Comparative efficacy of hydroxychloride and organic sources of zinc, copper, and manganese on egg production and concentration of trace minerals in eggs, plasma, and excreta in female broiler breeders from 42 to 63 weeks of age.

Comparative efficacy of hydroxychloride (HC) and organic (OR) sources of Zn, Cu and Mn on performance of broiler breeders (BB) between 42 and 63 weeks of age (WOA) was investigated. A total of 408 ♀ Ross 708 and 48 ♂ Yield Plus cockerels were placed in pens (17 ♀ and 2 ♂) housed in 2 rooms (12 pens/room) and allocated to one of 2 diets in a completely randomized block design (n=12). The diets had similar nutrient specifications but differed in Zn, Cu, and Mn sources: 1) HO, a blend of 80% HC and 20% OR sources, and 2) OR, 100% OR sources. Birds were fed and managed according to breeder guidelines. The egg count was recorded daily and categorized as normal or abnormal. Egg yolk color, albumen height, Haugh unit, eggshell thickness, and eggshell breaking strength were assessed every 4 wk. Individual hen body weight (BW) was recorded at 5-wk intervals to determine BW uniformity. At 52 and 63 WOA, the eggs and excreta samples were collected. At the end of the trial, 4 hens per pen were bled for plasma concentration of trace minerals and organs (liver, gizzard, spleen, kidney, and thymus) weight. There were no interactions between source and age on any parameters (P > 0.05). There were no main effects of source on egg production, eggshell quality, BW, and organs weight (P > 0.05). Hens fed HO diets had darker yolk compared to those fed OR diets (P = 0.014). The concentration of Zn in the eggs of OR BB was higher (P = 0.022) than for HO birds. However, there were no dietary effects on the concentration of trace minerals in the egg, plasma, and excreta (P > 0.05). The results indicated that a mixture of HC and O as sources for Zn, Cu, and Mn was as effective as OR sources in supporting egg production, egg quality, and trace mineral utilization in broiler breeders.

In pursuit of a better broiler: welfare and productivity of slower-growing broiler breeders during lay.

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.

In pursuit of a better broiler: tibial morphology, breaking strength, and ash content in conventional and slower-growing strains of broiler chickens.

This study was conducted to determine the differences in bone traits in 14 strains of broiler chickens differing in growth rate. The strains encompassed 2 conventional (CONV; ADG0-48 >60 g/d) and 12 slower-growing (SG) strains classified as FAST (ADG0-62 = 53-55 g/d), MOD (ADG0-62 = 50-51 g/d), and SLOW (ADG0-62 <50 g/d), with 4 strains represented in each SG category. A total of 7,216 mixed-sex birds were equally allocated into 164 pens (44 birds/pen; 30 kg/m2) in a randomized incomplete block design, with each strain represented in 8 to 12 pens over 2-3 trials. From each pen, 4 birds (2 males and 2 females) were individually weighed and euthanized at 2 target weights (TWs) according to their time to reach approximately 2.1 kg (TW1: 34 d for CONV and 48 d for SG strains) and 3.2 kg (TW2: 48 d for CONV and 62 d for SG strains). Tibiae samples were dissected, and length and diameter were recorded. Left tibiae were used for tibial breaking strength (TBS) at both TWs and tibial ash at TW2. At TW1, CONV birds' tibiae were narrowest and shortest (P < 0.001), yet had similar TBS compared to the other categories (P > 0.69). At TW2, category (P > 0.50) had no effect on tibial diameter, yet CONV birds had the shortest tibiae (P < 0.001). The CONV birds had greater TBS:BW ratio than FAST and MOD birds at both TWs 1 and 2 (P < 0.039) and similar ash content as the other categories at TW2 (P > 0.220). At 48 d of age, CONV birds had the greatest absolute TBS (P < 0.003), yet lower TBS:BW ratio than SLOW birds (P < 0.001). Tibiae from CONV birds were longer than MOD and SLOW birds, and thicker in diameter than the other categories, yet CONV birds had the lowest dimensions relative to BW (P < 0.001) at 48 d, indicating a negative association between accelerated growth and tibial dimensions. These results indicate that differences in functional abilities among categories may be due to differences in morphometric traits rather than differences in bone strength and mineralization.

