Poultary

1. POULTRY
HOUSING
Types of poultry rearing
Layer farm: Birds kept for egg laying.
Broiler farm: Birds kept for meat purpose. Birds are kept in lots and are usually reared for 4-
6 weeks only.
Hatchery: Specialised unit where breeder stock is reared and eggs are hatched and chicks are
supplied to broiler/layer farms.
Backyard poultry: Unorganized poultry keeping were few birds are ket in the backyard of the
house. These birds serve as the source of eggs and meat for the house.
Location of poultry housing
1. Shall be located on a fairly raised and properly drained site not liable to flooding.
2. The farm should be located in area where there is good market for egg and chicken meat.
3. The farm should be well connected with road for transportation.
4. Electricity and water should be available at reasonable cost and ease.
5. Poultry farm should not be constructed in a city near residential area.
Free Range housing
 This system is adapted only when adequate land is available.
 Stocking density is 300-400 birds /hectare.
 A range should provide shelter, greens, feed, water and shade.
 Shelter is usually provided by temporary roofing supported by ordinary poles.
 Foraging is the major source for feeding the birds.
 This system is most preferred for organic egg production.
Semi-intensive housing
 The birds are half-way reared in house and half-way on ground or range
 The birds are confined to house in night or as per the need and they are also given
access to the runs.
 Feeding and watering facilities are provided in the pen
 Provides protection from inclement weather
 Stocking density: 4-5 birds /m sq in the house.
Intensive system
 Birds are totally confined to the house either on ground/ floor or on wire netting floor
in cages or on slats.
 It is the most efficient, convenient and economical system for modern poultry with
huge numbers.
Layout of poultry farm
A small size poultry house doesn’t require any special layout as it involves construction of
only one house. The medium or large farms require special consideration for placement of
building in the farm premise. The basic principles to be observed in layout are
 The shed should be so located that the fresh air first passes through the brooder shed
followed by grower and layer shed. This prevents spread of disease from layer house
to brooder house.
 There should be minimum distance of 50-100 feet between chick and grower shed and
the distance between grower and layer shed should be minimum 100 meter.

2.  The egg store room, office room and the feed store room should be located near the
entrance to minimise the movement of people around the poultry shed.
 The disposal pit and isolation shed should be constructed at the extreme end of the
site.
Types of poultry houses
 Brooder house: It is used to brood and rear chicks from 0-8 weeks of age
 Grower house: It is used to grow egg-type birds from 9 to 18 weeks.
 Brooder cum grower house: The birds are reared from 0-18 weeks of age
 Layer house: Birds over18 weeks of age and usually up to 72 weeks of age are reared
in this house
 Broiler house: It is used for rearing broiler upto 6 weeks of age
 Breeder house: Both male and female breeders are maintained at appropriate sex
ratio.
 The brooder house and/or layer house may also be used for housing growing stock
after the brooding stage.
Key consideration for a poultry house
 Orientation of the house: The long axis of the shed should be constructed in east-
west direction to avoid direct sunlight in areas which experience heat and draught in
most part of the year. The long axis to be North-South if the farm is located in cold
region
 Size: Each broiler require one square foot of floor space and the layer require two
square feet of floor space under deep litter system of rearing. So the size of the house
depends on the number of birds to be reared.
 Length: The number of birds reared and the availability of land determines the length
of the poultry house.
 Width: Under tropical condition the poultry shed should not be wider than 9m.
 Height: A ceiling at 3.5m or more is desirable where summer is severe.
 Foundation: The foundation of the house should be concrete with 1-1.5 feet below
the surface and 1 to 1.5 feet above the ground level.
 Floor: The floor may either be cement concrete or brick laid in cement mortar or
stone slabs set in cement mortar or moorum. The floor shall be constructed at least 25
cm above the ground level.
 Walls: The lower portion of the wall up to 1/2 height should be of solid brick and
masonary work and the upper portion of the wall may be made of chicken wire mesh
supported by brick masonary pillars of 30x30 cm spaced along the outside of the side
wall and ends of supporting the raftors and roofs.
 Partitions: When a big shed is divided into smaller compartments with a central
passage, the partition wall between the compartments may be made 30cm high in
brickwork and above that with galvanised wire mesh.
 Roof: The roof may be lean to gabled type. In case the width of the house is more
than 10 m, gabled type of roof with ridge ventilation is recommanded. The roofing
material may be aluminium sheets, galvanised iron sheets, asphalted corrugated or
thatch. In case the roof is of thatch, the thickness of the material shall be atleat 15 cm
and it should be made rain proof and fire proof. The roof of any matellic sheets may
be covered with a layer of thatch to keep the house cool in summers and warm in
winters. The upper surface of matellic roof should be painted with white aluminuium
paint to reflect the sun rays.
 Overhang: The eaves of the roof shall project out at least 1m to prevent rain water
entering into the house.

