scholarly journals High Levels of Dietary Iodine for Delaying Sexual Maturity of Egg Production Type Pullets

1968 ◽  
Vol 47 (5) ◽  
pp. 1535-1539 ◽  
Author(s):  
H.R. Wilson ◽  
L.R. Arrington ◽  
R.H. Harms
Keyword(s):  
Sexual Maturity ◽  
Egg Production ◽  
Production Type

The population dynamics of metacercariae of Apatemon gracilis (Trematoda: Digenea) in three species of lake-dwelling leeches

Parasitology ◽  
1986 ◽  
Vol 93 (3) ◽  
pp. 517-530 ◽  
Author(s):  
S. M. Spelling ◽  
J. O. Young
Keyword(s):  
Population Dynamics ◽  
Relative Density ◽  
Sexual Maturity ◽  
Egg Production ◽  
Seasonal Pattern ◽  
Distinct Pattern ◽  
The Other ◽  
Mean Intensity ◽  
Density Values ◽  
Host Mortality

SUMMARYMonthly samples of the leeches Erpobdella octoculata, Glossiphonia complanata and Helobdella stagnalis were taken over a two-year period from an eutrophic, English lake to detect metacercariae of the trematode, Apatemon gracilis. In each cohort of each of the three leeches, prevalence was low in young individuals, rose to a peak in autumn/winter, and then declined until the cohort had almost died out; in E. octoculata and H. stagnalis a final brief increase occurred. Mean intensity and relative density values followed a similar seasonal pattern of change to that of prevalence in these last two species, but in G. complanata values fluctuated irregularly with no distinct pattern. The frequency distribution of the parasite in G. complanata was highly over-dispersed, but less so in the other two species. Infected E. octoculata reached sexual maturity. The parasite reduced egg production in G. complanata and H. stagnalis, but only by maximum values of 2·5 and 9% respectively. This reduction in fecundity is low compared to the subsequent high mortality, at 95% or more, of newly recruited young from as yet unidentified causes. Parasite-related host mortality was difficult to assess in young leeches, but there was some evidence for its occurrence in older leeches of E. octoculata and H. stagnalis. However, this is unlikely to play a prominent role in the control and regulation of lacustrine leech populations.

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

scholarly journals Heterosis effect in hybrid laying hens

2014 ◽  
Vol 30 (2) ◽  
pp. 303-311 ◽  
Author(s):  
P. Hristakieva ◽  
M. Oblakova ◽  
M. Lalev ◽  
N. Mincheva
Keyword(s):  
Sexual Maturity ◽  
Egg Production ◽  
Live Weight ◽  
Egg Laying ◽  
Production Traits ◽  
Egg Weight ◽  
Group V ◽  
Paternal Line ◽  
Group I ◽  
Heterosis Effect

The new original egg laying lines T, P and N selected at the Institute of Agriculture - Stara Zagora were used. Hybrid ?? ? ??, ?? ? ?? crosses were obtained and used for paternal line. Thereafter, the following breeding schedule of paternal and maternal lines was applied: Group I - (?????)? ?N?; group ?? - (?????)? ?N?; group ??? - ???N?; and group ?V - ???N?. The production traits of original and hybrid birds were recorded: live weight at the age of 8 and 18 weeks, age of sexual maturity in days, 150 days egg production, average egg weight - at 2-week intervals until end of lay; livability, heterosis effect. The live weights of hybrids at 8 and 18 weeks of age were statistically significantly lower compared to original lines. The values of heterosis for this parameter were negative for all four hybrid combinations. The earliest beginning of egg lay occurred in (?????) ? ?N? (162.08 days of age) and ???N? (163.11 days of age). The relative (%) heterosis for age of sexual maturity of studied hybrid combinations had moderate to low negative values. Average egg weights of hybrids were higher and the values of heterosis - positive for all four groups varying from 0.97% to 1.63%. The average 150 days egg production was lower in purebred lines compared to hybrids. The highest average 150 days egg production was determined in ???N? hybrids - 142 eggs. The heterosis effect for egg production in hybrids was significant.

