killing methods were assessed on anesthetized chicks (intramuscular injections of medetomidine [0.3 mg/kg BW] and ketamine [30 mg/kg BW] were used to induce clinical anesthesia). CD and ACD were also evaluated using conscious chicks to compare the killing methods and to determine the effect of anesthesia on response variables. There were no differences in time to loss of pupillary light reflex, cessation of heartbeat, or duration of gasping between conscious chicks killed with CD and ACD, but these values were all longer for conscious compared to anesthetized chicks. KED resulted in longer latencies to loss of pupillary light reflex, cessation of heartbeat, and duration of gasping. Radiographs revealed that both CD and ACD resulted in cervical luxation, mainly below the C4 vertebra, whereas KED did not cause luxation in any of the 8 chicks tested. Chicks killed by CD and ACD presented more subdural hemorrhage (SDH) at the site of cervical dislocation than those killed by KED. None of the killing methods resulted in brain trauma. Compared to CD and ACD, KED resulted in longer latency to brain death and less anatomical pathology indicating a lower efficacy of KED as an on-farm killing method.

Using time to insensibility and estimated time of death to evaluate a nonpenetrating captive bolt, cervical dislocation, and blunt trauma for on-farm killing of turkeys.

The effectiveness of a pneumatic nonpenetrating captive bolt (Zephyr) was assessed for on-farm euthanasia of turkeys and compared with blunt force trauma, manual cervical dislocation, and mechanical cervical dislocation using a burdizzo. The Zephyr (n = 46) and burdizzo (n = 26) were evaluated in turkey hens (11.4 +/- 0.1 kg), the Zephyr (n = 46) and blunt trauma (n = 32) were evaluated in turkey toms (13.1 +/- 0.2 kg), and the Zephyr (n = 12), blunt trauma (n = 11), and manual cervical dislocation (n = 7) were evaluated in broiler turkeys (4.1 +/- 0.3 kg). The nictitating membrane and pupillary light reflexes were monitored continuously to determine when insensibility occurred. Time of death was estimated based on the end time of convulsions and sustained absence of breathing. The nictitating membrane reflex was present immediately after treatment in all 26 hens killed with a burdizzo versus 8 of 46 hens killed with the Zephyr (P < 0.001). The presence of eye reflexes did not differ between the Zephyr and blunt trauma for toms (1 of 26 toms killed with blunt trauma, 2 of 44 toms killed with the Zephyr, P = 1.0). The nictitating membrane reflex persisted in a greater proportion of broiler turkeys killed with cervical dislocation (7 of 7) versus the Zephyr (0 of 12, P < 0.001) and blunt trauma (2 of 9, P = 0.003) but did not differ between blunt trauma and the Zephyr (P = 0.2). End time of convulsions did not differ between the Zephyr and burdizzo for hens (204 +/- 8 vs. 114 +/- 10 s, P = 0.5) or between the Zephyr and blunt trauma for toms (200 +/- 7 s vs. 218 +/- 11.8 s, P = 0.4) but was shorter after cervical dislocation in broiler turkeys (cervical dislocation: 138 +/- 13 s, Zephyr: 165 +/- 7 s, blunt trauma: 178 +/- 13 s, P < 0.001). Results demonstrated that the Zephyr (discharged twice in immediate succession) and blunt trauma (single hit) were similarly effective at consistently causing immediate insensibility. Conversely, neither method of cervical dislocation caused immediate insensibility. This study may assist in revising current poultry euthanasia recommendations.

The effect of alternative feeding strategies on the feeding motivation of broiler breeder pullets.

