Factors influencing bacterial eggshell contamination in conventional cages,furnished cages and free-range systems for laying hens under commercial conditions

1.?The aim was to assess eggshell contamination in various laying hen-housing systems and to identify factors influencing this contamination.

2.?Fifty-eight laying hen farms in France were studied, including 21 flocks housed in conventional cages, 7 in furnished cages and 30 kept on-floor.

3.?Sixty eggs per flock were analysed to obtain counts of the total mesophilic flora. Data on equipment and hen management were collected.

4.?Mean bacterial count on eggshells tended to be higher in on-floor systems (4·82 ± 0·51 log CFU/eggshell) than in cage systems (4·57 ± 0·58 log CFU/eggshell, P = 0·09).

5.?Contamination increased with age of the hens, airborne dust concentration, manual packing of the eggs, and packing in plastic rather than in recycled-pulp egg-flats.

6.?The effect of the housing system on eggshell contamination, previously described in experimental assays, was confirmed under production conditions.     

Performance of commercial laying hen genotypes on free range and organic farms in Switzerland,France and The Netherlands

1. A total of 257 farmers with free ranging laying hens (organic and conventional) in Switzerland, France and The Netherlands with 273 flocks were interviewed to determine the relationships between the genotype of the hens, management conditions and performance.

2. Almost 20 different genotypes (brands) were present on the farms. In France, all birds were brown feathered hens laying brown eggs. In Switzerland and The Netherlands, there were brown, white (white feathered hens laying white eggs) and silver (white feathered hens laying brown eggs) hens. In Switzerland, mixed flocks were also present.

3. The overall effect of system (organic vs. conventional free range) on egg production and mortality was significant, with higher mortality and lower egg production among organic hens. In pair wise comparisons within country, the difference was highly significant in The Netherlands, and showed a non-significant tendency in the same direction in Switzerland and France.

4. White hens tended to perform better than brown hens. Silver hens appeared to have a higher mortality and lower production per hen housed at 60 weeks of age.

5. There were no significant relationships between production, mortality, feather condition and use of outside run or with flock size.

6. There was more variation in mortality and egg production among farms with a small flock size than among farms with a large flock size.     

Bone structure and breaking strength in laying hens housed in different husbandry systems

1. Bone structure and breaking strength were measured in hens that had been housed throughout a laying year in battery cages or in Perchery, Naturel or Litter and Wire husbandry systems.

2. Battery caged hens had the poorest bones, as assessed by measurements of cancellous bone volume, radiographic density, cortical thickness and three‐point breaking strength.

3. Humeri from birds in the Litter and Wire system were less dense radiographically and weaker than those from Perchery or Naturel birds but leg bone characteristics were similar with these three systems.

4. There were no differences in bone characteristics between birds in Perchery and Naturel systems.

5. There were strong correlations between radiographic densities and strengths of contralateral humeri and tibiae over all husbandry systems. Humerus structural and strength characteristics may be the best criteria of osteoporosis in hens.

6. It is concluded that the extent of movement allowed by different husbandry systems affects structural bone loss and bone strength in laying hens.

7. It is further concluded that the breaking strength of a hen's bone is closely related to morphometric measures and radiographic density of its structural components.     

Multi-factorial investigation of various housing systems for laying hens

1.?The advantages and disadvantages of various housing systems for laying hens were compared as a pilot study for work in commercial conditions.

2.?At 16 weeks of age, 284 hens were introduced into one of 6 housing systems: two types of conventional cages (small: SC; large: LC), furnished cages (small: SF; large: LF), and non-cage systems (single-tiered aviary: SA; free-range: FR).

3.?We evaluated the welfare, egg production, and immune response of the birds in these housing systems, built in the same location, for 18 months. For welfare evaluation, we examined their ethology, physiology, anatomy, production, and physical condition.

4.?The non-cage systems, especially FR, had a low score for freedom from pain, injury, and disease, together with other disadvantages, such as pale eggs and increased feed intake for production. However, the score for freedom to express normal behaviour was high and immune response was good in the non-cage systems.

5.?In the furnished cages, behaviour was more diverse in SF than in LF, and in SF immune response was comparable with the non-cage systems.

6.?For freedom from fear and distress, the non-cage systems had high scores for some indicators such as TI duration, H/L ratio and claw length, while aggressive pecking and feather pecking was worse in the housing systems with large group sizes.     

Lighting and mortality rates in domestic fowl

1. Data from intermittent and conventional lighting trials were analysed to investigate the effect of daily illumination upon mortality during the laying period and in 49‐d‐old broilers.

