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Domestic chickens may live in environments which restrict wing muscle usage. Notably, reduced wing activity and accompanying muscle weakness are hypothesized risk factors for keel bone fractures and deviations. We used radio-frequency identification (RFID) to measure duration spent at elevated resources (feeders, nest-boxes), ultrasonography to measure muscle thickness (breast and lower leg) changes, radiography and palpation to determine fractures and deviations, respectively, following no, partial (one-sided wing sling) and full (cage) immobilization in white- and brown-feathered birds. We hypothesized partially immobilized hens would reduce elevated resource usage and that both immobilization groups would show decreased pectoralis thickness (disuse) and increased prevalence of fractures and deviations. Elevated nest-box usage was 42% lower following five weeks of partial immobilization for brown-feathered hens but no change in resource usage in white-feathered birds was observed. Fully immobilized, white-feathered hens showed a 17% reduction in pectoralis thickness, while the brown-feathered counterparts showed no change. Lastly, fractures and deviations were not affected in either strain or form of wing immobilization; however, overall low numbers of birds presented with these issues. Altogether, this study shows a profound difference between white- and brown-feathered hens in response to wing immobilization and associated muscle physiology.

Effects of rearing cage type and dietary limestone particle size (LPS) on growth, apparent retention (AR) of nutrients, and bone quality were investigated. The treatments were arranged in a 2 × 3 factorial with cage (conventional, CON and furnished, FUR) and LPS (fine, < 0.595 mm, F; medium, 0.595 to < 1.68 mm, M; and 1:1 mixture of F and M wt/wt; FM). A total of 900-day-old Lohmann LSL-Lite chicks were placed in CON (20 chicks/cage) and FUR (30 chicks/cage) based on BW. The diets were formulated according to breeder's nutrient specifications for starter, grower, and developer phases. At the end of 4, 12, and 16 wk of age (woa), 2 pullets/cage were euthanized for samples. At 12 and 16 woa, 1 pullet/cage was transferred to metabolism cages for AR measurements. There was no interaction (P > 0.05) between cage type and LPS on response variables. At 4 woa, body (P = 0.002) and bone (P < 0.05) weight was higher for CON than FUR pullets, but this was reversed (P

Emerging market differentiation for broiler meat from strains exhibiting a range of growth rates is necessitating comparative research on various physiological and production aspects of these strains. The objective of the present study was to compare select gastrointestinal, tibial, and plasma attributes in a sample of 48-day-old (50 male and 50 female) broilers obtained from fast-and slow-growing flocks maintained under similar feed and management regimens. Eight birds were randomly selected from a fast (B; representative of modern commercial strains) and each of the 4 slow-growing strains (SG; D, H, M, and E). The strains differed by estimated time to reach 2.2 kg bodyweight corresponding to 36, 50, 42, 44, and 50 D for B, D, H, M, and E, respectively. Blood samples were collected to determine plasma metabolites, and birds were subsequently euthanized, weighed, and necropsied for gizzard and small intestine weight, jejunal tissue for histomorphology, ceca digesta samples for concentration of short-chain fatty acids (SCFA) and left tibia for ash content. Gizzard was heavier (P 0.05) strain differences on SCFA, jejunal villus height and crypt depth, plasma proteins, and electrolytes. Strains D, H, and M exhibited higher (P = 0.01) tibia ash concentration than B; E was intermediate and not different (P > 0.05) from any strain. Specifically, the tibia ash for B, D, H, SG 3, and E were 1.24, 1.44, 1.43, 1.49, and 1.39 g/kg BW, respectively. The B birds showed higher (P

Feather loss in domestic chickens can occur due to wear and tear, disease or bird-to-bird pecking. Flight feather loss may decrease wing use, cause pectoral muscle loss and adversely impact the keel bone to which these muscles anchor. Feather loss and muscle weakness are hypothesized risk factors for keel bone fractures that are reported in up to 98% of chickens. We used ultrasound to measure changes in pectoral muscle thickness and X-rays to assess keel bone fracture prevalence following symmetric clipping of primary and secondary feathers in white- and brown-feathered birds. Four and six weeks after flight feather clipping, pectoralis thickness decreased by approximately 5%, while lower leg thickness increased by approximately 5% in white-feathered birds. This pectoralis thickness decrease may reflect wing disuse followed by muscle atrophy, while the increased leg thickness may reflect increased bipedal locomotion. The lack of effect on muscle thickness in brown-feathered hens was probably due to their decreased tendency for aerial locomotion. Finally, pectoralis thickness was not associated with keel bone fractures in either white- or brown-feathered birds. This suggests that the white-feathered strain was more sensitive to feather loss. Future prevention strategies should focus on birds most susceptible to muscle loss associated with flight feather damage.