Due to genetic selection for fast growth and high breast meat yield, commercial strains of broiler chickens and broiler breeders are predisposed to high feed intake; however, feeding broiler breeders ad libitum impairs their health and reproductive performance. Broiler breeders are feed-restricted throughout rearing to maintain health and performance, yet feed restriction results in hunger, feeding frustration and lack of satiety. The objective of this study was to examine the effect of alternative feeding strategies, including feed additives (separately or combined) and a fixed non-daily feeding schedule, on the feeding motivation and welfare of broiler breeders during rearing. At 3 weeks of age, 180 Ross 308 breeder pullets were allocated to 90 cages and fed with one of five isocaloric treatments: (1) daily control diet (control), (2) daily calcium propionate diet (CaP), (3) daily soybean hull diet (SBH), (4) daily alternative diet (alternative: CaP + SBH) and (5) 4/3 control diet (four on-feed days and three non-consecutive off-feed days per week). The CaP diet included calcium propionate at 1.4% from 3 to 6 weeks of age, and at 3.2% from 7 to 12 weeks of age, and the SBH diet contained soybean hulls included at 40%. The alternative diet included both soybean hulls and calcium propionate at the same inclusion rate as the SBH and CaP diets, respectively. Pullets were weighed and scored for feather coverage every week. A feed intake test was conducted at 3, 4, 8, 10 and 11 weeks of age for 10 min during on- and off-feed days. At 12 weeks of age, feather samples were analysed for fault bars. Data were analysed using linear mixed regression models, with cage nested in the models and age as a repeated measure. At 4 weeks of age, pullets fed soybean hull-enriched diets (SBH and alternative diets) and those on the 4/3 schedule had lower feed intake than control pullets (P = 0.02). Feathers from pullets fed the SBH diet had fewer fault bars than those fed the CaP diet (P = 0.04). The results indicated that the inclusion of soybean hulls (alone or combined with calcium propionate) and a 4/3 feeding schedule can reduce feeding motivation of broiler breeders during early rearing.

Strain differences and effects of different stocking densities during rearing on the musculoskeletal development of pullets.

There are few published studies on the effect of stocking density (SD) of pullets, particularly between different genetic lines. The objectives of this study were to determine if strain or SD affects musculoskeletal development of pullets and determine any impact on the productivity and keel bone health of adult hens. Lohmann Selected Leghorn Lite (LSL), Dekalb White (DW), and Lohmann Brown (LB) pullets were reared at 4 different SD (247 cm2/bird, 270 cm2/bird, 299 cm2/bird, and 335 cm2/bird) in large cages furnished with elevated perches and a platform. At 16 wk of age, the keel bone, the muscles of the breast, wings, and legs, and the long bones of the wings and legs were collected to compare keel bone development, muscle growth, and bone breaking strength (BBS) between strain (adjusted for bodyweight) and SD treatments. Stocking density did not have an effect on the metasternum length, height, or area of the keel bone, the weights of the bicep brachii, pectoralis major or pectoralis minor, or the BBS of any of the selected bones. However, strain differences were found for all keel bone characteristics, all muscle weights, and the majority of BBS measures. The keel metasternum, height, and overall area of the keel bone were found to be smaller in LB pullets compared with LSL and DW pullets (P < 0.0001); however, cartilage length and overall percentage of the cartilage present on the keel bone was greatest in LB pullets (P < 0.0001). Leg muscles were heaviest in LB pullets (P < 0.05); however, breast muscles were heavier in LSL and DW pullets (P < 0.0001). Lohmann Brown pullets had lower BBS of the tibia (P < 0.0001) and femur (P < 0.0001) compared with LSL and DW pullets, whereas DW pullets had greater BBS of the humerus (P = 0.033). Additionally, there was a higher prevalence of keel bone fractures at 50 wk of age in LB hens compared with DW (P = 0.0144). Overall, SD during rearing used in this study had little impact on the musculoskeletal growth of pullets; however, significant differences were found between strains which may reflect strain-specific behavior. Additionally, differences in keel bone development between strains may lead to differences in keel bone damage in adult hens.

Defining characteristics of immersion carbon dioxide gas for successful euthanasia of neonatal and young broilers.

