2. The double‐laced phenotype had been presumed to be caused by the addition to the laced genotype of the gene Pg which causes pencilling. The error of this presumption was demonstrated by the appearance of double‐laced bantams in the F2 generation of a mating specifically designed to avoid the addition of Pg to the laced genotype.
3. Examination of the F2 generation demonstrated that the elimination of the eumelanin restrictor gene Co from laced fowl permits the double‐laced phenotype to be manifest. 相似文献
2. A mating of the chocolate‐coloured female with a black male, F2 and backcross matings demonstrated that the chocolate phenotype is caused by a recessive sex‐linked gene to which I assign the symbol ?CHOC.
3. A mating of ‘chocolates’ inter se yielded all chocolate offspring. 相似文献
2. The F2 generation consisted of 5 phenotypes, three of which could be attributed to the effect of Pg in the absence of Ml. The other two phenotypes were double lacing and an intermediary between double lacing and pencilling, with presumed genotypes Ml/Ml and Ml/ml+ respectively, indicating that Pg and Lg are one and the same gene for which I retain the symbol Pg.
3. The action of Ml when homozygous is therefore to both add an outer lace and increase the width of the inner rings of eumelanin, so changing pencilling into double lacing. 相似文献
2. After a return to a normal diet (3% Ca) egg weight, shell weight, ovarian characteristics and oviduct size were of a similar nature in the two groups, though the differences in egg weight, shell weight and shell calcium were significant at the 1 % level.
3. Bone weight and bone ash did not differ significantly between the groups but after a return to normal rations, bone weight and bone ash became higher in the group that had received the 0.05% Ca diet.
4. There were no clinical signs of bone demineralisation during the experiments. 相似文献
2. This could indicate that reserpine or its derivatives should not be used for breeding poultry. 相似文献
2. In contrast with normal eggs, the surface of the cuticle‐less shell was irregularly contoured and, in many instances, deeply fissured. 相似文献
2. Further examination of these apparently conflicting results suggests the possibility that there may be a single gene producing the wheaten phenotype which appears to be dominant if melanin restriction genes are present at other loci, or recessive by interaction with melanin intensifier genes. This gene may also require the presence of down‐diluting gene(s) to produce the wheaten phenotype. 相似文献
2. Citrate significantly reduced pre‐storage PCV of the DF in comparison with the effect of ethylenediamine tetra‐acetic acid (EDTA).
3. It further decreased (P<0.05) the PCV of the blood of DF and GF over 3 d of storage; this was similar to the effect of EDTA on the PCV of the GF blood.
4. Citrate and oxalates induced haemolysis of blood of the DF and the GF in storage faster than EDTA, but overall the haemolysis was more pronounced from red cells of the GF than from those of the DF.
5. The mean fall in the PCV of the DF was significant at 3.0 mg EDTA/ml of blood in contrast to the fall in the PCV of the GF blood. 相似文献
2. Differences in plasma concentrations of testosterone and oestradiol between cockerels and hens were clearly reflected in faecal hormone concentrations. Faecal concentrations of oestradiol were low in males and did not overlap with much higher concentrations in females, whereas there was some overlap between the sexes in faecal concentrations of testosterone.
3. The correlation coefficients (r2) between plasma and faecal steroid concentrations were 0.464 for testosterone and 0.852 for oestradiol (log‐transformed data). The coefficients did not increase when the mean hormone concentrations for several droppings produced by each bird during a collection period were used.
4. Faecal steroid concentrations can be used as a measure of plasma steroid concentrations and hence of gonadal activity in chickens. The resolution of the faecal steroid method is less than if plasma measurements were used, but it offers a practical alternative to blood sampling that is non‐invasive and does not require birds to be handled. 相似文献
2. Some of these embryos were injected with primordial germ cells (PGCs) after 55 h of incubation to attempt to repopulate the gonads.
3. Primordial germ cells transfected with a defective retrovirus containing the reporter gene lac Z were shown to settle in these sterilised gonads.
4. Quantitative histology of 6‐d embryos showed that busulphan produced 75% sterilisation but that PGCs could repopulate these gonads.
5. The technique of producing such germ line chimaeras is of value in studying cell kinetics, gonad differentiation and the production of transgenics. 相似文献
2. The Sinai egg was found to be smaller and less permeable to water vapour than the eggs of the Leghorn and crossbreds. The differences were statistically significant.
