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.     

Growth,viscosity and beta‐glucanase activity of intestinal fluid in broiler chickens fed on barley‐based diets with or without exogenous beta‐glucanase

1. Three groups of birds were fed for up to 35 days on diets containing 500 g barley (cv. Condor) /kg diet, with or without exogenous β‐glucanase, either a commercial preparation or a recombinant endoglucanase.

2. Birds which received diets containing the exogenous enzymes grew faster for the first 3 weeks but after that there was no apparent difference in rate of growth.

3. β‐Glucanase activities in the crop and small intestine of birds given exogenous enzymes were generally higher than those of birds given only the basal diet.

4. Viscosity of intestinal fluid in birds given only the basal diet decreased with age but there was no corresponding increase in β‐glucanase activity. This discounts bacterial β‐glucanase as a contributory factor in the adaptation to β‐glucanase apparent in older birds.     

Welfare assessment of broiler breeder and layer females subjected to food restriction and limited access to water during rearing

1. A factorial experiment was conducted to assess the welfare at different ages of two strains of broiler breeder and one layer strain during rearing using a range of indicators. The birds were fed ad libitum or restricted and provided with free or limited access to water.

2. Food‐restricted birds spent a large proportion of time scratching and pecking the litter compared with birds fed ad libitum.

3. The heterophil/lymphocyte ratio and the proportion of basophils were raised at 8, 12 and 16 weeks, and the plasma concentrations of corticos‐terone were higher at 8 and 12 weeks of age in restricted birds compared with those fed ad libitum.

4. Creatine kinase activity was higher in broiler breeders fed ad libitum compared with layers and restricted broiler breeders. The activity of aspartate transaminase was higher in restricted layers compared with birds fed ad libitum and was similar in broiler breeders.

5. Plasma viscosity was lower in food‐restricted compared with ad libitum‐fed birds.

6. Limiting access to water had little or no effect on the welfare indicators although food‐restricted birds with free access to water spent more time drinking than birds fed ad libitum.

7. There were no important differences between the two broiler strains. Layers spent less time resting than broiler breeders and had higher plasma corticosterone concentrations at 3 and 16 weeks of age.

8. It was concluded that there was evidence for physiological stress associated with restricted feeding at least between 8 and 16 weeks of age. It was suggested that the altered behaviour of broiler breeders kept on litter may indicate that they can cope with food restrictions and that this may be acceptable in relation to the long‐term benefits of limiting body weight during rearing. The same may not be true for layers.     

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.     

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.     

Welfare of broiler breeder and layer females subjected to food and water control during rearing: Quantifying the degree of restriction

1. A factorial experiment was conducted with females of two broiler breeder and one layer strains. The birds were fed ad libitum or restricted and were provided with free or limited access to water to simulate commercial rearing practices.

2. There was little difference between the broiler breeder strains except in body weight at 16 and 18 weeks of age.

3. Food intake relative to body weight was higher in the broiler breeders compared with the layer strain.

3. The degree of restriction was defined as the food intake of re‐stricted birds as a proportion of the estimated intake of birds of the same body weight fed ad libitum. The value declined from 0.60 to 0.45 during the rearing period.

5. In the ad libitum treatments broiler breeders drank more than layers, whereas when restricted, layers drank more than broiler breeders.

6. Water intake was 2.50 times higher in restricted compared with ad libitum‐fed layers and 1.25 times higher in restricted than ad libitum‐fed broiler breeders, with free access to water.     

Increased small intestinal fermentation is partly responsible for the anti‐nutritive activity of non‐starch polysaccharides in chickens

1. The mechanism of the anti‐nutritive activities of soluble non‐starch polysaccharides (NSPs) in broiler diets was investigated with emphasis on the inter‐relationship between viscosity and fermentation along the gut. Isolated soluble NSP were added to a control diet to effect high gut viscosity, and in vivo depolymerisation of the NSP was achieved using a commercial glycanase.