This study investigated how the carbon dioxide (CO2) concentration within a chamber affects the efficacy of CO2 euthanasia and how the efficacy of CO2 induction methods changes as birds age. In experiment 1, pairs of broiler chicks (n = 192; 0, 3, and 6 D of age) were immersed into a chamber prefilled with 70, 80, 90, or 100% CO2. For experiment 2, 3- and 6-day-old broiler chicks (n = 88) were immersed in pairs into 100% CO2 or exposed to CO2 gradual fill in a chamber with a displacement rate of 28% chamber volume per minute. Latency to performance of headshaking (HS) and gasping (GS) as potential indicators of distress, loss of posture indicative of insensibility, and the cessation of rhythmic breathing (CRB) and cessation of movement (COM) as the indicators of death were monitored (live focal sampling/video recordings). The duration and frequency of HS and GS were assessed. For both experiments, behavior data were analyzed for CO2 method and age (4 × 3 factorial). Age and CO2 concentration interacted for latency to CRB and COM, with longer latencies for 0-day-old chicks immersed into 70% CO2 than other concentrations and ages. CO2 concentration did not affect latency to HS, GS, or loss of posture but affected CRB and COM, with latencies longest for 70% and shortest for 90 and 100% CO2. Newly hatched chicks had a longer latency to CRB and COM and longer duration and frequency of distress behaviors than older chicks. At all ages, initiation of all behaviors occurred later with gradual fill compared to immersion. There was an increased duration and frequency of distress behaviors with gradual induction compared with immersion. Overall, immersion into 90 to 100% CO2 resulted in the shortest time to insensibility and death, with a decreased duration and frequency of distress behaviors. Chicks immersed into 70% CO2 had the longest duration of GS and time to death. Age affects the efficacy of CO2 euthanasia, with increasing age decreasing time to death and the duration and frequency of distress behaviors.

Effects of rearing and adult laying housing systems on medullary, pneumatic and radius bone attributes in 73-wk old Lohmann LSL lite hens1.

We determine interactive effect of a combined model of housing systems for rearing pullets and raising adult birds on bone quality. The LSL-Lite pullets were reared in either an aviary system (A) or conventional cages (C). At week 16, the birds were transferred either to the same housing type through the adult stage (A-A or C-C, for rearing and adult phase, respectively) or to enriched system (A-E or C-E, respectively). In the rearing stage, C cages housed 16 pullets/cage (week 0 to 6) and 8 pullets/cage (week 6 to 16) with a space allowance of 145 and 290 cm2/pullet, respectively; the rearing aviary housed 756 pullets/enclosure allowing 285 cm2/pullet (week 0 to 6) and 754 cm2/pullet (week 6 to 16). In the adult phase, C cages were 58.4 cm wide × 66.0 cm deep (482 cm2/pullet, 8 pullets/cage). For adult A, a commercial multi-tier aviary provided a space allowance >1000 cm2/hen system with litter area. Enriched system housed 60 birds/cage at 750 cm2/bird with perches, nest, and scratch mat. Bone samples were collected from the adult phase (week 73) and analysed for bone quality indices including bone breaking strength (BBS), total bone weight (TBW), ash content of the medullary (femur and tibia), pneumatic (humerus and keel), and radius bones. The A-A hens had the greatest (P < 0.05) TBW for medullary (femur and tibia) and pneumatic (humerus and keel) bones compared with hens from other housing models with exception of C-E hens. In addition, ash content was heavier (P = 0.048) for both A-A and C-E managed birds compared to the other housing. Birds in C-C system had the least score (P < 0.05) for TBW and ash content in all bone types. Regardless of the housing system, BBS was correlated (r = 0.60; P < 0.01) with the amount of ash and TBW, particularly for humerus and tibia. The results provide an insight on the impact of type of housing system in rearing and production stages on late cycle bone quality.

The effect of alternative feeding strategies for broiler breeder pullets: 2. Welfare and performance during lay.

