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PubMed1987

Effect of increased circulating corticosterone on serum and thyroidal concentrations of iodothyronines and the responses to thyrotrophin in the immature fowl (Gallus domesticus).

Four-week-old fowl were given subcutaneous implants containing a mixture of corticosterone: cholesterol (1:4, w/w) to raise serum corticosterone concentration. The effects on circulating thyroxine (T4), triiodothyronine (T3), and reverse T3 (rT3), thyroidal T3 and T4 and responses to thyrotrophin (TSH) were examined. Increased circulating corticosterone caused an increase in the plasma concentration of T4 and a decrease in T3 and rT3 indicating reduced extrathyroidal 5 and 5' monodeiodination of T4. After single injections of 0.1 IU TSH/kg body weight were given 3 and 13 days after corticosterone implants there was an increase in the T3 response and a delay and reduction in the T4 response. This may have been due to a corticosterone-induced increase in the synthesis of T3 relative to that of T4. Although the relative increase in thyroidal T3 concentration was greater 3 days after corticosterone implants were given, no significant shift in the T4:T3 ratio in the thyroid glands was observed.

Animals↗
PubMed1987

Plasma immunoreactive-growth hormone in domestic fowl: measurement by homologous and heterologous radioimmunoassays.

Concentrations of immunoreactive (IR) growth hormone (GH) in the plasma of domestic fowl have been measured by homologous and heterologous radioimmunoassays and the estimates compared. Both assays detected an age-related decline in the circulating IR-GH concentration, an increase in IR-GH secretion following TRH-stimulation or fasting, and a fall in the IR-GH concentration following adrenocorticotropin administration. However, while the overall estimates of IR-GH concentration were significantly correlated, the magnitude of the changes in IR-GH concentration determined by the homologous assay were far greater than those detected by the heterologous system, which failed to show any inhibitory effect of anesthesia or exogenous thyroid hormones on basal or stimulated IR-GH release. These results suggest that the heterologous GH radioimmunoassay lacks the sensitivity of the homologous chicken GH assay and that circulating GH in birds is probably composed of heterogeneous moieties with differing immunoreactivities with rat GH antibodies.

Adrenocorticotropic Hormone↗
PubMed1988

Thyrotrophin-releasing hormone induces growth hormone secretion in adult hypothyroid fowl.

While thyrotrophin-releasing hormone (TRH) stimulated growth hormone (GH) secretion in adult anesthetized cockerels, the GH response was blocked in anesthetized birds pretreated with thyroxine (T4) or triiodothyronine (T3). Moreover, whereas GH secretion in conscious adult birds was poorly responsive to TRH stimulation, conscious birds made hypothyroid by goitrogen pretreatment (with propylthiouracil, methimazole, or thiourea) were responsive to TRH challenge. Basal circulating GH concentrations in the goitrogen-pretreated birds were also higher than in the vehicle-injected controls. Surgical thyroidectomy similarly increased the basal GH concentration in adult birds and promoted TRH-induced GH secretion. These results demonstrate inhibitory effects of the thyroid hormones on basal and stimulated GH secretion in adult domestic fowl and suggest that GH release in adults is partly under tonic thyroidal inhibition.

Animals↗
PubMed1988

Effect of fatty acid administration on plasma thyroid hormones in the domestic fowl.

