Comparative development of digestive organs,intestinal disaccharidases and some blood metabolites in broiler and layer‐type chicks after hatching

1. Body weight, digestive organ weights, and activities of disaccharidases (maltase and saccharase) activities were determined from day of hatch to 21 d of age in meat‐ and egg‐type chickens. Blood plasma was analysed for enzyme activities and metabolite concentration.

2. In meat‐type chickens food intake and growth rate were about 3‐fold those in egg‐type chickens. Food efficiency was superior in meat‐type chickens throughout the experimental period.

3. Meat‐type chickens hatched with disaccharidase activities exceeding those found in their egg‐type counterparts 2‐ to 5‐fold. From 7 d of age on, this trend reversed, i.e. activity was much higher in egg‐type than in meat‐type chickens.

4. Blood plasma amylase activity increased gradually in meat‐type chickens and was higher than in egg‐type chickens to 14 d of age. No breed differences were observed for alkaline phosphatase or lactate dehydrogenase activities during the experimental period.

5. Blood plasma concentrations of total protein, albumin, glucose, and calcium, were lower in meat than in egg‐type chickens.     

Response of three class‐IV major histocompatability complex haplotypes to Eimeria acervulina in meat‐type chickens

1. The importance of MHC genes and background genes in controlling disease resistance, including resistance to avian coccidiosis, has not been clarified in meat‐type chickens.

2. The role of class IV MHC genes in resistance to Eimeria acervulina was assessed in F2 progeny of a cross between 2 meat‐type lines, selected divergently for immune response to Escherichia coli.

3. Disease susceptibility was assessed by lesion score, body weight, packed cell volume and carotene absorption.

4. Chickens with the “K” class IV MHC haplotype had lower lesion scores than chickens with “F” and “A” haplotypes.

5. Plasma carotene concentrations were higher in chickens with “K” haplotype and lower in chickens with “F” and “A” haplotypes whereas body weight and packed cell volume were less sensitive measures of Eimeria infection.

6. Eimeria acervulina resistance appears to be associated with MHC class IV genes; information about MHC haplotypes may be useful in selecting for increased resistance of meat‐type chickens to coccidiosis.     

Digestibility studies in broiler chickens: Influence of genotype,age, sex and method of determination

1. The influences of genotype, age and sex on droppings digestibility coefficients of a compound food were studied using male and female broiler chickens of three different genotypes at 2, 4 and 6 weeks of age.

2. Because the traditional method of determination of droppings digestibility coefficients of nitrogen may lead to systematic errors in estimating the feeding value of foodstuffs, a method is proposed to determine the ileal digestibility coefficients. The ileal method is compared with the droppings method for a mixed food and for two foodstuffs: wheat and solvent‐extracted soyabean meal.

3. Birds selected for efficient food conversion showed distinctly higher digestibility coefficients for all nutrients than birds selected for high growth potential or birds from a commercial strain.

4. The influence of age on digestibility coefficients was not consistent.

5. Female birds showed digestibility coefficients which were, in general, 3% higher than those of male chickens.

6. Interactions between genotype and sex and between genotype and age for energy metabolisability were the only interactions observed for digestibility measurements.

7. The method of determination influenced the amino acid digestibility coefficients of the mixed food and the relative feeding values of wheat and soyabean meal.

8. It is important to use well defined animals (genotype, sex, age) in evaluating foodstuffs.

9. The preferred method for determination of digestibility coefficients of nitrogen and amino acids is based on ileal sampling, although the differences in amino acid digestibility coefficients were small between methods.     

Automatic weight separation of broiler chickens

1. The individual weight gains of 371 broiler chickens in a commercial flock were monitored to establish individual growth patterns.

2. The relationship between early and final body weight was investigated for individual chickens.

3. The feasibility of automatic separation of birds into different weight groups was evaluated and consideration given as to whether this technique could be used for sex‐separation of an as‐hatched flock.

4. The results suggest that the present commercial practice of male selection at flock depopulation may be less reliable than many producers believe.     

Are genetically lean broilers more resistant to hot climate?

1. Genetically lean (LL) or fat (FL) male chickens were exposed to either high (32°C) or control (22°C) ambient temperature up to 9 weeks of age. They were fed on one of two isoenergetic diets differing in protein content: 190 or 230 g/kg.

2. At 22°C, weight gain of LL broilers was the same as in FL chickens, but at the high temperature LL birds grew to a greater weight than FL ones.

3. Food conversion efficiency was not affected by ambient temperature in LL chickens but was depressed in FL ones at 32°C.

