Stress and the domestic fowl: a physiological appraisal

Mode of Action of Dietary Dexamethasone May Not Be Dependent Upon Microbial Mechanisms in Broilers

Dexamethasone (Dex), a synthetic glucocorticoid (GC), in feed has been shown to increase gut permeability via stress-mediated mechanisms, but the exact mode of action on gut barrier function is not fully understood. Stress has been reported to alter the profile and virulence of intestinal flora predisposing for opportunistic disease. This study aimed to evaluate the relationship between dietary Dex and recoverable intestinal microbial profile in broilers to better understand mode of action and refine future uses of the model. Three experiments were conducted that administered Dex-treated feed for one week in conjunction with the antibiotics BMD (bacitracin methylene disalicylate) or Baytril^® (enrofloxacin) to evaluate if enteric microbial mechanisms were important in Dex-induced permeability. Serum fluorescein isothiocyanate-dextran (FITC-d) and bacterial translocation (BT) have been reported to increase after Dex treatment and were used to assess gut epithelial leakage. Shifts in bacterial profiles were also measured on selective agar. Combining Dex with BMD or Baytril resulted in increased (P < 0.05) serum FITC-d versus Dex-only. Additionally, Baytril did not reduce aerobic BT and bacterial profiles remained similar after Dex. These results suggest a minimal role of intestinal microbes in Dex-induced changes to intestinal barrier function.

Metabolism and distribution of p,p'-DDT during flight of the white-crowned sparrow, Zonotrichia leucophrys

This study evaluated the interactions of flight, fasting, and 1,1,1-trichloro-bis(4-chlorophenyl)ethane (p,p'-DDT) loading on residue metabolism and distribution in recently exposed white-crowned sparrows (Zonotrichia leucophrys). Female sparrows were dosed with 5 mg p,p'-DDT per kg body weight over 3 d. Following 1 d of recovery, sparrows were flown in a wind tunnel for up to 140 min, in 15-min blocks. Food was withheld from the start of the flight period until birds were euthanized. DDT, 1,1-dichloro-2,2-bis(4 chlorophenyl)ethane (DDD), and 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene (DDE) were present in all tissues examined. 1-Chloro-2,2-bis(4-chlorophenyl)ethene (DDµ), 1,1-bis(4-chlorophenyl)ethane (p,p'-DDη), and 2,2-bis(4-chlorophenyl)ethanol (p,p'-DDOH) were not found. Fasting did not significantly affect the rate of residue increase over time in any of the tissues examined. When sparrows flew and fasted simultaneously, fasting seldom contributed to an increase in tissue residues. However, the length of time flown was significantly correlated with increasing toxicant concentrations in the brain, kidney, and liver, effectively demonstrating the potential for brief flights to enhance mobilization of DDT and its metabolites. Dose, flight, and fasting also increased residues in brain tissue. These contaminant redistributions may have important ramifications on the stresses experienced by migratory birds.

Impact of housing technology on blood plasma corticosterone levels in laying hens

The aim of the present study was to test the hypothesis that keeping laying hens in an enriched environment supposed to represent a better welfare for the birds is accompanied by decreased corticosterone levels, compared to hens kept under traditional conditions. Plasma corticosterone levels in hens reared in standard and enriched cages and those kept on deep litter from 15 to 75 weeks of age were evaluated. The highest corticosterone levels were observed in hens kept on deep litter, which was associated with a lower intensity of egg production, longest time of movement and a high percentage of time spent dustbathing and scratching. Hens housed in the enriched environment exhibited low levels of aggression, low body weight at the end of the experiment and similar or higher corticosterone levels compared to those of hens kept under standard conditions. Thus, the results of the present study show that housing technologies which are more similar to the animal's natural environment need not be associated with decreased levels of plasma corticosterone. Keeping hens in traditional cage technology was not found to be particularly stressful, which may be an important finding with respect to the current restrictions on outside housing in regions with an increased risk of viral infection.

Vitamin E supplementation reduces dexamethasone-induced oxidative stress in chicken semen

1. We examined the effects of supplemental dietary vitamin E (Vit E) on semen quality and antioxidative status in male domestic fowls exposed to oxidative stress induced by synthetic glucocorticoid, dexamethasone (DEX) injection. 2. Thirty-six Egyptian local cross males, 42 weeks old, were housed individually in cages in an open-sided building under 16 h light:8 h dark and were provided with commercial feed and water ad libitum. Birds were divided into 4 groups: DEX (4 mg/bird/d), Vit E (200 mg/kg diet), DEX + Vit E (4 mg/bird/d + 200 mg/kg diet, respectively) and control, n = 9. All treatments lasted for 7 continuous days. 3. Oxidative stress induced by injection of DEX (4 mg/bird/d) resulted in decreased sperm count and motility correlated with an increased percentage of dead sperms. Vit E (200 mg/kg diet) enhanced sperm count and viability when supplemented to stress-induced birds, compared to DEX treatment alone. 4. In seminal plasma, low calcium concentration, high lipid peroxidation and reduced activity of glutathione peroxidase were associated with the oxidative stress. Vit E reduced lipid peroxidation in the seminal plasma. 5. In conclusion, excessive supplemental dietary Vit E improved semen quality when cockerels were subjected to stress conditions. It increased both sperm count and motility, reduced the percentage of dead sperm and enhanced the antioxidative status of seminal plasma.