3.  Door: the door must open outside in deep litter system. The size of the door should be
preferably 6x2.5 ft. At the entry foot bath should be constructed and filled with
disinfactant.
 Lighting: Light should be provided 7-8 ft above the ground and hanged from
ceiling.If incandescent bulbs are used, the interval between two bulbs is 10ft and in
case of fluorescent light the intervalis 15 ft.
System of Housing
Cage system
 Birds are raised on wire netting floor in smaller compartments, called cages, either
fitted with stands on floor of house or hanged from the roof.
 Feeders and waterers are attached to cages from outside except nipple waterers, for
which pipeline is installed through or above cages.
 Auto-operated feeding trolleys and egg collection belts can also be used in this rearing
system.
 The droppings are either collected in trays underneath cages or on belts or on the floor
or deep pit under cages, depending on type of cages.
Deep litter
 In this system the birds are kept in litter floor.
 Arrangement for feed, water and nest are made inside the house.
 Fresh litter materials spread on the floor.
 The birds are kept on suitable litter material of about 3” to 5” depth.
 Usually paddy husk, saw dust, ground nut hulls, chopped paddy straw or wood
shavings are used as litter materials.
 This arrangement saves labour involved in frequent cleaning of faecal matter
(droppings), however it needs periodical stirring.
 The litter is spread on the floor in layers of 2” height every fortnightly till the required
drying is achieved.
Floor space requirement for poultry
Floor space requirement for poultry - layers
Age (weeks) Deep litter
(ft2
)
Cages
(ft2
)
0-8 0.60 0.20
9-18 1.25 0.30
18-72 1.50 0.50
Floor space requirement for poultry–broilers
Age Floor space/ bird
Up to 18 days 450 cm2
(0.5 sq.ft.)
From 19 days to
42 days
1000 cm2
(1.1 sq.ft.)

4. HATCHERY MANAGEMENT
Hatching of Eggs: Hatching of eggs refers to the production of chicks. In early days eggs
were hatched by placing them under broody hens. Desi hens proved to be ideal for this
purpose. Only 10 to 12 eggs can be put under 1 hen. This method of hatching is highly
unsatisfactory for large-scale production of chicks. Incubators, which provide similar
environment as that of broody hens, but more efficient, are used at present for hatching of
eggs.
Incubation: The physical factors necessary for successful incubation are temperature,
humidity, gaseous environment and turning of eggs.
Temperature: Optimum and uniform temperature inside the incubator is very essential for
obtaining satisfactory results. The incubator temperature should be maintained as
recommended by the manufacturer. It usually varies from 99.5° to 100.5°F (37.2°C - 37.8°C)
for forced draft-type incubators and about 1°F higher for still-air incubators. Low temperature
slows down the development of embryo and higher than optimum temperature hastens the
embryonic development. When abnormal temperature conditions extend over a long period,
hatchability is adversely affected by increase in embryonic mortality and weak and deformed
chicks.
Humidity: Humidity in the incubator affects hatchability. In fowls egg takes about 21 days to
hatch. The relative humidity should be around 60 per cent during the first 18 days of
incubation and 70 per cent in the last 3 days for optimum hatchability. In the forced draft-
type incubators the· temperature requirement decreases as the humidity increases.
Ventilation: For maximum hatchability the oxygen content is 21% and carbondioxide
between 0.3-0.5%.
Setting of eggs: Fertile eggs are loaded into the incubator with broad end up. Hatchability
decreases when eggs are placed in the incubator with narrow end up as the embryo develops
with its head in the small end.
Turning of eggs: Turning or eggs in the incubator improves hatchability. Eggs should be
turned at least 4 times during a day when turning is done by hand. Modem incubators are
provided with devices for automatic turning of eggs at least 8 times or more during 24 hours.
In this egg trays turn through an angle of 90. No turning is required after 18 days of
incubation. Use of separate hatcher improves hatchability. When separate hatcher is used
temperature is maintained at about 98°F and relative humidity at 70 to 80 per cent to obtain
good hatch. Use of separate hatcher facilitates cleaning, disinfection and fumigation without
disturbing other eggs.
Testing of Incubated Eggs: The eggs are candled from fifth to seventh days of incubation to
remove infertile eggs and on 18th
day to remove dead germs. In most commercial
establishments, candling is done on 17th
or 18th
day of incubation to save labour. Depending
upon the passage of light through the egg, the eggs are classified as infertile when
transparent, dead germ when translucent and eggs with live embryos when opaque. Eggs with
live embryos only are transferred to the hatcher.
Hatchery Management
1. At the beginning of hatching season the incubator and hatchers should be thoroughly
checked for their functioning and defects, if any, rectified.