4. Increasing dietary protein content did not alleviate heat‐induced growth depression irrespective of the genotype.

5. Gross protein efficiency was higher in LL chickens and was less depressed at 32°C than in FL birds.

6. Fat deposition decreased with increasing protein concentration at normal temperature in both genotypes; at high temperature, high protein content enhanced fatness, particularly in LL chickens.

7. Thus, genetically lean broilers demonstrated a greater resistance to hot conditions: this was indicated by enhanced weight gain and improved food and protein conversion efficiencies.     

A comparison of the energy and nitrogen metabolism of fed ducklings and chickens

1. Energy measurements were made over 4 d on groups of three ducklings (aged from 5 to 22 d), and three broiler chickens (aged from 11 to 32 d) offered high‐ or low‐energy diets.

2. Food, metabolisable energy (ME) and water intakes were significantly higher for ducklings than for chickens. The ratio of water : food was 4.2 : 1 and 2.3 : 1 for ducklings and chickens, respectively. The food conversion ratio differed between diets but not species. Performance was generally better for both species on the high‐energy diet.

3. Heat production, energy, fat and protein retentions were higher for ducklings than chickens, and ducklings retained 0.44 of their energy as fat compared with 0.37 for chickens. Overall the ratio of protein (g) to fat (g) retention was 2.2 : 1 and 2.8 : 1 for ducklings and chickens respectively.

4. For ducklings, metabolisability of the high‐energy diet declined from 0.774 to 0.747, and to a lesser extent of the low‐energy diet, as they aged. There was no such decline for chickens. Net efficiency of utilisation of ME for gain was 0.64 for ducklings compared with 0.50 for chickens.

5. Fractional retention of dietary nitrogen (N) was 0.62 for ducklings and 0.55 for chickens. Gaseous ammonia‐N was 4.5 and 2.2%, respectively, of N retained.

6. In a second experiment groups of ducklings only, were offered high‐and low‐protein diets from 12 to 22 d of age. Comparisons among four diets showed that food and energy intake was lower on the low‐protein diet than on the other three. Energy retention on the high‐energy diet was greater (P<0.05) than on the other three diets.

7. It was concluded that a high‐energy diet is important for ducklings and chickens for maximum biological performance during the first 4 weeks of life.     

Genotype‐level of protein interaction for growth rate in broilers

1. Two groups of White Plymouth Rock which were related to each other as half‐sibs were fed on diets containing either a normal or reduced amount of protein.

2. Compared with the normal diet the low‐protein diet caused a decrease in growth rate which at 38 d was 37% and 25% for male and female chickens, respectively.

3. A genotype‐level of protein interaction was demonstrated for weight at 38 d. Expressed as a genetic correlation for the same trait and measured in the two feeding environments the values were about 0.33.

4. In estimating the genetic correlation the interaction as well as the covariance method were used. The two methods did not give the same estimates.

5. Heritabilities for weight at 38 d tend to be larger in the low‐protein environment.     

Short‐term stressor effects of propranolol

1. The effects of propranolol (10 mg/kg) on plasma cholesterol, glucose, corticosterone and free fatty acids, on adrenal mass and cholesterol content and on body temperature were determined over a 24‐h period in 3‐week‐old Light Sussex chicks.

2. Changes in plasma cholesterol were equivocal, though there was perhaps a trend towards hypercholesteraemia.

3. Birds became hypoglycaemic within an hour but were hyper‐glycaemic between 2 and 4 h. At 24 h they were normoglycaemic.

4. Plasma corticosterone was increased markedly at 1 h but was decreased compared with the control at 2 h (P<0.01). Thereafter the concentration was in the normal range.

5. There was an enhanced hyperlipacidaemia in the treated birds after 1 h.

6. Adrenal cholesterol stores were decreased by 10% at 4 h but were unaffected at all other times.

7. Colonic temperature decreased by 1–6 °C after 2 h but was normal by4h.

8. It is concluded that propranolol has mild stressor activity which is lost within 24 h.     

Pulsatility of plasma growth hormone and hepatic growth hormone receptor characteristics of broiler chickens divergently selected for abdominal fat content

1. Plasma growth hormone (GH) pulsatility and hepatic GH receptor characteristics were compared in experimental lines of meat‐type chickens selected for high (HF) or low (LF) abdominal fat content.

2. Mean GH concentration, baseline and amplitude of pulses were slightly, but not significantly, greater in LF chickens. Length and frequency of pulses were similar.

3. LF chickens exhibited higher plasma triiodothyronine (T3) concentrations. This difference between genotypes disappeared when the diet was supplemented with 1 mg/kg T3.