Physiological Stress in Laying Hens

Stress responses in laying hens were mediated by continuous infusion of adrenocorticotropin (ACTH) via osmotic pumps. The ACTH was dissolved in saline solution (0.85%), and each pump delivered 8 IU of ACTH per kilogram of BW per day at the rate of 1 microL/h for 7 d. Control hens received pumps loaded with saline. Measurements were made at 6 d postpump implantation, unless otherwise indicated. The ACTH-treatment increased BW and total carcass, rear half of carcass, intestinal, and liver weights. Proximate analyses of liver showed increases in dry weight, moisture, protein, fat, carbohydrate, and ash content. Weights of the front half of the carcass, as well as weights of the abdominal fat pad, heart, head, feet, and skin were unaffected by ACTH-treatment. Plasma corticosterone, glucose, cholesterol, and high-density lipoproteins were increased by ACTH, whereas triglycerides were decreased. Feed and water intake, total excreta, and excretory DM were all increased in ACTH-treated hens. The ACTH decreased carbohydrate in excreta, whereas ash, protein, fiber, and gross energy of excreta were unaffected. The ACTH did not affect digestibility of dry matter, proteins, carbohydrates, fats, or gross energy; however, absorption of ash, protein, carbohydrates, and gross energy were increased by ACTH. Antibody levels to sheep red blood cells, cell-mediated immunity (wattle index to phytohemagglutinin-phosphate), and relative spleen weight were reduced by ACTH, whereas heterophil:lymphocyte ratio was increased. Reproduction in hens was negatively affected by ACTH treatment, as measured by cessation of laying on the third day of treatment, atretic follicles, and decreased oviduct weight.

Episodic Gonadotropin Secretion in the Mature Fowl: Serial Blood Sampling from Unrestrained Male Broiler Breeders (Gallus domesticus)1

Forty-week-old male broiler breeders were used in two experiments. Males were reared as recommended by the breeder, housed in individual cages, and cannulated to facilitate blood sampling. In experiment 1, blood samples were collected at 10- min intervals for 4 h commencing the day of cannulation (Day 0) and for 12 h on each of Days 1 and 2. In experiment 2, blood samples were collected at 10-min intervals for 8 h on Day 1. After centrifugation, plasma was stored at -20 degrees C until LH, FSH (experiment 1 and 2), testosterone, and corticosterone (experiment 1) concentrations were determined by RIA. Different statistical methods used to identify hormone secretion profiles revealed a characteristic pulsatile pattern of LH and FSH in plasma. However, LH pulses were more frequent and had greater amplitude than FSH pulses. Less than 32% of the FSH pulses were associated with LH episodes. Conversely, the association between LH and testosterone pulses averaged 83% in birds with testis weight greater than 10 g. Concentrations of corticosterone tended to increase after cannulation and remained elevated for only 3-4 h. Our data indicate that LH, FSH, and testosterone secretion is pulsatile in male broiler breeders. Additionally, LH pulses are associated with testosterone episodes but not with FSH pulses. The pulsatile pattern of FSH secretion, which is unique from those of LH, in adult males suggests that FSH secretion is independently regulated in the adult male fowl.

The influence of stress from transport and handling on hematologic and clinical chemistry blood parameters of racing pigeons (Columba livia domestica)

In the present study, the influence of stress from handling and transport on some frequently examined blood parameters of racing pigeons was evaluated. After 3 hr, there was a highly significant (P < 0.01) increase in the number as well as in the percentage of heterophils and decrease of lymphocytes. In clinical chemistries, increases of creatine kinase and glucose and a decrease of uric acid were observed. There was a mean decrease of the total white blood count of >15% that was less significant (P < 0.05). Changes in lactate dehydrogenase, basophils, and monocytes did not prove to be significant; eosinophils, aspartate aminotransferase, total protein, and the packed cell volume were not influenced by stress.

