Knowledge of the behaviour of the stock and the application of that knowledge in the care of the stock plays an important part in the maximisation of production efficiency of a poultry production enterprise. In addition, the management of the domestic fowl has received considerable attention over recent years from the community, particularly animal liberation groups, because of the way that commercial poultry management systems have intensified. As a consequence, the study of poultry behaviour is important to the unit manager, not only to ensure that the welfare of the birds and production efficiency are maintained but also to minimise the influence of what is often uninformed debate. Behaviour is the way that animals respond to the different stimuli they encounter in their environment. The stimuli may be from other birds, their environment, people or any other thing or occurrence.
The domestic fowl by nature is a wary, shy animal with limited ability and short-term flexibility. However, in the longer term, it displays a good ability to adapt to different circumstances and changing conditions. It has excellent vision and hearing, but its other senses tend to be poorly developed. In the wild state it lives on the jungle floor in a thick forest habitat and its behaviour tends to fit into that niche. Here it uses the ground space for foraging, dust bathing and nesting. At night it perches in the trees as a protection measure against ground predators. A number of these behaviour activities are innate (inborn) and it is believed that inability to carry them out may lead to a state of frustration.
Fowls are a gregarious species with an elaborate social behaviour based on a definite group structure when kept in flocks. They maintain personal space by communication by postural changes. Important signals are associated with the position of the head and the relative angles of the head and the body to other birds. They maintain contact with flock mates by sight up to intermediate distances and by vocal communication at longer distances or if out of sight. The wild and/or feral male establishes a territory with his harem. Subordinate, unattached males occupy the same territory so long as they adopt a subordinate relationship to the dominant male. However, these subordinate males do most crowing while the dominant male suppresses all hens fighting in the vicinity.
The hen is a seasonal breeder and is secretive about its nesting site. It lays on a 23 to 26 hour cycle producing up to 10-15 eggs before incubating them with only one major daily break for feeding and plumage care. The male mates regularly with the hen and acts as an escort to and from the nest. On hatching, the chickens rapidly imprint (bond) onto the hen. They move about with her, initially staying quite close and are brooded very often. As they grow and their need for brooding diminishes they range further and further from the hen. Her brood remain living on the ground until the chickens are about 6 weeks of age when the hen re-commences to roost, encouraging the chickens to join her. When the chickens are about 10 to 12 weeks old she starts the weaning process by driving the chickens from her. When they are weaned by about 16 to 18 weeks the hen rejoins the harem and the chickens join the juvenile flock.
Factors governing behaviour responses
There are a number of factors that influence the behaviour responses of fowls to any stimuli. These are:
· Genetic - the bird’s genetic make-up has an important influence on its reaction to any stimuli. Some strains are more docile than others and this characteristic responds to selection pressure. In a similar way, the fowl responds to selection for a number of behavioural characteristics, some considered to be quite important in their management.
· Experience - while much of their behaviour is innate, there is that which has to be learned. Chickens know instinctively how to eat, but they do not know what to eat or where to find it. In the natural situation, the hen teaches her brood what to eat and where to find it.
· Age - in addition to the need to learn many aspects of their behaviour, age has another implication. Certain behaviour is not expressed until the chickens reach appropriate ages. Examples of these behaviours include the development of the peck order and reproduction behaviour.
· Environment - the environment plays an important part in the way chickens respond or behave. High light intensity tends to increase activity which is a beneficial response in very young chickens in encouraging them to seek food and water. However, in older birds it can lead to harmful behaviour such as cannibalism.
FIG 1: DIAGRAMMATIC REPRESENTATION OF A FOWL’S FIELD OF VISION
The sense of sight is good with the embryo showing its first reaction to light at about day 17 after the start of incubation. Fowls have little mobility of the eye and while they have approximately 300° of vision, only 26° are binocular. Fowls have excellent acuity or sharpness of vision. They see colour in much the same way as humans and like humans are most sensitive to green. However, chickens prefer blue objects with red being the next preferred followed by orange and green. The contrast in colour is very important in attracting chickens e.g. to food and water.
