Antibody transmitting ability of hens from lines of chickens differing in response to SRBC antigen

1. Hens from White Leghorn lines selected for high (HA) or low (LA) antibody response to sheep red blood cells (SRBC) were inoculated with 0.1 ml of either 0.25% or 2.50% SRBC suspension. Eggs laid over the next 15 d were grouped into 5, 3‐d collection periods and incubated. Maternal antibody titres were determined in chicks at hatch and 7 d after hatch.

2. In a subsequent experiment, hens of the 2 lines were inoculated with 0.1 ml of 2.50% suspension of SRBC, and eggs laid on days 10 to 13 after inoculation were incubated. Maternal antibody titres were determined in 15 and 18‐d embryos as well as in chicks at 0, 5, 10, 15, 20, and 25 d after hatch.

3. Dosage of SRBC had no effect on the antibody titres in line HA; however, the higher dosage elicited greater antibody titres than the lower dosage in line LA.

4. Maternal antibodies were detected earlier in chicks of line HA (eggs laid on days 7 to 9) than those of line LA (eggs laid on days 10 to 12) regardless of dosage administered to the hens.

5. In both lines, antibodies specific to SRBC were observed on day 15 of incubation, with the frequency of responders greatest at hatch. The high frequency of HA responders was maintained for 15 d after hatch, whereas there was an immediate decline with age in LA responders.

6. It was concluded that lines HA and LA have diverged in the pattern of maternal antibody levels as a result of the divergent selection for antibody response to SRBC.     

In ovo oral vaccination with cmpylobacter jejuni establishes early development of intestinal immunity in chickens

1. Chick embryos were orally immunised at day 16 of incubation by injection of heat‐killed Campylobacter jejuni organisms into the amniotic fluid. The response to vaccination was observed at 5 d after hatching or, in some birds which received a postnatal oral booster vaccination, at 7 d after hatching, and the response was observed at 14 d of age.

2. The titres of antibody in serum, bile and intestinal scrapings, the distribution of immunoglobulin‐containing cells in the spleen, duodenum and ileum and the expression on peripheral blood leukocytes (PBL) of the T cell surface markers CD3, CD4 and CD8 were determined.

3. Whereas low titres of anti‐flagellin antibody were detected in serum, bile and intestinal scrapings of unimmunised birds, high titres were observed in immunised birds.

4. An increase in antibody of all isotypes was detectable in serum but the elevation in IgA antibody in intestinal scrapings and bile was particularly striking. This response was reflected in a dramatic increase in immunoglobulin‐containing cells, detected by fluorescent histology, particularly diose associated with IgA and IgM isotypes in the spleen and intestine of immunised birds.

5. Secondary oral boosting after hatching resulted in a depression in serum anti‐flagellin antibody in immunised birds compared to pre‐boosting titres (although still significandy higher than in non‐immunised controls) but an increase in IgA antibody in intestinal scrapings and bile. The number of immunoglobulin‐containing cells was also increased after boosting.

6. Neither immunisation regimen caused a significant change in the numbers of circulating CD3, CD4 or CD8 T cells.

7. These results indicate that in ovo oral immunisation with C. jejuni antigens stimulates the precocious development of immunity in chicks.     

Encapsulated benzoic acid supplementation in broiler diets influences gut bacterial composition and activity

1. The present study investigated the effects of encapsulated benzoic acid (BA) supplementation in broiler feed on performance and gastrointestinal microbiota.

2. Eighty broilers were randomly divided into two groups. Birds in the control group were fed on maize–soybean-based diets. Birds in the treatment group were provided the same diet supplemented with 2 g/kg BA encapsulated in a vegetable oil matrix.

3. At the end of the trial (d 35), pH, bacterial composition and metabolites were determined in the crop, jejunum, ileum and caecum.

4. Growth performance variables and pH were not significantly different.

5. BA concentration decreased rapidly in the proximal gut. However, the treatment diet showed higher BA in the crop, jejunum, ileum and caecum.

6. Total lactate in the crop and D-lactate in the jejunum was higher in the BA treated group. Caecal total and branched chain fatty acids were decreased due to the treatment.

7. Lactobacilli populations were significantly altered by BA supplementation. A trend for increased lactobacilli was observed in the crop, while it became significant in the jejunum and ileum. Lactobacillus species responded differently to the treatment. Four of 5 measured Lactobacillus species, particularly in the ileum, followed the course observed for total lactobacilli; only Lactobacillus salivarius was not modified.

