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PubMedDate not supplied

Dominant white plumage-color somatic mosaic in the domestic fowl.

An unusual feather-color mosaic of the variegated type is described in the fowl. The bird, a female, has the e+/e+ wild-type plumage pattern with light tan or buffish colored feathers intermingled over her sides and dorsal surface. This condition is bilateral and symmetrical with whole feathers being diluted in some areas and parts of feathers in others. Breeding tests with e+/e+ males showed that the bird was heterozygous for dominant white (l/i+) and homozygous for e+. All her e+/e+, l/i+ offspring were of the red-pyle pattern as would be expected from that genotype. The possible cause of this mosaic condition may be due either to the loss of the l-bearing locus or to a reverse mutation to i+ in neural crest cells destined to become the primordial melanoblasts.

Animals↗
PubMed1998

Rearing with males accelerates onset of sexual maturity in female domestic fowl.

Two experiments were conducted to investigate the effects of male presence on sexual maturation and sexual responses toward humans in laying strain females. In Experiment 1, two flocks of 50 medium-hybrid females were reared without males (separate-sex) and two flocks with males (mixed-sex) from 1 d of age. Mixed-sex females came into lay sooner and laid more eggs up to 22 wk of age than separate-sex females (P < 0.05). Comb size was also greater in mixed-sex females at 15 and 20 wk of age (P < 0.05). In Experiment 2, six replicate groups per treatment with n = 10 females per group were reared in separate-sex, mixed-sex, or adjacent to mixed-sex groups. Rearing adjacent to mixed-sex groups, which allowed visual and auditory contact with males, was just as effective for accelerating sexual maturation as was rearing in mixed-sex groups. Females reared in and adjacent to mixed-sex groups began to lay earlier (P < 0.05) and had larger combs (P < 0.05) than separate-sex females. However, after 22 wk of age, egg production rates of separate-sex females surpassed those of mixed-sex and adjacent females, resulting in similar numbers of eggs produced through 30 wk of age (P > 0.10). During tests for sexual responsiveness to humans, over 80% of females in separate-sex and adjacent to mixed-sex groups assumed a sexual crouch, whereas less than 20% of females in mixed-sex groups crouched (P < 0.001, chi-square). The degree of contact with males during rearing affected the females' physiological measures of reproductive function differently than behavioral measures.

Age Factors↗
PubMed1999

Identification of an androgen receptor within the uterus of the domestic fowl.

Cytosolic and nuclear fractions of the uterus (shell gland) of the hen's oviduct were found to contain a specific [17alpha-methyl-3H]-methyltrienolone ([3H]R1881; a synthetic androgen) binding component having properties of an androgen receptor; i.e., binding specificity, high affinity, and limited capacity. The value of the equilibrium dissociation constant (Kd) was of the order of 10(-9), and did not differ between laying and nonlaying hens. The maximum binding capacity (Bmax) per gram of tissue of both fractions was greater in laying hens than in nonlaying hens. When 5alpha-dihydrotestosterone was administered exogenously, the Bmax of the cytosolic fraction decreased and that of the nuclear fraction increased without any change in Kd. The specific binding in both fractions was at an increased level from 4 to 11 h before oviposition, suggesting that androgen binding may be related to certain events during an early stage of shell formation in the uterus of laying hens.

Animals↗
PubMed1999

Patterns of growth and feed intake in divergent lines of laying domestic fowl selected for residual feed consumption.

At Generations 15 (males) and 18 (females) of a divergent selection experiment on residual feed consumption (RFC) in laying poultry, patterns of growth, feed consumption, and associated traits were monitored between the ages of 4 and 34 wk. This monitoring was done to determine how the well-established RFC and feed intake (FI) divergences between adults of the low intake R- line and of the high intake R+ line took place, in relation to the evolution of correlated traits. In males and females, BW and BW gain were higher in the R- line in the first weeks of test, but patterns of BW were quite similar in both lines afterwards. However, R- hens remained heavier than R+ females to the end of the experiment. Line difference for BW was achieved by 28 wk of age, at 2,974 and 2,094 g, and the R- line was then 135 and 133 g heavier, respectively, for males and females. After a fast initial increase in both sexes, FI diverged quickly around 16 to 18 wk of age (sexual maturity), to attain 13 g/d in males and 28 g/d in females, well before the end of the experiment. At the same time, a divergence was observed for wattle length, which was 21% higher in R+ females. Residual feed consumption gradually diverged in the two lines, and the difference became significant at 14 wk of age. At the same age, shanks were 8% longer in R+ hens. Finally, levels of triiodothyronine decreased faster in the R- line, as FI divergence was increasing. These results indicate that the RFC difference between R- and R+, lines obtained in adult birds by divergent selection lines, starts somewhat early in life. In addition, the RFC difference appears to be associated with specific growth periods, around 14 wk and 18 to 20 wk. It is at this time that large differences appear in morphological traits involved in body heat loss. No significant correlations were found between early (6 wk) measures of FI, feed efficiency, and RFC, with adult values (32 to 34 wk) for RFC and FI.