4. Specific binding of GH to liver membranes was higher for the fat line but was depressed by T3 supplementation to the same level in both lines. No difference was observed between lines for affinity constants.

5. It is concluded that direct selection for leanness has a less pronounced, if any, effect on GH pulsatility as compared with selection for food conversion efficiency; therefore, different physiological mechanisms are triggered to achieve leanness.     

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.     

Traits influencing the hatching performance of Japanese quail eggs

1. Japanese quail eggs from moderately heavier sires showed superior fertility; while fertile eggs from moderately heavier dams hatched slightly better than the eggs from lighter dams.

2. Higher rates of fertility and hatchability of Japanese quail eggs were observed from parents of 10 to 19 weeks of age, with peak fertility and hatchability at 14 and 12 weeks of age, respectively.

3. Sex ratios of 1:2 to 1:5 gave comparable fertility and hatchability results.

4. The hatching performance of quail eggs from cage and deep litter reared breeders was comparable.

5. Fertility and hatchability were directly proportional to the egg weight.

6. Quail egg shell colour, tints and blotches were found to influence hatching performance.

7. Storing quail eggs at 16 ± 2°C and 75 ± 5% relative humidity for more than 4 d reduced hatchability.

8. Hatchability of eggs stored at room temperature was improved if they were sealed in polyethylene bags.

9. Provision of light during the first 14 d of incubation resulted in a photo‐acceleration of about 3.2 h.     

Monoclonal antibodies identifying chick gonadal cells

1. The aim of the present study was to raise monoclonal antibodies (MAbs) which discriminate gonadal cell types in chickens.

2. A panel of 180 MAbs was generated, from which 14 were chosen for their specificity.

3. These MAbs were characterised immunohistologically on frozen sections of embryonic, newly‐hatched and adult, male and female, left gonads.

4. Three of these MAbs are described: AGC5, AGC7, and AGC13 which recognise respectively germinal epithelial cells, supporting cells and germ cells.

5. These MAbs may be useful in following the developmental pathways in the chicken gonad and analysing the interactive role(s) taking place between gonadal stromal cells and primordial germ cells.     

The relationship between hatching egg weight and subsequent performance of broiler chickens

Small eggs constitute a high proportion of the eggs laid by pullets. The literature shows that chick hatching weight is strongly correlated with egg weight, but evidence on the influence of egg weight on hatchability and subsequent performance of chicks is less certain.

The aim of this experiment was to determine the profit returned at 12 weeks by broiler chickens hatched from eggs ranging in weight from 44 g. to 58 g. at one gram intervals and to determine how competitive and separate rearing might modify the relationship.

A total of 6000 eggs were collected during 10 days from a 28‐week‐old, broiler breeding flock and graded into the above mentioned egg weight classes. From these, a total of 3480 day‐old broilers were housed. Each egg weight class was equally represented and balanced for sex.

Hatchability and fertility showed no consistent trend with egg weight for eggs above 46 g., but below the 47 g. level there was a trend of declining fertility and hatchability.

A strong positive relationship was found between the weight of the chick at 1 day of age and egg weight for both males and females with no significant difference overall in body weight between the two sexes.

Body weight to 12 weeks was found to be strongly related to egg weight, in a linear fashion, though this influence declined with age.

There was a greater influence of egg weight on body weight at all ages in the separate rearing treatment compared with competitive rearing but this was not significant after 10 weeks.

Egg weight had an important bearing on body weight and profit at 12 weeks, but no effect on food conversion or mortality.

The increased profit over food costs per 100 day‐old chicks was found to be 52.75 cents for the separately reared birds respectively for each 3 g. increase in egg weight.     

Comparative growth and development of the digestive organs and of some enzymes in broiler and egg type chicks after hatching

1. Body weight, the weight of digestive organs and activities of some digestive enzymes were determined from hatching to 14 d of age in meat‐ and egg‐type chickens.

2. Relative daily food intake and growth rate were much higher in meat‐than in egg‐type chickens. Relative daily food intake peaked at 30% of body weight at 3 d of age in meat‐type, and at 20% of body weight at 6 d of age in egg‐type chickens and then decreased gradually. The corresponding values for growth rate were 20 and 14%.

3. Allometric growth of the small intestine, intestinal contents and liver was greater in meat‐type chickens, but the growth of the pancreas attained a higher value in the egg‐type birds. Diminution of the vitelline residue was similar in the two breeds.