Feeding broiler breeders to satiety has negative consequences on their health and reproduction. Alternative feeding strategies during rearing can improve welfare, although their implications during lay are not well understood. The objective was to examine the effect of rearing feeding treatments on the reproductive performance and feeding behavior of broiler breeders under simulated commercial conditions. At 3 wk of age, 1,680 Ross 308 pullets were allocated to 24 pens under 1 of 4 isocaloric treatments: 1) daily control diet; 2) daily alternative diet (40% soybean hulls and 1 to 5% calcium propionate); 3) 4/3 control diet (4 on-feed days, 3 non-consecutive off-feed days per week); and 4) graduated control diet. Feeding frequency of the graduated treatment varied with age and finished on a daily basis. At 23 wk of age, group sizes were adjusted to 40 hens, and 5 mature Yield Plus Males roosters were introduced to each pen. Pens were under the same daily feeding management and same diet during lay. The performance of broiler breeders (growth rate, body weight uniformity, and reproductive performance) was determined until 64 wk of age. At the end of lay, feeding motivation was examined with a feed intake test and a compensatory feeding test. Data were analyzed using linear mixed regression models, with pen nested in the models and age as a repeated measure. The laying rate of hens reared on the graduated treatment decreased slower compared to control hens, resulting in a higher cumulative egg production (178.2 ± 3.8 eggs/hen) than control hens (165.2 ± 3.8 eggs/hen, P < 0.01) by 64 wk of age. Hens reared on non-daily feeding treatments laid lighter eggs with relatively heavier yolks and had higher feed intake at the end of lay than hens fed daily during rearing (P = 0.02). In conclusion, rearing feeding treatments impacted the growth rate and body weight uniformity during lay, feeding motivation at the end of lay, and the laying rate and hatchability depending on hens' age.

The effects of floor space and nest box access on the physiology and behavior of caged laying hens.

Confinement housing appears to be at the forefront of concern about laying hen welfare. This experiment examined the effects of floor space during rearing (315 or 945 cm2/bird) and adulthood (542 or 1648 cm2/bird) and access to a nest box on the welfare of caged laying hens. Measurements of the normality of biological functioning, such as plasma, egg albumen and yolk and fecal corticosterone concentrations, and heterophil to lymphocyte ratios, behavioral time budgets, mortality and efficiency of productivity, and measurement of hen preferences, such as choice behavior in Y maze tests, were used to assess hen welfare. There were no effects of treatment on physiological measurements. Hens given less space during adulthood spent less time mobile, inedible pecking, drinking, and preening and spent more time resting and feed pecking and sitting (P < 0.05). Hens with access to a nest box spent more time resting (P = 0.046) and less time sham dust bathing (P = 0.044) than hens without access to a nest box. There were no effects of space allowance on choice behavior for space or a nest box over food; however, hens with access to a nest box chose the nest box over food more than hens without access to a nest box (P = 0.0053). The present experiment provides no convincing evidence that either reducing space allowance in adulthood from 1648 to 542 cm2/bird or eliminating access to a nest box results in disruption of biological function. Less space and no access to a nest box did not increase the choice for more space or a nest box, respectively, over food in the preference tests. However, reduced floor space reduced behavioral freedom and denying access to a nest box eliminated the opportunity for the motivated behavior of laying their eggs in a discrete enclosed nest box, both of which presumably provide hens with the opportunity for positive affective experiences.

Evaluation of carbon dioxide induction methods for the euthanasia of day-old cull broiler chicks.

This study was conducted to evaluate the efficacy of 5 different CO2 euthanasia induction techniques for day-old cull chicks in minimizing distress and inducing a rapid loss of sensibility and death. Each induction treatment was characterized for concentration change over time, maximum concentration, and time to reach maximum. Sixteen chicks were euthanized with the gradual treatments to establish validity of treatment. Then, all 5 treatments were evaluated for effect on distress, insensibility, and death. Day-of-hatch cull chicks (n = 110) were euthanized in pairs by either immersion into 100% CO2 or gradual induction to 100% CO2 at displacement rates of 7, 14, 21, or 28% of chamber volume added per min (% vol/min). CO2 concentration was measured at chick level. Live focal observations and video recordings were used to assess latency to behavioral responses: head shaking (HS) and gasping (GS) as indicators of distress; loss of posture (LOP) as an indicator of insensibility; and cessation of rhythmic breathing (CRB) and movement (COM), indicating death. All behaviors occurred at the earliest with immersion compared to gradual treatments, and time between first signs of distress and LOP was shorter for immersion than gradual treatments. Gradual treatments showed a linear decrease in latency to HS, GS, and LOP as displacement rate increased. Latency to CRB decreased quadratically with increasing displacement rate, while COM decreased linearly. Within gradual treatments, HS and GS occurred at CO2 concentrations between 0.43 and 1.14%, LOP between 11.1 and 17.5%, while CRB and COM occurred between 61.8 and 78.4%. Overall, immersion induced distress, insensibility, and death significantly faster and with the shortest interval between distress and insensibility. For gradual treatment, insensibility and death occurred faster with increasing displacement rates. Behavioral signs of distress were observed with all treatments, and occurred at concentrations lower than those causing insensibility. In conclusion, immersion into 100% CO2 environment resulted in the shortest time of distress and fastest time to death compared to gradual displacement rates of any speed measured.

