Observations on the laying behaviour of hens in battery cages

Observations were made on the laying behaviour of hens from each of two commercial strains kept in a Thornber battery cage system. Attention was paid to the following behavioural components of oviposition: the position of the hen in the cage; the stance of the hen; the height through which the egg fell; the orientation of the egg; the time taken to oviposit; the time taken for the egg to roll out of the cage and the incidence of pecking at the egg.

Less detailed observations were made on the pre‐laying behaviour of the hens.     

Genetic analysis of strain differences in pre-laying behaviour in battery cages

The behaviour of hens of two strains during the 10 min before laying in battery cages was studied. Hens of one strain typically exhibited backward-and-forward pacing before laying. Hens of the other strain did not pace and tended to sit. Individual hens of both strains were consistent in their expression of pacing and sitting before laying. There was genetic variation in the expression of both pacing and sitting before laying, and both traits responded to selection. Crosses between the two lines indicated additive genetic variation in the expression of sitting behaviour and non-additive variation in the expression of pacing behaviour.     

Effect of cage height and area on the behaviour of hens housed in battery cages

Medium hybrid hens were housed as pairs and observed at three cage heights: 30.0, 42.5 and 55.0 cm, and at three area allowances per bird: 570, 807 and 1045 cm2. With increased height, head stretching, head scratching and body shaking were performed at a higher rate and feeding and cage pecking at a lower rate. There was also an increase in the time spent sitting. With increased area, head scratching, body shaking and feather raising were performed at a higher rate and cage pecking at a lower rate. It is concluded that spatial restriction may increase the cost of performing certain 'comfort' activities, resulting in the reductions in performance rate observed in the above experiments. Welfare implications are briefly discussed and considered to depend on the motivational state of the birds.     

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.     

Behavioral changes in laying hens after introduction to battery cages, furnished cages and an aviary

A variety of investigations into alternative systems and furnished cages for laying hens have been conducted, mainly in the European Union. However, comparative studies about the behavior of laying hens just after introduction to these housing systems are few. Therefore, this study aimed to investigate the changes of location and behavior of laying hens just after introduction to three housing systems. In total, 181 White Leghorns were used. Thirty‐six birds were allocated to 12 battery cages with three birds per cage (613 cm²/bird); 36 birds were allocated to nine furnished cages with four birds per cage (1170 cm²/bird); and 109 birds were allocated to an aviary (1130 cm²/bird). Direct observations using scanning techniques were conducted over 2 weeks for 4 h/day from the day following the introduction. Scan samples of location and behavior were taken at 10 min intervals. The proportion of birds that stayed at each location in the furnished cages was stable during the observation period. In the aviary, 78% of birds were observed on the floor on the first day, and thereafter the proportion linearly decreased (P < 0.01). The proportions of birds eating in both the battery and furnished cages were stable, indicating that the caged birds would adjust to these environments within a short period. Display of aggression was lower in both the cages (both 0.3 ± 0.1%) than in the aviary (3.5 ± 1.0%, P < 0.001), which indicates the early establishment of social order in both cage systems. In the aviary, the birds were observed eating less frequently than in both the cages on the first day, and the proportion thereafter linearly increased (P < 0.01), and the use of tiered wire floors with feeders accompanied this (P < 0.01). Comfort behaviors, including dust bathing, were noted less in the aviary than in the furnished cages throughout the observation period (both P < 0.05). These results suggest that adjustment of aviary birds to their new environment had been delayed compared with caged birds because of the prerearing conditions and the environmental complexity of the aviary.     

The hen's egg: Shell cracking at oviposition in battery cages and its inheritance

It is known that there is much variation between individual hens and between strains of hen in (a) the incidence of egg‐shell cracking and (b) the height through which the egg is dropped at oviposition. Pilot experiments are described from which it is concluded that:

1. most cracks that occur in a battery cage are produced when the egg drops on to the floor at oviposition;

2. they are located predominantly in the two polar thirds of the shell;

3. their incidence is determined mainly by the effective mass of the cage floor, the mean drop height and the mean attitude of the eggs at emergence from the cloaca (broad or narrowpole first) ;it is affected only slightly by the mean shell thickness and the overall mean shell curvature (egg size);

4. if a hen is kept on a floor with a high effective mass, an indirect estimate of her mean drop height can be obtained quickly, easily and with high precision from observations made on her eggs after they have been laid; the observations required are the incidence of eggs with poorly formed shells, the type, location and incidence of cracks in eggs with well‐formed shells and the mean weight of the eggs;

5. the incidence of cracking on a heavy cage floor can be used to predict the incidence on a normal floor;

6. the incidence of cracking is heritable and responds rapidly to downward selection.