In pursuit of a better broiler: walking ability and incidence of contact dermatitis in conventional and slower growing strains of broiler chickens.

In this study, the mobility, incidence, and severity of contact dermatitis and litter moisture content were assessed in 14 strains of broiler chickens differing in growth rate. The strains encompassed 2 conventional (CONV; ADG0-48 > 60 g/d) and 12 slower growing (SG) strains categorized as FAST (ADG0-62 = 53-55 g/d), MOD (ADG0-62 = 50-51 g/d), and SLOW (ADG0-62 < 50 g/d), with 4 strains in each category. A total of 7,216 mixed-sex birds were equally allocated into 164 pens (44 birds/pen; 30 kg/m2) in a randomized incomplete block design, with each strain represented in 8 to 12 pens over 2-3 trials. From each pen, 4 to 6 birds were tested in the latency-to-lie (LTL) and group obstacle tests 1 wk prior to the birds reaching 2 target weights (TWs) of approximately 2.1 kg (TW1: 34 d for CONV and 48 d for SG strains) and 3.2 kg (TW2: 48 d for CONV and 62 d for SG strains). The incidence of footpad dermatitis (FPD) and hock burns (HB) were evaluated a day prior to each TW. Litter moisture content was determined biweekly from d 14 to d 56. At TW1, CONV and SLOW had longer LTL than FAST birds. At TW2, CONV, MOD, and FAST birds had similar LTL. At both TWs, CONV birds were lighter than FAST birds in the group obstacle test, yet their number of obstacle crossings was similar. At TW1, CONV birds had greater incidence of FPD than FAST and MOD, while at TW2, CONV birds had greater incidence than the other categories. The incidence of HB in CONV and MOD was greater than SLOW birds at TW1, while at TW2, the incidence of HB was greater in CONV and FAST birds vs. MOD and SLOW birds. Litter moisture content was high in all categories from d 28 onward. Our results indicate that both BW and growth rate influence leg strength and walking ability, whereas the overall high litter moisture content and to a lesser extent growth rate influenced the incidence of contact dermatitis.

In pursuit of a better broiler: a comparison of the inactivity, behavior, and enrichment use of fast- and slower growing broiler chickens.

Selection for rapid growth has produced heavier, more efficient broiler chickens, but has also introduced health and welfare issues, which may cause or be caused by inactivity. Rapid growth may also limit the performance of motivated behaviors, whereas the provision of enrichment may increase these behaviors and general activity. This study aimed to evaluate the inactivity, behavior patterns, and enrichment use of 2 fast- (CONV) and 12 slower growing broiler strains (categorized as fastest [FAST], moderate [MOD], and slowest slow [SLOW]), based on their growth rates; 4 strains/category]. To evaluate inactivity, one male and one female from 153 pens were outfitted with omni-directional accelerometers from d 21 until processing (14-24 birds/strain from 8 to 12 pens/strain). Additionally, to supplement inactivity data, 5-min continuous behavioral observations of four focal birds per pen (2 males, 2 females) were conducted on days 26, 42, and 56 (72-148 observations of 8-12 pens/strain) to quantify the duration and frequency of various behaviors; at the same time, 5 to 11 instantaneous scan samples were also performed for pen-based enrichment use. Inactivity peaked at 78 to 80% of the day for all strains; however, those with slower growth rates reached these levels at older ages. Compared to slower growing strains at the same age, faster growing strains were more inactive, spent more time sitting and feeding, spent less time standing and walking, and used enrichments less; these differences mostly occurred at younger ages. Generally, at the same age, strains with similar growth rates (within the same category) behaved similarly, with only a few exceptions. Results suggest that not all strains identified as "slow-growing" broilers behave differently from fast-growing broilers, nor do they all behave similarly to each other. As such, results suggest that improved broiler welfare, particularly with respect to reduced inactivity, the performance of a wider range of normal, motivated behaviors, and/or increased enrichment use, is related to the broiler strain's specific growth rate.

