THE PHYSIOLOGICAL SIGNIFICANCE OF ANDROGEN-INDUCED OVULATION IN THE HEN

1980 ◽  
Vol 84 (1) ◽  
pp. 163-171 ◽  
Author(s):  
F. CROZE ◽  
R. J. ETCHES
Keyword(s):  
Body Weight ◽  
Effective Dose ◽  
Physiological Role ◽  
Laying Hen ◽  
Physiological Significance ◽  
White Leghorn ◽  
Blood Samples ◽  
Induced Ovulation ◽  
Single Comb

The ovulation-inducing property of androgens in the laying hen was investigated. In a first experiment, four different androgens were injected subcutaneously into single-comb White Leghorn hens on the day of the last oviposition of a sequence. The hens were killed 10 h later and examined for the presence of an ovum in the oviduct. Testosterone induced ovulation in accordance to the dose injected (median effective dose, 966 ± 193 μg/hen) but the responses to 5α-dihydrotestosterone and 5α-androstane-3α, 17β-diol were not dose-related. The effect of 4-androstene-3,17-dione was more like that of progesterone since it induced ovulation 2 h earlier than the three other androgens. The physiological significance of the ovulation response to an injection of testosterone was examined in more detail in experiment 2. Seven out of ten hens which were injected with 1 mg testosterone/kg body weight ovulated within 10 h after the injection. Blood samples were taken at hourly intervals and the concentrations of testosterone and progesterone were determined by radioimmunoassay. An injection of testosterone produced an increase in the concentration of testosterone in plasma which was considerably greater and occurred earlier than the preovulatory increase of testosterone in the control birds. The increase in the concentration of progesterone in the hens injected with testosterone was similar in magnitude but occurred earlier than the spontaneous preovulatory increase of progesterone in the control hens. The possible physiological role of testosterone in the ovulation cycle is discussed.

scholarly journals DOMINANCE AND EPISTASIS IN HETEROSIS OF WHITE LEGHORN STRAIN CROSSES

1987 ◽  
Vol 67 (3) ◽  
pp. 663-680 ◽  
Author(s):  
R. W. FAIRFULL ◽  
R. S. GOWE ◽  
J. NAGAI
Keyword(s):  
Body Weight ◽  
Sexual Maturity ◽  
Egg Production ◽  
Significant Contribution ◽  
Production Traits ◽  
White Leghorn ◽  
Cross Combination ◽  
Commercial Strain ◽  
Better Than

Four unrelated pure strains of White Leghorns including a grandparent strain from industry and 12 two-strain, 24 three-strain, 24 four-strain and 12 F2 strain crosses produced contemporaneously were used to examine the role of dominance and epistasis in heterosis. A control strain and a commercial strain were also included. For egg weight, the heterosis observed closely approximated that expected due to dominance alone. For sexual maturity and body weight, dominance was the major component of heterosis, but epistasis made a significant contribution — additive by additive (A × A) genetic effects for sexual maturity and 140-d body weight, and parental epistasis for mature body weight. Both dominance and epistasis played a significant role in heterosis for egg production traits. A × A, dominance by dominance (D × D) and additive by dominance (A × D) epistasis were all important for hen-housed egg production and hen-housed egg yield. For hen-day rate of egg production, A × A epistasis was significant only early in the laying year (to 273 d), A × D and D × D were significant to 385 d and in the full year (to 497 d); however, none (A × A, A × D and D × D) was significant near the end of lay (386–497 d). Overall heterosis estimates for full year egg production measured as hen-housed egg production to 497 d or hen-day rate from housing to 497 d clearly showed that on average two-strain crosses were superior to three-strain crosses which were superior to four-strain crosses which in turn exceeded the F2 crosses. Nevertheless, several three-strain crosses had performance for egg production that was equal to or better than the two-strain cross with the highest egg production. Thus, in commerce, where the level of egg production is of great economic importance, the testing and use of a specific three-way cross combination will usually result in a better commercial product. Key words: Heterosis, egg production genetics, epistasis, stocking rate, strain cross, White Leghorn