Force-feeding procedure and physiological indicators of stress in male mule ducks

1. The effects of the force-feeding procedure and its different components on various physiological indicators of acute and chronic stress were investigated in male mule ducks before and during a 12-d cramming period. 2. The highest concentration of corticosterone were measured after injection of ACTH agonist, during the pre-experimental period when the ducks were still housed in collective floor pens and at the time of transfer. 3. During the cramming period, corticosterone measured before and after force-feeding did not differ significantly though there was a non-significant trend towards an increase in certain cases. 4. The different components of force-feeding, including manipulation, intubation, force-feeding with a standard or a large amount of food had no significant effect upon corticosterone concentrations. 5. There was no indication from ACTH agonist challenge either of a change in adrenal sensitivity or a change in its responsiveness. 6. The heterocyte-lymphocyte ratio measured before and at the end of the cramming period did not differ significantly. 7. In conclusion, we observed no significant indication that force-feeding is perceived as an acute or chronic stress by male mule ducks, in our experimental conditions. Nevertheless, it remains to be shown that their adrenocorticotropic axis is responsive to acute stressors.

Growth performance and immune response of two commercial broiler strains fed diets containing Lactobacillus cultures and oxytetracycline under heat stress conditions

1. Hubbard x Hubbard (HH) and Shaver x Shaver (SS) chicks given a dietary supplement of either 50 mg/kg oxytetracycline (OTC) or 1 g/kg Lactobacillus culture (LC) were exposed to 36 +/- 1 degrees C for 3 h daily from day (d) 21 to 42. 2. Prior to heat treatment, body weight (d 21) and weight gain (d 1 to d 21) of OTC and LC birds were greater than those fed the control diet. Chicks given LC had the best food efficiency followed by OTC and control birds during d 1 to d 21. Body weight (d 1 and d 21) and weight gain (d 1 to d 21) were greater for HH tlhan SS chicks. 3. After 3 weeks of heat exposure, birds receiving the LC diet had greater body weight and weight gain, higher food intake and lower food efficiency than OTC and control chicks. 4. Antibody production against Newcastle discase vaccine on d 21 was not affected by strain or diet. On d 42, while diet had negligible effect on this variable among the SS broilers, HH birds fed LC had higher antibody production than those on the control diet. 5. Neither strain nor diet had a significant effect on mortality.

The effect of early age feed restriction on subsequent response to high environmental temperatures in female broiler chickens

This study was conducted to determine whether early age feed restriction improves heat tolerance in female broiler chickens. Chicks were brooded for 3 wk and then maintained at 24+/-1 C. On Day 0, chicks were assigned to one of four feeding regimens; each regimen was applied to four cages of chicks. The feeding regimens were 1) ad libitum feeding (ALF); 2) 40% feed restriction at 4, 5, and 6 d of age (F40); 3) 60% feed restriction at 4, 5, and 6 d of age (F60); and (4) 80% feed restriction at 4, 5, and 6 d of age (F80). From 35 to 41 d of age, all birds were exposed to 38+/-1 C for 2 h/d. Serum concentrations of glucose were elevated by the heat challenge, but were not affected by the feeding regimen. The heat treatment resulted in hypocholesteremia among ALF and F80 chicks, whereas the concentrations increased and remained constant in the F60 and F40 birds, respectively. Subjecting chicks to F60 improved growth and survivability and reduced heterophil to lymphocyte ratios (H/L) in response to the heat treatment as compared with the ALF and F80 regimens. The survivability rate and H/L of F40 chicks were similar to those attained by chicks on other regimens. Newcastle disease antibody titer of ALF birds declined with duration of heat treatment. It is concluded that the F60 regimen is beneficial for alleviating, at least in part, the detrimental effects of heat stress in female broiler chickens.

Risk factors for abattoir condemnation of turkey carcasses due to cyanosis in southern Ontario

Cyanosis is a category of condemnation for poultry, as defined by Agriculture and Agrifood Canada. A retrospective study to examine the seasonal patterns and trends for turkey cyanosis condemnation was conducted for the years 1987 to 1995 with the use of condemnation records made available by a single abattoir in Ontario. Condemnation for cyanosis had a significant seasonal pattern, with major losses occurring in the colder months (October to March). A prospective longitudinal study was conducted during January to March and October to December 1996 in the same abattoir and the 75 turkey farms that contracted to process their birds through it and all the 913 truckloads of turkeys processed in these two 3-mo periods. The data from this prospective study were used for multivariate modeling of the effects of potential risk factors on the incidence of cyanosis. Risk factors (at P < or = 0.05) included bird type (broiler age turkeys, mature toms, and mature hens compared to toms and hens), ambient temperature (cold: -9.9 to 0.0 C and very cold: < or =-10.0 C compared to mild: >0.0 C), clean-out lot (the last shipped from a poultry house), shipping time > or =8 h, and emaciation (proportion of turkeys in the lot condemned for insufficient muscle mass). The crate density was a sparing factor, and an increase in turkey density during shipping resulted in a lower incidence of cyanosis. This study suggested that the number of turkeys condemned for cyanosis was associated with cold, shipping stress, and subclinical syndromes.

