November 22, 2008

Animal behaviour and welfare: Poultry Part 2


Reproduction: Nesting: Brooding: Hen & chicks: Chick behaviour

By Dr Clive Dalton

The male
  • Males normally reach sexual maturity between 12-16 weeks old. This varies with management system and genetics, with the feeding and lighting regime having a major effect.
  • Crowing by the male increases greatly between 24 and 68 weeks. Crowing is not related to the male's sex drive or ability to mate, but it does indicate a cock's general vigour of pre-mating courtship, and appears to be related more to aggression than fertility.
  • Scoring males for sexual activity by counting the number of mounts in a given period does not appear to be very useful.
  • Hatchability percentage and male mating ability can be used to measure commercial success in hatcheries and these traits are critical in profit. Hatchability has varied from 0-74% in some studies.
  • Males have a very elaborate courting ritual. It has not changed from its Jungle Fowl ancestors.
  • The cock approaches the hen that either runs, side-steps or crouches.
  • This stimulates the male to waltz, trailing a wing before mounting.
  • During mounting the cock treads with his feet on the hen's back.
  • Then their vents (cloacas) come in contact and the male ejaculates.
  • The cock steps off, may court again or stands, shakes himself and may run off.

Factors involved in success
  • Previous mating experience by the male is important.
  • Heavy-breed males court less and have fewer matings than light-breed males, but the heavies have higher sperm numbers.
  • Females crouched more often for young males which did more mating than older males.
  • High social-rank males initially mate more hens than low-ranked males, the advantage is short lived.
  • In controlled environments, more matings occur 15 hours after lights on which means a peak (80%) between 4pm and 6pm depending on the lighting regime.
  • Male/female ratios of 1:5, 1:10; 1:12, or 3:40 were equally successful.
  • Changes in light pattern increase or stimulate male sperm production, though normal semen production occurs with standard light levels.
  • Depriving males of water for 48 hours will reduce semen production for up to 6 weeks.
  • High levels of iodine (5000 ppm) and mouldy feeds reduce sperm quality.
  • Sperm production is improved in low temperatures.
  • In sexually active males, massage will not produce semen as it will in low-activity cocks.
  • Males will mate from 1 to 53 times a day.
  • Males kept together will mount (tread) each other.
  • Courtship. Caged males spend more time waltzing than colony males, the latter moving up on hens from the rear rather than the side.
  • Males in floor pens did more fighting, courting and mating than those in colony cages. Females avoided males more in the floor pens.
  • Bouncing insecure floors upset males more than rigid floors.

The capon
  • This is a castrated male.
  • Castration can be done surgically, removing the testicle through an incision in the body wall.
  • It is also done by using oestrogenic hormone implants, if the market allows this practice. This will stop testicle, comb, and wattle growth.
  • There is no need for this practice today as modern meat chickens grow at such a rate that castration produces no extra advantage.