In birds a severe stress is associated with a reduction in concentrations of plasma thyroxine. Studies in man and the rat have demonstrated that severe illness is associated with an increase in serum concentrations of free fatty acids, notably oleic acid, and that they are associated with a reduction in concentrations of serum thyroxine (T4) and/or triiodothyronine (T3). Since stress is associated with increased fatty acids in birds, we have, in the present study, examined the role of oleic acid and another polyunsaturated fatty acid, arachidonic acid, on thyroid function tests (plasma thyroxine, triiodothyronine, and T3 resin uptake (RT3U) index) and on the thyroidal response to exogenous thyroid-stimulating hormone (TSH) in the domestic fowl. In the first study we observed that the iv administration of arachidonic (10 mg/kg) or oleic acid (15 mg/kg) to groups of 10-week-old cockerels (six per group) was associated with a significant reduction in concentrations of plasma T4, whereas there was little change in saline-injected controls. However, administration of fatty acids to chickens was not associated with a significant change in RT3U index or in the levels of plasma T3. In the second study, groups of animals (n = 6) were injected with bovine TSH (0.5 IU/kg, im) or saline 2.5 hr after the fatty acid injection and blood samples were obtained at -2.5 to 24 hr after the TSH injection. A similar progressive increase in serum T4 was observed for the three groups studied whereas there was little change in the concentrations of plasma T3.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Steroidogenic cell subpopulations obtained from the theca of preovulatory follicles in the ovary of the domestic fowl.

The purpose of the present study is to provide further evidence in support of the theory which suggests that two cells are involved in the secretion of estrogens and androgens in the theca of the preovulatory ovarian follicles in the domestic fowl. The third (F3), the fourth (F4), and the fifth (F5), in order of decreasing size follicles, were obtained from white Leghorn hens. Theca cells were dispersed by trypsin treatment, and isolated cells were centrifuged in a continuous Percoll gradient (0-100%). Testosterone and 17 beta-estradiol secretion from cell samples in each density gradient fraction were radioimmunologically assayed. The highest secretion of 17 beta-estradiol was registered in cells isolated in density fractions ranging from 1.059 to 1.070 g/ml, while the maximal testosterone production was found in fractions from 1.037 to 1.048 g/ml. The different results were obtained from the three types of follicles studied (F3-F5). Morphological study of the F4 follicle showed typical steroidogenic cells with abundant lipid droplets in the cytoplasm in the theca interna, whereas clusters of poorly differentiated epithelial cells were visualized between fibroblast layers of the theca externa. The secretion of aromatizable androgens by the typical steroidogenic cells of the theca interna and estrogen production in the epithelial cells of the theca externa are postulated.

Animals↗
PubMed1991

Behavioral and hormonal correlates of social dominance in stable and disrupted groups of male domestic fowl.

An experiment was conducted to determine the behavioral and hormonal correlates of social dominance in stable and disrupted groups of male domestic fowl (Gallus domesticus). In addition, the relative importance of visual and auditory cues in the maintenance of dominance status in this species was assessed. Alpha roosters were removed from their six-bird home pens for 1 week, and placed in either (1) and adjacent pen in visual contact with penmates, (2) and adjacent pen where visual, but not auditory, contact was prevented, or (3) a different building where they were in visual and auditory isolation. Dominance rank, aggressive activity, and crowing frequency were intercorrelated during the premove period. There was a significant increase in both aggression and crowing among the males remaining in the home pen following removal of the alpha male, except in the treatment in which males were still in visual contact with the removed alpha, in which only aggression increased. Increases in crowing frequency were also noted in alpha males. High levels of aggression occurred when alpha males were returned except in those pens in which visual contact had been maintained. Visual cues thus appear to be more important than auditory cues alone with respect to the maintenance of dominant social status in roosters. There were no clear correlations between behavioral variables and plasma androgen or corticosterone levels in either the stable or disrupted flocks, and no consistent changes in the levels of these hormones as a result of experimental manipulation; several possible explanations for this finding are discussed.

Agonistic Behavior↗
PubMed1991

Cell-mediated immunity to Eimeria in the fowl: the absence of cross-species protection is not due to the lack of cross-reactive T cells.

Immunity to Eimeria species in the fowl has been shown to be species specific and it has been proposed that the lack of cross-protection between the species of Eimeria is due to the absence of T cells which recognize antigens from a heterologous species. When this hypothesis was tested the results showed that antigens from E. tenella elicited a strong specific response by cells from birds immune to E. tenella. In contrast cells from birds which were immune to E. acervulina responded to a similar magnitude to both E. tenella and E. acervulina antigens. This indicates that the lack of cross-protection is not due to the lack of cross-reactive T cells.

Animals↗
PubMed1986

Rupture of the intercondylar ligament in intertarsal joints of broiler fowls.