Model of physiological stress in chickens 1. Response parameters

A model was developed to study stress in chickens. Continuous administration of adrenocorticotropic hormone was employed (ACTH) using physiological mini-osmotic pumps. A validation of controls for this procedure showed that nonhandled (NHCON), sham surgical procedure for pump implantation (SMCON) and surgical implantation of a pump delivering saline (SALCON) were all acceptable controls. Continuous delivery of ACTH at 8 IU/kg BW/d for 7 d caused increases in plasma corticosterone (CS), glucose (GLU), cholesterol (CHOL), triglycerides (TRI), high-density lipoprotein (HDL), total protein (TP), and the heterophil/lymphocyte (H/L) ratio. Body weight, as well as relative weights of the major immunobiological organs (i.e., spleen, thymus, and bursa of Fabricius) were decreased. Finally, liver was increased due to lipid and moisture accumulation. This model is the first to show in a single experiment all the major adaptive stress responses of chickens.

Gordon Memorial Lecture. Stress, strains and resistance

1. Stress describes the bird's defence mechanisms and a stressor is the situation that elicits the defence response. 2. As the environment can be viewed as a composite of interacting stressors, the bird's success in coping with its environment depends on the severity of the stressors and the physiological ability to respond properly and thus maintain homeostasis. 3. The neural, endocrine and more recently immune systems are considered to be integrators of the stress response. Although stress responses may be necessary for survival in wild bird populations, they are often detrimental to efficient growth, skeletal integrity and disease resistance in domesticated fowl. 4. Stress responses are modified by the genetic components.

Gordon Memorial Lecture. The genetic-behavior interface and well-being of poultry

Marked changes have occurred in poultry production practices and in stocks bred for the production of meat and eggs. Of behavior pattern that originally favoured domestication, positive responses to humans and adaptability to environments are now most important. Development of specific strains for production of meat or eggs resulted in correlated responses in behavioural traits. Compared with egg strains, meat strains are docile and have excessive appetites, poor immunoresponsiveness and reduced motor ability. Genotype by environment interactions for behaviour limit inferences concerning responses of stocks across environments. Innate behaviour patterns and habituation processes can prevent some stimuli from causing physiological manifestations observed in general responses to stressors. Husbandry procedures should optimise phenotypic expressions of genetic potential to enhance well-being.

Effects of light environment and population density on growth performance of male turkeys: 2. Physiological changes

This study was designed to determine the effects of intermittent white light [2 h of light (L) followed by 2 h of dark (D) repeated six times per day] vs. diurnal white, blue, and red light (12L:12D), light intensities of 86.1 lx (high) vs. 5.4 lx (low) at high and low population densities, and season of the year on changes in the pineal, pituitary, and adrenal glands and testes of male turkeys. Pineal gland weights were unaffected by any of the factors under study. Pituitary gland weights significantly increased only in 12-wk-old males reared during the fall and winter compared with those reared during the spring and summer, but were unaffected by the imposed light environments or population density. Adrenal glands were significantly larger in males reared under high population density conditions in comparison with those reared under low density housing. The different light environments were ineffective in altering the effects of population density on adrenal response. Intermittent, high intensity light caused precocious sexual development when males were between 12 and 23 wk of age. White light and red-filtered light stimulated testes activity and seminiferous tubule development, whereas blue-filtered light was nonstimulatory.

Selection of Japanese quail for contrasting blood corticosterone response to immobilization

Japanese quail (Coturnix coturnix japonica) were divergently selected for 12 generations for increased (high stress, HS) and decreased (low stress, LS) blood corticosterone (B) response to unfamiliar environments. Response lines were selected initially on the basis of wild-type quail B response to albino (ALB) quail intrusion (S1 to S3) and subsequently on B response to immobilization (IMB) (S4 to S12). Using ALB intruders as stressors proved unsuccessful, therefore the practice was abandoned in favor of using IMB, which proved successful. Across nine generations of selection, using the IMB stressor, the HS line exhibited a mean serum B response that was approximately 58% greater than that of the random-bred (control stress, CS) line, whereas the LS line had a mean response approximately 23% less than that of the CS line. Selection differentials were approximately three-fold greater in the HS than in the LS line whereas realized heritabilities (h2) were approximately two-fold greater in the HS than in the LS line.