Reproductive biology of two sympatric colubrid snakes, Chironius flavolineatus and Chironius quadricarinatus, from the Brazilian Cerrado domain

2010 ◽  
Vol 31 (4) ◽  
pp. 463-473 ◽  
Author(s):  
Roberta Richard Pinto ◽  
Otavio Augusto Vuolo Marques ◽  
Ronaldo Fernandes
Keyword(s):  
Reproductive Biology ◽  
Sexual Maturity ◽  
Egg Production ◽  
Sympatric Species ◽  
Egg Laying ◽  
Reproductive Pattern ◽  
Brazilian Cerrado ◽  
Wet Season ◽  
Reproductive Cycles ◽  
First Time

AbstractThe reproductive biology of Chironius flavolineatus and C. quadricarinatus from the Brazilian Cerrado domain is described, including sexual maturity, female fecundity, and reproductive cycles of males and females. Egg-laying is recorded here for the first time for C. quadricarinatus. Males of both species attain sexual maturity with a smaller snout-vent length than females. Females of C. flavolineatus have an extended reproductive cycle with egg production during the wet season, whereas males exhibit year-round sperm production. Chironius quadricarinatus has continuous reproductive cycles in both sexes. Differences in reproductive pattern between these two sympatric species are probably related to phylogenetic constraints on intrageneric lineages of Chironius.

The performance of laying hens fed various dietary protein levels in the growing period and first laying year

1971 ◽  
Vol 11 (49) ◽  
pp. 161 ◽  
Author(s):  
JK Connor ◽  
HW Burton
Keyword(s):  
Dietary Protein ◽  
Sexual Maturity ◽  
Egg Production ◽  
Bodyweight Gain ◽  
Protein Restriction ◽  
Protein Layer ◽  
Egg Weight ◽  
Protein Levels ◽  
Growing Period ◽  
Laying Performance

Two experiments examined the effects of protein restriction in the growing period on the production of egg type pullets. The protein levels of diets fed in the growing period were 15, 13, and 11 per cent. The treatments were incorporated in factorial designs with nutritional treatments in the laying period involving diet protein levels of 17, 15, and 13 per cent and, for one of the experiments, with housing densities of either 4 sq. ft. or 2 sq. ft. per bird. Restriction of protein during the growing period retarded growth and delayed sexual maturity, but neither of the levels of restriction examined increased subsequent laying performance. Eggs lost due to delays in the onset of production were not compensated for by increases in subsequent production and egg weight was generally depressed by protein restriction. The pattern of egg production was altered by restriction. A 13 per cent protein layer diet introduced at point of lay also reduced bodyweight gain and delayed age at sexual maturity. Interactions between nutritional and housing treatments in the growing and laying periods were apparent in egg production and egg weight.

Changes in female lobster (Homarus americanus) size at maturity and implications for the lobster resource in Long Island Sound, Connecticut

2001 ◽  
Vol 52 (8) ◽  
pp. 1283 ◽  
Author(s):  
Donald F. Landers Jr ◽  
Milan Keser ◽  
Saul B. Saila
Keyword(s):  
Sexual Maturity ◽  
Egg Production ◽  
Long Island ◽  
Homarus Americanus ◽  
Long Island Sound ◽  
Female Size ◽  
Size At Maturity ◽  
Size At Sexual Maturity ◽  
Average Size ◽  
Island Sound

Population theory predicts that, under conditions of high age/size-specific mortality rates, individuals in highly exploited populations increase their fitness by decreasing size at sexual maturity, relative to less exploited populations. The benefit of early reproductive maturation is that individuals have a higher probability of surviving to maturity and contributing progeny to maintain the population. Empirical evidence, based on morphometric data from nearly 60 000 female lobsters collected since 1981, suggests that size at sexual maturity of female lobsters in Long Island Sound (USA) has recently decreased. Our findings were supported by decreases in average size and increases in abundance of egg-bearing females over the past two decades. Changes in female size at maturity and subsequent higher egg production may also help to explain the recent increase in lobster recruitment and landings. It is unclear whether these changes were caused by density-dependent factors related to the high exploitation of the species, by natural environmental factors (e.g. higher seawater temperatures), or a combination of the two.

scholarly journals The effect of sexual maturity and egg production on skeletal muscle (pectoralis major and gastrocnemius) protein turnover in broiler breeder pure lines

2018 ◽  
Vol 97 (2) ◽  
pp. 531-539 ◽  
Author(s):  
Karen Vignale ◽  
Justina V. Caldas ◽  
Judy A. England ◽  
Nirun Boonsinchai ◽  
Phiphob Sodsee ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Turnover ◽  
Sexual Maturity ◽  
Egg Production ◽  
Pectoralis Major ◽  
Broiler Breeder ◽  
Pure Lines
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