On examination of the intertarsal joints of approximately 150 lame broiler fowls, the intercondylar ligament was found to be ruptured, either partially or totally, in 22 birds. In some cases, rupture of the intercondylar ligament occurred in joints with gross angulation and usually in association with collateral ligament instability. In other birds, intercondylar ligament rupture occurred in limbs with minimal angulation but often with concomitant ligament or tendon failure in the same or contralateral limb. A fibrovascular layer was frequently identified between collateral ligaments and their distal tibiotarsal attachment. Haemorrhage in the fibrovascular tissue appears to be responsible for the establishment of the cyst-like structures which were present in some distal tibiotarsi.

Animals↗
PubMed1987

Meniscal lesions in knee joints of broiler fowls.

Post-mortem examination of the knee joints of 28 broiler type fowls revealed abnormalities in one or both medial menisci. Certain abnormalities appeared to be associated with knee ligament disruption. These included torn or frayed menisci and those which were displaced, usually in a mesial direction. Histopathological studies revealed that each of these abnormalities was normally associated with degenerative meniscal lesions. Other meniscal abnormalities showed no association with knee ligament disruption. Such menisci can be regarded as being of aberrant shape and most commonly the medial meniscus was enlarged and "discoid". Discoid medial menisci frequently showed histological abnormalities. As in other species, it is suggested that discoid menisci are predisposed to injury probably because of their larger contact area.

Animals↗
PubMed1988

Further studies on collateral ligaments of knee and intertarsal joints in domestic fowl.

Collateral ligament attachments in distal femora and distal tibiotarsi were examined in broilers on ad libitum and restricted feeding and in laying strain fowls fed ad libitum. Histopathological studies revealed morphological changes in ligaments of ad libitum-fed broilers which were less apparent or absent in other birds examined. One such change was loss of crimp pattern in collagen bundles of ligaments, which suggested that structural derangement had occurred. Chondroid metaplasia and foci of hyaline cartilage were observed in ligaments of ad libitum-fed broilers and may result from tissue ischaemia. Similarities were noted between ligament attachments in broilers and Osgood-Schlatter disease in man; lesions in broilers may well have a similar aetiology. It is concluded that although feed restriction restores some semblance of normality in broiler ligaments, the propensity for abnormality remains and becomes apparent in heavier birds. Such reasoning casts doubt on the wisdom of modern broiler breeding practice where feed restriction can mask genotypic predisposition to clinical disease.

Animal Husbandry↗
PubMed1989

Oestrogen and progesterone receptors and their relationship to histological grades of epithelial tumours of the magnum region of the oviduct of the domestic fowl.

Tumours of the proprial tubular glands of the magnum region of the oviduct of the domestic fowl (Gallus domesticus) were found to contain receptors for oestrogen and progesterone. The distribution of the receptors in the cytosol and nucleus of the tumour cells was similar to that of the normal magnum under oestrogen stimulation. Receptor content showed a positive correlation with increasing clinical stage and histological grade, i.e., malignancy and undifferentiation of the tumours. These tumours are unusual for hormonally responsive tumours in that their receptor mechanism remains intact with loss of differentiation.

Animals↗
PubMed1992

Effects of fowl adenovirus infection on the immune system of chickens.

A virulent strain of serotype 8 fowl adenovirus (FAV) was isolated from an outbreak of inclusion body hepatitis (IBH) in broiler flocks. Post-mortem changes included characteristic liver lesions with intranuclear inclusion bodies in the hepatocytes and severe lymphocytic depletion in the bursa, thymus and spleen. The packed cell volume was reduced by 50 per cent or more and varying amounts of cell depletion were observed in the bone marrow. Typical IBH was reproduced in specific pathogen-free chickens inoculated orally with the FAV isolated from the natural infection. There was severe depletion of lymphocytes in the bursa, thymus and spleen of the experimentally infected birds and FAV antigens were detected by ELISA and immunocytochemical staining in various lymphoid tissues. Humoral antibody responses against sheep red blood cells, detected by the haemagglutination test, were decreased in the chickens infected with FAV. These findings suggest that the damage caused by replication of this virulent strain of FAV in lymphoid tissues compromises the immunological capabilities of infected chickens.