High fearfulness in commercial laying hens can negatively affect production parameters and animal welfare. Brown and white egg layers differ in several behavioral characteristics, though reported differences in fearfulness are inconsistent. A meta-analysis was conducted to determine whether there are systematic differences in measures of fearfulness between brown and white layers. Twenty-three studies that examined either 1 or both of 2 behavioral tests were included: tonic immobility (TI) (longer duration = higher fearfulness, 16 studies) and novel object (NO) test (lower approach rate = higher fearfulness, 11 studies). The 2 tests were analyzed separately. TI analyses: A generalized linear mixed effect model (GLMM) with a lognormal distribution was fitted to describe the data with experiment nested in study as a random effect. Explanatory (X) variables were considered through backward selection, where potential X-variables included color (brown vs. white layers), decade (1980s, 2000s, 2020s), age (prelay vs. in lay), genetic stock (hybrid vs. grand-/parent stock), and methodology (back vs. side position). NO test analyses: univariable GLMMs with a beta distribution were fitted with approach rate as the Y-variable and color, decade, age, stock, or 2 methodological factors (test duration, single vs. group testing) as X-variables. Models were evaluated by assessing information criteria, residuals/random effect normality, significance of X-variables and model evaluation statistics (mean square prediction error, concordance correlation coefficient). TI duration was best explained by a color-by-decade interaction (P = 0.0006). Whites in the 1980s had longer TI durations (709.43 ± 143.88 s) than browns in the 1980s (282.90 ± 59.70 s), as well as in comparison to browns (208.80 ± 50.82 s) or whites (204.85 ± 49.60 s) in the 2020s. The NO approach rate was best explained by color (P ≤ 0.05 in 3 models), age (P < 0.05 in 3 models), and decade (P = 0.04). Whites had a higher approach rate (0.7 ± 0.07) than browns (0.5 ± 0.11), birds in lay a higher rate (0.8 ± 0.07) than birds prelay (0.4 ± 0.12), and approach rate for papers published in the 2000s (0.8 ± 0.09) was higher than in the 2020s (0.2 ± 0.12). The phylogenetic difference in the 1980s was no longer detectable after enforcing an upper limit on TI durations (10 min), as became common practice in later studies. Our findings suggest that phylogenetic differences in fearfulness and changes over time are test dependent, and this raises important questions and potential consequences for assessing hen welfare in commercial egg production.

Ground-dwelling species of birds, such as domestic chickens ( Gallus gallus domesticus ), experience difficulties sustaining flight due to high wing loading. This limited flight ability may be exacerbated by loss of flight feathers that is prevalent among egg-laying chickens. Despite this, chickens housed in aviary style systems need to use flight to access essential resources stacked in vertical tiers. To understand the impact of flight feather loss on chickens' ability to access elevated resources, we clipped primary and secondary flight feathers for two hen strains (brown-feathered and white-feathered, n = 120), and recorded the time hens spent at elevated resources (feeders, nest-boxes). Results showed that flight feather clipping significantly reduced the percentage of time that hens spent at elevated resources compared to ground resources. When clipping both primary and secondary flight feathers, all hens exhibited greater than or equal to 38% reduction in time spent at elevated resources. When clipping only primary flight feathers, brown-feathered hens saw a greater than 50% reduction in time spent at elevated nest-boxes. Additionally, brown-feathered hens scarcely used the elevated feeder regardless of treatment. Clipping of flight feathers altered the amount of time hens spent at elevated resources, highlighting that distribution and accessibility of resources is an important consideration in commercial housing.