2. Addition of soluble NSPs significantly (P<0.01) increased gut viscosity, reduced the AME of the diet and depressed the growth and FCE of the birds. Enzyme supplementation of the NSP‐enriched diet reversed the adverse effects, increasing (P< 0.01) weight gain, FCE and AME. Comparisons of the viscosities (mPa) in birds fed on the NSP‐enriched diet and the same diet supplemented with enzyme were respectively: 11–9 v. 2–3 in the duodenum; 78–3 v. 4–4 in the jejunum and 409–3 v. 10–8 in the ileum.

3. Caecal volatile fatty acid concentration was markedly (P<0.01) elevated by enzyme supplementation, whereas ileal fermentation was inhibited.

4. Microscopic examination revealed that, among birds fed on the NSP‐enriched diet, there had been extensive small intestinal fermentation, which was eliminated by the enzyme supplementation.

5. Addition of a synthetic antibiotic (Amoxil) had no beneficial effects.

6. The current study demonstrated that increased fermentation occurs in the small intestine when a large amount of viscous NSPs is present in the diet and this is detrimental to the performance and well‐being of poultry.     

Voluntary food restriction by laying hens mediated through dietary self‐selection

1. Individually caged Single Comb White Leghorn hens simultaneously received two diets which allowed selection of certain nutrients: these “ split‐diets “, essentially provided concentrated sources of either protein and energy (191 g crude protein, 12.82 MJ ME and 4.7 g Ca/kg diet), or calcium (107 g CP, 7.28 MJ ME and 131 g Ca/kg).

2. During four, 28‐d periods of lay, birds offered these split‐diets consumed some 7% less food in total than did control birds receiving a conventional diet ad libitum.

3. Calculation of nutrient intakes showed that birds on the split‐diets consumed significantly less protein, energy and calcium than the control birds.

4. Giving split‐diets also resulted in superior shell quality; treatment differences were also noted in the timing of oviposition.

5. It is suggested that the voluntary reduction in food intake noted for birds offered split‐diets is associated with an appetite for calcium.     

Efect of intermittent feeding on blood plasma growth hormone and prolactin in chickens of a heavy breed

1. Variations in plasma growth hormone (GH) and prolactin concentrations were determined during growth (at 20, 33, 56 and 83 d of age) in ad libitum (control) and intermittently (alternate days) fed chicks.

2. In each group of birds the concentration of plasma GH was inversely related to age. The mean prolactin concentration was highest in the youngest (20‐d‐old) birds.

3. The concentration of plasma GH in the intermittently‐fed birds deprived of food for 24 h (depleted birds) was significantly higher than that in the controls at 33, 56 and 83 d of age. The mean GH concentration in the intermittently‐fed birds 24 h after refeeding (repleted birds) was less than that in the depleted ones.

4. The overall mean concentration of plasma prolactin in the depleted birds was significantly less than that in the control and repleted birds.

5. These results are consistent with the effects of fasting on GH and prolactin secretion and demonstrate that growth retardation in the intermittently‐fed birds was not due to impaired GH secretion.     

The effects of restricted feeding on adrenal cortical activity in the immature domestic fowl

1. The effect of reducing food intake to 75% of the ad libitum intake was determined from hatching to 8 weeks in young Light Sussex chickens.

2. Restricted birds were lighter throughout the experiment.

3. Relative adrenal weight tended to be greater in restricted birds but the difference decreased with time.

4. There was no depletion of adrenal cholesterol: from week 5 there was a significantly greater amount in the adrenals of restricted birds.

5. After 1 week of restriction plasma corticosterone concentration was 73% greater than in controls. It decreased progressively, falling within the normal range at 5 weeks.

6. Restricted birds were hypoglycaemic from weeks 2 to 7 and hyper‐lipacidaemic throughout. A negative correlation between plasma glucose and free fatty acids was found.     

Effects of restricting the amounts of medium or low‐energy diets fed to laying hens in different colony sizes

1. Light hybrid hens between 32 and 68 weeks of age kept 4, 5 or 8 birds to the cage received one of three energy intakes, from a medium‐ or low‐energy diet.

2. Ad libitum fed birds laid more and heavier eggs than any of those restricted. A decrease in daily egg output of about 5 g was associated with each 100 kJ decrease in daily intake of metabolisable energy.