The female
  • The start of sexual behaviour is greatly affected by the environment, especially feeding, lighting regime and genetic strain.
  • In the wild and in free-range systems, young females (pullets) show mating behaviour as early as 18 weeks of age, but this varies greatly.
  • Most hens, regardless of breed, start to show mating behaviour 4-8 days before the start of the new laying season - whether there is a male present of not.
  • Egg laying and nesting.The egg laying behaviour of hens is very elaborate, and selection of a nest is done with great care, often in association with the male.
  • Studies have shown that nesting activity and ovulation are linked so a good nest favours high production.
  • Nesting is characterised by secrecy and careful concealment, and nest selection has four phases.
  • First - seeking a place to lay. This can be very protracted as the hen becomes restless, paces about giving the pre-laying call and showing characteristically body postures. In a deep litter laying house, she examines the walls and corners.
  • Second - inspection of a number of possible sites between feeding, preening or sleeping, and finally pushing into one of them. Inside she continues her examination, lifting her legs with care with her neck horizontal.
  • Third - settling, squatting, making a nest hole by crouching and rotating several times using her keel bone to shape the nest. Then she sits and lays, often standing to expel the egg.
  • Fourth - after laying she may continue to examine the egg with her beak then rises and returns to the flock cackling.
  • Nesting behaviour in cages: In the limited space of a cage, the hen adopts the same behavioural sequences but obviously their expression has to be modified.
  • In a multiple-bird cage, which most commercial ones are, the hen about to lay searches the cage pushing other hens away. She may creep between the legs of other hens, sometimes 100 times before she settles.
  • She spends laying time putting her head between the wires, pushing and often being pecked by birds in the next cage.
  • Intentional movements to try to fly may be shown by tail extended and wings slightly raised. She may even try to climb the cage.
  • Then suddenly she squats and lays. Her breathing rate is high and her calls are generally weak. Eggs are often laid in the same area of the cage before they roll away.
  • Caged hens paces to fill up the time normally spent in the pre-laying behaviour seen in free-range birds. Pacing varies between strains from 100-2600 paces before laying.
  • Birds have been recorded as spending 55% of their time resting, 21% eating, 17% laying and 7% drinking.
Nest design
  • In the wild Jungle fowl, nesting is mainly on the ground in a bamboo habitat with semi darkness and shadow patterns.
  • In domestic fowls, we want them to nest in boxes off the ground to keep eggs clean, but which still mimic their natural preferences.
  • Generally one nest is needed for every four birds. Nests should be clean, and have ample litter such as straw (a favourite), shavings, sawdust, wood fibre, and so on. The key is to stop birds sleeping in the nest boxes or using them as roosts.
  • The box should be large enough for the bird to turn round.
  • Studies have shown a bird preference for a triangle-shaped entrance, and some for a square one. Boxes are best sited 450-500 mm above the ground litter.
  • Leaving dummy eggs in the nest is an old trick to encourage hens to lay, but the hen is probably more attracted to the nest litter than the eggs.
  • Some systems use communal nests of 60 x 200 cm that can accommodate 50 birds.
  • Hens have been identified as those that prefer solitary nests, and others that prefer communal nests. Communal nests have more behavioural problems caused by shy birds not wanting to use them, and birds crowding inside them and keeping others out.
  • Breeders use trap nests where the bird triggers a slide with her tail, and has to be let out manually after recording her Identification number with her egg.

Eggs and egg problems
  • The wild Jungle fowl has a brood of about 6 chicks, with egg clutches from 2-10. Free-range commercial hens produce around 220 eggs/year, with those on deep litter around 245 and fully caged birds around 260 eggs/year.
  • Cracked eggs are a problem and vary with the husbandry system. Risks are greater on wire floors than on litter. In cages the floor slope and wire gauge are among many variables concerned.
  • Ground laying is natural in the wild fowl but eggs laid on the floor are a major loss in commercial poultry production. They have to be picked up and are dirty, and risk being broken and starting hens to eat their eggs.
  • To change the behaviour and stop floor laying - these points are worth trying:
  • Start with nest boxes on the floor and slowly raise them.
  • Don't make the floor litter too deep. Use 7-8cm rather than 15cm of litter.
  • Pick up all floor eggs regularly and put real or dummy eggs in the nest boxes.
  • Direct access from roosts to nests will allow shy birds in to lay.
  • Make the nests attractive with regularly renewed litter.
  • Keep the nests in semi darkness. Make sure they are vermin proof.
  • Try to eliminate dark corners in the pen.

