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PubMed1996

Enhanced forebrain nitric oxide synthase activity in epileptic fowl.

Nitric oxide synthase (NOS) activity was examined in forebrain, cerebellum and optic lobes of adult domestic fowl, having a hereditary primary generalized convulsive disorder. NOS was approximately 2-fold higher in only the forebrain of adult epileptic fowl compared to non-epileptic (carrier) hatchmates. A significant increase in NOS was also evident in forebrains of 1-day-old epileptic chicks. Ca(2+)-dependency experiments confirmed that these increments were principally due to type I NOS (NOS-I). Induction of convulsions by intermittent photic stimulation did not affect pre-existing forebrain NOS-I activity. The present data suggest that an enhanced NO signaling may ensue in selected regions of the brain as an adaptive response to hereditary epileptogenesis.

Animals↗

PubMed1983

Comparison of turkey luteinizing hormone (LH)- and ovine LH-induced progesterone production in granulosa cells of the turkey (Meleagris gallopavo) and of the domestic fowl (Gallus domesticus).

Progesterone production was compared in short-term cultures of turkey and fowl granulosa cells isolated from preovulatory follicles of different maturities. In both species cells from the most mature follicle produced the greatest amount of progesterone under stimulated conditions and in response to ovine or turkey LH, the latter being significantly more potent. Whereas basal production of progesterone was higher in turkey cells, the response to LH or cAMP stimulation was significantly greater in chicken granulosa cells both in absolute terms and particularly in relation to unstimulated levels. These species differences may reflect difference in the intensity of reproductive activity of the turkey and the domestic fowl selected for egg production.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed1984

A comparison of the luteinizing hormone-releasing activities of synthetic chicken luteinizing hormone-releasing hormone (LH-RH), synthetic porcine LH-RH, and buserelin, an LH-RH analogue, in the domestic fowl.

The luteinizing hormone-releasing activities of synthetic chicken luteinizing hormone-releasing hormone (chLH-RH), synthetic porcine LH-RH (pLH-RH), and an analogue of LH-RH (buserelin, D-Ser-(But)6-des-Gly10-LH-RH ethylamide) were compared in the domestic fowl. In adult cockerels, intravenous injections of 0.5 or 1 microgram chLH-RH/kg released the same amount of LH as the same doses of pLH-RH; subcutaneous injections of 0.5 or 1 microgram buserelin/kg were about twice as effective as the same doses of pLH-RH. In laying hens, injections of 1, 10, 20, and 50 micrograms buserelin induced more sustained releases of LH than the corresponding doses of pLH-RH. Daily injections of 1 or 10 micrograms buserelin/bird or of 10 micrograms pLH-RH/bird for 12 days synchronized the timing of most ovipositions showing that the injections of releasing hormone could induce preovulatory surges of LH. In contrast with mammals, daily injections of buserelin in laying hens did not reduce pituitary responsiveness to the analogue. It is concluded that the structural difference between mammalian and chicken LH-RH does not affect their LH-releasing activities in the domestic fowl. Although the LH-releasing activity of buserelin in the hen is greater than that of pLH-RH, the difference in activity is not as great as that observed in most mammals. This view is strengthened by the finding that chronic treatment with buserelin, which exerts an antagonistic effect on ovulation in mammals, does not do so in the domestic hen.

Animals↗

PubMed1986

Somatostatin inhibits thyroid function in fowl.

Plasma concentrations of thyroxine (T4) and triiodothyronine (T3) were marginally (less than 25%) lowered 10 and 60 min, respectively, following somatostatin (SRIF) administration (at doses of 10-30 micrograms/kg) in immature domestic fowl. When plasma iodothyronine levels were elevated by the administration of anti-SRIF (1.0 ml/kg) 10 min prior to SRIF challenge, the inhibitory effect of SRIF on T4 and T3 concentrations was greatly augmented. The relative reduction in the T3 concentration was greater than the decline in the T4 level, resulting in a decline in the T3:T4 ratio. These data indicate that SRIF inhibits thyroid function in fowl, possibly by direct effects on the thyroid gland and by effects on the peripheral conversion of T4 to T3.

Animals↗

PubMed1987

Structure of the right testis of sexually mature genetically female fowl experimentally masculinized during embryonic life and submitted to a posthatching left castration.

Posthatching left castration of genetically female fowl, Gallus domesticus, preceded, during embryonic life, by a masculinizing treatment associating a testis graft and an antiestrogen resulted in the development of the right rudimentary gonad into a testis. Examined after the sexual maturity, the right testis of most treated animals was entirely composed of seminiferous tubules possessing a spermatogenic cell complement. Spermiogenesis proceeded to the stage of spermatozoon in 4 out of 17 treated animals and was almost as well organized as in a normal cock testis in 3 of them. Testis development appeared then as clearly improved, compared to that described previously in only left-castrated, with or without treatment with an antiestrogen, or only sex-reversed female fowl. The possible mechanism of this improvement is discussed.

