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At least 685 records · Page 38Linked to original sources
PubMed1983

Effects of selective breeding and age on the ability of the domestic fowl (Gallus domesticus) to oxidize trimethylamine.

Groups of adults which were selected for low and high (normal) TMA oxidase activities produced chickens with a predominance of the same character showing that capacity for synthesizing the enzyme is strongly inherited. The low and high strains became homogenous in generations 2 and 3, respectively, demonstrating that the genetic factor that impairs the synthesis of TMA oxidase can be readily removed by selective breeding. There was a 7-fold difference in the hepatic TMA oxidase activities of the strains at the age of 1 day and a 26-fold difference at 22 days. The synthesis of the enzyme increased rapidly in the high strain between the ages of 8 and 36 days but did not alter significantly in the low strain. Sex had no effect on TMA oxidase synthesis. The high strain showed better feather development and laid eggs with paler shells. There was no difference in their growth rate, egg production or hatchability.

Age Factors↗
PubMed1983

Serotoninergic drugs affect prolactin and growth hormone secretion in the domestic fowl.

Adult fowl of both sexes injected with the monoamine oxidase inhibitor pargyline showed elevated circulating prolactin concentrations and reduced growth hormone concentrations. Young cockerels injected with the serotonin agonist quipazine and the antagonist methysergide showed responses consistent with a serotoninergic stimulatory control of prolactin. Injection of the serotonin precursor tryptophan and the serotonin re-uptake blocker imipramine resulted in elevated prolactin and reduced growth hormone levels. The similarities and differences in the control of prolactin and growth hormone in birds and mammals were discussed.

Animals↗
PubMed1992

Aflatoxin and glutathione in domestic fowl (Gallus domesticus)--II. Effects on hepatic blood flow.

1. The effect of aflatoxin on plasma aspartate aminotransferase (AST), protein, and hepatic glutathione (GSH) and hepatic blood flow (perfusion), were determined in 3-week-old male chickens. 2. Daily aflatoxin gavage (2 mg/kg body wt, in corn oil) for 5 and 10 days elevated plasma AST and hepatic GSH, and depressed plasma protein and hepatic perfusion. Also, renal GSH was elevated after 10 days of aflatoxin treatment. 3. Birds given aflatoxin for 10 days followed by a 10-day recovery period exhibited tissue GSH, plasma AST and protein levels that were not different from control, but hepatic perfusion remained depressed.

Aflatoxins↗
PubMed1992

Aflatoxin and glutathione in domestic fowl (Gallus domesticus)--I. Glutathione elevation and attenuation by high dietary methionine.

1. Changes in hepatic and renal glutathione (GSH) and plasma aspartate aminotransferase (AST) following single or daily oral doses of aflatoxin B1 (AFB1, 2 mg/kg BW) or corn oil vehicle (1 ml/kg BW) were determined in male chickens (14-21-day-old). 2. Plasma AST and hepatic GSH increased 2 and 8 hr, respectively, following a single AFB1 dose. 3. Hepatic GSH continued to increase through 5 daily doses of AFB1, but there were no differences in AST levels on days 1-5. Feeding a diet containing 150% of NRC requirement for methionine attenuated the AFB1-induced increase in hepatic GSH. Renal GSH was unaffected by AFB1 or dietary treatment.

Aflatoxin B1↗
PubMed1991

In vitro studies on steroidogenesis in the presence of pregnenolone as precursors by the follicular tissue of the domestic fowl (Gallus domesticus).

Chicken granulosa and theca cells were isolated from F1 and F4-6 follicles 2-4 h before ovulation, and the amounts of progesterone, testosterone and oestradiol released in the medium during incubation for 3 h, in the presence or absence of pregnenolone as a percursor and stimulatory drugs or inhibitory drugs, were measured. Progesterone synthesis by granulosa cells was stimulated with oLH or theophylline. Much more progesterone was synthesized when pregnenolone was added to the medium. The amount of testosterone produced by the granulosa cells was similar to that produced by the theca cells. The production of testosterone was increased by the addition of oLH or theophylline. Oestradiol synthesis by F4-6 follicles was higher than by F1 follicles, and it was higher in the theca cells than in the granulosa cells. The addition of oLH or theophylline increased oestradiol synthesis in the theca cells and the granulosa cells of F4-6 follicles. The results indicate that oestradiol can be produced from pregnenolone by the theca cells alone. It is possible, however, that the theca cells also take in the precursors for the production of oestradiol from the granulosa cells.

Animals↗
PubMed2004

Comparison of social ranks based on worm-running and aggressive behaviour in young domestic fowl.