Welfare and performance of slower growing broiler breeders during rearing.

Current commercial strains of broiler breeders can only achieve an optimal reproductive performance under feed restriction. However, chronic feed restriction in broiler breeders is a welfare concern because of physiological and behavioral signs of hunger, lack of satiety, and frustrated feeding motivation. The objective of this research was to assess the welfare and performance of slower growing broiler breeders during rearing. A total of 360 broiler breeder chicks from 3 female strains (100 chicks per strain) and 2 male strains (20 and 40 chicks per strain) were raised in four identical pens per strain. Strain B and C pullets and X cockerels were slower growing strains, and strain A pullets and Y cockerels were intermediate growing strains. Birds were weighed and scored individually for footpad lesions, hock burns and feather coverage. Data were analyzed using generalized linear mixed models with pen nested in the models and age as a repeated measure. Compared to B and C pullets, strain A pullets grew faster, had poorer body weight uniformity, and started feed restriction 2 wk earlier to control growth rate. Strain A pullets also had higher feeding rate at 3 and 5 wk, higher water intake at 4 and 5 wk, and higher prevalence of footpad lesions at 6 wk than the other pullet strains. Fault bars in wing feathers (an indicator of chronic stress) were more numerous in A pullets than in B and C pullets. Our results indicate that pullets showed little feather coverage loss during early rearing and had good body weight uniformity and low cumulative feed intake at the end of rearing. Slower growing broiler breeders may still require some degree of feed restriction to control growth rate, and strains with lower feed restriction exhibited lower signs of feeding frustration and high body weight uniformity.

Growth performance, organ attributes, nutrient and caloric utilization in broiler chickens differing in growth rates when fed a corn-soybean meal diet with multienzyme supplement containing phytase, protease and fiber degrading enzymes.

Growth performance, organ weight, ceca digesta short chain fatty acids (SCFA), jejunal histomorphometry, tibia ash, apparent retention (AR) of components and caloric efficiency were investigated in broiler chicken strains differing in growth rate fed diets with multienzyme supplement (MES). The strains differed in estimated time to reach 2.1 kg BW: 37, 43, 47, and 50 d and were designated C, F, J, and N, respectively. A corn-soybean meal diet was formulated for 2-phase program (starter and grower) and fed without or with MES containing phytase, protease and fiber-degrading enzymes. A total of 640-day-old chicks (42.3 + 0.01 g/bird) were housed in cages (5 cockerels and 5 pullets/cage) and allocated to give 8 replicates/ strain and diet combination. Equal amount of feed was fed based on observed ad-libitum intake of C strain in the starter (d 0-14) and grower (d 15-28). Body weight was monitored, grab excreta samples taken and at completion of allocated feed one bird per cage necropsied for samples. With exception of P, apparent metabolizable energy corrected for nitrogen (AMEn) and ceca digesta acetic acid, there was no (P > 0.05) interaction between strain and MES on examined responses. Strains differed (P < 0.01) on growth, FCR, gizzard weight, tibia ash, breast weight, ceca digesta concentration of lactic, propionic, and isobutyric acid and caloric efficiency. The final body weight (BW) was 1,344, 1,134, 959, and 916 g/bird for C, F, J, and N, respectively. Corresponding caloric efficiency was 4,930, 5,807, 6,680 and 7,199 kcal/kg BW gain, respectively. Birds fed MES had higher BW gain (P < 0.05) in grower phase, larger gizzard, higher AR of CP, crude fat, neutral detergent fiber, and Ca than non-MES birds. In conclusion, growth rate influenced organ attributes, nutrient, and caloric utilization. Enzyme supplementation improved growth in grower phase and nutrient utilization independent of strain, suggesting that effects of feed enzymes are not influenced by inherent growth rate.