5. 2. They should be properly cleaned, disinfected and fumigated to kill disease organisms
before storing and after transfer of eggs to the hatcher. This reduces the incidence and
spread of diseases.
3. Fumigation is usually done with formaldehyde gas using 40 ml of 40 per cent
commercial formalin and 20 g of potassium permanganate for each 2.8 m3
of space
inside the incubator or hatcher. Potassium permanganate may be placed in a glass or
earthenware container and formalin poured over it. Fumigation should preferably be
done-at the end of the working day and then the rooms closed. It is a good practice to
start the incubator and the hatcher at least 24 hours before setting the eggs to maintain a
constant temperature.
4. Persons working in the hatchery should use showers, and change clothes and shoes
before entering. Receipt of eggs from the farm and the delivery of chicks should be away
from each other to reduce infection. When electric supply is uncertain use of a standby
generator is advocated.

6. CARE OF CHICKS
Sanitation and hygiene: Brooding house should be cleaned at least a week before the chicks
arrive. Feeders and drinkers should be washed and disinfected. If the house is air tight, it is
desirable that the house and equipment be fumigated. Provide foot baths at the entrance with
a disinfectant. Arrange feeders and waterers alternatively like cart-wheel fashion.
Litter: Cover the floor with litter materials like ground mize cob, sawdust, dried crushed
sugercane pulp, groundnut shell et to a depth of 5 cm. The litter should be stirred at frequent
intervals to prevent caking. Wet litters if any should be removed and replaced by dry litter.
Brooding temperature: Light the brooder heat source an hour prior to chick arrival so that
the ring temperature measure 35C. During the first week the temperature should be 35C
which may be reduced by 5C during each successive weeks till 21C is reached.
Brooder guard: To prevent straying of chicks from the source of heat, brooder guards are
placed 60-75cm from the edge of the hover. Brooder guard may be moved by few cm apart
everyday so that growing birds get more space. The guard may be completely removed by 4th
or 5th day.
Floor space: Floor space of 0.05sq.m should be provided per chicks and should be increased
by 0.05sq. m after every 4 weeks until the pullets are about 20 weeks of age. For broilers at
least 0.1 sq. m of floor space for female chicks and 0.15 sq. m of floor space for male chicks
should be provided till 8 weeks of age.
Water space: A provision of 50 linear cm of water space per 100 chicks for the first two
weeks has to be increased to 150-190 linear cm at 6-8 weeks.
Feeder space: The requirement of feeder space varies from 2.5 to 3cm per birds from 0-8
weeks of age.
Feed Management during brooding: The feed for new chicks should be placed on flat
container to encourage the birds to eat. Metal feeders should be used after few days.
Light Management: Continuous lighting should be provided for the first 48-72 or till the
chicks learn the learn the place of heat, feed and water.
Temperature Management: Ideal brooding temperatures are as measured 5 cm above the
litter surface. Evening is the best time to observe the chicks and make temperature
adjustment.
The behaviour of chicks provides a better indication of whether they are getting desired
amount of heat. At very high temperature chicks will get away from the source of heat .
When temperature is less than required the chicks will get closer to the source of heat and
huddle together. When temperature is right the chicks will be found evenly scattered.
Debeaking: Debeaking prevents cannibalism and feed wastage. It is an established procedure
for poultry management, usually carried out by means of thermocautery by using electric
debeaker. It is important to remove only 1/3 of the upper beak and slight cutting only of the
lower beak. Debeaking can be carried out between one day and six weeks of age. Debeaking
may have to be repeated sometimes before the pullets are placed in the layer house, say at
about 16 weeks of age. Birds under backyard system are not to be debeaked. If indicated
broiler chicks may be debeaked during the first week. A trained person should carry out
debeaking.
Dubbing is the procedure of removing the comb, wattles and sometimes earlobes of poultry.
Dubbing of chickens prevents damage from freezing and fighting. Dubbing for some breeds
has become a tradition and is required for some birds to meet breed-specifications. Other
reasons include removing combs which have become so large they prevent the bird from
taking food into its mouth or making the head so heavy it sinks into the bird's chest. Dubbing
may be resorted to in day old chicken belonging to breeds, which have larger/lopped comb.
Using a sharp pair of scissors, clip the comb as close to the head as possible, following the