Broody hens

  • It's a strong innate behaviour of the hen that after she has laid a clutch of eggs, she goes broody and has a strong desire to sit on them. After brooding and rearing her chicks, the hen will probably moult her feathers before starting to lay again.
  • Selection has been strongly against these traits in modern strains of laying hens as they take up time that should be used for production.
  • To get good results from a broody hen, try these management tips below.
  • Make a nest from a hollowed-out turf (grass up) which you can keep damp during incubation to maintain humidity in the nest. Line it with plenty of straw.
  • Treat the broody for external parasites before sitting.
  • Let her sit on a few dummy eggs for a few days to see if she will sit tight. Then replace them with the eggs to be hatched - usually 10-15.
  • Allow the hen off the nest each day for exercise and feeding. Make sure she defecate and doesn't get constipated.
  • If she won't move, lift her off making sure she has no eggs under her wings.
  • Make sure she sits till all the chicks are hatched. This should be 20-21 days after setting.

The hen and her chicks
  • Studies of wild fowl and free-range domestic hens show the importance of the very strong maternal behaviour that develops between the hen and her chicks.
  • Chicks are very precocious and are active very soon after hatching. In the wild survival success depends on rapid bonding between mother and offspring.
  • It's very important that chicks imprint on their mother after hatching. They'll follow any moving object, which contrasts with the background about one hour after hatching.
  • Proper imprinting and bonding can take from 9-20 hours after hatching.
  • The hen "clucks" and the chick "peeps" and the more the hen clucks the less the chicks peep.
  • Chicks moving with their dam utter contentment twitters or distress cheeps. If the hen stops and calls, the chicks remain stationary. If she's too far away, the chicks peep and she goes to brood them.
  • If the call of a strange mother is played, the chicks stay still for longer and peep less often. This reduces the chance of being attacked by a strange hen.
  • The length and loudness of the call control chick behaviour, while the sound frequency leads to recognition of their own parent's voice.
  • Chicks feed freely n the presence of their own dam's call while alien calls will halt feeding altogether.
  • As chicks cannot recognise each other much before 10 days of age, the hen and her calling system keeps the brood together and prevents aggression among the chicks.
  • The hen also teaches the chicks to react to food and predators.
  • Chicks normally show fear 33-36 hours after hatching, but this is extended if they are kept in isolation. The experience of communal feeding needs to be achieved before 3 days post hatching.
  • Wild spring hatched chicks have been recorded as walking over 3km/day with the hen walking closely with them for 24% of the time.
  • Their active working day lasted 16 hours and the hen initiated most of the behaviour, especially feeding, tidbiting, pecking, and scratching the ground. She also prevented fights between chicks.
  • A broody hen and her chicks will keep to themselves and threaten other hens that come within 6m.
  • In the wild, chicks start to be left on the ground at nights by the dam at 5-6 weeks, when she returned to roost in a tree. By 10-12 weeks old when the chicks were feathered, the hen started to threaten them - their days with Mum were over.
  • The hen allows her chicks to run ahead of her before weaning, but they walk behind her afterwards because she claims a higher social status.
  • At 16-18 weeks old, the brood breaks up and adult behaviour patterns begin.
  • A hen will accept strange chicks 2-5 days after hatching if they are the same colour as her own. Thereafter she may kill them.