It is suggested that breeders should test the technique described, with a view to adopting it as a method of selecting for low crack incidence.     

Production and economic results of commercial flocks with white layers in aviary systems and battery cages

1. In the Netherlands aviary systems are in use on 19 commercial farms. In the present study the results of 19 flocks kept in aviaries, with an average flocksize of 16,000 hens, were analysed and compared with 47 flocks kept in battery cages.

2. The aviary flocks had lower egg weights, lower mortality rates and poorer food conversion. The difference in food intake per hen per day was not significant. The average percentage of floor eggs in aviaries was 4.6, ranging from 0.9 to 11.5.

3. Production costs per kg eggs produced in aviaries were 8.2% greater than in cages. This increase was mainly caused by higher costs for pullets, housing and labour.     

Perching behaviour and perch height preference of laying hens in furnished cages varying in height

1. The objective was to investigate the effect of cage height on perch height preference and perching behaviour in laying hens. Twelve groups of two hens and 12 groups of 14 hens were tested in furnished cages equipped with two wooden perches. These stepwise perches were designed such that hens could choose between 7 different heights (6, 11, 16, 21, 26, 31 and 36 cm). Day- and night-time perching behaviour was observed on 4 consecutive days with a different cage height each day: 150, 55, 50 and 45 cm. 2. Given that a minimum perch-roof distance of 19 to 24 cm was available, hens preferred to roost on the highest perches at night. 3. Lowering cage height not only forced hens to use lower perches, but also reduced time spent on the perches during the day (two-hen and 14-hen test) and night (14-hen test). Moreover, it affected daytime behavioural activities (more standing and less preening) on the perches in the two-hen tests (but not in the 14-hen tests). 4. During the day lower perches were used more for standing and walking, higher perches more for sitting and sleeping. This behavioural differentiation was most pronounced in the highest cages. 5. Perch preference and perching behaviour depend on both the floor-perch distance and the perch-roof distance. Higher cages provide more opportunity for higher perches (which hens prefer), for better three-dimensional spacing (and consequently reduced density at floor level) and for behavioural differentiation according to perch height.     

Salmonella gallinarum biovar gallinarum as the cause of a highly acute septicemic disease in adult laying hens kept in battery cages

Early in the summer of 1988 two flocks each of them consisted of about 7500 brown laying hens of a heavy hybrid line were affected by fowl typhoid. The birds have been bought at the age of 20 weeks and housed in two buildings placed close together in one farm. The disease started in flock I at the age of 26 weeks and in flock II at the age of 36 weeks. In repeated trials amoxicillin was effective in the treatment of fowl typhoid when given in the drinking water for ad libitum consumption over a 4-7 days period; however relapse occurred 3-4 days after withdrawal of the drug. All the hens were slaughtered 5 days after termination of the last therapy. In spite of the treatment 18.3% of the hens in flock I and 14.3% of those in flock II died within the observation period of 47 days and 22 days respectively. Egg production was not affected. The source of the fowl typhoid producing organisms could be not elucidated.     

Nesting,dust bathing and perching by laying hens in cages: Effects of design on behaviour and welfare

1. Laying hens (192 ISA Brown medium hybrids) were housed from 18 to 72 weeks as groups of 4 in conventional or experimental cages. The main area of all cages provided 675 cmVhen. All experimental cages had perches, dust baths and nest boxes, which were of three types: litter (L), artificial turf (A) or plastic rollaway (P). These facilities provided an additional 375 to 480 cm²/hen. The nest boxes and dust baths occupied either high or low positions. Behaviour, physical condition and production of the birds were regularly recorded.

2. Mortality was low (1.6% overall) and egg production very good in all treatments. The proportion of cracked and dirty eggs was slightly (but not significantly) higher in the experimental cages. In the experimental cages 90% of eggs were laid overall in the nest boxes and 3% in the dust baths. The proportion laid in the nest boxes was lower early in the laying cycle and increased with time, reaching 99% in A.

3. The facilities were heavily used. Birds spent about 25% of day time on the perches and 10–15% in or near the nest box and dust bath. At night, the majority of birds (90 to 94%) roosted on perches, but most of the remainder were on the lips of the nest box or dust bath, fouling the interiors.