Adenoviridae Infections↗
PubMed1984

Influence of vagotomy in domestic fowls on feeding activity, food passage, digestibility and satiety effects of two peptides.

The effects of bilateral vagotomy at the level of the proventriculus, in immature female fowls (VAG), on body weight, feeding activity parameters, rate of food passage, digestibility, and satiety effects of bombesin (BBS) and cholecystokinin octapeptide (CCK8), were compared with those in sham-operated controls (SHAM). SHAM birds gained weight at a greater rate postoperatively than before their operation, whereas VAG birds did not. Daily food intake did not change significantly as a result of the operation with either SHAM or VAG birds, and the only effect on feeding activity parameters was on the length of intermeal intervals, which increased in VAG birds. Rate of passage of the layers' mash diet was slower, and its apparent digestibility lower, in VAG than in SHAM birds. Short-term suppression of food intake, following intravenous injections of BBS (10 micrograms/kg) or CCK8 (10 micrograms/kg), did not differ between SHAM and VAG birds. The different postoperative weight gains may have been a consequence of different weights of food digested, and the difference in interval length was probably due to the different rates of food passage. The results of these experiments indicate that efferent information affecting rate of passage and digestibility travels via the vagus, but that afferent information concerned with initiation and termination of meals, and with satiety effects of BBS and CCK8, does not. Instead, such afferent information may travel via the intestinal nerve, which is unique to birds.

Animals↗
PubMed1986

Behavioral effects of intraventricular dibutyryl cyclic AMP in domestic fowl.

Intraventricular administration of dibutyryl cyclic AMP (dbcAMP) to domestic fowl induced behaviors within 60 seconds which persisted for 7-120 minutes. Stereotyped head movements and increases in preening were observed at the lowest dose (50 nmol), while at higher doses (150 and 225 nmol) head movements were interspersed with escape behavior, increases in locomotor activity, salivation and a loss of coordination. Administration also elicited vocalizations, mainly laying and type 1 warning calls. These calls contained many abnormal elements, possibly caused by relaxation of the syringeal musculature. The rate of calling was influenced by testosterone, being greater in hens and capons than in roosters or capons implanted with testosterone propionate. Caponization also intensified escape behavior. No behaviors were induced by administration of the hydrolysis product of dbcAMP, butyric acid. These behavioral effects of dbcAMP are similar to those reported to occur during electrical stimulation of loci in the avian brain.

Animals↗
PubMed1986

Food intake in the domestic fowl: effect of intrahepatic lipid and amino acid infusions.

Five experiments were conducted to determine the effect of hepatic and jugular infusions of amino acid and lipid solutions on short-term food intake of cockerels. Neither jugular nor hepatic infusions of amino acids had any effect on food intake of Single-Comb White Leghorn (SCWL) cockerels. Lipid infusions had no effect on SCWL cockerels when administered intrajugularly but decreased food intake significantly when infused intrahepatically. In contrast, no effect on food intake was observed when Rock-Cornish (RC) cockerels were infused intrahepatically with lipid. Thus, it appears that the liver of the SCWL cockerel is not responsive to plasma amino acid concentrations but is sensitive to circulating lipid levels. This lipid sensitive mechanism may be important in the peripheral control of food intake in a chicken such as the SCWL which has been bred for egg production but may be desensitized in fowl such as the RC broiler which has been selected for large body size and feed consumption.

Amino Acids↗
PubMed1987

An alternative explanation for apparent satiating properties of peripherally administered bombesin and cholecystokinin in domestic fowls.