3. The measured egg‐shell water vapour conductance of the Sinai breed was 25% lower than predicted on the basis of egg mass.
4. The low permeability of the Sinai egg shell might be related to its higher than predicted thickness, which did not interfere with the shell functional pore area.
5. The low water vapour conductance of the Sinai egg shell may reflect adaptations to its dry habitat. 相似文献
2. The pooled results were analysed to give a relationship between the Nusselt number (Nu) and Re in the mixed convective regime of: A combination of Nu, Re and Gr did not produce a better fit to the results.
3. Enhancement of heat transfer observed when Re was close to 103 was probably caused by an interaction between the forced and natural air currents. 相似文献
2. Food consumption and egg production decreased as dietary calcium decreased. Shell weight was unaffected on diets 1 and 2; on diet 3 there was slight reduction of shell weight and on diets 4 to 8 the reduction was marked. The proportion of calcium in the shell was affected particularly on diets 7 and 8, though those from diet 5 also showed a decreased shell calcium.
3. The values for calcium intake and calcium loss in the egg showed that, generally, birds restricted calcium loss to less than intake. Only on the very low concentrations of calcium (diets 6, 7 and 8) did output appear to exceed input.
4. The main mechanism for controlling calcium loss involves the regulation of the number of eggs produced, i.e. the number of ovulations. Alterations in shell quality are of less importance with respect to calcium balance, although shell strength was impaired on the more restrictive diets (5 to 8). 相似文献
2. Lesions typical of gizzard erosion could be produced by the addition of histamine to the diet.
3. The amount of histamine occurring naturally in fish meal depends on the species of fish and the extent and nature of bacterial spoilage.
4. These variables may explain why histamine has not been implicated previously and also why there have not been consistent associations between the condition and geographical source or common factors in bulk consignments of the meal. 相似文献
2. Compared with the fertility results with semen that had been stored in the hypertonic diluent or was fresh, the fertility of the White Leghorns was not affected after storage in the isotonic diluent; a decrease (P < 0.lb05) was observed, however, using Rhode Island Red semen and isotonic diluent.
3. Fresh RIR semen contained 2.lb31% “neck‐bent spermatozoa” (NBS) which was increased to 4.lb23% and 5.lb76% after dilution in hypertonic and isotonic diluents respectively and stored for 24 h. It is doubtful whether this increase (P < 0.lb05) is the sole reason for the lowered fertility obtained with this breed after storage in the isotonic diluent. 相似文献
2. The weight and cross‐sectional area of the PIF muscle increased with increasing body weight. However, the relative muscle development to body weight differed among the 7 breeds.
3. A quarter of Type I fibres were of the transitional variety in bantam fowls. Conversely, few, if any, Type I tr fibres were observed in the large breeds where the muscle was poorly developed.
4. As the histochemical properties of Type I fibres made an effective response to the different body weights and the relative PIF muscle development among breeds, it was concluded that PIF muscle performed an important function in supporting the body weight and maintaining posture. 相似文献
2. Enterocytes from the medial and distal caecal regions are unable to transport L‐valine uphill (cell concentration: 0.1 mM).
3. Amino acid accumulation by proximal caecal cells was Na+‐dependent and was inhibited by ouabain and 2,4‐dinitrophenol. L‐methionine inhibits L‐valine uptake and a 2.5 mM concentration abolishes the capacity of enterocytes to accumulate the substrate.
4. The high accumulation ratios shown by the proximal caecum for L‐valine suggest a role for this intestinal segment in the absorption of neutral amino acids present in the caecal chamber. 相似文献
2. Ultracentrifuge experiments at 2.7 × 105 g gave values of s 20, W = (1.49 + 0.16C) × 10?13 s for the sedimentation coefficient and D20 w = (1.12 + 0.19c) × 10?6 cm2 s?1 for the diffusion coefficient, c being the protein concentration (g/100 ml).
3. According to the Svedberg equation, these imply a molecular weight of 12,470 daltons, assuming [v_bar] = 0.74 ml/g.
4. Using refractometer measurements of protein concentration it was found that E 1% 1cm (278 nm) = 5.57 at pH 7.8.
5. From the ultraviolet absorption spectrum of the protein in 0.1 N NaOH it was concluded that the molecule probably contains four tyrosine residues and no tryptophan.
6. On this basis a revised amino acid composition is given. 相似文献