8. Correlation analysis showed that BA modified the intestinal microbiota. Lactobacilli correlated negatively to all studied clostridial clusters and enterobacteria. Clostridial clusters IV and XIVa were significantly increased in the jejunum, whereas only clostridial cluster XIVa was increased in the caecum.

9. Encapsulated BA modified the intestinal microbiota which can lead to the conclusion, that the main beneficial mode of action of BA in the gut appears to be the enhancement of lactic acid bacteria, which in turn may act as a vanguard against pathogens.     

Immunoresponsiveness of fast‐growing chickens as influenced by feeding regimen

1. Immunoresponsiveness and disease resistance were measured in broiler males maintained on ad libitum feeding throughout or on alternate‐day feeding. Alternate‐day restrictions were started 1 and 2 d after hatch so that on any one day there were chicks fed and fasted.

2. Severity of response to E. coli challenge as measured by lesion scores, and mortality was greater for chicks fed ad libitum than those fed on alternate days. For chicks fed on alternate days, lesion scores were lower for those without access to feed for the 24‐h period immediately after challenge.

3. Spleen weights, the indicator of response to marble spleen disease virus challenge, were higher for chicks fed ad libitum than those fed on alternate days.

4. Antibody response to sheep red blood cell antigen was not affected by feeding regimen.

5. Ratios of heterophils to lymphocytes were higher for chicks given access to feed for the previous 24‐h period than for those fasted during the previous 24‐h or those that had been fed ad libitum.

6. Results of this experiment suggest that for alternate‐day feeding programs, vaccination be administered on the day that chicks are not fed.     

Comparative mortality and predation in relation to egg production traits of Rhode Island Red,Black Australorp and Hyblack laying hens in scavenging production systems of rural Malawi

1. Black Australorp (BA), Rhode Island Red (RIR), and Hyblack (HB) birds were used in farm and field scavenging systems in Malawi, to study mortality through disease and predation in relation to laying performance.

2. Predation was higher in BA than HB.

3. Mortality through disease was higher in RIR than BA and HB.

4. Crossbred HB birds show the lowest combination of mortality and predation, suggesting a heterosis effect.

5. Mortality did not differ on farms and in field environments, suggesting an inability to improve biosecurity in farm conditions.

6. There was a positive relationship between eggshell strength and mortality. Calcium depletion from the birds’ bones, limiting foraging and escaping ability may be the explanation, which ultimately increases susceptibility to disease and predation.     

Corticosterone and fat deposition in broiler chicks: Effect of injection time,breed, sex and age

1. Corticosterone (680 μg/kg body weight per day) given as six daily injections to 3‐ or 7‐week‐old chicks decreased weight gain, but increased food consumption, abdominal fat pad weight, skin dry matter, relative liver size and liver fat concentration.

2. Time of day of injection did not modify the response to corticosterone of 3‐week‐old chicks kept under natural daylight nor of 7‐week‐old broilers receiving additional illumination.

3. Pure White Rock chicks and Cornish x White Rock crossbred chicks responded similarly to corticosterone injections at 3 weeks of age.

4. Seven‐week‐old female birds treated with corticosterone had significantly larger abdominal fat pads than similarly treated males.

5. Corticosterone injection was more effective in increasing the proportion of liver fat in 7‐week‐old birds than in 3‐week‐old ?hicks.

6. The increased amount of abdominal and liver fat due to corticosterone injections administered at 3 weeks of age disappeared after 3 weeks, but growth depression was still evident.     

Haematology and blood composition at two ambient temperatures in genetically fat and lean adult broiler breeder females fed ad libitum or restricted throughout life

1. Genetically fat and lean adult broiler breeder females were fed ad libitum or restricted throughout life. At one year of age, comparisons of blood viscosity and haematology and changes in blood chemistry after exposure to thermal stress were conducted.

2. Whole blood viscosity was more than twice as high, and plasma triglyc‐eride and haemoglobin concentrations were over 30% higher in fat line than in lean line females fed ad libitum or in restricted birds of both genotypes.

3. Mean cell haemoglobin concentration was higher and mean cell volume lower in fat compared with lean line females.

4. Food restriction was associated with lower plasma triglyceride concentrations, lower numbers of heterophils and monocytes and a lower heterophil‐lymphocyte ratio.