Animals↗
PubMed2000

An autosomal dwarfism in the domestic fowl.

A mutation in the Cornell K-strain of White Leghorns, first recognized when two adult males in a pedigreed family were definitely smaller than their two other brothers, proved to be an autosomal recessive mutation and gave rise to the autosomal dwarf stock. The effect of this gene (adw) can be recognized during embryonic development and leads to a normal adult, except for a 30% reduction in body weight. Selection for small size, egg production, and egg weight over a period of 15 yr yielded an efficient layer. Production for 11 mo from first egg was at a rate of 70%, with egg weight at 56 g and body weight at 1,160 g at 10 to 11 mo of age, based on data for the last four generations. Viability of the caged hens averaged over 95% for the 13 generations involved. Sexual maturity was delayed by about 2 wk, and good incubation (85+%) required 18+/- more hours than normal. When an autosomal dwarf male is used as a sire and mated to sex-linked dwarf (dw) females, all progeny are of normal size. Compared with problems of mating normal size males with dwarf females, the use of the two types of dwarfism can yield good fertility.

Animals↗
PubMed2001

Behavior of the domestic fowl in the presence of vertical panels.

The effects of environmental complexity on the time budget of chickens were investigated. It was hypothesized that the provision of vertical panels to pen centers would generate additional protective areas within the pen, influencing the amount of time spent performing different behaviors. The experiment consisted of three cover treatments (mesh panels, frame panels, and no cover) and two group sizes (80 and 110). Vertical panels, constructed of polyvinyl chloride piping, were positioned in pen centers, whereas pen centers in the no-cover treatment were left empty. Drinking, dust bathing, feeding, foraging, movement, preening, resting, and standing were recorded during continuous focal sampling of 210 focal individuals from 5 to 44 d of age. Resting was the most frequent behavior accounting for over 64% of the chicken time budget. Resting time was influenced by the presence of cover (P < 0.01), and was higher in pens enriched with panels. Time spent moving and standing in the different pen regions was influenced by the presence of cover (P < 0.01) and age (P < 0.05). The presence of cover did not influence time spent feeding or drinking, but both behaviors were affected by age (P < 0.05). The presence of cover influenced time spent foraging, which occurred more often in the pens containing no panels (P = 0.05). Preening and dust bathing were the only behaviors influenced by group size (P < 0.05). These results suggest that incorporating enrichment into the environment does influence the time a chicken will spend performing different behaviors.

Age Factors↗
PubMed2003

Deduction of a model for sperm storage in the oviduct of the domestic fowl (Gallus domesticus).

The mechanism of sperm storage in the fowl oviduct has remained a mystery since the 1960s, when sperm storage tubules (SST) were discovered between the shell gland and vagina. Previously, it was known that only motile sperm could ascend the vagina and enter these tubules. However, the means by which sperm resided therein was not clear. Research with computer-assisted sperm motion analysis has demonstrated that 1) seminal plasma glutamate acts as a motility agonist via N-methyl-d-aspartate receptors; 2) motility depends on extracellular Ca2+ and Na+; 3) straight-line velocity is a variable with a skewed distribution; 4) sperm cell trajectory is a function of straight-line velocity; and 5) specific inhibition of phospholipase A2 renders sperm immotile. An additional experiment demonstrated that Ca2+ acts as a second messenger and thereby modulates the content of long-chain acylcarnitine within sperm. Therefore, it is proposed that 1) the release of endogenous fatty acids fuels sperm as they ascend the vagina; (2) on entering the SST, motile sperm maintain position against a fluid current generated by SST epithelial cells; 3) resident sperm metabolize exogenous fatty acids released from lipid-laden epithelial cells; (4) motile sperm emerge from the SST when their velocity declines to a threshold at which retrograde movement begins; and 5) the skewed distribution of straight-line velocity accounts for the exponential pattern of sperm emergence from the SST. In summary, sperm residence within and emergence from the SST are phenomena most likely explicable in terms of sperm cell motility.

Animals↗
PubMed1983

Development of the testes in female domestic fowls submitted to an experimental sex reversal during embryonic life.

The sex differentiation of the female chick embryo can be totally inverted toward the male sex by an early extraembryonic testis grafting. This sex reversal remains permanent, as shown by three adult fowls described in this paper. They possess two testes associated with normally differentiated male excretory ducts and their Müllerian ducts have regressed. The development of male sex characteristics such as external features, behavior and complete spermatogenesis is evidence that these cocks have endocrine and exocrine capabilities similar to those of normal cocks. Although these cocks were able to mate with female fowls, they were sterile. A mechanism is discussed by which grafted testes induce such modifications in females. Hypotheses considering the heterogametic sex (female in birds) as exerting a dominant influence on the phenotypic sexual differentiation can be discarded in light of our results because a homogametic testis provokes the definitive sex inversion of a female.

Animals↗