In pursuit of a better broiler: carcass traits and muscle myopathies in conventional and slower-growing strains of broiler chickens.

Selection for accelerated growth rate and high breast yield in broiler chickens have been associated with an increase in myopathies, including wooden breast (WB) and white striping (WS). To investigate effects of growth rate on carcass traits and incidence of myopathies, 14 strains were evaluated, encompassing 2 conventional (CONV; strains B and C: ADG0-48 > 60 g/d) and 12 slower-growing (SL) strains. The latter were categorized based on growth rate: FAST (strains F, G, I and M; ADG0-62=53-55 g/d), MOD (strains E, H, O and S; ADG0-62=50-51 g/d), and SLOW (strains D, J, K and N; ADG0-62<50 g/d). In a randomized incomplete block design, 7,216 mixed-sex birds were equally allocated into 164 pens (44 birds/pen; 30 kg/m2), with each strain represented in 8 to 12 pens over 2 to 3 production cycles. From each pen, 4 males and 4 females were processed at 2 Target Weights (TWs) based on their expected time to reach 2.1 kg BW (TW 1: 34 d for CONV; 48 d for SL strains) and 3.2 kg BW (TW 2: 48 d for CONV; 62 d for SL strains). Weights and yields for the carcass, breast, drumsticks, thighs, and wings were obtained; breast fillets were assessed to determine the presence and severity of WB and WS. At both TWs, breast yield was higher as growth rate increased (P < 0.001), with CONV having greater breast yield than other categories. Strain F had the greatest breast yield at both TWs (P < 0.001) within the FAST category. At TW 2, CONV had the greatest incidence of WB and WS (P < 0.001). However, within FAST, strain F had the greatest incidence of myopathies (P < 0.001) at both TWs, exhibiting values as high or as greater than CONV birds. The incidence of WB and WS in strains with differing growth rates but high breast meat yield suggests that the latter may play a major role in the occurrence of these myopathies.

In pursuit of a better broiler: growth, efficiency, and mortality of 16 strains of broiler chickens.

To meet the growing consumer demand for chicken meat, the poultry industry has selected broiler chickens for increasing efficiency and breast yield. While this high productivity means affordable and consistent product, it has come at a cost to broiler welfare. There has been increasing advocacy and consumer pressure on primary breeders, producers, processors, and retailers to improve the welfare of the billions of chickens processed annually. Several small-scale studies have reported better welfare outcomes for slower-growing strains compared to fast-growing, conventional strains. However, these studies often housed birds with range access or used strains with vastly different growth rates. Additionally, there may be traits other than growth, such as body conformation, that influence welfare. As the global poultry industries consider the implications of using slower growing strains, there was a need for a comprehensive, multidisciplinary examination of broiler chickens with a wide range of genotypes differing in growth rate and other phenotypic traits. To meet this need, our team designed a study to benchmark data on conventional and slower-growing strains of broiler chickens reared in standardized laboratory conditions. Over a 2-year period, we studied 7,528 broilers from 16 different genetic strains. In this paper, we compare the growth, efficiency, and mortality of broilers to one of two target weights (TW): 2.1 kg (TW1) and 3.2 kg (TW2). We categorized strains by their growth rate to TW2 as conventional (CONV), fastest-slow strains (FAST), moderate-slow strains (MOD), and slowest-slow strains (SLOW). When incubated, hatched, housed, managed, and fed the same, the categories of strains differed in body weights, growth rates, feed intake, and feed efficiency. At 48 d of age, strains in the CONV category were 835 to 1,264 g heavier than strains in the other categories. By TW2, differences in body weights and feed intake resulted in a 22 to 43-point difference in feed conversion ratios. Categories of strains did not differ in their overall mortality rates.

