scholarly journals The Role of Plasma Thyroid Hormones in the Regulation of Body Weight of Single Comb White Leghorn and Broiler Embryos

1990 ◽  
Vol 69 (8) ◽  
pp. 1388-1393 ◽  
Author(s):  
W.H. BURKE ◽  
K.D. ARBTAN ◽  
N. SNAPIR
Keyword(s):  
Body Weight ◽  
Thyroid Hormones ◽  
White Leghorn ◽  
Single Comb

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

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 SOCIAL AND PHYSICAL ENVIRONMENTAL INFLUENCES ON CAGED SINGLE COMB WHITE LEGHORN LAYERS

1976 ◽  
Vol 56 (4) ◽  
pp. 733-738 ◽  
Author(s):  
A. E. SEFTON ◽  
D. C. CROBER
Keyword(s):  
Body Weight ◽  
Behavioral Response ◽  
Egg Production ◽  
Environmental Influences ◽  
Inbred Lines ◽  
White Leghorn ◽  
Individual Bird ◽  
Cage Size ◽  
White Leghorns ◽  
Single Comb

Pullets from two-way crosses between three highly inbred lines of Single Comb White Leghorns were housed in two sizes of commercial laying cages, two pullets per cage. Individual bird egg production records were kept when birds were 68–72 wk of age. During this period, peck order within each cage, fearfulness and body weight of each individual were determined. Differences between matings for fearfulness, body weight and egg production were not significant. However, in the case of egg production, both the mating × cage size and mating × cage tier interactions were significant. The genotype × environment interactions were interpreted to be due, in part, to varied behavioral response to the environment. Dominant birds had both a higher rate of egg production and heavier body weight than their subordinate cage mates. Birds housed in the larger cages (516 cm2 per bird) were less fearful than those in the smaller cages (412 cm2 per bird). Lower fearfulness was associated with higher egg production.

scholarly journals A role for thyroid hormones in the regulation of diet-induced thermogenesis in birds

1997 ◽  
Vol 78 (6) ◽  
pp. 963-973 ◽  
Author(s):  
Jean-François Gabarrou ◽  
Claude Duchamp ◽  
John Williams ◽  
Pierre-André Géraert
Keyword(s):  
Body Weight ◽  
Thyroid Hormones ◽  
Binding Capacity ◽  
Sulfhydryl Group ◽  
Deiodinase Activity ◽  
Diet Induced Thermogenesis ◽  
Peripheral Conversion ◽  
Stimulation Of

The possible involvement of thyroid hormones in avian diet-induced thermogenesis (DIT) was investigated in two lines of cockerels divergently selected for high (R-) or low (R+) food efficiency. For a given body weight, R+ cockerels exhibited a higher food intake than R- cockerels (+49 to +76%) and increased DIT (+25%). Plasma thyroxine (T4) levels did not differ between lines whatever the feeding status of the birds. Plasma 3,5,3'-triiodothyronine (T3) level was lower in fasted R+ than in fasted R- cockerels while the opposite was observed after a meal. Iopanic acid injections reduced both plasma T3 concentrations and heat production to the same levels in both lines. Hepatic 5'-deiodinase activity measured with an exogenous sulfhydryl group (dithiothreitol) did not differ between lines, but when the sulfhydryl group was omitted, the activity was higher in R+ than in R- birds (90 ν. 42 pmol T3/min per liver). T3-binding capacity of isolated hepatic nuclei was higher (+76%) in R+ than in R- birds. Long-term or acute pair-feeding of R+ cockerels to the level of R- controls did not alter these results. The present results suggest that T3, mainly originating from peripheral conversion of T4 to T3, is involved in DIT in the R+ line. Availability of endogenous sulfhydryl groups appears to play an important part in the modulation of hepatic deiodinase activity. The higher concentration of nuclear T3 receptors may further increase the effects of the hormone, suggesting a major role of thyroid hormones associated with catecholamines in the stimulation of avian DIT. The underlying thermogenic mechanisms remain to be elucidated.

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