The threshold of activity (the intensity when fowls become active under normal circumstances) is believed to be higher than for humans and this is used as an aid to management by scheduling handling procedures at night whenever possible. The colour of light influences some behaviour and aspects of production efficiency but white light is generally preferred because it requires less power to achieve a given intensity and hence is more cost effective.
It is believed that fowls have very limited smelling ability because they are not repelled by obnoxious odour.
The fowl’s ear is well developed but is minus the ear lobe or pinna. It is located behind the eye and a tuft of feathers protects the opening. Calls in the range of 250 to 3000 hertz are used in vocal communication. A large number of calls by chicks and adults have been identified. Chickens are attracted to sounds that have a low frequency, short duration and which are repetitive i.e. the sound of a broody hen clucking to her chickens. A chicken in distress gives a loud, high frequency call.
Fowls have approximately 300 taste buds and they discriminate between strong tasting compounds, particularly in the drinking water. They will reject water that is above approximately 32°C although they will drink very cold water.
They respond to touch- females will often adopt a sexual crouch when touched on the back.
While much of the fowls’ behaviour is inherent, they do need to learn in order to survive. Newly hatched chickens know how to eat but they do not know what to eat or where to find their food. Individuals will copy others and this is an important part of the learning process. When a bird sees another pecking at something, it will copy, thus learning what to eat, and where to find food (and water).
Fowls are highly adaptable and become conditioned to many environmental and management situations. Training in relation to a number of management requirements is an important part of flock management. Fowls soon learn to pull, tug, peck, and scratch and their nature is such that they will remain at these tasks for lengthy periods. They are good at visually discriminating tasks and tend not to generalise, i.e. they stay at the task at hand without becoming bored or becoming sidetracked. This limited flexibility means that they adapt to intensive forms of housing very easily and quickly unlike those species which do generalise and which do get side-tracked and bored.
There are a number of factors that influence social behaviour. These include:
i. Individual recognition
ii. Communication
iii. Pecking and the peck order
Fowls recognise each other by appearance based on the shape of the comb, wattles and head generally. Colour changes in plumage are identifiable, with intense colours being more noticeable than lighter or those with a washed appearance. Only very abrupt, major changes result in a failure to recognise flock mates that have been altered. However, they forget each other fairly quickly. Members of flocks that are broken up forget each other within 3 to 4 weeks.
The fowl uses a variety of sounds in order to communicate with other fowls. The most commonly used are food calls, predator alarm calls, pre- and post-laying calls and rooster crowing. Chicken distress calls draw immediate attention from their broody hen. The clucking calls of the broody hen to her brood will result in all of the chickens gathering close to her. They will respond to these calls even played as a recording.
Fowls communicate also with others by displays and changes in posture such as head up or head down, tail up or tail down, or feathers spread or not spread. Displays play an important part in mating behaviour. Thus communication plays an important part in the maintenance of individual personal space, flock organisation and integrity in a group situation.
Pecking as a skill is recognised as being species specific for fowls. They peck to escape from the shell, to feed, to drink, to obtain and keep personal space and to establish relationships as well as for other reasons. Hens maintain a personal space around their heads and keep a distance from each other by holding their heads at an angle and maintaining a specific body orientation or angle to other birds. If a direct head to head stance is adopted, pecking will usually result.
Submission is usually demonstrated by escape or crouching. However, the main purpose of pecking is for eating which is a precisely tuned movement of the head and neck. The food is picked up by one action and swallowed by another. Beak trimming changes the relationship between the top and bottom beak and, in so doing changes their ability to peck. They can no longer pick food particles from hard, flat surfaces and, consequently, food and water troughs must carry an adequate depth of food and water to ensure that the birds are able to obtain a sufficient quantity of both.