Current commercial strains of broiler breeders display reproductive dysregulation when fed to satiety, but they can achieve optimal hatching egg production under feed restriction. However, chronic feed restriction in broiler breeders is a welfare concern due to physiological and behavioral signs of hunger, lack of satiety, and frustrated feeding motivation. The purpose of this study was to assess the welfare and productivity of slower-growing broiler breeders during lay. A total of 336 broiler breeders from 5 strains of slower-growing broiler breeders (3 female strains: 100 hens per strain, and 2 male strains: 12 and 24 roosters per strain) were kept in 12 identical pens throughout lay, 4 pens per combination of roosters and hens: A hens with Y roosters, B hens with Y roosters, and C hens with X roosters. According to guidelines, strain B and C hens and X roosters were slower growing strains and strain A hens and Y roosters were intermediate growing strains. Egg production was recorded daily, and settable eggs laid at 30, 40, and 50 wk of age were incubated to hatch. Growth rate, feed and water intake, and welfare indicators (feeding motivation, behavior, and physical assessment: feather coverage, foot and leg health, and keel bone status) were recorded during lay. Additionally, a subsample of 5 hens per pen was dissected for anatomical analyses. Laying rate started and peaked earlier in B hens than in A hens and remained above 70% in both strains, yielding high cumulative egg production (165 eggs/hen) until 53 wk of age. Until 50 wk of age, fertility and hatched of fertile was high in slower growing broiler breeders, on average, above 95 and 80%, respectively. Compared to A hens, B and C hens had better feather coverage, lower feeding motivation, and lower daily water and feed intake. Results of this study suggest that slower growing broiler breeders show reduced signs of poor welfare and improved productivity during lay although susceptibility to obesity-related problems on laying rate may be strain-specific.

The impact of varying light intensities on layer pullets is not yet well understood. Behaviorally, brighter illumination may increase pullet activity levels by allowing better navigation in the complexity of non-cage systems. In addition, light intensity was previously demonstrated to affect the levels of calcium and phosphate regulating hormones in mice. The objective of this study was to examine how exposure of pullets to different light intensity affects their calcium and phosphorus homeostasis. Lohmann LSL-Lite and Lohmann Brown-Lite pullets were randomized into 4 individually controlled rooms with 6 pens per room, which were assigned to 10 or 50 lux light intensity supplied via white LED lighting during the photophase. After 8 and 16 wk of exposure, plasma calcium, phosphorus, and magnesium were measured by inductively coupled plasma optical emission spectrometry; and parathyroid hormone, 1,25-dihydroxyvitamin D, fibroblast growth factor 23, and markers of bone formation and resorption were measured by ELISA. Intestine and kidney samples were collected at 16 wk and gene expression of receptors for calcium and phosphate regulating hormones was assessed. The data were analyzed by one-way ANOVA. Lohmann Brown-Lite pullets exposed to 50 lux for 8 wk exhibited lower ionized Ca levels and a trend for increased bone formation markers compared to pullets reared in 10 lux. Thus, higher light intensity during rearing may beneficially affect calcium homeostasis and bone formation in young Lohmann Brown-Lite chicken.

To study the effects of pre-lay dietary Ca and strain on Ca utilization and femur quality at 1st through to 50th egg, 30 Lohmann Brown (LB) and 30 Lohmann Selected Leghorn-Lite (LSL) pullets (14 weeks of age, woa) reared under same management regimen were used. Six pullets/strain were necropsied for baseline femur samples and the rest (24 pullets/strain) placed in individual cages (65 × 30 × 45 cm3) and fed 1% Ca developer diet for 2 wk. At 16 woa, all pullets were weighed and allocated within strains to pre-lay diets (2.5 vs. 4.0% Ca) effectively creating a 2 × 2 factorial arrangement. The pullets were offered pre-lay diets for 2 wk and switched to 4% Ca diet at 18 woa. The diets contained TiO2 to determine apparent retention (AR) of Ca. The age, BW, and feed intake (FI) at 1st, 25th, and 50th egg were recorded. Excreta samples were taken during pre-lay, at 1st and 25th egg and 4 hens per treatment were necropsied for femur samples at 1st, 25th, and 50th egg. There was no interaction (P0.05) between pre-lay Ca and strain on Ca intake, femur mineral density (FMD), mineral content (FMC), breaking strength (FBS), and ash (FA) content at 1st, 25th, and 50th egg. At 1st egg, pre-lay Ca interacted with strain on AR of Ca (P = 0.014) such that LB hens retained more Ca at 2.5 vs. 4.0% Ca or LSL at 2.5% Ca. Pre-lay Ca had no effect (P0.05) on FMD, FMC, FBS, and FA at 1st, 25th, and 50th egg lay. Compared with LB hens, LSL hens had higher FMD (0.30 vs. 0.19 g/cm2; P = 0.010) and FA (51.9 vs. 42.5%; P0.01) at 1st egg and FBS (259.4 vs. 173.8 N, P0.01) at 25th egg. In conclusion, except at 25th egg, pre-lay Ca and strain had independent effect on Ca utilization. Femur attributes to 1st egg suggested innate need for LSL birds to accumulate critical bone mass prior to first oviposition.