3. For the same energy intake, egg output of birds fed on the low‐energy diet was markedly greater than that associated with the medium‐energy diet.

4. The mortality of birds receiving restricted quantities of the medium‐energy diet was two to three times greater than that associated with similar rationing of the low‐energy diet.     

The use of rapeseed meals and a mustard seed meal as a protein source in diets for laying pullets

1. Three experiments with laying pullets were carried out in which rapeseed meals (B. napus and B. campestris) and a mustard seed meal (B. juncea) formed 12% of the diet.

2. Dietary rapeseed had no effect on the onset of lay when fed from 17 weeks of age but caused a delay when fed from 10 weeks of age: changing to a control soyabean diet for the laying period resulted in normal egg production.

3. Diets containing B. napus but not B. campestris consistently depressed egg production and reduced egg weight in one experiment. Mustard seed meal did not affect performance.

4. Significant number of eggs with a “fishy” taint were laid by brown‐egged birds fed on a diet containing rapeseed.

5. Thyroids of birds fed on rapeseed meal diets during the laying period were significantly heavier than those of birds fed on diets containing mustard seed or soyabean.

6. The enlargement of the thyroid gland is probably related to the oxazolidinethione content of the rapeseed.     

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.     

Effects of restricting body weight gain or limiting the photoperiod during rearing on sexual maturity,viability and semen production in large white Turkey males

1. Severe restriction of food from 6 to 54 weeks of age resulted in lower body weights and smaller testes weights in male turkeys.

2. As a proportion, mortality was 0.5 in turkeys fed ad libitum and 0.1 in those which were restricted. There were significantly fewer leg problems in the birds undergoing food restriction.

3. Sexual maturity was delayed 4 weeks by food restriction although semen quality was similar to that in ad libitum‐fed birds.

4. Individual semen production was lower after food restriction but, because mortality and food consumption were also lower, semen production per male housed and semen production per kg of food eaten were proportionally 0.30 and 0.32 greater in restricted‐compared with ad libitum‐fed turkeys.

5. Useable quantities of good quality semen were obtained from ad libitum‐fed turkeys at 23 weeks of age.

6. A short photoperiod (7L:17D) from 10 to 18 weeks of age in ad libitum‐fed turkeys produced more rapid development of normal semen production compared with turkeys given a longer photoperiod (14L:10D).     

Identification of tissue hypoxia in the livers of ascitic and hypoxia‐induced broilers using trypan blue

1. The perfusion of livers with the vital dye trypan blue was performed to test for evidence of tissue hypoxia in 3 groups of young broiler chickens, namely, ascitic, hypoxia‐induced and controls.

2. Hepatocytes that stained with trypan blue were considered to be dead or dying before fixation and represented damaged cells.

3. The proportion of trypan blue‐stained hepatocytes in the livers of ascitic birds was slightly less than half that observed in the hypoxia‐induced birds but significandy more than the proportion of stained cells observed in control birds.

4. Liver damage in the ascitic birds was also assessed biochemically by an altered enzyme profile.

5. The study demonstrated that increased trypan blue uptake in the livers of ascitic birds reared at sea‐level may be the consequence of hypoxia stress caused by reduced oxygen utilisation.     

Protective effect of ubiquinone (coenzyme Q9) on ascites in broiler chickens

1. The effect of ubiquinone (C0Q9) on ascites in broiler chickens was investigated.

2. The commercial broilers were divided into 2 groups of 100 birds each; CoQ9‐treated group and non‐treated group.

3. The chickens were grown in a positive‐pressured house with double high efficiency particulate air filtered intakes and exhaust, and thus were strictly isolated from infectious agents.

4. The chickens (15 to 21 d old) were exposed to cold stress in order to induce ascites.

5. The number of birds with ascites in the C0Q3‐treated group was significantly lower than in the non‐treated group.

6. Survival and production rates were better in the CoQ^‐treated group than in the non‐treated group.     

Influence of diet on the intestinal microflora and meat flavour of intensively‐reared broiler chickens

1. An attempt has been made to modify the composition of the gut flora of broiler chickens by dietary means in order to determine any concurrent changes in meat flavour.