2. Iiveability in laying hens was improved by the use of intermittent lighting: the degree of improvement was proportional to the reduction in daily illumination achieved by the intermittent programme.

3. The reduction in mortality with intermittent lighting in laying hens was not the result of intermittent lighting per se. Intermittent regimens which did not reduce daily illumination did not reduce mortality.

4. Mortality in both conventionally‐lit laying hens and 49‐d old‐broiler chickens increased with photoperiod.     

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.     

Feeding layers of different genotypes in organic feed environments

1.?Two experiments were carried out to evaluate the suitability of an experimental laying hen genotype (SH) in organic egg production. SH had been selected over 25 generations on a low protein diet (130 g/kg) based on home grown feedstuffs. SH hens were compared with LSL (Experiment 1) and Hyline (Experiment 2) hens. The birds were kept in 12 aviary pens with access to outdoor runs.

2.?Four diets, which were different in each experiment, were used. A control diet was compared with diets based on feedstuffs supposed to be able to be grown and produced according to organic standards. The diets differed in the content of sulphur amino acids.

3.?There were no significant differences in mortality caused by diets or genotypes but an incidence of cannibalism occurred in one Hyline group fed on the diet with the lowest methionine content.

4.?Severe feather pecking of LSL birds occurred and was worst on the low protein diet. In Experiment 2, signs of feather pecking of birds on the low protein diet occurred at the end of the experiment, but there was no difference between the genotypes. There was no significant difference in number of eggs produced between diets. Egg weight was influenced by diets in both experiments and by genotype in Experiment 2. Number of misplaced eggs was higher in SH hens in both experiments. There were few significant diet × genotype interactions.

5.?The use of the outdoor area was influenced by diets and genotype in both experiments.

6.?In conclusion, diets low in methionine content influenced predominantly plumage condition and egg weight, although production of eggs by number was unaffected. The SH hen adapted well to organic conditions, as did the Hyline genotype.     

Whitening of brown shelled eggs: Individual variation and relationships with age,fearfulness, oviposition interval and stress

1. Fearfulness, shell colour, incidence and degree of shell whitening and the interval between ovipositions were studied in two populations of 30 brown egg laying hens with family histories of a low or a high incidence of egg shell whitening.

2. Hens of the population with the high incidence of whitening appeared to be more fearful than hens of the population with the low incidence of whitening.

3. Brown colouration of the egg shell and the incidence and degree of shell whitening declined as the hens aged.

4. Brown colouration and egg shell whitening were most pronounced on the blunt ends of the eggs.

5. A large part of the variation in egg shell whitening was attributable to the individual (hen) component of variance.

6. Differences in egg shell whitening, between the two populations, were detectable throughout the 26 weeks of the experiment.

7. Oviposition intervals were similar for normal and coated eggs when birds were not exposed to disturbance.

8. Disturbance of hens increased oviposition intervals and the incidence and degree of shell whitening, to a similar extent, in both populations.

9. It is concluded that stress‐related egg retention is not the sole factor responsible for abnormal egg shell whitening. Shell whitening may occur as a consequence of the premature termination of shell pigmentation as well as a consequence of the retardation of oviposition which occurs when hens are disturbed.     

Ovarian morphology and rates of ovarian follicular development in laying broiler breeders and commercial egg‐producing hens

1. Ovaries from a light‐bodied egg laying strain and a broiler breeder strain were compared at 26 and 82 weeks of age.

2. The rate of lay in both strains was lower in the older hens. The 82‐week‐old hens were subdivided into good and poor layers: the poor layers produced eggs at about half the rate of the good layers.

3. The yellow‐yolky ovarian follicles in both strains were smaller, more numerous and more closely ranked in hierarchies in 26‐week‐old hens than in 82‐week‐old hens.

4. No marked differences were seen between the strains at 26 or 82 weeks of age in the sizes, numbers or hierarchical arrangements of yellow‐yolky ovarian follicles.

5. The ovaries from 82‐week‐old good and poor layers from both strains contained similar numbers of yellow‐yolky follicles.

6. After feeding a fat‐soluble dye, the number of days over which eggs containing dye were laid did not differ between 26‐, 52‐ and 113‐week‐old hens from an egg laying strain. However, fewer eggs with dyed yolks were laid by the older hens.

7. These observations suggest that the decrease in egg production with age is due initially to a reduction in the rate of recruitment of yellow‐yolky follicles. Towards the end of the laying year it may also be due to an increased incidence of follicular atresia, internal ovulation and the production of membraneous or soft shelled eggs.     

