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.

Utilization of heterosis in poultry

1958 ◽  
Vol 9 (4) ◽  
pp. 599 ◽  
Author(s):  
FHW Morley
Keyword(s):  
Body Weight ◽  
Genetic Variation ◽  
Genetic Variability ◽  
Sex Chromosome ◽  
Inbred Lines ◽  
White Leghorn ◽  
Egg Weight ◽  
Additive Genetic Variation ◽  
White Leghorns ◽  
Recessive Genes

Records were analysed of 500-day production, egg weight, 11-week and mature body weight, sex maturity, and broodiness of the crossbred progeny of inbred lines of Australorps mated to White Leghorns, and inbred lines of White Leghorns mated to Australorps. Clear differences between lines of both breeds mere found in most characters, indicating the presence of potentially useful amounts of additive genetic variation. Non-additive genetic variation was also found to be present in varying degrees in different characters. Because of the difficulties of developing and maintaining inbred stocks of poultry, and the importance of sex-linked characteristics in some commercial environments, a scheme is proposed which may enable heterosis to be exploited without the use of inbred material. The basis of this scheme is the combination of the White Leghorn sex chromosome, with varying proportions of Australorp and White Leghorn autosomes, in a new breed. Assuming that the heterosis observed in the F1 is due to elimination of certain biochemical blocks determined by recessive genes, the formation of the new breed should enable the methods of closed flock breeding to be used in material at a higher level of production, and likely to contain more genetic variability, than either parent breed.

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

Single crossing between White Leghorn and Australorp

1958 ◽  
Vol 9 (6) ◽  
pp. 842 ◽  
Author(s):  
JA Morris ◽  
F Skaller
Keyword(s):  
Body Weight ◽  
Artificial Insemination ◽  
Sexual Maturity ◽  
Egg Production ◽  
The Body ◽  
White Leghorn ◽  
Reciprocal Crosses ◽  
Related Data ◽  
Single Crossing ◽  
White Leghorns

Egg production and related data are presented for 1520 pullets resulting from nine generations of single crossing between White Leghorns and Australorps. Both types of reciprocal crosses were consistently superior to the better of the parental breeds (White Leghorn) in hatchability, chick viability, and egg production. This superiority became still more apparent when pure and crossbred half-sisters were compared. Crossbreeding was not effective in improving the viability of adult birds or the body weight, the latter remaining intermediate between that of the two pure breeds. The number of days required to reach sexual maturity was decreased as a result of crossbreeding. The crossbreds showed less variation in egg production and included in their sample a much smaller percentage of extremely low-producing pullets. A comparison between the two types of crossbreds shoved differences in individual years, but when viewed over the whole period of the experiment the only consistent differences were the superior hatchability and higher fertility, under artificial insemination conditions, when the White Leghorn served as the dam. There were no significant differences in production characters between the two types of crossbreds when housed on deep litter.

The inheritance of shank colour in single comb White Leghorn and Australorp fowls

1951 ◽  
Vol 2 (4) ◽  
pp. 494
Author(s):  
F Skaller ◽  
GW Grigg
Keyword(s):  
White Leghorn ◽  
Genetical Analysis ◽  
Different Types ◽  
White Leghorns ◽  
Single Comb ◽  
Mode Of Inheritance

Evidence has been presented in the literature on the mode of inheritance of shank colour in various breeds of chickens, but little has hitherto been known about the same aspect in an Australian breed, the Black Australorp. Observations on the incidence of shank colour in different types of crosses between yellow-shanked White Leghorns and black-shanked Australorps are reported in this paper. According to the observations made by other workers on White Leghorn and other breeds, a hypothesis is advanced regarding the genes involved in determining shank colour in the White Leghorn and Australorp. A genetical analysis of the observations made by the authors on 847 single crosses, 71 backcrosses, and 31 zig-zag crosses is presented and shows close statistical agreement with the hypothesis. A genetical formula, including four autosomal and two sex-linked genes, is suggested which would explain the mode of inheritance of shank colour in White Leghorns and Australorps.

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

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

Effects of cage population and stocking density on the performance of layers in Queensland

1975 ◽  
Vol 15 (76) ◽  
pp. 619 ◽  
Author(s):  
JK Connor ◽  
HW Burton
Keyword(s):  
Egg Production ◽  
Control Measure ◽  
Stocking Density ◽  
Housing System ◽  
Feed Consumption ◽  
White Leghorn ◽  
Housing Systems ◽  
Cage Size ◽  
Cage Population ◽  
Production Characteristics

Three commercial egg production strains, a White Leghorn and two White Leghorn x Australorp, were used in two experiments which examined the effects of cage size and number of birds per cage on production characteristics. Nine cage housing systems varying from a 23 cm frontage single bird cage to a 61 cm frontage cage housing seven birds were compared. The efficacy of debeaking again at 12 or 20 weeks of age following routine debeaking at five days of age as a cannibalism control measure in a comparison of five housing systems was examined in another two experiments. Further experiments examined the practice of housing birds according to body weight in either one, two or three bird cage populations. Increasing bird numbers per cage or stocking density had little effect on egg weight, feed consumption or liveweight gain but decreased egg production and increased mortality in experiments where cannibalism was a significant cause of death. Hen housed egg production was an accurate measure of bird performance for comparison of housing systems. In experiments where additional debeaking was carried out the incidence of cannibalism was insignificant and debeaking at 12 or 20 weeks had no detrimental effect on bird performance. No strain x cage housing system interactions were observed and no improvement in performance resulted from housing birds in multiple bird cages according to liveweight.

Body Weight and Egg Production Performance of Induced Moulted White Leghorn Layers

2006 ◽  
Vol 5 (10) ◽  
pp. 996-1000
Author(s):  
P. Thirunavukkarasu . ◽  
M. Moorthy . ◽  
K. Viswanathan .
Keyword(s):  
Body Weight ◽  
Egg Production ◽  
Production Performance ◽  
White Leghorn
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