Plasma catecholamine and corticosterone levels during manual restraint in chicks from a high and low feather pecking line of laying hens

Neurosympathetic and adrenal responsivity to manual restraint was studied in two White Leghorn chicken lines which differ in their tendency to feather peck. Blood samples were taken from freely moving cannulated birds during resting conditions and during manual restraint (placing the bird on its side for 8 min) to determine plasma noradrenaline. adrenaline and corticosterone. Plasma corticosterone levels in low feather peckers (LFP) were significantly higher during resting conditions and restraint as compared to the high feather peckers (HFP). In response to manual restraint the HFP hens showed a significantly larger plasma noradrenaline response than LFP hens. No difference in plasma adrenaline levels was observed under resting conditions or during manual restraint.

Effect of novelty and restraint on catecholamines in plasma of laying hens

1. The present study describes the effects of novelty (experiment 1) and restraint (experiment 2) on the catecholamine responses in laying hens. 2. Manual restraint caused a higher catecholamine response than mere visual exposure to a human being wearing yellow gloves and swinging his hand in the bird's home cage. 3. A relationship could be shown between adrenaline concentrations in plasma after a novel stimulus and the duration of tonic immobility.

Open-field and tonic immobility responses in domestic chicks of two genetic lines differing in their propensity to feather peck

1. The open-field and tonic immobility reactions of female domestic chicks of 2 genetic lines which showed high (HP) or low (LP) levels of feather pecking were compared. 2. Chicks of the LP line showed less freezing, and vocalised and walked sooner and more in the open field than did their HP counterparts. 3. There were no differences between lines in the durations of their tonic immobility responses, at least in the present study. 4. The pattern of results may reflect line divergence in underlying social motivation rather than fearfulness.

The effect of environmental temperature on episodic growth hormone release of meat-type chickens selected for 6 week body weight or for improved feed efficiency between 3 and 6 weeks of age

The effect of a high (33 degrees C) compared to a normal (23 degrees C) ambient temperature on the pulsatile release of growth hormone (GH) has been studied in 4-week-old, cannulated male meat-type chickens selected for high body weight (GL line) or for improved feed efficiency (FC line). When reared in the normal temperature environment, overall circulating mean and amplitude GH values of FC chickens were significantly higher than those of GL chickens. There were no differences in GH pulse length or frequency between genotypes. The high rearing temperature completely abolished the pulsatility of GH in the plasma in both lines, but without affecting overall mean GH levels.

The concept of metabolic clearance rate in endocrinology. A case study of growth hormone in different lines of meat-type chickens

Disappearance of growth hormone from blood (plasma) was studied in young broiler chickens in two experiments: a) following single injection of GH (50 micrograms or 250 micrograms/kg) to anesthetized chicks; b) injection of GH (50 micrograms/kg) (under anesthesia) to two lines of broilers selected for either rapid growth or feed efficiency. Clearance of GH never followed a single negative exponential curve. Characterization of the disappearance by a single metabolic clearance rate and half-life time were found to be inaccurate and inappropriate on methodological grounds. High doses of hormone might disturb receptor or catabolism equilibria and result in aberrant values of MCR which could probably be because of the very dynamic nature of the GH clearance system, which appeared to be influenced by dose, line (or genetics of the animal) and by some indices of clearance. Therefore, physiological significance of such data must be interpreted carefully.

Endogenous viral genes in thirteen highly inbred chicken lines and in lines selected for immune response traits

Thirteen highly inbred lines of chickens of Leghorn, Spanish, and Egyptian Fayoumi origin, four partly inbred Leghorn lines selected for MHC alleles and immune response to GAT (Ir-GAT), and two replicated, noninbred Leghorn lines divergently selected for multiple immune response traits were subjected to molecular genotyping for endogenous viral (ev) gene sequences. In all highly inbred lines of Leghorn origin, ev1 alone or both ev1 and ev2 were observed. The Spanish and Fayoumi lines had three and five ev genes, respectively, most of which were not readily identifiable with standard Leghorn ev gene loci. The Leghorn lines selected for MHC and Ir-GAT had ev1 fixed in the population. Differences in ev3 and ev5 gene frequency were associated with Ir-GAT in the B1 haplotype, but not in the B19 haplotype. In the noninbred lines, which were divergently selected for multiple traits of immune responsiveness, ev6 and ev9 differed in frequency between lines, and both were in lower frequency in the lines selected for high immunoresponsiveness. These two ev genes are the only ones known in White Leghorns that have the gs-chf+ phenotype [expressing chicken helper factor (chf) but not expressing group-specific antigen (gs)].