Effects of short intermittent lighting on food consumption and performance of dwarf broiler breeders and progeny

1. Two hundred and sixty four dwarf broiler breeder hens were subjected to ad libitum or restricted feeding and to four lighting patterns: 15L (bright light):9D (dark), 15L:9d (dim light), 2L:10d: 1L:11d, (0.5L:3.5d) × 6.

2. Breeder hens fed ad libitum and subjected to either conventional or intermittent lighting ingested respectively, 25 g and 14 to 17 g more than hens restricted to 115 g/d.

3. Body weight was greater in hens fed ad libitum irrespective of the lighting pattern and of the amount of food intake.

4. Persistency of egg production was impaired by intermittent lighting.

5. Ad libitum feeding reduced egg fertility. The decrease was larger in breeder hens on intermittent lighting.

6. Hatchability was increased in hens submitted to the symmetrical lighting pattern (0.5L:3.5d).

7. Egg and chick weights were higher in hens fed ad libitum.

8. Shell index and shell breaking strength increased in restricted hens on the intermittent lighting pattern (0.5L:3.5d) × 6.

9. The best performance was obtained in restricted hens on the conventional lighting pattern.     

Changes in eggshell conductance,water loss and hatchability of layer hens with flock age and moulting

1.?Changes in water loss, eggshell conductance and hatchability with flock age were monitored in layer hens in a commercial hatchery.

2.?Optimal water loss for maximal hatchability of layer eggs was found to be 12 to 13% of initial egg mass at d 18 of incubation.

3.?Mass specific water vapour conductance (GH₂Osp) increased linearly with flock age from 0·31 mg/(d·g·Torr) at the beginning of the first breeding season to 0·40 mg/(d·g·Torr) at its end after 77 weeks (=4·21 and 5·44 mg/(d·100 g·kPa), respectively).

4.?After forced moulting GH₂Osp increased from 0·35 to 0·41 mg/(d·g·Torr) (=4·76 and 5·58 mg/(d·100 g·kPa), respectively).

5.?The coefficients of variation of GH₂Osp increased with flock age from 14% at the beginning of the breeding season to 31% at the end of the second breeding season.

6.?In order to preserve normal incubation water loss for maximising hatchability, the humidity setting of an incubator should increase gradually, with flock age, from 53% RH to 66% RH in the first laying season and from 61% RH to 67% RH after forced moulting.

7.?A 3·5-fold increase (from 2 to 7%) in the difference between mean and median GH₂Osp of egg batches with flock age was found, indicating increasing frequency of microscopic cracks in eggshells with flock age. This has to be taken into account when setting the humidity regime in the incubator.     

Analysis of sperm storage ability using duration of fertility in hens

1.?The objective of this study was to determine hens’ sperm storage potential.

2.?Efficient duration (De, number of days between insemination and the first clear egg), maximum duration (Dm1, number of days from the day after insemination to the last fertile egg before two consecutive infertile eggs) and maximum duration (Dm2, number of days from the day after insemination to the last fertile egg) of fertility, fertile egg number, egg production, laying rate and fertility during the 24 d following the latter of two inseminations (with 1 × 10⁸ spermatozoa) on two consecutive days were measured in a total of 150 dual-purpose hens at 30 weeks of age.

3.?De, Dm1 and Dm2 were 12·06, 14·44 and 16·17 d, respectively, and the three definitions of fertility duration (DF) differed greatly.

4.?Significant correlation coefficients between De and Dm1, Dm1 and Dm2, and De and Dm2 were 0·51, 0·57 and 0·23, respectively.

5.?We suggest that De and fertile egg number should be used to assess the ability of storing spermatozoa in female fowl.     

Effect of dietary supplementation of bacteriophage on performance,egg quality and caecal bacterial populations in laying hens

1. Bacteriophages (BP) have gained increasing attention as a treatment of bacterial infection for animals. However, the data pertaining to dietary application of BP for laying hens have been limited.

2. This study aimed to investigate the effect of dietary BP on laying performance, egg quality and caecal bacterial populations in laying hens.

3. The dietary BP used in this experiment was a mixture of individual BP targeting Salmonella gallinarum, Salmonella pullorum, Salmonella typhimurium, Salmonella enteritidis, Salmonella derby and Staphylococcus aureus.

4. A total of 360 Hy-Line Brown laying hens of 32 weeks of age were allotted to one of three dietary treatments with 6 replicates in a completely randomised design. The basal diet was prepared, and 0.4 or 0.8 g/kg BP mixture was supplemented to the basal diet. Diets were fed to hens for 8 weeks.