Research Note: Comparative gastrointestinal, tibia, and plasma attributes in 48-day-old fast- and slow-growing broiler chicken strains.

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 < 0.01) for D, H, and M than that for B and E, whereas the small intestine was lighter (P < 0.01) for B, D, and H than for M and E. There were no (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 < 0.01) plasma concentrations of aspartate transaminase, creatine kinase, lactate dehydrogenase, and creatinine than SG strains. In conclusion, although B and some SG strains had lighter gastrointestinal tract indicative of energy efficiency, higher circulating plasma enzymes in B birds suggested impaired hepatic function. Moreover, lower tibia ash in B suggested disproportionate body mass relative to skeletal support.

Evaluation of Brain Death in Laying Hens During On-Farm Killing by Cervical Dislocation Methods or Pentobarbital Sodium Injection.

This study investigated changes in the electroencephalograph (EEG) power spectrum as well as physiological and behavioral responses to on-farm killing via mechanical cervical dislocation (MCD), manual cervical dislocation (CD) or intravenous pentobarbital sodium administration in lightly anesthetized laying hens, to evaluate the welfare impact of each method. A mixed group of 44 white Leghorn and Smoky Joe laying hens (60 weeks-old) were anesthetized with isoflurane in oxygen and maintained at 1.5-2% isoflurane/O2 until the killing method was applied. Birds were randomly assigned to one of three experimental groups on each trial day. The EEG was recorded bilaterally in a four-electrode montage. After recording a 5-min baseline, the killing method was applied and EEGs and other behavioral and physiological responses, including convulsions, gasping, cessation of body movements and feather erection were recorded for 5 min. Changes in EEG frequency bands (alpha, beta, delta, theta), median frequency (F50), 95% spectral edge frequency (F95), and total power (Ptot) were used to assess the quality of the on-farm killing event. Within 15 s after administration of pentobarbital sodium, there were significant decreases in mean frequency bands, increases in mean F50 and F95, and decreases in Ptot, suggesting brain death. In addition, birds presented a shorter latency to cessation of movement after pentobarbital sodium injection compared to MCD and CD (22 vs. 115 s and 136 s, respectively). There were significant increases in F95 and decreases in Ptot at 120 s after application of CD; and a concomitant decrease in the frequency bands at 135 s and isoelectric EEG at 171 ± 15 s. Changes consistent with brain death after MCD included isoelectric EEG at 207 ± 23 s and a significant decreases in some frequency bands at 300 s post-application. No other significant spectrum frequency changes were observed in the MCD group, suggesting brain death likely occurred near the 5-min endpoint. There was no clear association between behavioral, physiological, and EEG responses within CD and MCD treatments. The data demonstrate that pentobarbital sodium induced a rapid death with minimal behavioral and physiological responses regardless of strain of hens. In comparison, use of CD and MCD resulted in a slow onset of brain death in hens.

Conditioned place avoidance using encapsulated calcium propionate as an appetite suppressant for broiler breeders.

Broiler breeders, the parent stock of meat chickens, are feed-restricted throughout the production cycle to avoid obesity-related problems in their health and reproductive performance. Broiler breeders often show signs of chronic hunger, lack of satiety and feeding frustration, and the development of alternative feeding strategies has investigated the inclusion of calcium propionate (CaP) as an appetite suppressant. The mechanisms involved in the reduction of voluntary feed intake are unknown, but are thought to be due to low palatability, gastrointestinal discomfort, or both. The objective of this experiment was to examine the effect of CaP as an appetite suppressant on the experience of a negative affective state, using a conditioned place preference test. Twenty four broiler breeders were trained to associate the consumption of CaP or a placebo pill with a red or blue place, depending on inherent colour preference. Pullets consumed two pills followed by 20 g feed allotment. The CaP pill contained 160 mg of CaP and the placebo pill had 160 mg of feed. Conditioning lasted for 90 min/pullet/day over 8 consecutive days at 7 and 9 weeks of age, and pullets' choice was tested in a T-maze twice on two consecutive days at both 8 and 10 weeks of age. Data were analysed using a linear mixed regression model, with pen nested in the model and age as a repeated measure. Pullets were less likely to choose the place conditioned with the consumption of CaP (P<0.05) and the preference of the placebo linearly increased with training sessions (P<0.05). These results suggest that calcium propionate as an appetite suppressant can induce a negative affective state, reducing feed intake in broiler breeders fed CaP diets by causing an avoidance response rather than satiety.