The pecking habit is used to establish a hierarchical organisation or ranking structure in the flock of dominant and progressively subordinate members. This organisation is established separately for males and females in the same flock. Called the peck order, the organisation commences at an early age and, depending on flock size and complexity, will be established by 10 to 16 weeks. This process follows a well-recognised sequence:
· For day 1 to 3 there is a strong imprinting or bonding period when the newly hatched chicken bonds onto the broody hen. In commercial situations they bond onto other objects and, because of this, are more easily trained.
· This is followed fairly quickly by the development of escape behaviour - a protective mechanism.
· Shortly after, the first signs of aggressive behaviour are seen. Two chickens approach each other aggressively and then, before contact is made they race away i.e. escape.
· This stage is followed by a period of play fights where they spar but do not make real contact.
· The final stage is where real contact is made and is the truly aggressive stage. It is from these true fights that the dominant/subordinate relationships are established. The age that this is completed depends on the size and complexity of the flock but would be sometime after 10 weeks of age in most cases.
· A separate peck order is established for males and females in mixed sex flocks.
Once established the birds live in a harmonious state with no obvious dominant/subordinate relationship until the flock structure is altered. In the practical situation, the manager must give consideration to the various aspects of the social organisation of his flock in order to minimise the disturbance of established relationships at those times when performance could be affected. Some key points in this aspect are:
1. Form new groups of hens before production starts, ie. move new layers into the laying house before production is due to start.
2. Do not move single birds or even small groups of birds from one flock to another.
3. Provide adequate space needs - floor, eating, drinking and, if appropriate, nesting space.
4. If it is necessary to join two groups, do so by separating the pen into two with wire netting and housing the groups, one on each side for a few days. Provide food and water for each group. After an appropriate time open the netting barrier a small amount to allow the two groups to mingle gradually. The conflict that will probably develop in the combined flock if the two groups are mixed immediately will probably result in a significant number being injured by pen mates.
5. Run males together as a group before placing them in the breeding pens.
6. Place a male in with a group of females to reduce pecking (this will produce some fertile eggs).
The desire to roost or perch above the ground is an inherent protective mechanism against ground predators. However, modern commercial stock do not necessarily seek to use perches when provided with them. This indicates that, in these strains, the urge has been weakened and some managers believe it is unnecessary to provide them. There is strong evidence, however, that layer and breeder replacements can be trained to better use nests thus reducing the number of floor eggs if platforms carrying food and water are located in pens of growing replacements.
The inclusion of roosts or perches and providing direct entry to nests from them in the laying house will also reduce the number of floor eggs in most cases. The development of the ‘perchery’ system of housing is aimed at using the inherent behaviour to perch. The perchery permits a significant increase in the number of birds that will comfortably occupy the house. Another important benefit of perches in the pen is to provide a place of escape from harassment from pen-mates during periods of light.
This is another example of inherent behaviour and has the function of maintaining feather condition. These activities include dust bathing, oiling (of the feathers from the uropygial or preen gland) and preening with the beak or foot. Dust bathing is claimed to be a behaviour need of hens with the functions of ridding them of external parasites and to align the feathers. Failure to dust bathe is believed to lead to frustration.
Eating (maintenance) behaviour
At hatching, chickens inherently know how to peck and they can pick up objects i.e. eat. However, they do not know how to discriminate between what they should or should not eat. It is largely by trial and error that they find out the difference. Therefore, the first feeding experience should provide easy access to food and deny access to material other than food. The normal practice is to place paper on the floor of their accommodation and to sprinkle a small quantity of food on that for the first 24 hours. The paper is usually removed after about 3 days. It is also normal practice to place food in large, shallow trays called scratch trays or chick-type feeders for the first 7 - 14 days.
When reared by a hen the chickens’ feeding problems are greatly reduced because the hen shows them what to eat and what not to eat. She does this by example and vocal calls. There are a number of feeding systems that may be used by the poultry manager to feed the stock. Fowls are able to adapt to different types of feeders very easily provided the opportunity is given to do so progressively when changes are made. Therefore, once the chickens have learnt to discriminate between what is food and what is not, feeding systems can be changed and those systems can be operated at a height to minimise wastage and to fit other management requirements. Fowls are very adept at moving food particles with their beak. This can lead to selectivity of larger particles or in excessive wastage of food (up to 10%). The problem of selectivity is overcome by preparing the food in finer form (but not too fine) or by pelleting. Placing a mesh on top of the food after filling can reduce food wastage from manually filled troughs. The mesh (recommended size 25 - 30 mm) prevents the birds flicking food particles and thus reduces food wastage.