5. Laying performance and egg quality were not affected by dietary treatments. As inclusion levels of BP mixture in diets were increased, the DNA copy numbers for Salmonella spp. in the caecal contents decreased linearly, whereas the DNA copy numbers for Escherichia coli in the caecal contents increased linearly.

6. Results indicate that dietary supplementation of BP mixture decreases the target Salmonella spp. populations but increases Escherichia coli populations in the gastrointestinal tract of laying hens with little impact on laying performance and egg quality.     

Effect of lycopene on semen quality,fertility and native immunity of broiler breeder

1.?The effect of drinking water supplementation with lycopene on the semen quality, fertility and immunity of broiler breeders was evaluated.

2.?Broiler breeder males were individually caged from 25 to 42 weeks old and divided into two group: L group, treated birds (lycopene 0.5 g/l) and C group, control birds. Laying hens were divided into two groups and artificially inseminated.

3.?Semen variables were evaluated and daily fertility recorded. Serum bactericidal activity was tested.

4.?Semen production and viability were affected by lycopene supplementation. Serum bactericidal activity was better in L than in C group. The fertility rate curve of the L group displayed a positive trend.     

The nutritional value of algae for poultry. Dried chlorella in layer diets

1. The nutritional value of a sample of algae meal, mainly Chlorella, was assessed in an experiment with laying hens. The algae meal was that described by Lipstein and Hurwitz (1980).

2. Diets formulated by linear programming contained up to 120 g algae meal/kg with supplementary DL‐methionine.

3. There were no significant effects of dietary algae meal on egg output, food conversion or egg‐shell quality. Thus algae meal at the concentrations tested can be a useful substitute for soyabean meal in diets for laying hens.

4. High concentrations of dietary algae meal caused a deep yellow yolk colour of acceptable appearance.     

Influence of dietary calcium and phosphorus on metabolism and production in laying hens

1. The effects of different dietary concentrations of calcium (24 to 56.9 g/kg) and phosphorus (4.5 to 14.2 g/kg) on production and some aspects of metabolism were studied in laying hens.

2. Treatments did not affect egg numbers, food consumption, conversion efficiency of food to egg, bodyweight gain or mortality.

3. Increasing dietary calcium (Ca) significantly increased plasma Ca and inorganic phosphorus (P), breaking strength at the radius and egg specific gravity and significantly decreased plasma alkaline phosphatase and egg weight.

4. Increasing dietary phosphorus increased plasma P and decreased egg specific gravity significantly.

5. Plasma Ca, P and alkaline phosphatase and radius breaking strength were suitable indices of the Ca status of the hens.     

Effects of dietary supplementation of resveratrol on performance,egg quality,yolk cholesterol and antioxidant enzyme activity of laying hens

1. This experiment was conducted to evaluate the effects of dietary supplementation of resveratrol on laying performance, egg quality, egg yolk cholesterol and antioxidant enzyme activities of laying hens.

2. A total of 360 Beijing PINK-1 laying hens (60 weeks old) were randomly distributed among five dietary treatments, each of which included 6 replicates of 12 hens. Dietary treatments were basal diet supplemented with 0 (control), 0.5, 1.0, 2.0 and 4.0 g/kg diet resveratrol. The study lasted for 9 weeks including 1 week of adaptation and 8 weeks of the main experimental period.

3. The results indicated that dietary resveratrol significantly improved feed conversion ratios during 5–8 weeks and 1–8 weeks of the trial. Increasing dietary concentrations of the resveratrol linearly improved Haugh unit and albumen height of eggs.

4. The content of total cholesterol (TC), total triglyceride (TG), low density lipoprotein cholesterol (LDL-C), very low density lipoprotein cholesterol (VLDL-C) in serum and cholesterol in yolk was significantly decreased by dietary resveratrol, and there were significant linear correlations between these indexes and resveratrol supplemental levels.

5. Dietary resveratrol supplementation significantly improved serum Glutathione peroxidase (GSH-Px) enzyme activity and decreased serum malondialdehyde (MDA) content in groups with 2.0 and 4.0 g/kg resveratrol as compared to the control, respectively. However, supplementation of resveratrol did not affect the activity of serum superoxide dismutase (SOD).

6. It is concluded that resveratrol supplementation has a positive effect on performance, lipid-related traits and antioxidant activity of laying hens.     