5. Fat line birds had a higher blood pCO₂ and lower pH than lean line birds.

6. Thermal stress was associated in ad libitum‐fed birds with a rise in blood pH and a decrease in pCO₂, and in restricted birds with a decline in blood pH and an increase in pCO₂.

7. Blood creatine kinase activity increased in all groups under thermal stress.     

Effect of nephropathogenic infectious bronchitis viruses on renal function in young male broiler chickens

1. The acute effects of challenge with Australian T‐strain infectious bronchitis virus (IBV) on renal function were evaluated, following primary vaccination in 1‐d‐old male broilers.

2. Challenge with T‐strain IBV decreased body weight and induced kidney hypertrophy and kidney asymmetry.

3. Haematocrit was reduced in birds challenged with the Australian T‐strain IBV and plasma uric acid was elevated in unvaccinated birds exposed to the IBV challenge.

4. Challenge with T‐strain IBV caused significant increases in urinary water losses, accompanied by decreased urine osmolality and increased fractional excretion of sodium, calcium and potassium.

5. Vaccination at 1‐d‐old with Vic S‐strain IBV provided a limited degree of protection against an heterologous challenge with T‐strain IBV at 15 d of age.     

Blood flow distribution during graded treadmill exercise in domestic cockerels

1. White Leghorn cockerels were exercised continuously for 45 minutes on a treadmill at work loads equivalent to 2.1 and 2.7 times pre‐exercise metabolic rates, the latter being close to the performance limits of the experimental birds.

2. Relative blood flow to the abdominal viscera and selected leg muscles was estimated using ¹¹³Sn‐, ¹⁵³Gd‐ and ⁴⁶Sc‐labelled microspheres, injected into the root of the aorta.

3. There was no significant shift of blood flow away from the viscera towards the leg muscles at either work load. However, relative colonic and duodenal blood flow fell significantly at both work loads and relative pancreatic blood flow doubled at the higher work load.

4. It is concluded that, as previously reported in female domestic fowl performing physical exercise close to their performance limits, male fowl are largely refractory to shifts in blood flow away from the viscera to the working muscles. Nevertheless, there is evidence of blood flow shifts between visceral organs, probably related to the intermediary metabolism of fuel substrates.     

The role of ion transport in the formation of sub‐embryonic fluid by the embryo of the Japanese quail

1. Using a modification of the method of New (1955) explanted blastoderms of the Japanese quail were cultured for up to 72 h, and the role of ions in the formation of sub‐embryonic fluid (SEF) investigated.

2. Culture media deficient in either sodium or chloride ions reduced the volume of SEF secreted by up to a quarter. Ionic composition of the fluid was little altered, and sodium was transported against a concentration gradient.

3. Amiloride, an inhibitor of Na⁺/H⁺ exchange, reduced SEF production by half, whereas ionic composition and osmolality of the fluid was unchanged.

4. Likewise, acetazolamide, an inhibitor of carbonic anhydrase, reduced SEF production by the blastoderm, and left the ionic composition and osmolality of the fluid unaltered.

5. Neither furosemide or 4,4´‐diisothiocyanatostilbene‐2,2´‐disulfonic acid at the concentrations used changed the volume of SEF formed or its ionic composition.

6. It is concluded that the secretion of SEF is dependent upon the active transport of sodium across the blastoderm; an amiloride‐sensitive Na⁺/H⁺ exchanger and carbon dioxide hydration catalysed by carbonic anhydrase are also involved.

7. Furthermore, it is proposed that fluid transport across the blastoderm is the result of local osmotic gradients, not from a sub‐embryonic fluid hyperosmotic to albumen, as has been suggested previously.     

Heterophil to lymphocyte ratios during perinatal and neonatal stages in chickens

1. Heterophils (H) and lymphocytes (L) were measured in embryos that had pipped into the air cell and through the shell, and in chicks from 0‐d‐old to 8 d of age.

2. Numbers of lymphocytes in the perinatal stages were very low with H:L ratios greater than 5.0.

3. Posthatching H:L ratios decreased in a quadratic manner from 1.76 at hatch to 0.39 on day 8.     

GD3 cells in the intestine of broilers inoculated with intestinal homogenate

1. Reactivity of polyclonal rabbit CD3 antiserum to human T cells and density of CD3 cells in chicken intestine were studied after the inoculation of 1‐d‐old broilers with intestinal homogenate to develop the Runting and Stunting Syndrome.