Interorgan metabolism of amino acids, glucose, lactate, glycerol and uric acid in the domestic fowl (Gallus domesticus)

Arterial--venous differences for metabolites across liver, kidney and hindquarters were measured in fed or starved, artificially ventilated chickens. The results indicate that the liver takes up amino acids under both conditions. Urate and glucose are released by the liver in both the fed and the starved state. Lactate and amino acids are extracted from blood by the kidneys, and this increases in the starved chicken. Urate is removed from the circulation by the kidney in the fed and starved state and excreted. In the fed bird there is no significant arteriovenous difference of glucose across the kidney, but in the starved state the kidney releases glucose into the circulation. The hindquarters take up glucose in the fed but not in the starved state. The branched-chain amino acids valine and leucine were taken up by the hindquarters in the fed, but not the starved, chicken. Glycerol is released by the hindquarter of fed and starved chickens. In the starved state, alanine and glutamine represent 57% of the amino acids released by the hindquarter. Lactate is released by the hindquarter of starved chickens and represents the major gluconeogenic carbon source released by the hindquarter and taken up by kidney and liver. Although the liver is the major gluconeogenic organ in the starved chicken, the kidney accounts for approx. 30% of the glucose produced.

The effect of furazolidone on some clinical and biochemical parameters in goats

Furazolidone (FZ) administered to goats orally at the recommended therapeutic dose (10 mg/kg body weight for 5 days) resulted in significant decreases in heart rate, pulse rate, and rectal temperature. No change was observed in respiratory rate or body weight, although a tendency towards a decrease in the latter was observed. An increase in the number of the erythrocytes was found. FZ also produced significant decreases in the pseudocholinesterase activity and plasma concentrations of total protein and ascorbic acid. A significant increase in the adrenal cholesterol concentration was observed while the weight of adrenal glands and their ascorbic acid concentration and content were unaffected. No significant histopathological changes were observed in treated goats.

Effects of cage and floor pen management on behavior, production, and physiological stress responses of laying hens

Behavior, physiology, health, egg production, and egg quality characteristics of laying hens housed either 1/1394-cm2 cage (S), 2/1394-cm2 cage (HD), 2/2788-cm2 cage (LD), or in floor pens (P), each containing 25 hens, were monitored in order to assess hen welfare in different management systems. Egg production was highest in P and S hens. There were no differences among treatment groups in feed efficiency, egg weight, or egg taste, although egg shell breaking strengths were lower in HD hens despite their relatively low egg production. Blood spots were most common in eggs from caged hens. With respect to behavior, penned hens locomoted more, spent less time in stationary exploration than caged birds, and utilized nest boxes for activities in addition to egg laying. The HD hens fed less frequently than did the LD, and HD cage pairs engaged less frequently in simultaneous feeding, drinking, and resting behavior than LD pairs. Plasma corticosterone levels were initially found to be higher in pens than cages; this difference disappeared when the use of trap-nesting to capture P birds for sampling was discontinued. Nighttime corticosterone levels were higher in HD hens. In contrast, primary and secondary hemagglutination titers to sheep erythrocyte (SRBC) antigen, heterophil to lymphocyte ratios, hepatic zinc metallothionein, serum zinc, and body weights did not differ among treatments. Mortality, however, was lower in pens. It was concluded that, although there were striking dissimilarities in behavior between the pen and cage environments, physiological and production data did not provide evidence of stress associated with cage housing per se. High density caging, however, may be a stressor; this is discussed with reference to other research.

Genetic variation of neonatal stress response to reduced temperature brooding in a randombred population of chickens

Chicks from a randombred population were assessed for genetic variation in 1-day body weight and serum corticosterone under two brooding temperatures (26.7 and 32.2 C). Brooding at 26.7 C resulted in lower 1-day body weights and higher corticosterone levels. Heritability estimates (h2) for 1-day body weight were moderately high in both temperature groups but were low for gain in both temperatures. The h2 for corticosterone level from chicks brooded at 26.7 C was moderate, whereas estimates for those brooded at 32.2 were very low. Statistically significant (but low) negative phenotypic correlations were obtained for corticosterone with body weight and gain in both temperature groups. A significant negative genotypic correlation was observed between corticosterone and body weight for chicks brooded at 26.7 C but not for those brooded at 32.2 C. Corticosterone data from the highest and lowest responding sire families revealed a significant response group by temperature interaction. Chicks from the first of two additional hatches showed significant response group differences in serum corticosterone to the reduced brooding temperature. The neonatal serum corticosterone response to cold stress has a genetic basis; however, because there was a negative genotypic correlation between serum corticosterone and body weight, selection for increased corticosterone levels under reduced temperature brooding would likely result in decreased body size.