There are a number of factors that will affect a bird's voluntary feed intake. Commercial poultry are usually fed a mixed feed that supplies the proper balance of nutrients, however poultry have the ability to balance their own dietary requirements if the main ingredients are provided separately in different receptacles. The materials supplying the major nutrient groups are provided independently and the hens eat sufficient of each to satisfy individual needs. Fowls eat small quantities frequently. However, their crop provides them with a good storage capacity and consequently, there is no relationship between the length of time between meals and the amount eaten. Even if deprived of food for several hours they can consume more when the food is available and store it in the crop till required.
Drinking (maintenance) behaviour
Chickens initially approach the water because they are attracted to some physical aspect eg. a bubble or dust on the surface. The mirror surface of very still water is less likely to attract them. Chickens hatched in incubators operated at low humidity or high temperature, or from eggs with thin shells, or where the eggs have been incorrectly stored prior to setting are likely to be dehydrated on arrival on the farm. High early brooding temperatures add to these effects. It is, therefore, imperative that they are given a drink as soon as possible after their arrival and that easy access to clean, cool, good quality water continues throughout their life.
Once they have learned where to find their water the drinkers should be adjusted for depth and height to ensure that spillage is kept to a minimum. The recommended depth is up to one centimetre and the height of the lip of the trough level with the bottom of the birds’ wattles. It is important with young chickens newly placed in the brooder that they be attracted to the drinkers. It thought that troughs are better for day olds than are bell type drinkers for this. Bottles are also better than bells. Important features are contrast, eg. the yellow and red of bottles at the base and with lip height less than 6 cm, i.e. not too high for them to see the water.
Water consumption and maximum temperature
Water consumption increases with egg production and with temperature. High environmental temperature causes the bird to commence panting to increase the elimination of body heat by the evaporation of water from the surfaces of the respiratory organs. If this did not occur the bird’s body temperature would increase until it becomes overly stressed and died from heat prostration. Therefore, the availability of good quality, cool, clean water is of the utmost importance in hot climates. Drinker systems that supply enough at lower temperatures may not be adequate at high temperatures. It should be noted also that poultry do not drink water that is over approximately 32°C.
Fowls will adapt to different types of drinker systems providing the change is progressive. Sudden changes may result in some birds not learning to use the new system for some time. Recent research has shown that the type of drinker is not as critical as is that the water is easily available. The water and food should be co-located in the pen. Domestic fowls are discriminating in relation to taste in the water. They are likely to reduce consumption when the water’s taste is too strong. This could have serious effects when using the water as a means of administering some medication.
Males usually reach sexual maturity at 16 weeks and upwards and this will vary greatly with management and genotype. Nutrition and lighting programs are of great importance in this respect, especially with modern commercial strains. Meat chicken breeders mature at an older age as a rule than do layer type stock.Although there is significant variability because of genotype the following are important in achieving good mating performance from males:
1. The males have had previous mating experience.
2. Light breed males are more active than heavier genotypes but produce semen with lower sperm counts.
3. Females will usually crouch more frequently for younger males that, in turn mate more often.
4. Higher socially ranked males mate more frequently initially, but this advantage is short lived.
5. Most mating occurs after mid-afternoon.
6. Mating ratios – 8-10 males per 100 layer type females and 10-12 males per 100 for meat type breeders.
7. Increasing day length will stimulate semen production although sufficient is produced on normal day length.
8. Water deprivation for 48 hours or longer will lead to a lower semen production for up to 6 weeks.
9. High iodine intake in excess of 5,000 ppm causes a reduction in sperm quality.
10. Mouldy food, if eaten, may result in a lower sperm quality.
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