Laced and double‐laced plumage pattern phenotypes of the domestic fowl

1. An investigation was conducted among the progeny from crosses between Gold‐Laced Wyandotte and Silver‐Pencilled Wyandotte bantams into the relationship between two plumage pattern pheno‐types, lacing and double‐lacing, both of which are arrangements of eumelanin expressed on a background of phaeomelanic pigmentation.

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.     

Inheritance of the plumage pattern of the double‐laced Barnevelder bantam

1. An investigation was conducted among the progeny from crosses between Gold‐Laced Wyandotte and Double‐Laced Barnevelder bantams into the genotype of the plumage pattern of the latter.

2. The double‐laced phenotype has been shown to depend upon homozygosity of the linkage of a eumelanin intensifier melanotic Ml with a pattern gene Pg in the presence of either wheaten e^Wh or brown e^b alleles at the E‐locus.

3. Examination of the female F₂ generation demonstrated that the plumage pattern phenotype of the Double‐Laced Barnevelder depended upon homozygosity of e^b(Ml‐Pg).     

Inheritance of the lace‐tailed laced plumage pattern of the sebright bantam

1. An investigation was conducted firstly among progeny from a cross between Blue Andalusian and Silver‐spangled Hamburgh bantams, and secondly between crosses of selected progeny of this mating with a Silver Sebright bantam in an effort to determine the genotype of the lace‐tailed laced plumage phenotype of the latter.

2. The genotype of the black‐laced blue and the spangled plumage phenotypes of the Andalusian and the Silver‐spangled Hamburgh had, respectively, been shown to depend on homozygosity of E, Co, db⁺, Ml and Pg, and of co⁺, Db, Ml and Pg together with a black down allele at the E‐locus presumed to be E, but also hypothesised to be E^R. The genes E and E^R are the extended black and birchen‐like allele at the E‐locus whilst Co, Db, Ml and Pg are, respectively, the eumelanin restrictors, Columbian and dark‐brown Columbian, the eumelanin extension melanotic and the pattern gene. The Sebright had been hypothesised to possess the E allele at the E‐locus, and to be homozy‐gous Co, Ml and Pg, a combination shown to be responsible for the black‐tailed laced phenotype of the Wyandotte.

3. Segregation in the F₂ generation varied from that expected if both parental genotypes were E/E, but gave close agreement if the Silver‐spangled Hamburgh was E^R/E^R.

4. A lace‐tailed laced segregant in the F₂ generation of the first mating, presumed to be homozygous E^R, Co, Db, Ml and Pg was mated to a Sebright. The F₁ generation failed to segregate at the 5 loci, thus suggesting the genotype of the lace‐tailed laced phenotype of the Sebright to be homozygous E^R, Co, Db, Ml and Pg. Segregation in the F₂ generation of a mating of the female F₁ with a Silver‐spangled Hamburgh male confirmed the genotype of the lace‐tailed lacing of the Sebright bantam, and demonstrated that of the Silver‐spangled Hamburgh to be homozygous E^R, co⁺, Db, Ml and Pg‐.     

Chocolate: A sex‐linked recessive plumage colour mutant of the domestic fowl

1. A mating between Black Orpington bantams produced, in addition to blacks, a single female in which the black colouration was replaced by dark chocolate.

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.     

Notes on the “wheaten” plumage phenotype of the domestic fowl

1. A study was made using a Light Sussex bantam hen to determine the allele present at the E locus. Conflicting results occurred on mating with different males suggesting the presence in one case of the dominant allele e^Wh and, in the other, of the recessive e^y.

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.     

Inheritance of the spangled plumage pattern and the marbled chick down phenotypes of the silver‐spangled Hamburgh Bantam

1. An investigation was conducted among the progeny from crosses between Silver‐Spangled and Gold‐Pencilled Hamburgh bantams, and between Silver‐Spangled Hamburgh and Double‐Laced Barnevelder bantams.

2. Two subjects were studied: the relationship between three plumage pattern phenotypes, spangling, transverse‐barring and double‐lacing, all of which are arrangements of eumelanin expressed on a background of phaeomelanic pigmentation and the inheritance of the marbled chick down of the Silver‐Spangled Hamburgh bantam.