Efficacy of a Novel Mechanical Cervical Dislocation Device in Comparison to Manual Cervical Dislocation in Layer Chickens.

The main objective of this study was to assess the efficacy of mechanical cervical dislocation using the Koechner Euthanasia Device Model C (KED) in comparison to manual cervical dislocation in layer chickens. Laying hens and/or roosters in three different age groups (12, 27-29, and 65-70 weeks old) were randomly assigned to one of three experimental groups: manual cervical dislocation in conscious birds (CD), manual cervical dislocation in anesthetized birds (aCD), or mechanical cervical dislocation by KED in anesthetized birds (aMCD). Anesthetized birds received an intramuscular dose of 0.3 mg/kg medetomidine and 30 mg/kg of ketamine to achieve clinical anesthesia. A comparison of CD vs. aCD responses confirmed that the anesthetic plane abolished or reduced clonic convulsions, nictitating membrane reflex, tonic convulsions, and cloacal relaxation. Time to loss of the pupillary light reflex (~123 s), and time to cardiac arrest (~172 s) were longer (p < 0.001) in the birds in the aMCD group than aCD (~71 and ~137 s, respectively). Radiographs revealed that the majority of the birds killed by manual cervical dislocation (CD + aCD) had dislocations between the skull and atlas (C1) or between cervical vertebrae C1-C2. The KED resulted in a majority of dislocations at C2-C3. Birds killed by manual cervical dislocation presented more subdural and parenchymal hemorrhage in the brain stem compared to birds killed by KED. Radiographs indicated the presence of fractures in a few birds killed by either method (CD + aCD versus aMCD). Compared to manual CD, KED resulted in less brain trauma and a longer latency to brain death, indicating a lower efficacy of KED as an on-farm killing method.

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

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.

Mortality and Early Feeding Behavior of Female Turkey Poults During the First Week of Life.

Turkey poults are susceptible to early mortality and poor initial feeding behavior for reasons that are not well-understood. This study was conducted to investigate the relationship between the development of turkey poult feeding behavior and early mortality, with a focus on the effect of biological age and diet. We hypothesized that increasing biological age would increase mortality, and that poults that had earlier feeding behavior would have decreased mortality. Nine hundred and sixty female turkey poults were randomly assigned to 24 pens (40 poults per pen). The study was conducted as a completely randomized block design with a factorial arrangement of two ages (early and standard hatch) and three diets (control, modified A, and modified Ca/P B, differing primarily in the Ca/P ratio and percent fines). The behavior during the first 24 h after placement of newly placed poults was examined. Growth performance and mortality throughout the first week of life was also measured to determine if early behavior had any impact on these variables over time. Behavior during the first 24 h was similar between the age treatments; both spent ~2.5% of the time drinking, 7% of the time feeding, 12% of the time active and 80% of the time inactive/resting. There was no effect of diet or age treatment on latency to feed or drink. Growth variables were not affected by biological age. However, there was a significant diet and biological age effect on bodyweight and mortality. Standard hatch poults fed a control diet were lighter than other poults at 7 d, while standard hatch poults fed the diet with the lowest Ca:P had the highest mortality. For all treatments, early mortality was primarily due to yolk sac infection, although >1% of placed poults died due to starvation. Findings of the present study indicate that, regardless of biological age or diet, poults established feeding behavior within the first 24 h and the majority of early poult mortality under these experimental conditions was due to factors other than starvation.