Effects of chronic changes in dietary electrolytes and acute stress on plasma levels of corticosterone and aldosterone in the duck (Anas platyrhynchos)

Plasma levels of corticosterone and aldosterone were determined by radioimmunoassay in ducks consuming diets containing different concentrations of sodium and potassium. Compared with control diet birds, maintenance on a high-Na+ diet for 5 days caused a 2-fold increase in the basal plasma corticosterone concentration, while adaptation for 8 days to a low-Na+ diet resulted in a 2.6-fold increase in the basal plasma concentration of aldosterone. Both corticosterone and aldosterone basal plasma levels were greatly elevated in birds denied access to drinking water for 4 days. Adaptation to a high-Na+ diet or deprivation of water resulted in hyperosmolality and hypernatremia, while the high-K+, low-Na+/low-K+, and low-Na+ diets did not significantly alter the plasma sodium or potassium levels from the control levels. In addition, birds were stressed by semi-immobilization to determine the effects of acute stress-induced ACTH secretion on the adrenocortical response following changes in dietary sodium and potassium intake. In ducks adapted to low-Na+/low-K+, high-Na+, and low-Na+ diets, stress-induced adrenocorticotrophic hormone (ACTH) increased the aldosterone, but not the corticosterone, response to a level significantly greater than in the controls. These results demonstrate that in the duck secretion of corticosterone and aldosterone can be independently regulated. Furthermore, the endocrine changes that are induced by altered sodium and potassium intake are reflected in the adrenocortical responses to acute stress.

Changes in serum corticosterone concentration of laying hens as a response to increased population density

The response of adrenal glands of Single Comb White Leghorn laying hens housed under different population densities was studied. The birds were reared in floor pens until they were 19 weeks of age, after which they were housed in cages. Cage size was 30.5 X 50.8 cm. Three, four, or five birds were housed per cage. Corticosterone concentrations were measured in all birds 48 and 96 hr following housing in cages and weekly thereafter for 6 weeks. Corticosterone concentrations were consistently higher in the serum of birds housed five per cage than in birds housed three or four per cage. It was concluded that in order to minimize physiological stress in cage layers, more than 387 cm2 per bird should be considered.

Relationship of plasma corticosterone and adrenal cholesterol and corticosterone to the production of soft-shelled and shell-less eggs

Two experiments were conducted to determine if plasma corticosterone and adrenal cholesterol and corticosterone levels differed among hens that laid soft-shelled (SS) or shell-less (SL) eggs when compared with hard-shelled (HS) egg layers. For Experiment 1, four groups of White Leghorn hens were bled at 22 to 34 weeks of age in the morning (0600 to 1200 hr) and at 66 to 74 weeks of age in the morning and evening (1500 to 1900 hr). Group 1 consisted of birds that had just laid SS or SL eggs, whereas Group 2 hens had SS or SL eggs in utero. Groups 3 and 4 represented hens with HS eggs in their uteri and hens that had just laid HS eggs, respectively. For Experiment 2, adrenal cholesterol and corticosterone levels were assayed in high (18+%) and low (0%) incidence SS plus SL egg layers at 73 and 78 weeks of age. Both younger and older hens that laid SS or SL eggs in the morning had similar plasma corticosterone concentrations when compared to HS egg layers. Morning plasma corticosterone levels were significantly higher among hens that laid an egg when compared to hens with eggs in utero, regardless of whether the egg was SS, SL, or HS. However, plasma corticosterone levels of hens producing SS or SL eggs in the evening were significantly higher than levels of hens that laid evening HS eggs. Evening HS egg layers demonstrated the oviposition related peak in plasma corticosterone, but concentrations were 1 ng/ml higher among the evening SS or SL egg layers. Adrenal cholesterol and corticosterone concentrations were similar between high and low incidence SS plus SL layers at either age. It is postulated that evening production of SS or SL eggs is a consequence of elevated plasma corticosterone.

A surgical technique for serial blood sampling or continuous infusion of adult turkey hens

A technique for cannulating the jugular vein of turkey hens is described. The procedure is relatively easy to perform with no deleterious effects elicited by the procedure. Cannulae have remained patent for up to 1 month.