Animals↗

PubMed1987

Calcium participation in thyroid function in fowl (Gallus domesticus).

The effects of the calcium antagonists ethyleneglycol-bis-(beta-aminoethylether)-N,N,N',N'-tetraace tic acid (EGTA), cobalt chloride (CoCl2), and magnesium chloride (MgCl2) on the concentrations of plasma thyroxine (T4) and triiodothyronine (T3) and on the basal and stimulated release of T4 from incubated thyroid glands have been determined in the domestic fowl. Plasma T4 levels were consistently reduced 2 hr after the administration of each calcium antagonist, although only EGTA and CoCl2 lowered the concentration of plasma total calcium. Concentrations of plasma T3 were increased following MgCl2 treatment but reduced after CoCl2 administration. The basal release of T4 by incubated thyroid glands was reduced following in vivo EGTA and CoCl2 treatment, but increased after MgCl2 injection. The addition of bovine thyroid stimulating hormone (TSH, 200 mU) to the incubation consistently stimulated in vitro T4 release, although the magnitude of the stimulation was increased following in vivo EGTA or CoCl2 treatment and reduced after MgCl2 administration. These results demonstrate the involvement of calcium dependent mechanisms in the control of T4 release in fowl.

Animals↗

PubMed1986

Further studies on knee ligament failure in broiler breeding fowls.

A group of 88, predominantly male, broiler breeding fowls was examined and, in 38, knee ligament failure was identified. All birds were aged between 15 and 60 weeks when examined. Although derangement of the caudal cruciate ligament was the most frequent finding (25 birds), partial or total rupture of the cranial cruciate ligament was also identified (10 birds). Medial (10 birds) and lateral (5 birds) collateral ligament failure was also noted. Knee ligament failure may, in part, be age related. The most frequent concomitant finding in individual birds was tendon or ligament failure elsewhere in the same skeleton. It can therefore be assumed that male broiler breeding fowls are predisposed to ligament and tendon failure and a high proportion will have lesions at more than one skeletal site.

Animals↗

PubMed1987

Destructive cartilage loss in the joints of adult male broiler breeding fowls.

Patterns of destructive cartilage loss were studied in 60 male broiler breeding fowls. All showed destructive lesions in their hip or intertarsal joints and were between 18 and 62 weeks old when killed. Although surface regressive changes in articular cartilage were common, deep fibrillation, as seen in human and mammalian osteoarthrosis, was not identified. This difference probably reflects the more fibrous nature of articular cartilage in birds, but a number of similarities to hyaline cartilage degeneration were noted. Destructive cartilage loss resulted from partial or full thickness detachment of uncalcified cartilage. Clefts in deep cartilage preceded segmental detachment and occurred in cartilage with an intact articular surface. Detachment of segments of uncalcified cartilage may be the principal method of destructive cartilage loss in all avian species. It is concluded that clefts and destructive cartilage loss in adult broiler fowls can be a consequence of articular osteochondrosis or may result from osteoarthrosic lesions.

Acetabulum↗

PubMed1987

Thinning of articular cartilage in the domestic fowl.

Thinning of articular cartilage was identified in pelvic limb joints of broiler and Leghorn-type fowls. Almost all of 100 fowls examined showed cartilage thinning or loss in hip and knee joints. Particular attention was paid to proximal femora; in these, the principal mechanism of cartilage loss involved processes described as "peripheral remodelling". From the edge of cartilage sheets, fibrovascular tissue removed articular cartilage by two mechanisms. Either a pannus of fibrovascular tissue covered the articular surface or non-osseous tissue invaded through discontinuities in the bone plate. As in man, peripheral remodelling appears to be age-related and unrelated to regressive or destructive cartilage loss.

Animals↗

PubMed1989

Disturbed endochondral ossification in the axial skeleton of young broiler fowls.

Physeal lesions have been studied in thoracic vertebrae (T3, T4 and T5) of 51 broiler fowls between 28 and 53 days old. Vascular perfusion studies performed on 10 birds confirmed that the cartilaginous epiphyses of T3, T4 and T5 were essentially avascular and thus differ from those of the major long bones. Findings confirm the observation that a number of morphologically distinct lesions of osteochondrosis occur in broiler fowls and that, when physeal clefts can be implicated in their aetiology, the term "osteochondrosis" is inappropriate. Although the location of clefts often differs in long bone and vertebral physes, when metaphyseal vessels are disrupted, the end-result on endochondral ossification is the same in both the axial and appendicular skeleton. Other lesions were observed both independently and in association with osteochondrosis. Such lesions include necrotic seams devoid of haemorrhage, acellular foci and chondrolysis, all of which were most frequently observed in the same vertebral end-plates. Because osteochondrosis was also most common in the same vertebral end-plates, a common aetiology is suggested. Surface regressive changes were common in the articular cartilage of T3, T4 and T5, and it is noteworthy that such changes, although common in older birds, are present in birds so young.