Effect of amount and source of manganese and/or phytase supplementation on productive and reproductive performance and some physiological traits of dual purpose cross-bred hens in the tropics

1.?The effect of different amounts of added manganese (Mn) (0, 10, 20 and 40 mg/kg) in inorganic and organic form and phytase (0 and 300 U) was investigated on productive, reproductive and haematological traits on 480 hens and 60 cocks (Inchas breeds) divided into 12 groups: 10 and 20 Mn × 0 and 300 phytase × 2 Mn sources (8 groups), two negative controls (0 Mn × 2 levels of phytase) and two positive controls (40 Mn × 2 Mn sources).

2.?Phytase supplementation increased laying rate by 1·1% and egg weight by 0·4 g.

3.?Manganese supplementation at 10 mg/kg over dietary sources improved hatchability, at 20 mg/kg decreased death embryos and abnormality as those of hens supplemented with 40 mg/kg Mn. Inorganic Mn at 10 mg/kg significantly increased egg mass compared to the organic form. Inorganic Mn was more efficient in decreasing abnormal chicks than organic Mn. Phytase supplementation significantly increased hatchability of fertile eggs and decreased the number of abnormal chicks of groups fed on diets unsupplemented with Mn and those supplemented with 10 mg/kg Mn.

4.?Mn supplementation at 10 mg/kg over dietary sources significantly improved sperm mass motility and decreased abnormal sperm. Phytase significantly decreased lymphocyte cells and plasma AST.

5.?Mn supplementation of the control diet (containing only 16 mg/kg from raw materials) with 20 mg/kg of Mn from either organic or inorganic source is adequate to support egg production traits, egg quality, reproductive traits and economic efficiency of dual purpose cross-bred hens; however, phytase supplementation may reduce the required Mn supplementation to 10 mg/kg.     

Design of nest boxes for laying cages

1. ISA Brown hens were housed in groups of 4 in cages with different designs of nest boxes provided, to determine the effects of nest box design and management on their use and on the pre‐laying behaviour shown by the birds.

2. There were 5 treatments: control (C); a wire‐floored nest box attached to the back of the cage (W); a nest box containing a fibreglass rollaway hollow (N); two rollaway nest boxes (T); a rollaway nest box, protected by a partition from the main part of the cage (P).

3. The holes in the rollaway nests in treatment N, T and P were shut initially, but the proportion of eggs laid in these nests only reached 50%. This proportion rose to over 80% when wood shavings were added daily, but fell to below 30% when rollaway holes were opened. These rollaway hollows are apparently not suitable for use in laying cages.

4. Use of nest boxes in treatment W varied between 60 and 80%. However, when pre‐laying behaviour was recorded (in 19 hens) two birds which laid in the nest boxes nevertheless showed abnormal behaviour.

5. Individual hens had on average 29 to 60% of their pre‐laying behaviour overlapped by that of others in the cage. Nesting space for at least two birds is probably necessary in a cage for 4 birds. However, in treatment T pre‐laying behaviour was disturbed by hens moving between the two boxes. This would be avoided by provision of one box big enough for two hens.

6. Soiling of hollows resulted in dirty eggs and suggested that nest boxes for laying cages may have to be provided with doors to prevent hens from roosting in them.     

Behavioural adaptation of laying hens to dilution of diets under mash and pellet form

1. Two laying diets, control (A) and a low‐energy (B) diet diluted by adding 450 g/kg wheat bran, were fed to semi‐heavy hens in three different forms: mash, small pellets and large pellets. The behavioural adaptations and the production characteristics for these six regimens were studied on 72 individually caged hens, between 19 and 29 weeks of age, subjected to a lighting pattern of 14 h light/24 h.

2. Diet B, as mash, showed a lower apparent physical density than the others. The hardness and durability of the pelleted diets were similar.

3. Hens fed the mash diet B could not completely adjust their food intake to compensate for the dilution and showed reduced egg output and body weight gain compared to the other groups.

4. Video observation of each hen for 14 consecutive hours showed that mash‐fed hens ate for longer periods than pellet‐fed hens during the first 11 h (proportion of time spent eating: 41.3% mash B, 32.5% mash A and 20% to 25% for all the pelleted diets). These differences were less pronounced during the last 3 h of the photoperiod.

5. Trough‐oriented stereotypies were noted in 14 out of 22 mash‐fed hens and in 12 out of 47 pellet‐fed hens. Dilution of the diet did not appear to exacerbate stereotyped behaviours under the conditions of the study.

6. This experiment demonstrates that the feeding behaviour of laying hens is affected by the physical characteristics of the diet and that this may lower their productivity.

7. Low‐energy pelleted diets might be used to feed hens efficiently in tropical countries where cereal by‐products are abundant.