Reproductive performance of broiler breeders exposed to cycling high temperatures from 17 to 20 weeks of age

Forty male and 240 female broiler breeders were placed in cages within environmental chambers (20 males or 40 females per chamber) at 14 weeks of age. Chamber temperatures were maintained at 21.3 +/- 2.5 C, and relative humidity (RH) ranged from 40 to 50%. Ventilation rate was approximately 47.2 liters/sec per chamber, and light was provided from 0600 to 1800 hr. Feed was restricted daily according to industry recommendations, and water was provided ad libitum. From 17 to 20 weeks of age, control (C) chambers were kept at constant 21.0 +/- 1.4 C with 45 +/- 5% RH, and heat-treated (HT) chambers were cycled from 24.4 +/- 5.5 C (45 +/- 5% RH) during 1800 to 0800 hr to 36.0 +/- 2.8 C (15 +/- 5% RH) during 0800 to 1800 hr. Body weights were recorded at biweekly intervals. At 18 and 20 weeks of age, blood samples and rectal body temperatures were obtained randomly from five fasted birds per chamber at 0800 and 1400 hr. From 20 to 60 weeks of age, all birds were kept in individual cages in a conventional fan-ventilated house. Maximum temperature never exceeded 30 C, and average RH was 65.0%. Reproductive parameters were monitored and body weights were obtained at 4-week intervals. There were no significant treatment effects for body weight, body temperature, or differential leukocyte counts. Hematocrits were significantly lower for HT females than controls, and heat treatment did not result in consistent changes in plasma glucose or total proteins.(ABSTRACT TRUNCATED AT 250 WORDS)

Handling, ACTH, ACTH1-24, and naloxone effects on preening behavior in domestic chickens

Excessive grooming behavior has been well documented in various animals as a result of stress or intraventricularly administered ACTH and ACTH1-24. In the present study, handling, ACTH, and ACTH1-24 were associated with significant increases in preening of domestic chickens when compared to saline-treated controls. Naloxone-treated birds showed preening levels similar to those of unhandled and saline-treated birds.

The effect of furazolidone on the adrenal glands of the chicken

In the chicken, the weights of the adrenal and thyroid glands (as percentages of body weight) were selectively increased following administration of furazolidone (0.04 per cent w/w in the feed, 10 days). The increase in the weight of the adrenal glands most probably represents hypertrophy of the cortex, as the amount of catecholamines in the glands was unaffected by furazolidone. Furazolidone (0.04 per cent w/w, 10 days) produced a small reduction in the concentration of cholesterol in the adrenals. The concentration of ascorbic acid in the gland was unaffected by the drug.

Effects of population density on the growth, organ weights, and plasma corticosterone of young broiler chicks

Two trials were conducted with broiler chicks to determine the effects of population density on the growth, feed efficiency, and several physiological parameters associated with stress in birds. Chicks were brooded in batteries at 116, 232, 348, and 697 cm2/chick. Chicks brooded at 348 cm2/chick grew and utilized feed significantly better than those brooded at 697 cm2/chick during the first week. For maximum growth and feed efficiency, 116 cm2/chick was adequate for the first week; 232 cm2/chick was adequate during the second and third weeks. Increasing cage density significantly decreased percentage heart and spleen weights (g/100 g body weight) and plasma corticosterone at 3 weeks.

Factors affecting broiler processing parameters and plasma corticosterone

Two experiments were conducted to determine the influence of broiler strain, sex, and age on resting plasma corticosterone levels and the latter's relationship to various broiler production and processing parameters. In Experiment 1, strain and sex differences in 58-day farm weight (FWT), dressed carcass weight (DC), yield (Y), abdominal fat (AF), abdominal fat expressed as a percentage of DC (PAF), and plasma corticosterone (C) measures were assessed in five commercial broiler strains fed a lower [3086 kcal metabolizable energy (ME)/kg] versus higher (3306 kcal ME/kg) energy ration. The higher energy diet was formulated and used to produce excess abdominal fat. In Experiment 2, the effect of broiler age (4, 6, and 8 weeks) on resting plasma C was determined. Results of Experiment 1 indicated that although strain significantly influenced AF, and although feeding the higher energy diet significantly elevated FWT, DC, Y, AF, and PAF, strain and dietary energy effects on plasma C were nil. However, a significant strain X dietary energy interaction on plasma C levels was observed. Likewise, although female broilers had greater PAF measures than male birds, sex did not influence resting plasma C values. Plasma C was not correlated to AF measures. Experiment 2 results showed plasma C at 6 (3.3 ng/ml) and 8 weeks (2.9 ng/ml) was significantly depressed from the 4-week (4.9 ng/ml) sampling. Thus, future studies involving adrenal functioning in broilers should take into consideration the influence bird age might have on interpretation of results.