Modelling quality variations in commercial Ontario pork production.

This study explores the interactions of sensory and nutritional environment with genotype occurring in current commercial pork production in Ontario, Canada, which may interact to result in poor quality meat. The study focussed on identifying factors and signalling mechanisms that contribute to poor meat quality, in order to develop strategies to reduce the incidence of unacceptable product quality. In the first phase of the work reported here, animal behaviour and muscle metabolism studies were related to meat colour, tenderness and water-holding capacity measurements from commercially-produced pigs killed in a commercial packing plant. A partial least squares analysis was used to determine the most important of the principal production variables, peri-mortem biochemical measures and post-mortem carcass condition variables studied, in terms of their influence on water-holding, toughness and colour (L*-value). Variations between producer and kill day at the slaughterhouse were very strong contributors to variability in these three meat quality parameters, followed by pH variations. A second phase of the study is currently underway to characterize patterns of gene expression related to extremes of end-product quality and to reduce quality variations by nutritional and behavioural management strategies.

Opportunities for exercise during pullet rearing, Part II: Long-term effects on bone characteristics of adult laying hens at the end-of-lay.

Osteoporosis in laying hens has been a production and welfare concern for several decades. The objective of this study was to determine whether differing opportunities for exercise during pullet rearing influences long-term bone quality characteristics in end-of-lay hens. A secondary objective was to assess whether differing opportunities for exercise in adult housing systems alters bone quality characteristics in end-of-lay hens. Four flock replicates of 588 Lohmann Selected Leghorn-Lite pullets were reared in either conventional cages (Conv) or an aviary rearing system (Avi) and placed into conventional cages (CC), 30-bird furnished cages (FC-S), or 60-bird furnished cages (FC-L) for adult housing. Wing and leg bones were collected at the end-of-lay to quantify bone composition and strength using quantitative computed tomography and bone breaking strength (BBS). At the end-of-lay, Avi hens had greater total and cortical cross-sectional area (P < 0.05) for the radius and tibia, greater total bone mineral content of the radius (P < 0.001), and greater tibial cortical bone mineral content (P = 0.029) than the Conv hens; however, total bone mineral density of the radius (P < 0.001) and cortical bone mineral density of the radius and tibia (P < 0.001) were greater in the Conv hens. Hens in the FC-L had greater total bone mineral density for the radius and tibia (P < 0.05) and greater trabecular bone mineral density for the radius (P = 0.027), compared to hens in the FC-S and CC. Total bone mineral content of the tibia (P = 0.030) and cortical bone mineral content of the radius (P = 0.030) and tibia (P = 0.013) were greater in the FC-L compared to the CC. The humerus of Conv hens had greater BBS than the Avi hens (P < 0.001), and the tibiae of FC-L and FC-S hens had greater BBS than CC hens (P = 0.006). Increased opportunities for exercise offered by the aviary rearing system provided improved bone quality characteristics lasting through to the end-of-lay.

Opportunities for exercise during pullet rearing, Part I: Effect on the musculoskeletal characteristics of pullets.