3. Examination of the F₂ generations demonstrated that, in conjunction with silver (S) gene(s) and extended black (E) alleles at the E‐locus the silver‐spangled phenotype can be produced by the addition to the genotypes of the Gold‐Pencilled Hamburgh, homozygous e^bc (Db‐ml⁺‐Pg), and Double‐Laced Barnevelder, homozygous e^b (db⁺‐Ml‐Pg), of Sp and Db genes respectively. Consequently Sp and Ml are one and the same gene, for which I retain the symbol Ml, and the genotype of the Silver‐Spangled Hamburgh is homozygous E (Db‐Ml‐Pg), where the buttercup (e^bc) and brown (e^b) are alleles of the E‐locus and Db, Ml, Sp and Pg are respectively the eumelanin restrictor dark‐brown Columbian, the eumelanin extension melanotic, plumage pattern spangling and the pattern gene.

4. The exact correlation between S/‐ E/E Db/Db and the marbled chickdown phenotype demonstrated the latter to be a pleiotropic effect of Db/Db, thus enabling the mapping of Db, Ml and Pg in group 3 on chromosome 1.     

Faecal measurements of oestradiol and testosterone allow the non‐invasive estimation of plasma steroid concentrations in the domestic fowl

1. Radioimmunoassays were validated for oestradiol and testosterone in faecal and plasma samples from domestic fowls. Faecal samples were prepared in phosphate buffer. A delay of up to 24 h between defaecation and the freezing of a dropping did not affect faecal steroid concentrations.

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.     

A comparison of the effects of two low‐calcium diets on egg production in the domestic fowl

1. Hens fed on a diet containing 0–05% calcium virtually ceased egg laying (production <4%) whereas those fed on a diet containing 0–5% Ca maintained production at between 20 and 30%.

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.     

The effect of reserpine on plasma LH concentrations in intact and Gona‐dectomised domestic fowl

1. Reserpine was found to inhibit the secretion of luteinising hormone when injected into intact and gonadectomised fowl at a dose rate which caused heavy sedation.

2. This could indicate that reserpine or its derivatives should not be used for breeding poultry.     

The structure of the ileo‐caeco‐golic junction of the domestic fowl (Gallus Gallus L.)

1. The structure of the ileo‐caeco‐colic junction of domestic fowl aged from 3 to 12 weeks was investigated by histological techniques and the preparation of latex casts of the lumina.

2. The caeca open ventro‐laterally from the cranial end of the colon. At this level a muscular ring of tissue, formed from the circular muscle of the lamina muscularis of the ileum, projects into the colon lateral to the caecal openings. The location of this muscular ring is discussed in relation to the possible mechanisms of caecal filling.

3. The longitudinal muscle of the lamina muscularis of the caudal region of each caecum is continuous with that of the colon and ileum. The circular muscle of the lamina muscularis of each caecum begins in the muscularis mucosa of the colon at a distance of 1 to 2 mm from the caecal openings. At the level of the caecal openings the musculature is complex, consisting of parts of the lamina muscularis of the colon, caeca and ileum.

4. The openings of the caeca from the colon are narrow and filled with villi. It is suggested that the junction may be involved in filtering material during the filling of the caeca.     

Egg‐shell water Vapour conductance of the domestic fowl: Comparison between two breeds and their crosses

1. A comparison of egg water loss and egg‐shell water vapour conductance was made between the Sinai fowl (a desert inhabiting breed) and the commercial White Leghorn, together with their reciprocal crossbreds.

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.     

Manipulations of germ‐cell populations in the gonad of the fowl

1. Embryos of the domestic fowl have been partially sterilised by injecting the drug busulphan into 24‐h incubated eggs.

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.     

The role of histamine and fish meal in the incidence of gizzard erosion and pro‐ventricular abnormalities in the fowl

1. The role of certain fish meals in the production of localised gizzard erosion is confirmed.

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.     

Differences in egg‐shell quality among the Sinai Bedouin fowl,the commercial white leghorn and their crossbreds

1. A comparison of egg‐shell characteristics was made among the Sinai breed (a desert inhabiting strain), the commercial White Leghorn and their reciprocal crossbreds.

2. The Sinai egg was smaller and its shell thicker and stronger than the Leghorn egg. All the differences were statistically significant.

3. Shell thickness and strength of Leghorn eggs were in accordance with values predicted on the basis of egg mass, while those of the Sinai and the two crosses were considerably higher than predicted.

4. The apparent differences in mean egg mass between Sinai and Leghorn breeds did not explain the differences in egg‐shell quality, neither did the shape index which was very similar among all breeds.

5. The findings suggest that the differences in egg‐shell properties are of a genetic origin.

6. The thick, strong and less permeable egg‐shell of the Sinai breed may reflect adaptations to its arid environmental origin and to incubation in the open.

7. These genetically‐determined egg‐shell characteristics might serve in a future selection for improved egg‐shell quality in poultry.     