Circulating corticosterone responses of feed and water deprived broilers and Japanese quail

Experiments were conducted to delineate the acute stress response of commercial broilers to feed and water deprivation for 10 hr. The effect of method of nutrient deprivation, cooping versus removal of feed and water from broiler floor pens, was also considered. Bihourly plasma corticosterone measures were made during 10-hr withdrawal periods, and significant alterations in this adrenal steroid were considered indicative of stress. In all studies, feed and water deprivation produced significant elevations in plasma corticosterone concentrations. Cooped broilers exhibited a shorter onset and more exaggerated magnitude of adrenal responsiveness than floor penned broilers deprived of feed and water. There was also evidence that plasma corticosterone secretion in floor penned broilers was continual (linearly increasing) throughout the 10-hr withdrawal period. In contrast, maximal corticosterone responses followed by waning hormonal levels (an increasing quadratic function) were evident in cooped broilers. It was concluded that procedures involved in physically cooping birds, as well as the restraint cooping imposed, were acting additively to the stress associated solely with feed and water deprivation. Changes in plasma volume, as evidenced by percent packed cell volume changes during treatment periods, were not responsible for the corticosterone elevations observed. In a separate experiment, battery housed Japanese quail deprived of feed and water for 12 hr exhibited a temporal plasma corticosterone response very similar to that observed in floor penned broilers deprived of feed and water. Full-fed control quail exhibited only random temporal hormonal fluctuations during this time. It was likewise concluded that the practice of feed and water deprivation in quail constitutes a significant nonspecific stressor.

Survival under heat stress of lines selected for fast and slow growth at two temperatures

Two replicates of four lines of White Leghorn chickens previously selected for fast and slow gain from 5 to 9 weeks of age in a hot (32.2 C) and cold (21.1 C) selection environment were grown from 5 to 9 weeks in the hot and cold temperature environments and then subjected to high temperature stress at 40.6 C. Four different experiments were run. The percent mortality was analyzed when approximately 50% of the birds had died. Birds reared in the cold environment were heavier and consistently had higher mortality than those reared in the hot environment when both were subjected to acute heat stress (40.6 C). The importance of acclimation to mild heat stress on response to acute heat stress was demonstrated by the mortality difference. No significant differences in survival under heat stress were found between lines selected in the hot and the cold selection environments. Lines selected for fast growth had significantly higher mortality rates under high temperature stress than lines selected for slow growth in replicate 1 but not in replicate 2. Estimates of the genetic correlation between weight gain from 5 to 9 weeks of age and percent mortality under heat stress after two generations of selection in replicate 2 was -.004, and after three generations of selection in replicate 1 was +.076.

The effects of chronic handling on the incidence of leg abnormalities and several blood parameters in turkeys

Twelve hundred day-old Nicholas toms were randomly distributed among 47 pens as part of two experiments designed to evaluate the effects of chronic handling on leg weakness and several blood parameters. From 5 until 19 weeks of age, one half of the birds, designated as the handled group, was subjected to physical examination once each day, 5 days a week, in an effort to detect the development of leg abnormalities. They were also removed from their pens and weighed at 5, 10, 15, and 20 weeks of age. The remaining birds, referred to as nonhandled, were exposed to the minimum amount of human contact necessary for proper management. Experiment 1 involved only birds in the handled group. When a leg weakness was detected, the afflicted bird and a healthy control from the same pen were bled. Determinations were made of packed cell volume, hemoglobin concentration, total leukocyte count, and the plasma levels of uric acid, inorganic phosphate, calcium, alkaline phosphatase activity, testosterone, and corticosterone. Lame birds were found to have significantly higher total leukocyte counts and plasma corticosterone concentrations than healthy controls, the other parameters being unaffected. Experiment 2 was performed using both handled and nonhandled birds, 19 weeks of age. Lame and healthy subjects from each group were selected. Blood parameters identical to those in Experiment 1 were measured; it was found that lame birds had significantly higher plasma corticosterone levels than healthy controls and that chronic handling caused significant decreases in packed cell volume, uric acid, alkaline phosphatase activity, and corticosterone. Handling did not affect the incidence of leg weakness or mean final body weight.

The influence of microorganisms and of stress on the chick's requirement for pantothenic acid

1. The responses of germ-free (GF) and conventional (CV) chicks to suboptimal amounts of dietary calcium pantothenate (CaPa) were compared. At the lower levels of supplementation the signs of deficiency were more severe in the CV chicks. 2. Calculations based on mean body-weights of chicks given graded dietary supplements of calcium pantothenate (CaPa) in both environments showed that, to achieve the same body-weight and freedom from signs of deficiency, the GF birds required only approximately two-thirds the amount of CaPa as was needed by corresponding CV birds. 3. Increasing the dietary supplement of CaPa resulted in increased contents of PaA in the livers. GF birds had more PaA per liver than their CV counterparts. In both instances the effect was due to the larger liver size. Concentration of PaA in the liver was not affected by dietary supplement nor by the environment. 4. CV birds were deemed to be under greater stress than GF birds because their adrenal glands were heavier and contained less cholesterol. 5. CV chicks deliberately stressed by injections of adrenocorticotrophic hormone had heavier adrenals with lower cholesterol contents than unstressed controls, but the condition was not altered by increasing the dietary supply of CaPa.