SUBSTITUTION OF SORGHUM FOR WHEAT IN DIETS FOR LAYING HENS

1982 ◽  
Vol 62 (1) ◽  
pp. 305-306 ◽  
Author(s):  
E. E. GARDINER ◽  
D. J. MAJOR ◽  
S. DUBETZ
Keyword(s):  
Body Weight ◽  
Key Words ◽  
Egg Production ◽  
Laying Hens ◽  
Feed Consumption ◽  
White Leghorn ◽  
Egg Weight ◽  
Single Comb

The effects of substituting various levels of sorghum for wheat in diets for laying hens were studied. Egg production, egg weight, feed consumption, body weight and hatchability of eggs from Single Comb White Leghorn hens were not affected by the proportion of sorghum in the diet. Key words: Sorghum, wheat, nutrition, egg production

Effect of actively immunizing sheep against growth hormone-releasing hormone or somatostatin on spontaneous pulsatile and neostigmine-induced growth hormone secretion

1995 ◽  
Vol 144 (1) ◽  
pp. 83-90 ◽  
Author(s):  
E Magnan ◽  
L Mazzocchi ◽  
M Cataldi ◽  
V Guillaume ◽  
A Dutour ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Body Weight ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Physiological Role ◽  
Gh Secretion ◽  
Igf I ◽  
Plasma Gh ◽  
Hypophysial Portal

Abstract The physiological role of endogenous circulating GHreleasing hormone (GHRH) and somatostatin (SRIH) on spontaneous pulsatile and neostigmine-induced secretion of GH was investigated in adult rams actively immunized against each neuropeptide. All animals developed antibodies at concentrations sufficient for immunoneutralization of GHRH and SRIH levels in hypophysial portal blood. In the anti GHRH group, plasma GH levels were very low; the amplitude of GH pulses was strikingly reduced, although their number was unchanged. No stimulation of GH release was observed after neostigmine administration. The reduction of GH secretion was associated with a decreased body weight and a significant reduction in plasma IGF-I concentration. In the antiSRIH group, no changes in basal and pulsatile GH secretion or the GH response to neostigmine were observed as compared to controls. Body weight was not significantly altered and plasma IGF-I levels were reduced in these animals. These results suggest that in sheep, circulating SRIH (in the systemic and hypophysial portal vasculature) does not play a significant role in pulsatile and neostigmine-induced secretion of GH. The mechanisms of its influence on body weight and production of IGF-I remain to be determined. Journal of Endocrinology (1995) 144, 83–90

Carcass traits and reproductive organ morphology in 62-week-old SCWL hens

1995 ◽  
Vol 75 (3) ◽  
pp. 341-344 ◽  
Author(s):  
H. L. Bjerstedt ◽  
F. E. Robinson ◽  
R. T. Hardin ◽  
T. A. Wautier
Keyword(s):  
Body Weight ◽  
Follicular Development ◽  
Reproductive Organ ◽  
Breast Muscle ◽  
Liver Fat ◽  
White Leghorn ◽  
Reproductive Disorders ◽  
Fat Pad ◽  
Muscle Weight ◽  
Single Comb

The influence of body weight on reproductive organ morphology and the incidence of reproductive disorders was investigated with 324 Shaver Starcross 288-strain Single Comb White Leghorn hens at 62 wk of age. The hens were fed a typical laying ration (2720 kcal ME kg−1, 16.3%, CP, 3.5% Ca) ad libitum. All birds were housed two birds per cage in a windowless poultry house, with a photoperiod of 14L:10D. The total group of hens was separated into eight weight groups, on the basis of 62-wk body weight, ranging from 1100 to 2700 g, at 200-g increments. Birds were killed by cervical dislocation and dissected to observe carcass and reproductive organ traits. The length of the shank and the weights of the breast muscle, liver, fat pad, ovary and ovarian stroma increased significantly as hen weight increased. Ovary weight was increased because of an increase in the number of large follicles, as well as an increase in the weights of individual large follicles Ovarian regression occurred more often in hens weighing less than 1700 g than in hens weighing more than 1700 g. Internal oviposition occurred most often in hens near the population body weight (1803 g). Internal ovulation occurred more often in hens more than 1900 g in body weight than in hens less than 1900 g. These data suggest that hens that are heavier than average have increased follicular development, compared with low-weight hens. Key words: Single Comb White Leghorn, abdominal fat pad weight, breast-muscle weight, body weight, ovary morphology, reproductive disorders