2. Birds given a diet containing an increasing proportion of whole wheat supplemented with fresh green vegetable matter (special diet) were compared with conventionally‐fed controls. At 12 weeks of age those receiving the special diet had 10 to 100‐fold higher counts of Escherichia colt and faecal streptococci in the duodenum and lower small intestine and showed differences in the intestinal incidence of species and biotypes of lactobacilli.

3. Evaluation of cooked breast‐meat samples by a trained sensory panel showed a significant difference in flavour (P < 0.01) between conventional and special‐diet birds which varied from perceptually very slight to slight. The main terms used in distinguishing special‐diet birds from conventional controls included ‘richer’, ‘meatier’ and ‘sweeter’.

4. Storage of plucked, uneviscerated birds at 4 °C for 8 d maintained the flavour difference between the dietary groups but the effect of storage on flavour was greater in both groups of birds than the influence of diet alone. The likely influence on flavour of autolytic changes occurring in the muscle during storage of the birds is discussed.     

Plumage loss in medium‐bodied hybrid hens: The effect of beak trimming and cage design

1. Plumage loss was assessed by visual scoring in 288, 78‐week‐old hens, housed as groups of four in battery cages, which differed in the design of the cage front and the position of the nipple drinkers.

2. Half the hens had undergone beak trimming at 18 weeks, but in many cases regrowth had occurred.

3. Plumage damage and loss was significantly reduced in beak‐trimmed birds compared with birds with normal beaks. Tier and cage design had no effect.

4. This finding supports the idea that feather pecking is the important factor in causing plumage damage, rather than abrasion.

5. A comparison between 64 birds in which beak regrowth had occurred, and 64 in which it remained truncated, showed that both groups had similar plumage scores.

6. It appears to be the beak‐trimming procedure which is important; subsequent regrowth being irrelevant.     

Administration of Lactobacillus johnsonii FI9785 to chickens affects colonisation by Campylobacter jejuni and the intestinal microbiota

1. Campylobacter jejuni is the most common bacterial cause of human food-borne gastroenteritis in the world. A major source of human infection is the consumption of contaminated meat, particularly poultry. New control measures to reduce or eliminate this pathogen from the animal gastrointestinal tract are urgently required, and the use of probiotics as competitive exclusion agents is a promising biocontrol measure to reduce C. jejuni in the food chain.

2. In this study, we assessed the potential of Lactobacillus johnsonii FI9785, which has shown efficacy against Clostridium perfringens, to combat C. jejuni. The effect of prophylactic administration of L. johnsonii on the ability of C. jejuni to colonise chickens was determined.

3. Two doses of L. johnsonii given a week apart led to a reduction in C. jejuni colonisation in the caecal contents, but this biocontrol seemed reliant upon a high level of initial colonisation by the probiotic.

4. The microbial composition in the chicken gut was significantly altered by the probiotic treatment, as shown by denaturing gradient gel electrophoresis of 16S rRNA gene amplicons.

5. Together these results demonstrate the potential of this probiotic strain to be tested further as a competitive exclusion agent in poultry against C. jejuni.     

On estimating non‐additive genetic parameters in chickens 1

1. Several economically important traits in two Leghorn populations (over 9000 birds) were examined for additive and non‐additive components of genetic variance and sex‐linked effects. Data were analysed by two different statistical models based on least‐squares procedures.

2. Six different covariances were first calculated between relatives; i.e., full‐sibs, 3/4‐sisters, half‐sisters, dam‐daughters, grandam‐granddaughters and aunt‐nieces.

3. From the covariances, weighted least‐squares equations were used to obtain estimates of variance components for additive genetic, dominance, maternal and sex‐linkage effects.

4. The estimates of non‐additive components were highly variable but generally small compared with the additive genetic estimates.

5. In general this study suggests that for most traits, with the possible exception of rate of egg production, there is relatively little non‐additive genetic variation.

6. The consequences of possible negative correlations between additive effects and maternal effects are considered as they might apply to egg production in poultry.