Worm-running is behaviour in which a chick runs carrying a worm-like object while flock mates follow and attempt to grab the object from its beak. We hypothesised that social ranks based on worm-running frequency are stable over time and are positively correlated with social ranks based on success in aggressive interactions when older. At 8-12 days of age, we scored worm-running in 17 groups of 12 female White Leghorn chicks during three 10-min tests. Based on instantaneous scans at 5-s intervals, the bird carrying the 'worm' most often was placed in rank one and so on down the rank order. These tests were repeated at 68-70 days of age. An aggression index for each bird was calculated as the number of aggressive acts given, divided by the number given and received, during three 1-h observation periods when the birds were 68-70 days. Ranks obtained in worm-running tests were positively correlated over the two age periods (P < 0.05) but were not correlated with ranks based on the aggression index (P > 0.05). Our results indicate that worm-running ranks are not predictive of success in aggressive interactions. Instead, worm-running fits some criteria for play.

Aggression↗
PubMed2005

Heterogeneity of growth hormone immunoreactivity in lymphoid tissues and changes during ontogeny in domestic fowl.

Growth hormone (GH) expression is not confined to the pituitary and occurs in many extrapituitary tissues. Here, we describe the presence of GH-like moieties in chicken lymphoid tissues and particularly in the bursa of Fabricius. GH-immunoreactivity (GH-IR), determined by ELISA, was found in thymus, spleen, and in bursa of young chickens, but at concentrations <1% of those in the pituitary gland. Although the GH concentration in the spleen and bursa was approximately 0.82 and 0.23% of that in the pituitary at 9-weeks of age, because of their greater mass, the total GH content in the spleen, bursa, and in thymus were 236, 5.18, and 31.5%, respectively, of that in the pituitary gland. This GH-IR was associated with several proteins of different molecular size, as in the pituitary gland, when analyzed by SDS-PAGE under reducing conditions. While most of the GH-IR in the pituitary was associated with the 26 kDa monomer (40%), the putatively glycosylated 29 kDa variant (16%), the 52 kDa dimer (14%) and the 15 kDa submonomeric isoform (16%), GH-IR in the lymphoid tissues was primarily associated (27-36%) with a 17 kDa moiety, although bands of 14, 26, 29, 32, 37, 40, and 52 kDa were also identified in these tissues. The heterogeneity pattern and relative abundance of bursal GH-IR bands were determined during development between embryonic day 13 (ED13) and 9-weeks of age. The relative proportion of the 17 kDa GH-like band was higher (45-58%) in posthatched birds than in the 15 and 18-day old embryos (21 and 19%, respectively). The 26 kDa isoform was minimally present in embryos (<4% of total GH-IR) but in posthatched chicks it increased to 12-20%. Conversely, while GH-IR of 37, 40, and 45 kDa were abundantly present in embryonic bursa ( approximately 30% at ED13 and approximately 52-55% at ED15 and ED18, respectively), in neonatal chicks and juveniles they accounted for less than 5%. These ontogenic changes were comparable to those previously reported for similar GH-IR proteins in the chicken testis during development. In summary, these results demonstrate age-related and tissue-specific changes in the content and composition of GH in immune tissues of the chicken, in which GH is likely to be an autocrine or paracrine regulator.

Animals↗
PubMed2001

Quantification of the crowding effect during infections with the seven Eimeria species of the domesticated fowl: its importance for experimental designs and the production of oocyst stocks.

The 'crowding effect' in avian coccidia, following administration of graded numbers of sporulated oocysts to naïve hosts, is recognisable by two characteristics. First, increasing doses of oocysts give rise to progressively higher oocyst yields, until a level of infection is reached (the 'maximally producing dose') above which further dose increases result in progressive decreases in oocyst yields. Second, the number of oocysts produced per oocyst administered (the 'reproductive potential') tends to decrease as the oocyst dose is increased. The dose that gives the maximal reproductive potential is the 'crowding threshold' and doses exceeding this are 'crowded doses'. Graded doses of Eimeria acervulina, Eimeria brunetti, Eimeria maxima, Eimeria mitis, Eimeria necatrix, Eimeria praecox or Eimeria tenella were given to chickens of the same breed, sex and age, reared on the same diet, under identical management. The two characteristics of the crowding effect were demonstrated graphically and, by interpolation, the estimated crowding thresholds were 903, < or =16, 39, < or =14, < or =16, < or =16 or 72 sporulated oocysts, respectively, for the seven Eimeria species enumerated above. This is apparently the first report of definitive experiments to quantify a crowding effect in E. brunetti, E. maxima, E. mitis, E. necatrix and E. praecox. Maximum experimental reproductive potentials were considerably lower than the theoretical reproductive potentials for all seven species. The interaction between availability of host intestinal cells and immunity contributing to the crowding effect is discussed. Standard curves obtained under specified conditions should be used to estimate appropriate infective doses for experimental designs or in vivo production of oocyst stocks. For experiments on effects of chemotherapy or immunisation on oocyst production, an infective dose lower than the crowding threshold should be used. For efficient production of laboratory or factory oocyst stocks, the maximally producing dose (which is greater than the crowding threshold), should be used.

Animals↗