Animals↗

PubMed1989

Physeal clefts and disturbed endochondral ossification in broiler fowls.

Histopathological studies have been conducted on 35 physes from 19 broiler type fowls of different ages in order to elucidate the pathogenesis of dyschondroplasias. Findings support the suggestion that different forms of dyschondroplasia occur in broiler fowls and that histopathological studies are required if each is to be distinguished. It is concluded that physeal clefts produce one form of dyschondroplasia when epiphyseal blood vessels are occluded. A unifying concept is proposed that implicates epiphyseal and/or metaphyseal vascular disturbances in the differing morphology of some lesions, at least. This concept is supported by findings in this and other studies and is proposed as a possible explanation for morphological differences between avian dyschondroplasia and mammalian osteochondrosis.

Animals↗

PubMed1982

Properties of 5-ene-3 beta-hydroxysteroid dehydrogenase in granulosa tissue from the domestic fowl (Gallus domesticus).

Microsomal 5-ene-3 beta-hydroxysteroid dehydrogenase activity from fowl preovulatory granulosa tissue was solubilised by treatment with 2.0 M KCl. The efficiency of the solubilisation procedure was assessed by measuring the amount of activity remaining in the supernatant after centrifugation at 105,000 g for 8 h. The microsomal activity was resolved into two components: a fraction solubilised by the salt treatment and a fraction remaining membrane bound. The results indicate that the enzyme exists in two different environments within the membrane. The time course for the thermal inactivation of the microsomal enzyme supported this conclusion. The properties of the solubilised enzyme were compared with the untreated microsomal preparation, with respect to steroidal inhibition. Progesterone, 4-androstene-3,17-dione and oestradiol-17 beta all inhibited the enzyme and no difference was observed between the two preparations. The results are discussed in relation to the involvement of 5-ene-3 beta-hydroxysteroid dehydrogenase in the control of progesterone production in fowl granulosa tissue.

3-Hydroxysteroid Dehydrogenases↗

PubMed1985

An investigation into the role of the crop in control of feeding in Japanese quail and domestic fowls.

With normal diets, removal of the crop in Japanese quail and domestic fowls caused reductions in mean meal lengths and sizes, and compensatory increases in meal frequencies, only in those (30-40%) birds that had previously eaten larger, less frequent meals. Sham operation had no such effect. Cropectomy had less effect on feeding activity parameters when quail were fed on a diluted (40% cellulose) diet, and had no effect on diurnal patterns of feeding with either undiluted or diluted food (all birds tending to eat more at the end of the day). This may have been because cropectomized birds could store food in the oesophagus in amounts similar to those previously stored in the crop. Cropectomy had no apparent long-term effect on food intake with undiluted diets, but may have suppressed it slightly with diluted food. In intact quail and fowls, with ad lib access to food when killed, crops were often found to be empty with undiluted food, but were rarely so with diluted food. Gizzards also tended to hold more with diluted food, but were never completely empty with any diet. The post-crop oesophagus and proventriculus were empty in nearly all birds. In quail fasted for two hours, then allowed to feed for 20 min and killed at intervals over a further two hours, maximum amounts of undiluted and diluted food in crops and gizzards were generally greater than in ad lib-fed quail. Crops and gizzards emptied faster with diluted than with undiluted food, but no gizzard was completely empty two hours after feeding. The results of these experiments indicate that, with normal diets, meal termination (satiety) during most of the day is associated with partial crop filling in (30-40%) birds that habitually eat larger, less frequent meals, and with varying degrees of gizzard filling in birds with smaller meals. Satiety involves more crop filling in more birds with diluted food, and this may also apply to other factors that cause increased feeding activity. Meal initiation (hunger) may be associated with partial gizzard emptying in all birds. At some stage towards the end of the day there is usually a conditioned change to cumulative filling of the crop with enough food to be processed overnight.

Animals↗

PubMed1986

Alteration of food intake following intracerebroventricular administration of plasma from free-feeding domestic fowl.