Other chick behaviour
  • Chicks are very active and when running, they extend their wings and flap them for use as breaks.
  • They will jump on to feeders but do not perch till 4-6 weeks old.
  • They stretch in a very precise way with a wing and leg on one side stretched out pointing to the rear with the wing primary feathers displayed.
  • Chicks spend a lot of time chasing and if they turn, face up and stare at each other, this can lead to regular fights by 2 weeks of age. These fights are only between two birds at a time (usually males) where they grab at neck feathers and pull the adversary to the ground.
  • Pecking and feather pulling clearly induce pain from day 13 and by day 18, weaker chicks can be pulled down and trodden.
  • Dust bathing starts at day 3 and is a copied activity.
  • Preening of wing and breast feathers may start at day 2, but no preen gland is used until day 14. The preening spells may last up to 4 minutes.
  • Chicks will start picking at toes by day 10. If conditions are hot, dry and too bright, they'll pick at wing and tail feathers until they bleed as well as picking at pasted up vents.
  • Chicks will pick at any bright object in the litter which may include nails and staples that can cause death if swallowed.
  • Litter scratching is a very stereotypical action from day 2. Its best described as a scratch with the right leg, then two with the left, then one with the right and so on, while the litter is flicked over with the beak.
  • The whole sequence takes about 15 seconds and occurs in the best-lit areas first. If the environment is too cold, litter may be eaten and the gizzard impacted.
  • A study of chicks up to 10 weeks old showed many behavioural activities:
  • Resting was high near hatching, declined till 3.5 weeks, rose to 8 weeks, then declined again.
  • Females rested more than males.
  • Leg stretching increased (especially in males) to a peak at 4-7 weeks old and then declined.
  • Scratching increased in the first week, declined to almost nothing at 7 weeks and then reappeared at 9 weeks old.
  • Preening increased with feather growth while running about decreased with age.
  • Frolicking increased up to week 4 and then declined as sparring started and reached a peak at week 5.
  • Agonistic (fighting) encounters replaced sparring by week 7 and this pecking reached a peak at 8 weeks by which time a clear peck order was established.

Temperature for chicks
  • The chick's first response after hatching is to seek warmth and cover. They are very vulnerable to draughts. Body temperature at birth is 38.6 C rising to 40 C by day 9.
  • If heating is inadequate, chicks huddle together in a semicircle facing outwards and can easily smother in corners away from draughts or in sunny spots.
  • When too hot they disperse away from the heat source.
  • Chicks will not move out into colder temperatures for food before 5-7 days.
  • Low rearing temperatures (e.g. 19.5°C) will slow growth, cause earlier feathering but increase size of organs such as the heart, thyroid and adrenal glands compared to chicks reared at 30°C.
Drinking behaviour of chicks
  • Chicks dehydrate quickly at the high temperatures of rearing, so they must find water quickly after hatching and learn to drink.
  • Drinking often starts with the chick pecking at a bubble, and some water movement helps to start them drinking.
  • A good idea is to lay paper on the floor and place the feed and water on that. The chicks will discover both by pecking. Remove the paper after a week as it will be soiled and by then they should all have learned.
  • Be guided by the smallest chicks as they'll be slowest to learn.
  • Provide 24 hours of light at this very vulnerable learning stage.
  • By 3½ weeks, a chick will have drinking sessions of a minute long, and drink 11 times with a few seconds pause between each.
  • Chick drinks by placing the beak in the water, scooping up a beak-full which is then swallowed by holding the head horizontally or slightly raised.
  • Drinker design has an important effect on chick drinking behaviour. Some trough designs are better than others at encouraging social facilitation in drinking, and some encourage roosting on the drinker. This is a fertile area for behavioural research.
Eating behaviour of chicks
  • Food recognition by the chick is complex.
  • They will peck indiscriminately at various objects in their environment such as sand grains, shiny objects, other chicks and so on. They achieve success in finding food mostly by trial and error.
  • If reared by a broody hen, the advantages of being taught by her tidbiting for food are obvious. She uses her vocal calls to encourage and guide them to eat the food items she indicates.
  • The use of glitter tape around the troughs or glass marbles among the feed is sometimes used to encourage chicks to start eating. Some starter feeds are often made up into three-dimensional crumbs to be more attractive, and feed is often placed on egg trays for the same purpose.
  • Studies showed that with a 10 hour light day regime, chicks up to 3 days old only spent 30% of their time eating, but by day 10, this had increased to nearly 60%.
  • Chicks ate 34 times/day on day 3 and 123 times/day on day 10. Other chicks were observed to eat solid feed 30-25 times/day and they drank water 22-45 times/day.
  • As age increases, the number of feeding times dropped but total feed eaten increased.

This material is provided in good faith for information purposes only, and the author does not accept any liability to any person for actions taken as a result of the information or advice (or the use of such information or advice) provided in these pages.

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