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.     

Individual variation in prelaying behaviour and the incidence of floor eggs

1. Floor eggs are a problem in non‐cage systems for laying hens, as they require secondary egg collecting. Failure to lay in a well‐defined nest site may also be a welfare problem for the hens, but only if their nesting motivation has been thwarted.

2. We investigated the relationships between a hen's prelaying behaviour and its tendency to lay on the floor by recording the behaviour of 20 hens housed individually in wire cages with single littered nest boxes.

3. Most floor eggs (80%) were laid by the same 6 hens. These 6 “floor‐layers” performed more nest seeking behaviour, less nest‐building behaviour and less sitting prior to oviposition than the 14 hens that consistently laid in nest boxes.

4. The incidence of floor eggs declined with age. Both nest and floor laying hens performed less nest seeking behaviour with age. Floor layers, however, increased their performance of nesting behaviour, whilst nest layers performed less nesting behaviour with age.

5. Floor laying hens behaved as if they found the nest box less attractive than nest‐laying hens; perhaps because they had lower nesting motivation, or perhaps because their nesting motivation was as high, but they less readily perceived the nest box as an appropriate nest site.     

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.     

Effects of nest linings,pecking strips and partitioning on nest use and behaviour in modified battery cages

1. Nine groups of 4 ISA Brown hens were housed in modified battery cages each containing 3 nest sites. Egg laying was performed exclusively in these sites.

2. In experiment 1, each cage contained one unlined nest (type A), one lined with neoprene rubber (type B) and one lined with rubber with an additional peckable strip of artificial grass attached above the nest rear (type C). Positions of the nests were systematically altered over 45 d.

3. Hens spent most time in and made most visits to nest type C. More eggs were laid in nest types B and C than in nest type A.

4. In experiment 2, all nests were of type C, but nests were divided within each cage either by wire mesh, or a solid nest partition, or no partition. Nesting behaviour was monitored over 20 d for each of the 3 conditions.

5. Hens spent most time in, and made most visits to the nests when solid partitions were present. However, disturbance of nesting birds was also significantly increased by solid partitions. There were no significant effects of partition type on the number or positions of eggs laid in the nests.     

Choice of social conditions by laying hens

1. To test the preferences of hens for particular social conditions when laying, they were provided with choices of nest‐sites varying in seclusion. Three experimental conditions were used.

2. In Experiment 1, nest‐site selection by members of a group of light hybrids was studied in a complex pen‐system. Eggs were clumped in distribution ; only one individual laid in the most secluded part of the system.

3. Experiment 2 provided light hybrids with an extensive outdoor area, but similarly clumped laying was observed; there was no indication that hens attempted to find concealment for nesting.

4. In Experiment 3, hens from a group of light hybrids just coming into lay and from a group of mature medium hybrids were tested singly, in an area that included a cage containing some of their flockmates. Most subjects from both groups laid near the other birds rather than in isolation.

5. In semi‐intensive conditions, the majority of hens are apparently gregarious rather than solitary in their nesting behaviour.     

Effects of relocation on production in caged layers

1. Two experiments were conducted to determine the effects on laying performance of relocating caged hens at 30, 42 and 54 weeks of age.

2. In experiment 1 with hens caged individually, treatment groups comprised relocated hens given 5 new neighbours and hens not relocated but given 0, 2 or 4 new neighbours.

3. In experiment 2 with hens housed two per cage, treatment groups comprised relocation with or without that hen which shared the cage before the move.

4. In both experiments relocated hens laid fewer eggs in the week following social reorganisation.

5. Relocated hens in experiment 1 ate less food in the week following the shift at 42 weeks of age than did hens not moved. In experiment 2 in which all hens were moved, food consumption was not affected.     

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.     

Comparative analysis of pre‐laying behaviour in battery cages and in three alternative systems

1. Pre‐laying behaviour was compared in battery cages (C) and in three alternative husbandry systems: perchery (P), deep‐litter (DL) and covered strawyard (S).

2. Twenty ISA Brown hens were observed in each system for 60 min before oviposition and 5 min afterwards.

3. There were significant between‐system differences in a number of behavioural elements associated with the nest. Most varied along the sequence: C, P, DL, S, but the differences between the three alternative systems were generally less than between them and C.