7. curvature of the head. Do not dub during times of stress, such as hot weather, disease
outbreaks, etc.
Sexing: Sexing of day old chicks can also be done with the help of sex-linked characters
such as rapid and slow feathering, barring and non-barring etc. Combs are more developed in
males than in the females.
MANAGEMENT OF BROILER AND LAYERS
Broilers
 Broilers can be housed in deep litter, slatted or wire floor or cages.
 Rear male and female broilers separately.
 It is desirable to provide 24 hours of light during brooding and early growing period.
Thereafter the house should be kept in dark to reduce the activity of the birds.
 Debeaking maybe done in 10 days old broiler chicks
 Ranikhet and Marek disease vaccination should be given to one day old chicks
Layers
 The flock should be transferred from grower to layer house at 18-20 weeks of age.
 In breeding flock male should be placed in the laying quarters 1 to2 days prior to
housing the females if they have been grown separately
 From 21 weeks onwards the lighting should be increased gradually till it reaches 16-
17 hours per day and maintained at that level thereafter.
 Cull the unproductive layers regularly.
 Provide well balanced layer mesh. The average feed consumption during the layimg
period ranges from 100-110g
 Deworming should be done regularly and at an interval of 6-8 weeks depending on
worm load especially when reared in deep litter system.
 Collect the eggs at least 5 times a day in deep litter system and two times a day in
cage system.
 Provide nest box for every 5 layers about a week before the first egg is laid.
 The nest should be provided with litter material. The litter material has to be replaced
at least one in a week to prevent contamination of the eggs. During night hours the
nest should be closed to prevent sitting of birds in the nest.
 In deep litter system the litter material should be racked in the evening daily after egg
collection is over. The litter should be treated chemically at least one in a month or
whenever necessary in case of wet litter problem to prevent ammonia emission in the
house.
 Broody hens may be eliminated and this broodiness may be eliminated by providing
diet containing more protein, vitamins and minerals, providing light throughout night
and by placing birds in cages.

8. SUMMER MANAGEMENT OF POULTRY
High temperature above 35C in poultry shed creates problem in adjusting body temperature
and ultimately disrupts the body output. For managing summer heat stress the following
managemental practices should be followed.
 The birds should be fed in the morning and evening hours
 Increase the amount of fat as compared to carbohydrate as well as synthetic amino
acid to reduce heat by digestion
 Addition of antioxidants like vitminE(250mg/kg of feed) and vitamin C (400 mg/kg
feed) improve the performance and reduce the mortality during heat stress.
 Supplementing Emblicaoffinalis (Amla) and Lemon juice @ 0.2% and 2%, in the feed
& water alleviate heat stress in Vanaraja chicken.
 Addition of dextrose and electrolyte (sodium, potassium, chloride) may help to
maintain the ionic balance of body during summer heat.
 Drinking water cooler than body temperature will absorb body heat, which will help
with cooling the bird.
 Poultry house should be on east-west direction.
 Exhaust fan, ceiling fan, foggers etc. can be used for cooling.
 Avoid overcrowding of birds and increase the floor space wherever possible.
 Sprinkling of water on roof top will reduce the temperature by 5-10F.
 Provide roof insulation by using straw/thatch on the roof or whitewash the roof
outside with a good thick coat of lime.