2. Reactivity of CD3 antiserum in chicken intestine was very good.

3. Increased numbers of epithelial lymphocytes as well as infiltration of CD3 cells into the lamina propria were demonstrated.

4. Intestinal homogenate caused impaired growth and bad feathering in broiler chickens until 21 d of age.     

Effects of food intake regulation on the energy metabolism of laying hens

1. The effects of dietary energy restriction on the energy metabolism of post‐peak‐of‐lay hens of two hybrid layer strains were studied by indirect calorimetry.

2. Starving and resting rates of heat production (SHP and RHP) were measured, over 1‐d periods, at intervals during a 25‐week period in which the experimental birds were individually restricted to 80% of their previous energy intake ad libitum.

3. In both strains mean RHP per bird was about 7% lower in the restricted birds than in controls fed ad libitum, but when RHP was expressed in terms of metabolic body size (kg^0.75) the two groups did not differ.

4. Mean SHP per bird was about 18% lower in the restricted birds of both strains than in the corresponding controls; the decrease in SHP per kg^0.75 was 12%.

5. Heat increment of feeding and calculated maintenance energy were higher, and net availability of metabolisable energy for maintenance and production was lower, in the restricted than in the control groups.

6. Gross efficiencies of egg production, in terms of both mass and energy, increased in the restricted birds.

7. Live‐weight and total carcass energy after 25 weeks of restriction were respectively about 15% and 30% lower in the restricted groups of both strains than in the groups fed ad libitum.     

The effect of an injection of corticotrophin on plasma concentrations of corticosterone,growth hormone and prolactin in two strains of domestic fowl

1. Three‐week‐old Light Sussex (LS) and Rhode Island Red (RIR) chicks were injected with long‐acting corticotrophin (ACTH: 30 IU/kg) and the plasma concentrations of corticosterone, growth hormone (GH) and prolactin were determined over a 6‐h period. Plasma concentrations of corticosterone and growth hormone were also measured after an injection of corticosterone (500 μg/kg).

2. The resting plasma concentration of corticosterone in LS was less than that in RIR birds. The increase elicited by ACTH was smaller in LS but, since it was maintained for longer, the plasma corticosterone response was at least 18% larger than that in RIR birds.

3. Plasma GH concentration was decreased after an injection of ACTH in both strains but the decrease lasted longer in the LS chicks.

4. Plasma prolactin concentration was unaffected by ACTH.

5. After intra‐abdominal injection of corticosterone, plasma GH concentration was depressed in both strains. It is concluded that ACTH‐induced depression of plasma GH and growth is mediated by corticosterone.     

Development and validation of a homologous radioimmunoassay using a biologically active recombinant turkey prolactin

1. A new homologous radioimmunoassay has been developed for the measurement of turkey prolactin.

2. A 25000 kDa purified recombinant derived turkey prolactin (rtPRL), the biological activity of which was tested using a crop sac assay, was used as immunogen for the production of rabbit antiserum. In this biological test, the rtPRL was as active as the ovinePRL.

3. The radioligand (rtPRL) was labelled with ¹²⁵I and the assay allowed the detection of standard doses of rtPRL ranging from 400 pg/tube to 50 ng/tube.

4. No cross reaction with chicken luteinising hormone and recombinant chicken growth hormone was detected.

5. The within and between assay coefficients of variability were 5.0 ± 2.7% and 16.3%, respectively. The overall mean recovery ratio was 1.01.

6. The dose‐response curves obtained with serial dilution of plasma and pituitary from turkey hens at different physiological stages and from male turkeys were parallel to those obtained with standard rtPRL.

7. The measured concentration of prolactin was 5 times higher in plasma from incubating than laying turkey hens, and the pituitaries from incubating hens contained 2 and 4 times more prolactin than those of laying and out of lay hens or males, respectively.

8. To further assess the validity of the assay, we measured changes in plasma concentration of prolactin in turkeys following stimulation with chicken vasointestinal peptide (cVIP). A single injection of 1 or 10 μg/kg body weight of cVIP to laying hens produced a large and rapid increase in plasma prolactin.

9. This new radioimmunoassay appears to be highly specific and sensitive for the measurement of turkey prolactin.     

Automatic weighing of individual laying hens in aviary housing systems

1. This study investigated when and where body weight and flock‐uniformity should be determined in an aviary system by using automatic weighing systems.