Growth hormone response to TRH in male broiler chickens selected for body weight gain or food conversion and reared at either a moderate or a high ambient temperature

The aim of the present experiment was to study the growth hormone (GH) response upon thyrotropin releasing hormone (TRH) challenge (2 micrograms/kg body weight) in broiler chickens selected for body weight gain (GL line: fat line) or for feed efficiency (FC line: lean line) reared at either a moderate (33-23 degrees C) or high (33 degrees C) ambient temperature. A higher plasma GH level at 5 min after TRH administration was observed in the high temperature conditioned chickens of both lines. Also at high ambient temperature, an enhanced GH decrease between 15 min and 30 min post-injection and a higher acute elimination rate was calculated compared to moderate ambient temperature. A significantly higher GH secretory response was observed in the leaner FC line chickens, which was probably related to the more pronounced pulsatory GH secretion rate in these chickens. There was no difference in GH acute elimination rate between both lines in both environments. No interactions between line and rearing temperature for these parameters of GH dynamics were observed.

Temporal secretory patterns of growth hormone in male meat-type chickens of lines selected for body weight gain or food conversion

1. The pronounced episodic release of chicken growth hormone (cGH) in male broiler chicks, as well as its peak interval of about 90 min was confirmed in this study. 2. Lines selected for 6-week body weight (GL line) or for food conversion between 3 and 6 weeks of age (FC line) not only differ in the selection criteria but also in percentage abdominal fat. 3. The overall mean plasma GH concentration was higher in the FC line in both experiments, and this was only caused by peak amplitudes which were almost twice as high as in the FC line. Peak intervals were identical in both selected lines. 4. These observations suggest that decreased abdominal fat and increased protein efficiency may be genetically linked to increased plasma GH peak amplitude. This, and earlier observations on the effectiveness of pulsatile administration of cGH on the growth of broilers suggest that the biological function of GH may depend on its secretory pattern rather than its mean concentration in plasma.

Concentrations of hormones, glucose, triglycerides and free fatty acids in the plasma of broiler chickens selected for weight gain or food conversion

1. The concentrations of growth hormone (GH), insulin-like growth factor I (IGF-I), thyroxine (T4), triiodothyronine (T3), reverse-triiodothyronine (rT3), triglycerides (Tri), free fatty acids (FFA) and glucose (Glu) were determined at 2, 4 and 6 weeks of age in blood plasma of male and female chickens of broiler lines selected for body weight (GL) or food conversion (FC). 2. Plasma concentrations measured in the same animal over a 24 h or a 2 week interval were not significantly correlated with each other. For different traits measured in the same plasma sample only the correlation between T4 and rT3 differed significantly from zero. 3. All traits were dependent on age. Line and sex effects were significant (P less than 0.05) for GH, T4, Tri, FFA and Glu. Additionally, line significantly influenced the plasma T3/T4 ratio and sex influenced plasma rT3. Interactions between line, sex and/or age were seldom significant. 4. Within line and sex, GH (at 6 weeks of age) and T3 (at 4 weeks of age) were negatively, and IGF-I and Tri (both at 6 weeks of age) positively correlated with the amount of abdominal fat at 6 weeks of age. No significant correlation between body weight at 2, 4 or 6 weeks of age and any of the plasma traits was found.