4. The main factor governing the expression of pre‐laying behaviour appeared to be the availability, the number and the arrangement of littered nests.

5. Behaviour elements preceding nest entry and which were associated with area per bird again varied along the sequence C, P, DL and S with the major discontinuity between P and DL.

6. In P and C the searching phase was extended, in C at the expense of sitting. In P much time was spent inspecting the nests and many nest entries were made.

7. The Gakel call appeared to be related to finding a suitable nest site. In P the number of calls and the mean duration per nest inspection declined in a parallel fashion towards oviposition. In C, where no suitable nest could be found, Gakel calling remained high during the whole observation period.

8. These behavioural differences suggested that pre‐laying behaviour was poorly expressed in C and most fully in S, but that expression was in general relatively complete in all three alternative systems.

9. The ability of hens to express pre‐laying behaviour fully and coherently may be relevant to their welfare.     

Influence of front curtain design on nest choice by laying hens

1. The aim of this study was to investigate the effect of front curtains, one-piece (OP) or sliced in stripes (SL), on the hens’ nest preference and laying behaviour in an aviary system. We predicted that hens prefer SL-nests as they could perform nest inspections and enter and leave the nest along its whole width leading to fewer conflicts and more settled laying behaviour.

2. Eight pens containing 20 White Leghorn laying hens were equipped with two roll-away nests, one with OP and one with SL curtains. Laying behaviour was recorded for two days at peak lay in weeks 25 and 26.

3. More nest visits and more nest entries and exits along the whole width of the nest were counted in SL-nests. More sitting events without egg laying were performed in the OP-nests. No differences were found in the number of hens visiting the nests, egg number or aggressive behaviour.

4. Hens appeared to value the seclusion and protection provided by a closed front curtain. However, sliced curtains provided more opportunities to perform nest inspections.     

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.     

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.     

Influence of Plasma Lipid Composition on Activity of Factors V,VII and X in Single Comb White Leghorn and Fatty Liver Haemorrhagic Syndrome-Susceptible Laying Hens

1.?Plasma lipids were investigated to determine whether they influence the biological activities of specific coagulation proteins Factors V, VII and X.

2.?Factor activities decreased when lipids were depleted from the plasma of Single Comb White Leghorn (SCWL) and Fatty Liver Haemorrhagic Syndrome-susceptible (FLHS) laying hens.

3.?Addition of lipids removed from SCWL laying hens and FLHS-susceptible laying hens into lipid-depleted plasma of both bird strains caused an increase and decrease, respectively, in Factors V and X activities.

4.?Omega-3 fatty acids were negatively correlated to Factors V, VII and X activities. When bird strain was considered, it was significant for Factor X in SCWL laying hens. Omega-6 fatty acids were positively correlated with Factors VII and X for FLHS-susceptible laying hens.

5.?The results suggest that the type of fatty acid in plasma phospholipids influences the activities of Factors V, VII and X and by altering lipid composition in the plasma, activities of coagulation factors may be affected.     

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.     

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.     

Behaviour,health and integument of four hybrids of laying hens in modified and conventional cages

1. In 2 trials the health and behaviour of a total of 3552 caged laying hens of 4 hybrids, Dekalb XL, Lohmann Selected Leghorn (LSL) and Shaver 288 in trial 1 and ISA Brown and LSL in trial 2, were studied. The cage designs were Get‐away cages (GA) with 15 hens per cage, a special version of the ‘Edinburgh modified cage’ called ‘Modified and enriched cage’ (ME) with 4 ISA or 5 Leghorn hens per cage, conventional metal cages with 4 hens per cage without (CO) and with a perch (PC) and conventional plastic cages (PL) with three hens per cage. GA and ME included nests, perches and sandbaths.

2. In the first trial two nest models were used, artificial turf and welded wire floor. In the second trial both nest models were used in GA, while all nests in ME were equipped with artificial turf. In the second trial there were 4 sandbath treatments in ME; no sandbath, sandbath (25×50 cm) first opened at 16 weeks of age, sandbath first opened at 26 weeks and double size sandbath (50 × 50 cm) first opened at 16 weeks. Hens in GA were allowed access to the sandbaths from 26 weeks.