Increased load-bearing exercise improves bone quality characteristics in a variety of species, including laying hens. Providing increased opportunities for exercise during the pullet rearing phase, a period of substantial musculoskeletal growth, offers a proactive approach to reducing osteoporosis by improving bone composition. The main objective of this study was to determine whether differing opportunities for exercise during rearing influences pullet musculoskeletal characteristics. Two flock replicates of 588 Lohmann Selected Leghorn-Lite pullets were reared in either standard, conventional cages (Conv) or an aviary rearing system (Avi) from day-old chicks until 16 wk of age. The keel bone and the muscles and long bones of the wings and legs were collected at 16 wk to measure muscle growth differences between rearing treatments and quantify bone quality characteristics using quantitative computed tomography (QCT) and bone breaking strength (BBS) assessment. Keel bone characteristics and muscle weights were adjusted for BW and analyses for QCT and BBS included BW as a covariate. At 16 wk of age, rearing system had an effect on the majority of keel bone characteristics (P < 0.05). The length of the keel metasternum, caudal tip cartilage length, and the overall percentage of cartilage present on the keel at 16 wk was greater in the Avi pullets compared to the Conv pullets (P < 0.01). Wing and breast muscle weights of the Avi pullets were greater than the Conv pullets (P < 0.001), but leg muscle weights were greater in the Conv pullets (P = 0.026). Avi pullets had greater total bone density, total cross-sectional area, cortical cross-sectional area, total bone mineral content, and cortical bone mineral content than Conv pullets for the radius, humerus, and tibia (P < 0.001). Avi pullets had greater BBS compared to the Conv pullets for the radius, humerus, and tibia (P < 0.01). Increased opportunities for exercise offered by the aviary rearing system increased muscle and bone growth characteristics in pullets at 16 wk of age.

Rearing system affects prevalence of keel-bone damage in laying hens: a longitudinal study of four consecutive flocks.

High flock-level prevalence of keel-bone fractures and deviations in laying hens are commonly reported across various housing systems; however, few longitudinal studies exist, especially for furnished and conventional cage systems. Load-bearing exercise improves bone strength and mineral composition in laying hens and has the potential to reduce keel-bone damage, especially if exercise is allowed during critical periods of bone growth throughout the pullet rearing phase. The objective of this study was to determine the prevalence of keel-bone damage in laying hens housed in furnished and conventional cages, and assess whether opportunities for exercise during the pullet rearing phase influenced the prevalence of keel-bone damage throughout the laying period. Four flock replicates of 588 Lohmann Selected Leghorn-Lite pullets/flock were reared in either conventional cages (Conv) or an aviary rearing system (Avi) and placed into conventional cages (CC), 30-bird furnished cages (FC-S) or 60-bird furnished cages (FC-L) for adult housing. Keel-bone status was determined by palpation at 30, 50, and 70 wk of age. Age (P < 0.001) and rearing system (P < 0.001) had an effect on the presence of keel-bone fractures. The presence of fractures increased with age, and hens raised in the Avi system had a lower percentage of fractures (41.6% ± 2.8 SE) compared to hens reared in the Conv system (60.3% ± 2.9 SE). Adult housing system did not have an effect on the percentage of keel fractures (P = 0.223). Age had an effect on the presence of deviations (P < 0.001), with deviations increasing with age. Rearing system (P = 0.218) and adult housing system (P = 0.539) did not affect the presence of deviations. Keel fractures and deviations were strongly associated with each other at all ages: 30 wk: (P < 0.001); 50 wk: (P < 0.001); and 70 wk: (P < 0.001). Increased opportunities for exercise provided by an aviary rearing system reduced the prevalence of keel-bone fractures through the end-of-lay.

Development of perching behavior in 3 strains of pullets reared in furnished cages.

Furnished rearing cages are becoming more widely available to replace conventional systems for pullets. To date, there is little information on how pullets develop perching behavior in furnished cages or how this varies among strains. The objective of this study was to evaluate the use of perches and a platform in a commercial furnished rearing "Combi-Cage" system by 3 pure-bred heritage strains of pullets (Rhode Island Red, Columbian Rock, and White Leghorn). Each cage had 4 elevated locations: one platform and 3 perches of differing heights and positions in the cage. The length of each cage was visually divided into 4 sections for observation. The number of birds using each section in each location was counted by one observer d per wk at 1200 h (d) from one to 14 wk of age and at 1600 h (night) right after lights were turned off from 4 to 14 wk of age. Mixed model repeated analyses were used to test effects of strain, age, and their interaction on the use of the platform, the 3 perches, and all 4 locations combined (vertical space use) at both time periods. GLM were used to compare overall use of the sections and locations. On average, pullets used vertical space more during the d than at night. There were also effects of age (P < 0.05) and strain (P < 0.05) on the use of the 4 locations in the cage at both time periods. Generally, the Columbian Rocks used the perches and platform the most, and Rhode Island Reds the least. The highest perch in the cage was rarely used and birds showed a preference for perching in sections that were closest to cage walls (P < 0.05). Differences across strains and low use of some perch locations indicate that the design of furnished rearing cages may still require improvements in order to ensure the furnishings are used by pullets as intended.