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.

The effect of alternative feeding strategies for broiler breeder pullets: 1. Welfare and performance during rearing.

Broiler breeders have impaired reproductive performance when fed to satiety but they can achieve an optimal hatching egg production under feed restriction. Feed restriction is a welfare concern due to signs of hunger, lack of satiety, and frustrated feeding motivation. The objective of this research was to examine the effect of a rationed alternative diet and non-daily feeding schedules on the performance and welfare of broiler breeder pullets reared under simulated commercial conditions. At 3 wk of age, 1,680 Ross 308 pullets were allocated to 24 pens fed with 1 of 4 treatments: 1) daily control diet (control); 2) daily alternative diet (40% soybean hulls and 1 to 5% calcium propionate); 3) 4/3 control diet (4 on-feed days per week; 3 non-consecutive off-feed days per week); and 4) graduated control diet (feeding frequency varied with age). Body weight and body weight uniformity were recorded at 3, 5, 7, 11, 17, and 21 wk of age. Pullets were scored for feather coverage, foot lesions, and hock burns biweekly. Physiological indicators (plasma glucose, corticosterone, hematology, and feather traits) and feeding motivation were also determined throughout rearing during on- and off-feed days. Data were analyzed using a linear mixed regression model, with pen nested in the model and age as a repeated measure. Compared to control, pullets under the 3 alternative feeding strategies had a lower feeding motivation during early rearing (P = 0.03), better feather coverage throughout rearing (P = 0.001), fewer feather fault bars (P = 0.006), and a delayed increase in the basophil to lymphocyte ratio (P = 0.001). These results indicate that the 3 alternative feeding strategies (the alternative, the graduated, and the 4/3 schedule) may decrease feeding motivation and alleviate stress compared to the control, suggesting an overall improvement in broiler breeder welfare without negative consequences on their performance.

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.

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.

An analysis of beak shape variation in two ages of domestic turkeys (Meleagris gallopavo) using landmark-based geometric morphometrics.

The objective of this study was to assess beak shape variation in domestic turkeys (Meleagris gallopavo) and determine the effects of age, sex, and beak size on beak shape variation using geometric morphometrics. Dorsal and right lateral images were taken of 2442 turkeys at 6 and 18.5 weeks of age. Landmarks were digitized in tpsDig in three analyses of the dorsal upper mandible, lateral upper mandible, and lateral lower mandible shape of each turkey at both ages. The coordinate data were then subjected to a principal components analysis (PCA), multivariate regression, and a canonical variates analysis (CVA) with a Procrustes ANOVA in MorphoJ. For the dorsal images, three principal components (PCs) showed beak shape variation ranged from long, narrow, and pointed to short, wide, and blunt upper mandibles at both ages (6 weeks: 95.36%, 18.5 weeks: 92.21%). Three PCs showed the lateral upper mandible shape variation ranged from long, wide beaks with long, curved beak tips to short, narrow beaks with short, pointed beak tips at both ages (6 weeks: 94.91%, 18.5 weeks: 94.33%). Three PCs also explained 97.80% (6 weeks) and 97.11% (18.5 weeks) of the lateral lower mandible shape variation ranging from wide and round to narrow and thin lower mandibles with superior/inferior beak tip shifts. Beak size accounted for varying proportions of the beak shape variation (0.96-54.76%; P < 0.0001) in the three analyses of each age group. For all the analyses, the CVA showed sexual dimorphism in beak shape (P < 0.0001) with female upper mandibles appearing wider and blunter dorsally with long, curved beak tips laterally. Whereas male turkey upper mandibles had a narrow, pointed dorsal appearance and short, pointed beak tips laterally. Future applications of beak shape variability could have a genetic and welfare value by incorporating beak shape variation to select for specific turkey beak phenotypes as an alternative to beak treatment.