9. FEEDING OF BROILERS
The feed can be offered to birds either in mash or pelleted form. But in each case, it is very
important to maintain calorie: protein ratio in the diet as it influences the feed consumption
and feed efficiency. If the energy content of feed is increased, feed intake reduces which
ultimately reduces the intake of other nutrients, so if the energy content of feed is increased,
it is suggested to increase the nutrients proportionally. The feed should be stored in clean,
dry, well ventilated room as wet feed may bring fungus infection. Also due attention should
be paid to control feed wastage by pests and rodents. It should be offered to birds in properly
designed feeders. Keep proper records on feed consumption per bird for each batch to
compare with the standard feed consumption pattern as low feed consumption may be due to
disease condition, low quality/un-palatability of feed or high temperature in poultry shed.
Composition of Broiler diets:
Ingredients Formulations
Types of ration Pre-starter Starter Finisher
Maize (%) 45.38 45.66 50.63
Broken rice (%) 2.38 3.22 2.88
Pearl millet (%) 12.75 12.00 14.00
Groundnut cake/ Soyabean meal (%) 29.83 29.33 23.08
Meat cum bone meal (%) 5.00 5.00 5.00
Soybean oil (%) 3.19 3.93 3.57
Dicalcium Phosphate (%) 0.08 - -
Lime Stone (%) 0.69 0.61 0.34
Salt (%) 0.25 0.25 0.25
Methionine (%) 0.18 0.14 0.10
Sodium bicarbonate (%) 0.01 0.01 0.01
Lysine (%) 0.11 - -
Vitamin supplement (%) 0.05 0.05 0.05
Trace minerals (%) 0.1 0.1 0.1
Total 100 100 100
Crude protein, % 22 21.5 19.5
ME (kcal/kg diet) 3000 3050 3100
Body weight, feed consumption and feed conversion of broiler chicks
Age
Body weight &
gain (kg)
Feed
consumption(kg)
Feed conversion
Weeks Days Average
weight
Weekly
gain
Weekly Cumulative Weekly Cumulative
1 7 0.17 - 0.1 0.1 0.81 0.81
2 14 0.28 0.15 0.23 0.34 1.53 1.21
3 21 0.48 0.2 0.34 0.67 1.64 1.4
4 28 0.73 0.25 0.47 1.14 1.93 1.50
5 35 1.00 0.29 0.63 1.77 2.16 1.77

10. 6 42 1.32 0.33 0.74 2.51 2.26 1.89
Watering
 Always give fresh and clean drinking water. Water should always be available to the
birds.
 Use properly designed watering equipment. Provide adequate watering space per bird.
 Always keep water-pots clean. Avoid birds entering inside pots.
 Provide cool water during summer. Store the water in tanks that are not exposed to hot
sun in summer.

11. FEEDING OF LAYERS
Bureau of Indian Standards (BIS), 2007 have recommended feed specifications for
egg type birds into four phases: Chick, grower, layer feed for Phase-I (LFP-I) and layer feed
for Phase-II (LFP-II). Phase-I feed fed to birds (when egg production starts and reaches at
peak production) from 21st
week to 45th
week of age, whereas Phase-II feed is to be fed to
laying birds from 46th
to 72nd
weeks of age. Phase-I and phase-II feeds in layer cycle are
necessary because there are changes in production, egg size, requirement of calcium,
efficiency of digestion, age, etc. Top dressing of extra calcium in the form of shell
grit/limestone at 4-5 g per bird per day is advisable in case of laying stage both in Phase-I and
Phase-II feeds. The nutrient requirements, maximum level of inclusion, feed requirement and
recommended rations for different categories of layer birds are presented in the tables
Feed specifications for Layer (BIS, 2007)
S.
No.
Characteristics
Requirement for
Chick Grower Layer
Phase-I
Layer
Phase-II
i) Moisture, %by mass, Max. 11 11 11 11
ii) Crude protein (N × 6.25), % by mass, Min. 20 16 18 16
iii) Ether extract, % by mass, Min. 2 2 2 2
iv) Crude fibre, % by mass, Max. 7 9 9 10
v) Acid insoluble ash, % by mass, Max. 4 4 4 4.5
vi) Salt (as NaCl), % by mass, Max. 0.5 0.5 0.5 0.5
Vii Calcium (as Ca), % by mass, Min 1 1 3 3.5
viii Total phosphorous, % by mass, Min 0.7 0.65 0.65 0.65
ix Available phosphorous, % by mass, Min 0.45 0.4 0.4 0.4
X Lysine, % by mass, Min 1 0.7 0.7 0.65
xi Methionine, % by mass, Min 0.4 0.35 0.35 0.3
xii Methionine + Cystine, % by mass, Min 0.7 0.6 0.6 0.55
xiii Metabolizable energy (Kcal/kg), Min 2800 2500 2600 2400
xiv Aflatoxin B1 (ppb), Max 20 20 20 20
Inclusion levels of various feed ingredients in the layer rations.
S. No. Ingredients Grower and Layers
Cereals
1 Maize 70
2 Bajra 60
3 Wheat 30
4 Rice kani 20
5 Barley 20
Cereal by product
6 Rice polish 30
7 De-oiled Rice Polish 30
8 Wheat Bran 10
Vegetable proteins
9 Soybean meal 25