Effect of space allowance and cage size on laying hens housed in furnished cages, Part I: Performance and well-being.

There are few published data on the effects of housing laying hens at different densities in large furnished cages (FC; a.k.a. enriched colony cages). The objective of this study was to determine the effects of housing laying hens at 2 space allowances (SA) in 2 sizes of FC on measures of production and well-being. At 18 wk of age, 1,218 LSL-Lite hens were housed in cages furnished with a curtained nesting area, perches, and scratch mat, and stocked at either 520 cm2 (Low) or 748 cm2 (High) total floor space. This resulted in 4 group sizes: 40 vs. 28 birds in smaller FC (SFC) and 80 vs. 55 in larger FC (LFC). Data were collected from 20 to 72 wks of age. There was no effect of cage size (P = 0.21) or SA (P = 0.37) on hen day egg production, egg weight (PSize = 0.90; PSA = 0.73), or eggshell deformation (PSize = 0.14; PSA = 0.053), but feed disappearance was higher in SFC than LFC (P = 0.005). Mortality to 72 wk was not affected by cage size (P = 0.78) or SA (P = 0.55). BW (P = 0.006) and BW CV (P = 0.008) increased with age but were not affected by treatment. Feather cleanliness was poorer in FC with low SA vs. high (P < 0.0001) and small vs. large FC (P < 0.0001). Feather condition was poorer in low SA (P = 0.048) and the best in small cages with high SA (P = 0.006), but deteriorated in all treatments over time (P < 0.0001). Treatments did not affect the breaking strengths of femur, tibia, or humerus, proportions of birds suffering keel deformations, or foot health scores. Overall, the SA studied in the 2 cage sizes in this trial had few effects on production parameters. However, stocking birds at the lower space allowance resulted in some measures of poorer external condition in both sizes of FC, which indicates that the welfare of hens housed at the lower space allowance may be compromised according to some welfare assessment criteria.

The effect of space allowance and cage size on laying hens housed in furnished cages, Part II: Behavior at the feeder.

Standards for feeder (a.k.a. feed trough) space allowance (SA) are based primarily on studies in conventional cages where laying hens tend to eat simultaneously, limiting feeder space. Large furnished cages (FC) offer more total space and opportunities to perform a greater variety of behaviors, which may affect feeding behavior and feeder space requirements. Our objective was to determine the effects of floor/feeder SA on behavior at the feeder. LSL-Lite hens were housed in FC equipped with a nest, perches, and a scratch mat. Hens with SA of either 520 cm2 (Low; 8.9 cm feeder space/hen) or 748 cm2 (High; 12.8 cm feeder space/hen) per bird resulted in groups of 40 vs. 28 birds in small FC (SFC) and 80 vs. 55 in large FC (LFC). Chain feeders ran at 0500, 0800, 1100, 1400, and 1700 with lights on at 0500 and off at 1900 hours. Digital recordings of FC were scanned at chain feeder onset and every 15 min for one h after (5 scans × 5 feeding times × 2 d) to count the number of birds with their head in the feeder. All occurrences of aggressive pecks and displacements during 2 continuous 30-minute observations at 0800 h and 1700 h also were counted. Mixed model repeated analyses tested the effects of SA, cage size, and time on the percent of hens feeding, and the frequency of aggressive pecks and displacements. Surprisingly, the percent of birds feeding simultaneously was similar regardless of cage size (LFC: 23.0 ± 0.9%; SFC: 24.0 ± 1.0%; P = 0.44) or SA (Low: 23.8 ± 0.9%; High: 23.3 ± 1.0%; P = 0.62). More birds were observed feeding at 1700 h (35.3 ± 0.1%) than any at other time (P < 0.001). Feeder use differed by cage area (nest, middle, or scratch) over the d (P < 0.001). The frequency of aggressive pecks was low overall and not affected by SA or cage size. Frequency of displacements was also low but greater at Low SA (P = 0.001). There was little evidence of feeder competition at the Low SA in this study.