The objective of this study was to determine the association between space allowance and in-transit loss of finishing pigs going to select abattoirs in Ontario during summer weather conditions. The study included data from 2- or 3-tiered trailers transporting ≥ 130 pigs in June, July, and August 2003 to 3 packers that processed 76% of Ontario market pigs. Daily in-transit loss data were merged with packer data to determine the number of pigs on each trailer. Space allowance (in square meters per pig) was estimated from the percentage of each trailer’s capacity that was filled by the load size. Actual pig weights were not available. Hourly temperature and relative humidity were obtained from 2 local Ontario weather stations. In-transit loss increased with environmental temperature, by 6.6 times at temperatures between 28°C and 34.2°C compared with < 17°C. At space allowances between 0.44 and 0.43 m2/pig compared with ≥ 0.515 m2/pig, in-transit losses increased 2.12 times when environmental temperatures were < 21°C. Temperature is likely a more important determinant of in-transit loss than space allowance. However, in-transit losses in hot weather are likely to be reduced by increasing space allowance or by adding a cooling device.

An observational study was conducted from July to October 2004 to determine the association between in-transit losses of swine and internal trailer temperature after controlling for loading density, trip distance, herd size, and random trip effect. A convenience sample of 3 trucking companies was used to collect temperature, relative humidity, and global positioning data for 104 trips that delivered 21,834 pigs from 371 producers to Ontario abattoirs. The association between in-transit loss and trailer temperature was determined using the 90th percentiles of internal temperature for each trip. Average loading density was 0.36 m2/100 kg pig (range 0.28 to 0.50 m2/100 kg pig). Average in-transit loss was 0.12%; however, 94% of producers experienced no losses. As the 90th percentile of internal trailer temperature increased from a range of 8.6 degrees C to 23.3 degrees C to a range of 23.4 degrees C to 26.1degreesC, average in-transit loss ratio increased approximately 3-fold, with an additional 2-fold increase as the range increased from 26.2 degrees C to 28.9 degrees C to 29.0 degrees C to 30.5 degrees C. As the 90th percentile of temperature increased by 1degreesC over the full range of temperatures in this study, in-transit loss was expected to increase 1.26 times. The in-transit loss was expected to decrease 0.81 times for each 50-km increase in distance traveled between the farm and the abattoir.

Animal care guidelines for poultry require that the methods used for routine killing result in rapid and irreversible loss of sensibility and cause minimal pain and distress. This thesis assessed the efficacy of three types of physical on-farm euthanasia methods in different age groups of layer chickens, and the degree of aversion and time to loss of sensibility for different CO2 concentrations (25%, 35%, 50%, and 70%) in laying hens. In Study 1, all three commercially available non-penetrating captive bolt devices tested caused sufficient brain trauma to result in rapid insensibility and brain death in four different age groups (10-11, 20-21, 30-35, 60-70 weeks) of layer chickens. This study also identified and corroborated practical behavioural indicators of death in layer chickens that can be used in field conditions to achieve the animal care guideline requirements of confirming the death before disposing of carcasses; onset of tonic convulsions, last movement, and cloacal relaxation were good indicators of clinical death. A second study assessed efficacy of a commercially available mechanical cervical dislocation device (MCD) in comparison to manual cervical dislocation (CD) in different age groups (12, 27-29, and 65-70 weeks) of layer chickens. Killing methods were assessed in anesthetized chickens to minimize welfare concerns. MCD resulted in a longer time to brain death than CD. Radiographs revealed that the majority of birds killed by CD had ideal dislocation sites between the skull and atlas (C1) or between cervical vertebrae C1-C2. The MCD resulted in a majority of dislocations at lower cervical vertebrae. There were few fractures in birds killed by either method. A final study demonstrated that concentrations of 50% and 70% CO2 were significantly more aversive to laying hens than 25% and 35%, based on an approach avoidance test. However, hens demonstrated headshaking and open mouth breathing at all tested CO2 concentrations, and some birds displayed conditioned place avoidance at the low concentrations. Loss of posture, indicating insensibility, occurred in less than 25s in all CO2 concentrations with shorter latencies at higher concentrations. The thesis provides important information for refinement of future euthanasia guidelines for the layer chicken industry. Chicken Farmers of Saskatchewan, Egg Farmers of Canada, Hybrid Turkeys, Natural Sciences and Engineering Research Council (NSERC) of Canada, the Ontario Ministry of Agriculture and Rural Affairs (OMAFRA), Turkey Farmers of Canada through the Canadian Poultry Research Council, and Turkey Farmers of Ontario through the Poultry Industry Council. Bock Industries, Inc., provided in-kind support.