4. Pre‐laying behaviour was much more settled in the experimental cages (45 min spent in the eventual laying position) than in the conventional ones (20 min) and total duration varied from 68 min in A to 87 min in P. The number of nest entries varied from 3.0 (A and P) to 4.3 (L); disturbance to sitting birds was correspondingly greater in L.

5. Dust bathing in the experimental cages generally took place during the afternoon in a single bout of about 5 min duration, whereas in the conventional cages it was brief and fragmented (3 bouts of 10 s each). The dust bath was also used for foraging behaviour (pecking and scratching). The treatments with small dust baths (A and P) caused problems for the birds.

6. Feather, foot and claw damage all tended to be less in the experimental than in the conventional cages, though only in the last case was the difference significant. Keel bone depressions appeared to be associated with perches; they were present in 43% of hens in the experimental cages but only 4% in conventional cages. There were no significant differences in body weight or in tibial or humerus strength between birds in the various treatments.

7. This study confirms that experimental cages with nest boxes, dust baths and perches offer appreciable benefits for welfare, with few production problems. The most successful treatment (A) could, with relatively minor modifications, form the basis of a practical design for large-scale commercial production.     

Evaluation of the effects of cage height and stocking density on the behaviour of laying hens in furnished cages

1. Limited information is available on how changes in horizontal and vertical space within enriched or furnished layer cages (as defined by Directive 1999/74/EC) influence hen behaviour. This study evaluated the effects of varying minimum cage heights and space allowances on the behaviour of laying hens housed in furnished cages. It was conducted on two flocks of medium brown hybrid hens housed in furnished cages with access to perches and nest boxes on a semi-commercial scale at ADAS Gleadthorpe. 2. Flock 1 consisted of two layer strains (ISA Brown and Babcock 380), housed at two minimum cage heights (38 and 45 cm) and 5 stocking densities between 609 and 870 cm2/bird, with 12 replicates of each of the 20 strain/cage height/stocking density treatment combinations. Stocking density was varied by varying the number of birds per cage from 10 to 7 in standard full-width cages or housing 7 hens in a narrower cage. As a consequence stocking density, group size and trough width per bird co-varied for 4 out of 5 stocking density treatments. 3. Behaviour of flock 1 was sampled at 33 to 36, 46 and 68 weeks of age. At each age one top-tier, one middle-tier and one bottom-tier cage was sampled for each treatment. 4. Few behavioural differences due to cage treatments were detected. Hens at 870 cm2 had shorter feeding bouts than hens at 609 and 762 cm2. Yawning was more common in the cages with greater cage height. 5. Video recordings of flock 1 examined cage height effects on hens' use of vertical space and provided additional data on stretching and self-maintenance activities. No differences in behaviour between 38 and 45 cm cages were found except that scratching head was more common in cages with greater cage height. 6. Flock 2 consisted of two layer strains (Shaver Brown and Hy-Line Brown), housed at 38 and 45 cm and 609, 762 and 1016 cm2/bird, with 18 replicates of each of the 12 strain/cage height/stocking density treatment combinations. Stocking density was varied by housing 10, 8 or 6 hens in standard full-width cages. Behaviour of flock 2 was sampled at 30, 48, 60 and 67 weeks from video recordings. Three cages per treatment from middle-tiers only were sampled at each age. 7. Hens housed at 609 cm2/hen had the longest mean feeding bout, greater than for hens at 762 cm2/hen but not hens at 1016 cm2/hen. More unsuccessful attempts to reach the feeder and sideways and backwards displacements from the feeder occurred at 762 and 609 cm2/hen than at 1016 cm2/hen. A maximum of 8 hens were observed feeding synchronously. 8. These results suggest that changes in horizontal and vertical space over the ranges we studied had little effect on behaviour other than feeding behaviour. Specifying a minimum useable trough space per hen, rather than calculating feeder space from total length of feeder per cage, irrespective of accessibility, might help avoid crowding at the feeder and associated disturbance of feeding bouts.     

A marginal income and cost analysis of the effect of nutrient density on the performance of white leghorn hens in battery cages 1

In an experiment lasting 40 weeks with 576 caged White Leghorn (WL) hens and using linearly programmed least‐cost rations, the influence of increasing the nutrient density by increments of 100 kcal metabolisable energy (ME)/kg food, within the range 2500 to 3200 kcal ME/kg, on production was studied.

Increasing the nutrient density was accompanied by increases in egg weight, body weight and ME intake/hen d but mortality and the number of eggs laid were not affected (P<0.01). From a regression analysis carried out on the combined results of this and of another similar experiment, it was found that with each 100 kcal/kg rise in the ME content, the mean ME intake/hen d increased by 3.14 ± 0.59 kcal, the body weight by 38.85 ± 10.7 g and the egg weight by 0.21 ± 0.04 g.