Variations in endogenous viral gene patterns in White Leghorn, medium heavy, White Plymouth Rock, and Cornish Chickens

The endogenous viral (ev) gene patterns of White Leghorn (WL; 6 lines), medium heavy (MH; 4 lines), White Plymouth Rock (WPR; 8 lines), and Cornish types (2 lines) of commercial chickens were compared. Southern blot analysis of SstI-digested genomic DNA of 151 chickens revealed that the number of ev gene-containing fragments in a chicken from the MH, WPR, or Cornish type is about twice twice the number of that in WL chickens. Also, the number of hybridizing fragments of different size found within one line was twice as high in the broiler (on average 16.0 bands per line) and MH lines (20.5 bands per line) than in the WL lines (10.0 bands per line). In studies with subregion-specific probes, all ev fragments detected contained the env (3') part of the viral genome. Only eight ev fragments, found in 7 animals of 2 lines, lacked the gag (5') part of the viral genome. Studies with the ev-1-specific flanking probe, pGd111, revealed that ev-1 is commonly present in the DNA of the WL chickens, but not within the DNA of the WPR chickens. The results suggest that use of the standard nomenclature for the ev genes based on restriction fragment length is not feasible within the WPR, MH, and Cornish lines because of the complexity of the ev gene patterns found within these lines.

Effect of corticosterone infusion on plasma corticosterone concentration, antibody production, circulating leukocytes and growth in chicken lines selected for humoral immune responsiveness

The effect of corticosterone on antibody production was studied in chicken lines selected for humoral immune response. 2. Twelve cockerels (33 days old) from lines selected for high or low antibody responses after immunisation with sheep red blood cells (SRBC) were implanted with mini-infusion pumps delivering corticosterone or vehicle continuously for 14 d. 3. Three days after implantation, the chickens were immunised intramuscularly with 0.25 ml packed SRBC. Blood samples were taken before implantation, before immunisation and 3, 5, 7 and 11 d after immunization. 4. Corticosterone infusion induced higher plasma corticosterone concentrations and heterophil/lymphocyte ratios than infusion of vehicle only. Growth was considerably depressed and relative weights of the thymus, bursa of Fabricius and spleen were less in the corticosterone-infused chickens. 5. An effect of corticosterone on antibody production could not be demonstrated, and differences between selection lines were unaffected.

Adrenocortical and heterophil/lymphocyte responses to challenge in hens showing short or long tonic immobility reactions

1. Adult White Leghorn hens showing short or long tonic immobility reactions were classified as low-fear (LF) or high-fear (HF) responders, respectively. Following cannulation, their adrenocortical responsiveness to ACTH administration and the effects of chronic frustration induced by thwarting of feeding on plasma corticosterone concentrations and heterophil/lymphocyte (H/L) ratios were measured at regular intervals. 2. ACTH injection elicited significant and similar mean increases in circulating corticosterone concentrations in both the LF and HF groups. 3. Absolute H/L ratios were higher in HF than in LF hens after cannulation, although both groups showed similar proportional increases from pre-operation ratios. 4. Plasma corticosterone concentrations and H/L ratios were significantly increased at 20 h and 44 h respectively after the frustration of feeding regime began. Thus, adrenocortical activation preceded increases in H/L ratios but, whereas the elevated plasma corticosterone concentrations found after 20 h remained virtually constant thereafter, H/L ratios rose progressively throughout the 68 h frustration period. 5. There were no significant differences between groups in their plasma corticosterone and H/L responses to frustration. However, a consistent trend towards greater adrenocortical activation was observed in the HF than in the LF hens.

[Effect of the laying nest on cortisone levels in the plasma of laying hens prior to oviposition]

The effects of a laying nest on egg-laying behaviour and plasma corticosterone levels are described. Three causes of increasing corticosterone levels are discussed: (1) an increase during egg-laying behaviour; (2) an increase during oviposition; (3) an increase due to removal of the laying nest.

Tonic immobility and heterophil/lymphocyte responses of the domestic fowl to corticosterone infusion

The tonic immobility (TI) fear reactions, plasma corticosterone concentrations and heterophil/lymphocyte (H/L) ratios of adults laying hens were measured before and at intervals of 4 and 11 days after the subcutaneous implantation of osmotic minipumps delivering either corticosterone solution (15 micrograms/hr) or only polyethylene glycol vehicle. The dummy pumps exerted no apparent behavioral or endocrine effects, whereas tonic immobility was significantly prolonged and circulating corticosterone concentrations significantly elevated at 4 and 11 days after implantation of the corticosterone minipumps. H/L ratios were significantly elevated from pre-treatment levels in both groups. However, H/L ratios were considerably higher at both post-treatment points among birds receiving corticosterone rather than vehicle. The present findings suggest that chronic elevations of plasma corticosterone not only alter the haematological profile but may also predispose birds to react more fearfully to alarming stimulation.