3. At 35 and 55 weeks the best plumage condition (feather cover) was found in PL and GA but plumage condition in ME was not significantly inferior than in GA. Hens in GA had the dirtiest plumage and most bumble foot but no toe pad hyperkeratosis. Some toe pad hyperkeratosis occurred in the other systems. Most keel bone lesions were found in systems with perches. The highest mortality was registered in GA. Hens in systems with perches, sandbaths and nests had increased strength of humerus at slaughter.

4. More eggs were laid in nests with artificial turf than in welded wire floor nests. LSL hens laid larger proportions of eggs in the nests (94% and 92% in the two trials) than the other hybrids. Less than 1% of the eggs in ME and 2% in GA were laid in the sandbaths.

5. The use of perches in ME and PC was approximately 30% in the day time. At night the use was 93% in ME and 89% in PC in trial 1 and 96% in ME and 81% in PC in trial 2.

6. Hens in ME with the double sized sandbath both visited the sandbath and performed dust bathing behaviour most, followed by hens in GA, hens in ME with access to the bath from 16 weeks and last, hens in ME with access to the bath from 26 weeks.

7. It is concluded that enrichments of laying cages are used by the hens to a large     

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.     

Selection for increased incidence of double‐yolked eggs in white leghorn chickens

1. Eleven generations of selection on two White Leghorn lines resulted in birds which, on the average, laid at least 30 double‐yolked eggs to 40 weeks of age.

2. The total number of yolks laid to 40 weeks was comparable with that of a control line selected for high egg number.

3. At peak production an F₁ cross of the two inbred lines laid 140 yolks per hundred hens per day.

4. Double‐yolk selected lines when crossed produced hens with a 20% increased body weight.

5. By the 10th and 11th generations the incidence of eggs with three or four yolks was increasing.     

Evaluation of bone strength,keel bone status,plumage condition and egg quality of two layer lines kept in small group housing systems

1. The aim of the present study was to determine the influence of large (54 or 60) and small (36 or 40) group sizes and tiers of the small group housing system “Eurovent German” on tibia and humerus bone breaking strength, keel bone status, plumage condition and egg quality for two commercial layer lines, Lohmann Selected Leghorn (LSL) and Lohmann Brown (LB), at the same stocking density (890 or 830 cm²/bird).

2. In 4 consecutive trials, 4752 hens were recorded for keel bone status. Evaluation of plumage condition was made for 1440 hens and bone breaking strength was recorded for 1200 hens. A total of 4962 eggs were analysed for internal and external egg quality traits. Analyses involved 30 small group compartments per trial.

3. The layer line had a much more pronounced influence on humerus breaking strength than on tibia breaking strength.

4. Plumage condition, particularly on the neck, was positively correlated with humerus breaking strength in both layer lines.

5. An average of 34% of LB and 23% of LSL hens showed keel bone deformities, with higher proportions of slight deformities.

6. Slight keel bone deformities, rather than moderate to severe, increased significantly during the laying period.

7. Stocking density had no influence on bone breaking strength, keel bone status and egg quality traits.

8. LB layers had a 1.4-fold higher humerus, but only a 1.06-fold higher tibia breaking strength compared to LSL layers.

9. Tibia breaking strength was significantly affected by the interaction of group size and layer line. LSL layers in small groups had lower tibia breaking strengths than those of the large groups.     

Effect of substrate provision on performance and behaviour of laying hens in the pecking and scratching area of furnished cages

1. An experiment was set up to study the effects of substrate provision on performance and behaviour in the pecking and scratching area (PSA) of non-beak-trimmed hens housed in large furnished cages (60 hens/cage).

2. Three layer hybrids (two brown and one white, ISA-Hendrix Genetics, France) and two substrate conditions (with or without wheat bran automatically distributed on the PSA) were compared in a 3 × 2 experimental design with 12 cages per treatment.

3. Substrate distribution improved laying rate with no impact on the frequency of dirty or cracked eggs.

4. Substrate distribution improved the viability and body integrity of hens, which were not beak-trimmed.

5. Distribution of substrate tended to increase the number of hens in the PSA and enhanced their pecking and scratching behaviours but had a negative impact on the number of dust bath bouts per cage and encouraged dust bathing on the wire floor close to the feeder.

6. The white hens laid more eggs in the nest than the brown birds and used the PSA more for pecking, scratching and dust bathing at the end of the day than the brown hens, underlining the necessity to adapt cage furnishing and rearing management to specific behaviours of each layer genotype.