2. An Individual Poultry Weighing System (IPWS) was developed to record time, duration, location and body weight of visits of individual hens to 4 weighing scales.

3. The number of hens that visited the weighing scales per 3 h period varied from less than 10 during the dark‐period to more than 60 during the light‐period.

4. The average number of visits per individual hen was 1–4 and the average number of successful weighings per hen was 0–6 during the light‐period.

5. Body weight showed a diurnal rhythm: the difference between the maximum body weight at night and the minimum body weight in the morning was 63 g.

6. The location of the scales influenced number of visits, number of weighings, mean body weight, flock‐uniformity and duration of visits.

7. Body weight per 3 h period did not differ between hens which were individually recognised and those which were not.

8. Flock‐uniformity was 2–6% higher during the light‐period if it was based on weighings of identified hen visits.

9. The average duration of the visits to the scales in the middle of the feeding tier during the light‐period was 63 s.

10. Of all the hens that visited the scales during a 24 h period, 54% visited them only once.

11. Automatic weighing systems without individual hen recognition can deliver reliable management information on mean body weight and flock‐uniformity in aviary systems if the weighing scales are located on the feeding tier in the middle of the house and if they are used during the light‐period.     

Utilisation of U‐14C‐lysine by young turkeys

1. U‐¹⁴C‐lysine was administered by tube into the crop to turkey poults fed on assay diets (maize + sesame + maize gluten meal) containing varying concentrations oflysine, and partition of the label into body components, carbon dioxide, and excreta was measured.

2. Deposition of ¹⁴C label into breast and heart muscles responded positively to dietary lysine concentration. There was no apparent relationship between dietary lysine intake and deposition of label into carbon dioxide or excreta.

3. Efficiency of lysine retention, above maintenance, was estimated to be 0.523 ± 0.034.

4. Turkeys exhibited variable metabolic efficiency in the use of lysine as indicated by loss of U‐¹⁴C‐lysine label to expired carbon dioxide and to excreta by individual turkeys.     

Effect of progesterone on the magnum proteins during primary stimulation of chick oviduct

1. The effect of progesterone on the secretion of protein by the magnum of 5‐d‐old, female chicks was determined.

2. The supernatant prepared by centrifuging an homogenate of the magnum at 105 000g was found, by immunodiffusion, to contain an antigenic component which precipitated the antisera for conalbumin 1, conalbumin 2 and ovalbumin after 5 d treatment with progesterone: there was no reaction to ovomucoid, lysozyme and avidin antisera.

3. Disc‐electrophoresis of the homogenate revealed two bands at the site of ovalbumin.

4. Incorporation of ³H‐lysine into the magnum proteins of progesterone‐treated chicks did not differ from that of controls.

5. The secretion available in the magnum may be only a transudate from the serum and not a true secretory product. Progesterone behaved qualitatively as oestrogen in this study although the action is much less pronounced and was delayed.     

Changes in polymorphic gene frequencies in strains of chickens selected for resistance to Marek's disease

1. Resistance to Marek's disease (MD) was selected over five generations in three strains and their four substrains.

2. MD mortality decreased consistently on natural exposure, but in birds artificially inoculated the mortality increased again in later generations.

3. Changes of gene frequencies at five polymorphic loci—blood group A, B and D, plasma esterase and alkaline phosphatase loci—were examined.

4. The frequencies of blood group A⁶ and B⁸ alleles showed a consistent trend of increase and the B ¹¹ allele gradually decreased in most strains. The Akp allele of alkaline phosphatase increased significantly in two of seven strains.

5. Comparisons of homozygotes and heterozygotes revealed a significant difference only at the A locus.     

Influence of stocking density and layer age on production traits and egg quality in Japanese quail

1. Japanese quail hens were housed from 6 to 26 weeks of age in cages providing areas of 150, 180, 210 and 240 cm²/bird.

2. Body weight gain, age at 50% egg production, mortality, hen‐day egg production and food conversion values showed significant improvement with proportionate increase in cage space per layer.

3. Egg weight gradually increased with age but shell thickness was influenced neither by age of the hen nor by stocking density.

4. Yolk index and colour were superior in the lowest stocking density (more cage space) group; other egg quality traits and egg weight were not influenced by stocking density.

5. The albumen index, internal quality unit, yolk index and yolk colour values increased with age.