12. 10 Full fat soybean meal 10
11 Groundnut Ext. 25
12 Sunflower cake 20
13 Mustard cake 5
15 Cotton seed meal 10
Animals proteins
19 Fish meal 6
20 Meat meal 5
21 Meat cum bone meal 5
Average growth rate and feed requirement for egg type chickens
Age in weeks Average weight of bird (gms.) Cumulative feed in kgs. per 1,000 birds
4 275 650
8 590 1900
12 850 3400
16 1100 5000
20 1300 7000
24 1550 10000
30 1600 14500
40 1700 22000
60 1700 37000
80 1700 52000
Recommended rations (per quintal of feed) for various age groups of layers
Composition Unit Chick
mash
(0-8 wks)
Grower
mash
(9-20 wks)
Layer mash
Phase-I
(21-42wks)
Phase-II
(43-72wks)
Yellow Maize kg. 29.0 26.0 35.0 40.0
Rice Polish kg. 33.7 43.8 32.1 31.1
Wheat Bran kg. - 2.0 - -
Groundnut cake extracted kg. 22.0 13.0 17.0 12.5
Fish Meal kg. 10.0 7.0 6.0 6.0
Lucerne Meal kg. 3.0 3.0 3.0 3.0
DL-Methionine gm. 4.0 - - 15
Molasses kg. - 3.0 - -
Mineral Mixture kg. 2.0 2.0 3.0 3.0
Vitamin A+B2+D3
supplement
gm. 20 20 30 30
VitaminB12 supplement gm. 20 20 20 20
Vitamin K mg. 100 100 100 100
Vitamin E mg. 200 200 200 200
Potassium Iodide mg. 20 20 20 20

13. Manganese Sulphate m. 5 3 3 3
Zinc Carbonate gm. 8 5 3 3
Shell Grit kg. - - 3.8 4.3
Antibiotic feed supplement gm. 50 50 50 50
Zinc Bacitracin gm 100 100 - -
Coccidiostats gm 50 32 - -

14. HEALTH CARE
1. Vaccinate birds against Marek’s disease, Newcastle disease (Ranikhet disease), fowl pox,
etc. for greater immunity.
2. Deworm birds regularly to protect from internal parasites due to their scavenging nature.
3. While debeaking is discouraged in rural poultry given that the birds need to forage and
scavenge, it is recommended if the farmer is rearing about 80- 100 or more birds to avoid
cannibalism, egg biting, feather pecking, etc.
4. After the first deworming, repeat at three-week intervals for a total of four deworming
sessions.
5. Avoid rearing different species of poultry together (chicken with ducks, turkeys etc.).
Separate young and adult stock.
6. Maintain hygiene in poultry houses and keep equipment clean.
7. Ensure proper disposal of dead birds.
Deworming schedule
42-50 days (may be done earlier if worms are noticed)
Continue deworming once in three months or as per requirement
Vaccination Schedule of poultry
Vaccine Age Dosage Route
Newcastle disease
Lasota Strain
At day 5-7 One drop Eye drop
Infectious Bursal
disease
Georgia Strain
At day 14 One drop Subcutaneous
injection
Pox At day 21 0.20 ml Subcutaneous
injection
Newcastle disease
Lasota
At day 28 One drop Eye drop
Newcastle disease
R2B Strain
At Week 9 0.5 ml Subcutaneous
injection
Pox
Fowl pox
At Week 12 0.20 ml Oral drop
The first day’s vaccination for Marek’s disease is generally done at the hatchery