This paper describes a series of experiments with domestic fowls designed to investigate different effects of peripherally administered bombesin (BBS) and cholecystokinin octapeptide (CCK8), with a view to gaining a better understanding of their proposed roles as physiological satiety signals. Following intravenous injections of 1-10 micrograms/kg BBS or CCK8, short periods of complete inhibition of feeding coincided with periods of abnormal gizzard motility, and longer periods of reduced feeding were associated with periods of abnormal gastrointestinal (GI) motility. Increases in heart rate, measured in a separate experiment, coincided with the periods of altered GI and feeding activities. Effects of the peptides on GI motility and feeding were strongly related to dose with CCK8, but not with BBS, and effects of (2 micrograms/kg) BBS and CCK8 on feeding were additive. Evidence from conditioned avoidance tests suggested that consequences of (10 micrograms/kg) BBS and CCK8 injections may be mildly aversive, perhaps more so with BBS, and in another experiment inhibition of feeding by (8 micrograms/kg) BBS (but not CCK8) was almost abolished in birds tranquillised with a reserpine derivative drug. CCK8 was more potent than BBS at suppressing feeding only when relatively high doses (8 and 10 micrograms/kg) were injected. It is suggested that peripherally administered BBS and CCK8 may act on feeding in similar ways, with animals being distracted by possible abdominal discomfort associated with the abnormal GI responses. The results indicate that immediate discomfort may be more severe with BBS, but that discomfort associated with CCK8 may last longer. It is further suggested that satiating properties of the peptides are less apparent in situations where animals are less easily distracted by discomfort, when their arousal is reduced, when their perception of discomfort is reduced and when their motivation to feed is increased.

Animals↗
PubMed1989

Altered spontaneous and osmotically induced drinking for fowls with permanent access to dilute quinine.

Fowls were given a dilute quinine solution as their sole source of fluid, and effects on normal ingestion and on drinking responses to dipsogenic stimuli were examined. Compared to controls with water, daily fluid intakes were depressed by 25% with quinine. There was no significant effect of quinine on food intake, but growth was suppressed slightly. Drinking in response to hypertonic NaCl injections was attenuated with quinine, and whereas an initial peak in water intake was seen directly after hypertonic NaCl injection, this was absent with quinine. Moreover, increases in quinine intake after hypertonic NaCl injections were insufficient to restore normal osmolality. Plasma analyses indicated that birds drinking quinine were permanently dehydrated and, unlike birds with water, they appeared to reduce the hyperosmolality induced by hypertonic NaCl injections in the absence of drinking. In contrast, drinking responses to angiotensin were generally similar with quinine and water, although birds drinking quinine tended to stop sooner with the highest dose of angiotensin. These results support previous suggestions that osmotic thirst is of primary importance in control of normal drinking, but also demonstrate that birds tolerate a degree of dehydration if a suitable fluid source is unavailable.

Angiotensin II↗
PubMed1994

Construct validation of behavioral indices of isolation stress and inflammatory nociception in young domestic fowl.

Isolation from conspecifics can elicit a variety of behavioral responses in young domestic fowl that include increased vocalizations (VOC), ventral recumbency posturing (VRP), hypoalgesia, and hyperthermia. During tests of acute inflammatory nociception, chicks not only display several pain-related behaviors (i.e., footpecks and lifts), but also VOC and VRP. However, systematic evaluation of whether these behaviors reflect converging indices of stress and nociception remains to be conducted. In two separate experiments, 7-day-old chicks received intraplantar formalin (0.05%) or saline (0.05 ml) and were placed in sound-attenuating chambers with or without two conspecifics for a 3 min observation period. The following measures were recorded: VOC, footlift frequency (LFT), and duration (DUR, Experiment 2 only), pecks (PKS), ventral recumbency latency (VRL), body temperature (BTMP), and body weight (WGT). Principal component analyses revealed the presence of two oblique and nonmonotonically related components, one consisting of pain-related measures (i.e., LFT, DUR, and PKS) and the other consisting of stress-related measures (VOC, VRL, and BTMP). A third component, consisting of BTMP and WGT ostensibly reflects maturational variability in thermoregulatory capability. These findings support the construct validity of these behavioral indices of isolation stress and inflammatory nociception and are consistent with the notion of stress effects on nociceptive processing.

Animals↗