Four experiments were conducted to investigate the presence of a factor in the plasma of the domestic fowl that alters food intake when injected into the lateral cerebral ventricle. Plasma collected from free-feeding and 24-hour fasted birds was lyophilized and reconstituted to 2, 4, or 5 times normal concentration. Stainless steel guide cannulae were stereotaxically implanted into the lateral cerebral ventricle of 8-week-old Single Comb White Leghorn cockerels. Free-feeding birds received 10 microliter intracerebroventricular (ICV) injections of normal (Experiment 1) and concentrated (Experiments 2, 3, and 4) plasma collected from free-feeding and 24-hour fasted birds. Artificial cerebrospinal fluid (aCSF) served as the control. Food intake was significantly decreased by ICV injections of 2, 4, and 5 times normal concentration of plasma from fed birds. Plasma from fasted birds did not alter food intake regardless of concentration, but did significantly reduce water intake when concentrated to five times normal. It appears that a satiety factor, which can be detected by the central nervous system, is present in the plasma of free-feeding domestic fowl.

Animals↗

PubMed1986

Influence of ambient temperature on feeding activity parameters and digestive function in domestic fowls.

In order to better understand the way in which domestic fowls regulate their food intake at different ambient temperatures, measurements were made of feeding activity parameters, drinking, rate of food passage, apparent digestibility and gut dimensions of immature female fowls acclimated to cool (8 degrees C), moderate (20 degrees C) and warm (32 degrees C) environments. At 8 degrees C birds had longer (p less than 0.05) intervals between meals, ate larger meals, ate faster within meals and digested their food more efficiently than at 20 degrees C. At 32 degrees C they ate less food per day, drank more water, had a higher water/food intake ratio, ate slower within meals, had a slower rate of food passage, and had smaller proventriculi, gizzards and caeca than at 20 degrees C. It is concluded that differences in daily food intake between temperatures are associated more closely with differences in meal size and rate of eating within meals than with differences in meal frequency. Effects of temperature on behavioural thermoregulation, drinking and rate of food passage all influence patterns of feeding activity shown.

Animals↗

PubMed1991

Red cell size and various lung arterial measurements in different strains of domestic fowl.

Red cell size and various lung arterial measurements were examined in different strains of young commercial broiler and layer fowls. The broilers were: Marshall, Cobb, Ross 'selected', Ross 'relaxed' and the layers were: Isa Brown, Ross Brown and Hisex Brown. The Ross relaxed bird had a significantly larger red cell than any other strain. Overall, broilers had larger red cells than layers. The internal elastic lamina, a measure of arterial size, was small in the Ross relaxed bird (138 microns) and was at its maximum (163 microns) in the selected Ross strain. The medial area (muscle coat) was least in the Ross relaxed bird (984 microns2) and greatest in the Cobb strain (1516 microns2). In some strains there was a slight correlation among birds between red cell and arterial size but not with the medial area. The results appeared to indicate that red cell size may not be the only important correlating factor in the aetiology of pulmonary hypertension in fowls.

Animals↗

PubMed1982

Blood flow distribution during artificially induced respiratory hypocapnic alkalosis in the fowl.

In birds, hyperthermia is normally associated with panting and progressive respiratory alkalosis. The effect of respiratory alkalosis on capillary blood flow distribution was examined by artificially hyperventilating normothermic fowls, thereby dissociating it of the normally occurring concomitant hyperthermia. In contrast with mammals, in which hyperventilation associated with hypocapnia reduced blood flow to the brain, uterus and other organs, in the hen blood flow distribution in most organs remained unaltered. This indicates that the potential change in acid-base balance which develops in the hyperthermic birds during panting is not likely to affect the regulation of blood flow. The comb and wattles were the only affected organs, in which capillary blood flow diminished to about 45% of normal values. This reduction did not prevent a vasodilatation in those organs in hyperthermic fowls, though it probably limited its full expression.

Alkalosis, Respiratory↗

PubMed1983

Oxygen affinity of blood of adult domestic chicken and red jungle fowl.

Respiratory properties of blood from adult domestic chicken (White Leghorn) and red jungle fowl (Gallus gallus, ancestor of domestic breeds) at 41 degrees C were investigated. Oxygen affinity was the same in blood of chicken and jungle fowl (P0.5 46.7 Torr at pH 7.5, 41 degrees C, PCO2 about 30 Torr). The Hill coefficient, nH, increased from 2 at oxygen saturation 0.1 to a maximum of 4.11 at saturation 0.8. Leghorn fixed acid and CO2 Bohr coefficients were -0.51 and -0.53, with little variation over the saturation range 0.15-0.95, indicating negligible specific CO2 effect. An nH value of greater than 4 may indicate polymerization of deoxyhemoglobin, comparable to that which occurs in sickle cell hemoglobin. A biphasic equilibrium curve shape (hump at the low end of the oxygen equilibrium curve) was noted in blood having some degree of hemolysis. Factors that may have contributed to the differences between previous investigations of chicken oxygen affinity are discussed.

Acid-Base Equilibrium↗