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At least 937 records · Page 52Linked to original sources
PubMed1975

Plasma iron transport during egg laying and after oestrogen administration in the domestic fowl (Gallus domesticus).

The concentrations of 59Fe and of radioiodinated transferrin and albumin were measured in the blood, liver, spleen, bone marrow and ova at different times after the injection of transferrin-bound 59Fe and the labelled proteins into non-laying, laying and oestrogen treated chickens. In the egg-laying and oestrogen-treated birds the 59Fe of the plasma was rapidly transferred from transferrin to another component with the properties of th phosphoprotein, phosvitin. Radioactive iron, and labelled transferrin and albumin to a lesser extent, entered the ova only while they were in the ovary. Relatively more labelled transferrin than albumin was found in all the tissues studied except in the ova, in which the two labelled proteins were present in the same relative concentration as in the plasma. It is concluded that, during egg laying and after oestrogen treatment, plasma iron bound to transferrin is taken up by the liver, incorporated into phosvitin and is then secreted into the plasma leading to elevation of the plasma iron concentration and transfer of iron to the ova.

Animals↗
PubMed1989

Factors determining gastrointestinal transit time of several markers in the domestic fowl.

The aim of this study was to find out how marker characteristics could affect digestive transit time in Gallus gallus. One soluble marker, Cr-EDTA, and two insoluble markers, Cr2O3 and chromium-mordanted plant cells of two sizes, were used. Three- to six-week-old chickens were killed in series after the oral administration of the markers at intervals of 0, 0.5, 1, 2, 3, 5, 7, and 9 h. The amount of chromium in each digestive segment was determined by atomic absorption. There were some differences in the initial distribution of markers; whereas almost the total amount of the chromium-mordanted rice husk of the largest size was found in the crop at time 0, less than half of the Cr-EDTA was found. Marker emptying out of the crop was fast and not related to either the type or size. In contrast, the emptying rate of the gizzard depended on marker particle size. As far as the caeca were concerned, the ileocaecal junction allowed the passage of soluble Cr-EDTA whereas solid markers were impeded (Cr2O3) or not allowed to pass through at all (vegetable fibre of any size). It can be concluded that marker selection is of major importance to transit time studies in chickens, since its characteristics can determine transit time in an absolute way.

Animals↗
PubMed1978

Metabolic rate: its circadian rhythmicity in the female domestic fowl.

1. In quasi-natural cyclic lighting, a circadian rhythm was observed in seven fowls; the range of oscillation of the rhythm was 50% of the mean metabolic level. Little variation was present between the individuals. 2. In fowls maintained for 15 days in isolation under 700 lx (ten fowls) or 0.07 lx (four fowls) constant lighting and at constant temperature free-running rhythms were evident; the range of oscillation was about 12% of the mean level. Large variation prevailed between the individuals in the range of oscillation and in the portion of variance accounted for by periodic regression. In dim light, rhythmicity declined to become non-significant by 8 days of exposure. 3. In four fowls maintained in a 6L/6D regimen for 12 days, metabolic rate was entrained to an ahemeral rhythm; there was no evidence of circadian influence on the metabolic response to light. Little variation was present between the individuals. Rhythmicity was maintained over the experimental period. 4. Metabolic levels were similar on 0.07 lx, 700 lx constant light, during the dark phase of the 6L/6D regimen and during night time in the quasi-natural cyclic lighting. They were also similar on the light phase of the 6L/6D regimen and the quasi-natural lighting.

Animals↗
PubMed1986

Intrinsic reflexes underlying peristalsis in the small intestine of the domestic fowl.

Peristalsis in the chicken small intestine was studied using either a modified Trendelenburg method or a technique in which changes in circular muscle activity were recorded in response to application of a localized radial distension. A localized radial distension had no effect on either the resting tension or the spontaneous activity of the circular muscle on the oral side of distension. On the aboral side of the distension a transient contraction was recorded in the ileum and jejunum after a mean delay of 2.74 s at 37 degrees C. In about a third of the preparations a tonic contraction was also present which persisted for as long as distension was maintained. The transient contraction was blocked by hyoscine (0.6-2.3 microM) and hexamethonium (275 microM); whereas the tonic contraction persisted in the presence of hyoscine. Both types of contraction were blocked by tetrodotoxin (0.31 microM). No such responses were recorded in the duodenum. The descending excitatory reflex responses were followed in all preparations by a fall in the amplitude and frequency of spontaneous contractions and in a few preparations by a concomitant fall in the tone of the circular muscle lasting for up to 3 min. This inhibitory component of the descending reflex was not blocked by guanethidine (3-10 microM). The transient contraction, which originated most frequently at the site of distension, always propagated aborally at a mean speed of 14.2 mm s-1. Surgical interruption of the longitudinal muscle and myenteric plexus effectively blocked the transmission of the excitatory and inhibitory components of the descending reflex past the site of the lesion. In the modified Trendelenburg apparatus raising the intraluminal pressure elicited peristalsis in the isolated ileum. Peristaltic contractions never started at the most oral end of the preparation but appeared instead at any other point on the ileum. This resulted in several contractions contributing to each emptying cycle. Peristalsis was blocked by tetrodotoxin (0.31 microM). These results are discussed in the terms of the organization of the descending reflex. It is suggested that within the enteric nervous system of the ileum and jejunum of the chicken, there are cholinergic and non-cholinergic excitatory neurones and non-adrenergic inhibitory neurones. The results of this study demonstrate that neurogenic peristalsis in the avian small intestine does not conform to the 'law of the intestine' as originally postulated by Bayliss & Starling (1899).

Animals↗
PubMed1961

Toxoplasma from the eggs of the domestic fowl (Gallus gallus).

Toxoplasmata of varying grades of virulence were isolated from eggs laid by clinically asymptomatic hens and from their internal organs. The strains so recovered were identified as Toxoplasna gondii by morphological, serological, cultural, and pathogenic criteria. These findings strongly suggest that toxoplasmosis may be contracted through the eating of raw or undercooked infected eggs.

Animals↗
PubMed1983

Floor space allowances for the caged domestic fowl.

The maximal cross-sectional area, the length and the width of 48 pure bred hens weighing between 1 and 4 kg were determined using a photographic technique. It is shown that the typical (2.4 kg) bird occupies an area of 637 cm2 but that this value is much affected by the degree of feathering. The same bird is 21.3 cm wide and 41 cm long. Space allowances for caged birds are discussed in the light of these data.

Animals↗