Hemopexin is a developmentally regulated, acute-phase plasma protein in the chicken

Identity has been established between chicken hemopexin and alpha 1-globulin "M," a plasma known for the hormone responsiveness of its synthesis in monolayer cultures of embryonic chicken hepatocytes (Grieninger, G., Plant, P. W., Liang, T. J., Kalb, R. G., Amrani, D., Mosesson, M. W., Hertzberg, K. M., and Pindyk, J. (1983) Ann. N. Y. Acad. Sci. 408, 469-489). Identification was based on immunological cross-reactivity, electrophoretic behavior on sodium dodecyl sulfate-polyacrylamide gels, heme-binding capacity, and pattern of cleavage by proteolytic enzymes. Electroimmunoassays were used to investigate plasma protein levels, particularly those of hemopexin, in the acute-phase response and embryonic development. Acute-phase plasma protein production, elicited by injection of chickens with turpentine, bore many similarities to the pattern of hepatocellular plasma protein synthesis produced in response to the addition of specific hormones in culture. The response of the stressed chickens included elevated levels of hemopexin and fibrinogen (5- and 2-fold, respectively) accompanied by a 50% drop in albumin. Hemopexin levels of developing chick embryos were measured for several days before and after hatching. Onset of hemopexin production occurred around the time of hatching, and was followed by a steep increase (more than 1000-fold over 4 days). Similarly, it was not until the 12th h of culture that hepatocytes isolated from both early and late stage chicken embryos began to produce hemopexin, although, from their initiation in culture, they secreted a number of other plasma proteins in quantity. After 12 h, hepatocellular output of hemopexin rapidly accelerated. This precocious induction ex vivo required no hormonal or macromolecular medium supplements. These observations indicate that the embryonic chicken hepatocyte culture system will provide a useful model for studying the regulation of hemopexin biosynthesis in hepatic development and the acute-phase response.

Comparison of the adrenal sensitivity to ACTH of laying hens with immobilization and plasma baseline levels of corticosterone

The effects of mammalian ACTH (0.01-10.0 IU/kg) given intraarterially on plasma corticosterone levels in laying hens were determined. A rectilinear dose-response relationship was found, y = 24.545 + 8.691x. Daily ACTH injections of 0.1 IU/kg on 3 successive days showed a good reproducibility in response in plasma corticosterone levels. Immobilization by hand also increases plasma corticosterone to a plateau level of about 4 ng/ml. The effects of ACTH and immobilization in individual birds showed a good correlation (r = 0.87). A rather low correlation (r = 0.49) existed between individual baseline levels of plasma corticosterone and adrenal sensitivity for ACTH. The adrenal sensitivity for ACTH was nearly two times higher in the morning than in the evening. A diurnal pattern, however, could not be shown in the corticosterone response to immobilization.

The role of corticosterone in the ovulatory cycle of the hen

This study was undertaken in laying hens to investigate the possibility that a diurnal increase in the concentration of plasma corticosterone is directly responsible for timing the preovulatory surge of LH which results in the first egg of a sequence. Provided that the ovary contained a mature follicle, i.m. injection of 0.5 or 2.0 but not 0.1 mg corticosterone/kg stimulated a preovulatory release of LH. The dose of 0.5 mg/kg was less effective than that of 2 mg/kg and induced release of LH in only four out of eight hens. However, it resulted in concentrations of plasma corticosterone which were outside the physiological range. Variations in the concentrations of plasma corticosterone were measured in ten hens on two successive nights for 8.5 h starting at the onset of darkness. The birds were maintained on a lighting regimen of 14 h light/day. The hens were selected so that on the first night there was no preovulatory release of LH of a sequence starting soon after the onset od darkness. No diurnal increase in the concentration of plasma corticosterone was observed during the first 6 h of darkness on either night nor was any increase seen before the preovulatory release of LH. These observations suggest that corticosterone is not directly involved in the timing of the first preovulatory surge of LH of a sequence.