Sensible heat transfer from the fowl: Boundary‐layer resistance of a model fowl

1. The sensible heat transfer from a physical model of an adult fowl was investigated for the range of air speeds encountered in poultry houses in the United Kingdom, 0.09 to 2.7 m/s, equivalent to Reynolds numbers (Re) from 10³ to 3 × 10⁴. The Grashof number (Gr) range studied was from 6 x 10⁶ to 10⁷.

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.     

Plasma growth hormone and insulin‐like growth factor‐I (IGF‐I) concentrations at the onset of lay in ad libitum and restricted broiler breeder fowl

1. Plasma concentrations of growth hormone (GH) and insulin‐like growth factor I (IGF‐I) were determined in individually caged broiler breeder females from 17 to 30 weeks of age. The birds were fed ad libitum or restricted during rearing in a randomised block design. Restricted birds were fed ad libitum after laying an egg and egg production was recorded to 54 weeks.

2. GH concentrations were higher in restricted compared with ad libitum‐fed birds at 17 to 21 weeks of age and were similar thereafter. Plasma IGF‐I concentrations were higher in restricted compared with ad libitum‐fed birds throughout the sampling period of the experiment.

3. The age at first egg was delayed by about two weeks in restricted birds. At 54 weeks of age they had laid 114 compared with 67 eggs in birds fed ad libitum throughout and had produced less than half the number of eggs with defective shells.

4. It was suggested that differences in egg production between ad libitum and restricted broiler breeder females could be related to changes in the pattern of GH and/or IGF‐I secretion.     

Molecular weight and amino acid composition of fowl delta‐globulin

1. The molecular weight of delta‐globulin was estimated chromato‐graphically to be about 10,700 daltons.

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 D_{20 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.     

Behavioural and anatomical consequences of two beak trimming methods in 1‐ and 10‐d‐old domestic chicks

1. To examine the effects of beak trimming on behaviour, beak anatomy, weight gain, food intake and feather condition 360 ISA Brown chicks were trimmed by hot cut or cold cut at 1 d or 10 d of age or were sham‐operated controls. The experiment was a 3 × 2 factorial design, with the chicks housed in littered pens in groups of 10 and observed for 6 weeks after trimming.

2. In the first week after trimming, when trimmed birds were compared with untrimmed controls, they were less active (sat and slept more), fed less, preened less and generally engaged in less beak‐related behaviour.

3. These differences waned sharply during week 2 and had disappeared by week 5. There were very few differences between hot‐ and cold‐cut birds.

4. There were also differences in production variables: trimmed birds grew more slowly during the week after trimming, their food intake was depressed for 3 weeks and food conversion efficiency improved for 2 weeks.

5. The only significant effect on feather scores was better plumage condition in the groups trimmed at 1 d and scored at 6 weeks.

6. To examine the anatomical effects 36 ISA Brown chicks trimmed by hot or cold cut at 1 d or 10 d of age were killed at 21 and 42 d after trimming, and their beaks were processed and examined histologically. In all trimmed groups healing was very rapid and no scar tissue was seen but, unlike the controls, the regrown tips contained no afferent nerves or sensory corpuscles.

7. Beak lengths immediately after trimming were 40% to 50% shorter than controls; the anatomical consequences of both methods were identical.

8. Overall, it was judged that the effects on behaviour and beak anatomy were much less severe than previously reported for birds trimmed at older ages. If birds do have to be trimmed then the procedure should be carried out in young birds: from the birds' standpoint 1 d appears to be the most suitable.     

Pathogenicity of two strains of Newcastle disease virus in the grey‐breasted helmet guinea fowl

Summary

Thirty‐five 6‐week‐old guinea fowl keets, seronegative for maternal antibodies to Newcastle disease virus, were infected with Hens strain (33/56) and Kumarov strain of Newcastle disease virus intramucularly (IM) or intranasally (IN).

Clinical signs were first noticed four days post infection (PI) in the group infected al but five days PI in the group infected IN with Hens strain of Newcastle disease virus. These clinical signs were similar in both groups and included anorexia, droopiness, huddling together, greenish diarrhoea and marked cachexia. Prominent nervous signs, including spasms of the head and neck, were observed in groups infected with Hens strain.

The major gross lesions observed were emaciation with prominent keel bone, empty intestinal tract and distended gall bladder in most keets.

The histological lesions were characterised by meningoencephalitis, necrosis and loss of lymphocytes from splenic and lymphoid aggregates. There was muscular degeneration and necrosis in the gizzard and mild pulmonary congestion and oedema in some keets.

Neither gross or microscopic lesions were observed in keels that had received the Kumarov strain.