A marginal income and cost analysis, using the above data, was carried out for three price situations of raw materials in 1970 and for two price situations of eggs and carcasses. The rations had a marginal cost structure for each nutrient density. From the analyses it appeared that the effect of the increases in egg and body weight in determining the most profitable nutrient density were at least as important from the economic point of view as the influence of the increased ME intake caused by increasing nutrient density. In the price situations considered, they neutralised the effect of one another, so that the diets with the lowest cost per calorie were also the most profitable.

For every price situation of raw materials, eggs and hens, the economical optimal food composition can be quickly and accurately determined by making use of the marginal profit analysis. It is also possible to couple the regression analysis for the adaptation of the mathematical functions to the parametric computer program which calculates the least‐cost rations.     

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.     

Field efficacy of phoxim 50% (ByeMite) against the poultry red mite Dermanyssus gallinae in battery cages stocked with laying hens

Infestations with the poultry red mite Dermanyssus gallinae represent a major ectoparasite problem in poultry and can affect egg layers worldwide. There is presently a lack of an ectoparasiticide in Europe for poultry which can assure a 0-day withholding period for eggs. In this study, ByeMite (phoxim 50%, Bayer HealthCare, Animal Health Division) was administered to treat a D. gallinae infestation in a poultry house stocked with egg-laying hens kept in a cage system. A layer house was sprayed twice within a 7-day interval using a solution containing 2000 ppm phoxim and a similar layer house was used as an untreated control unit. Specially developed D. gallinae traps made of cardboard were used to assess the mite density in both layer houses during a 49-day period after the treatment. In order to collect mites, the traps were placed on days--1, 2, 6, 9, 13, 20, 34 and 48 and always removed after 24 h. The collected mites were counted and differentiated according to their developmental stage (mite eggs, larvae, nymphs, adults). Three days after the first spray treatment, the efficacy against all mite stages (larvae, nymphs, adults) was 96.1%, and from day 7 post-treatment until the end of the trial (day 49) the efficacy exceeded 99%. In contrast, in the untreated layer house (negative control group) the mite population showed a 400% increase. No treatment-related side effects in chickens were detectable. It is concluded that two administrations of ByeMite within a 7-day interval are highly effective against D. gallinae infestations in a stocked poultry house.     

Bacterial eggshell contamination in conventional cages, furnished cages and aviary housing systems for laying hens

The influence of housing system on the initial bacterial contamination of the eggshell was studied. Two long-term experiments were performed. Bacterial eggshell contamination, as expressed by total count of aerobic and Gram-negative bacteria, was periodically analysed for eggs from a conventional cage, a furnished cage with nest boxes containing artificial turf or grids as nest-floor material and an aviary housing system. Results were log-transformed prior to statistical analyses. For both experiments no systematic differences were found between the conventional cage and furnished cage. The type of nest-floor material in the nest boxes of the furnished cages also did not systematically influence the bacterial contamination. A possible seasonal influence on contamination with a decrease in the winter period (up to > 0.5 log cfu/eggshell) of total count of aerobic and Gram-negative bacteria was observed in the first experiment. The contamination with total aerobic flora was higher (more than 1.0 log) on eggs from the aviary housing system compared to the conventional and the furnished cage systems. For Gram-negative bacteria this was not the case. During the entire period of both experiments, independent of housing system, shell contamination was not influenced by age of hens or period since placing the birds in the houses. For the total count of aerobic bacteria a restricted positive correlation (r2 = 0.66) was found between the concentration of total bacteria in the air of the poultry houses and initial shell contamination.     

The effect of environmental factors on activity,selected behaviour patterns and “fear” of fowls in cages and pens

The causes of feather pecking are closely linked with the nature of the environment in which the bird is kept. The object of this study was to assess the influences of group size, stocking rate and illumination intensity on general activity, preening, head shaking and “ fear ” responses and to relate these activities to feather pecking. In caged birds activity was increased by brighter light, by more space per bird and by more birds in a group; more preening was seen in birds housed at a lower density and no treatment had an effect on head shaking. “ Fear ” responses were greater in dim light and particularly when group size was large. Birds in pens appeared to lack completely “ fear ” responses to the stimulus used. In pens only stocking rate was varied; it had the same effect on activity as in cages. At higher stocking rates birds in pens showed more head shaking. The relationships between feather pecking, “ fear ” responses and general activity are discussed.