4. Pancreatic digestive enzyme activities were similar between stocks, but activities in the small intestinal contents were lower in meat‐type chickens.

5. The secretion of digestive enzymes in the newly‐hatched meat‐type chicken could be a limiting factor in digestion and, consequently, in food intake and growth.     

Comparative utilisation of sulphur‐containing amino acids by genetically lean or fat chickens

1. Genetically lean (LL) or fat (FL) male chickens were fed from 28 to 47 days of age on 5 experimental diets differing by their methionine + cystine content (5.4, 5.8, 6.2, 6.6 and 7.0 g/kg, respectively).

2. Growth rate of LL chickens was reduced by the lower sulphur‐containing amino acid (SAA) concentrations whereas that of FL was not modified.

3. LL chickens exhibited a larger feather protein gain than FL, which was stimulated by SAA intake.

4. SAA retention, when plotted against SAA consumption, was always greater in LL than in FL.

5. Large differences were observed between genotypes for plasma‐free amino acids. Lysine, glutamic acid, histidine and serine were found at significantly higher concentrations in LL birds. Branched amino acids, aromatic amino acids, SAA and arginine were found at higher concentrations in FL. No differences were observed for aspartic acid, glycine, alanine and total amino acids. Methionine supplementation decreased free amino acid concentrations, with the exceptions of arginine and leucine.

6. It is concluded that lean chickens require a higher dietary concentration of SAA than FL. This is mainly caused by their lower food consumption and their greater feather synthesis. However, LL use SAA more efficiently than FL.     

Metabolic and anatomical adaptations of light‐bodied chicks to intermittent feeding

1. Chicks of a light‐bodied strain were deprived of food on alternate days from 15 to 46 d of age.

2. Hyperphagia, amounting to twice the intake of control birds early in the experiment, occurred on the repletion day.

3. Final body weight attained 80% of that of the controls.

4. Body fat concentration decreased at first but returned to that of controls after 3 weeks.

5. A consistent hyperlipaemia was observed after food deprivation or restoration.

6. There was a marked increase in the digestive enzymes found in the small intestine, but not in the pancreas during the repletion day.

7. These responses may be considered as mechanisms to reduce the physiological manifestations of starvation.     

Effect of dietary DL‐ethionine on growth and liver metabolism

1. The effects of DL‐ethionine, given in the diet or by injection, on growth, hepatic glycogen and lipids, and the activities of some cytoplasmic NAD‐linked dehydrogenases and NADPH‐producing enzymes were investigated.

2. Growth virtually ceased after feeding ethionine for 2 d.

3. Ethionine induced an accumulation of lipid, decreased the activities of malic enzyme and isocitrate dehydrogenase and increased the activity of lactate dehydrogenase.

4. The concentration of glycogen in the liver of ethionine‐fed chickens increased for 3 d in spite of a decrease in food intake, but then decreased.     

Use of ambroxol and bromhexine as mucolytics for enhanced diffusion of furaltadone into tracheobronchial secretions in broilers

1. Ambroxol and bromhexine were evaluated as mucolytics and to enhance the passage of furaltadone into tracheobronchial secretions (TBS) in chronic complicated respiratory disease‐affected broilers.

2. Viscosity of TBS was noticeably increased in the ambroxol‐treated birds and only slightly increased in the bromhexine groups; however, the physical (nature) of TBS was superior in the ambroxol‐treated broilers.

3. There was a clear increase in the passage of furaltadone into tracheobronchial secretions only in the ambroxol‐treated birds.

4. Everyday use of ambroxol in broilers is discussed.     

Effect of pyridoxine on the distribution of chloramphenicol and its residues in the chicken

1. Chickens were given either a single dose of chloramphenicol (50 mg/kg body weight per os) or a dose of chloramphenicol together with pyridoxine (25 mg/kg per os) given 1 h before or 4 h afterwards.

2. Concentrations of chloramphenicol were determined in samples of serum and the rates of distribution and elimination extrapolated. Concentrations of chloramphenicol in muscle, liver and kidney were also determined.

3. Serum concentrations of chloramphenicol were lower in chickens given both pyridoxine and chloramphenicol compared with those given only chloramphenicol.

4. Differences were most pronounced during the post‐absorptive phase. The rates of disappearance of chloramphenicol residues from tissues were enhanced by pyridoxine.

5. The biological half life of chloramphenicol and area under the concentration‐time curve were both reduced by the concurrent administration of pyridoxine.

6. Availability of pyridoxine may be a rate limiting factor in the biotransformation of xenobiotics, though its indiscriminate use could cause failure of antibiotic therapy.     

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.