scholarly journals Effects of consecutive thiouracil exposures in the juvenile and adult single comb White Leghorn chicken on body weight and reproductive performance

1997 ◽  
Vol 76 (2) ◽  
pp. 236-243 ◽  
Author(s):  
ED Peebles ◽  
EH Miller ◽  
CR Boyle ◽  
JD Brake ◽  
MA Latour ◽  
...  
Keyword(s):  
Body Weight ◽  
Reproductive Performance ◽  
White Leghorn ◽  
White Leghorn Chicken ◽  
Single Comb

scholarly journals Effects of glucagon-like peptide 1 on appetite and body weight: focus on the CNS

2013 ◽  
Vol 221 (1) ◽  
pp. T1-T16 ◽  
Author(s):  
L van Bloemendaal ◽  
J S ten Kulve ◽  
S E la Fleur ◽  
R G Ijzerman ◽  
M Diamant
Keyword(s):  
Body Weight ◽  
Food Intake ◽  
Physiological Role ◽  
Brain Regions ◽  
Gastric Distension ◽  
Cns Activity ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1

The delivery of nutrients to the gastrointestinal tract after food ingestion activates the secretion of several gut-derived mediators, including the incretin hormone glucagon-like peptide 1 (GLP-1). GLP-1 receptor agonists (GLP-1RA), such as exenatide and liraglutide, are currently employed successfully in the treatment of patients with type 2 diabetes mellitus. GLP-1RA improve glycaemic control and stimulate satiety, leading to reductions in food intake and body weight. Besides gastric distension and peripheral vagal nerve activation, GLP-1RA induce satiety by influencing brain regions involved in the regulation of feeding, and several routes of action have been proposed. This review summarises the evidence for a physiological role of GLP-1 in the central regulation of feeding behaviour and the different routes of action involved. Also, we provide an overview of presently available data on pharmacological stimulation of GLP-1 pathways leading to alterations in CNS activity, reductions in food intake and weight loss.

Thyroid hormone dependent nuclear proteins from rat liver

1982 ◽  
Vol 99 (4) ◽  
pp. 567-572
Author(s):  
Angeles Rodriguez-Pena ◽  
Juan Bernal
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Hormones ◽  
Effective Dose ◽  
Rat Liver ◽  
Physiological Role ◽  
Nuclear Proteins ◽  
Single Administration ◽  
Minimum Effective Dose ◽  
Nuclear Level

Abstract. Two nuclear proteins from rat liver were shown to be dependent on thyroid hormones. These proteins were present in the nucleosol or nucleoplasmic fraction, and were extracted from the nuclei with 0.15 m NaCl at pH8. After thyroidectomy, a 120 000-Mr polypeptide decreased in concentration to levels below 10% of normal control rats and another polypeptide of 81 000-Mr was increased. Treatment with T4 at physiological replacement doses for several days restored the levels of both proteins to normal. A single administration of 50 μg T3 induced a detectable increase of 120K after 14 h, with maximal effects at 48 h after administration. The minimum effective dose of T3 on 120K was 0.5 μg administered for three days. Preliminary observations suggest that the response of 81K to thyroid hormones is much more sensitive than that of 120K. The physiological role of these polypeptides is unknown, but they could be involved in the mode of T3 action at the nuclear level.

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