Adverse season and poultry farming

The environment can be defined as the combination of external conditions which have an impact on animals and humans. Perhaps the most important physiological response of poultry to the environment is the constant maintenance of a homoeothermic state during exposure to extreme ambient temperatures. Environmental stress causes adverse effects on performance of poultry.

There are different types of stressors, namely:

Climatic stress (heat stress and cold stress)
Managemental stress (excess light, wet litter and poor ventilation)
Nutritional stress (excess salt and low nutrients)
Physiological stress(rapid growth, sexual maturity)
Physical stress (catching, injection, immobilization and transportation)
Social stress (overcrowding, poor body weight)
Psychological stress (fear and harsh caretakers)

Among all these types of stressors, environmental stress adversely affects the production performance of commercial poultry. In general the ideal temperature for optimum poultry production is 65-75^oF. Birds like mammals are homoeothermic which means they can maintain a relatively constant deep body temperature 41.7^oC (107^oF).

The environment in which poultry is maintained is the single most important factor affecting productivity. The thermoregulatory mechanism in birds is effective only upon the ambient temperature within certain limits (18-28^oC). Beyond this bird cannot adjust well. The upper lethal temperature in birds is about 47^o C (116.8^oF), this is called thermo neutral or zone of comfort during which birds do not change their behavior or signs of discomfort and use minimum amount of metabolic energy to maintain homoeothermic range of body temperature. Within the thermo neutral zone, body temperature is maintained by the thermal equation (heat production=heat loss).

1.0 MANAGEMENT OF CHICKS DURING SUMMER

Summer season causes number of deleterious effects on broilers and layers which ultimately reduces profitability. Summer stress a serious concern for poultry producers as it directly leads to financial losses by impaired poultry performance.

What happens in heat stress?

Birds become heat stressed when they have difficulty in achieving balance between body heat loss and body heat production, the normal body temperature of poultry being 41^°C. When environmental temperature exceeds 35^o C bird is likely to experience heat stress. In an effect to maintain body temperature birds first rely on losing heat from blood vessels near surface of skin by process called non-evaporative cooling. However, this mechanism is only effective when ambient temperature is lower than bird’s body temperature. As ambient temperature increases beyond bird’s thermo neutral zone, non-evaporative cooling becomes ineffective. At these higher temperatures, bird relies on panting / evaporative cooling as mechanism for controlling body temperature. Panting is an effective but energy expensive way for the bird to control body temperature and typically results in lower feed intake and growth as well as reduced feed efficiency between 20-30^o C feed intakes is reduced by 1-1.5% for 1^o C rise in temperature and by 5% above 32^o C.

The will increase water intake to offset water loss but situation is complicated by the fact that body’s ability to retain water is reduced as the evaporative cooling process escalates. During high ambient temperatures, the birds increase panting up to 10 times from a normal rate of 25 breathes/min to 250 breathes/min .This leads to an excessive loss of carbon dioxide resulting in raised blood plasma bicarbonate levels and increased blood ph. The bird attempts to correct blood ph by excreting bicarbonates via urine. Bicarbonates are negatively charged ions that must be coupled with positively charged ions such as potassium to be excreted in urine. However, as potassium is important in maintain intracellular water balance, a loss of potassium ions via urine reduces ability to maintain this water balance. Consequently, while birds do compensate for water losses associated with panting by consuming more water, its retention in the body cells is limited by simultaneous loss of electrolytes such as potassium in urine.

1.1 EFFECT OF HEAT

Most important effect of heat stress is decrease in body resistance and more susceptibility to E.coli and CRD etc. In summer outbreaks of gout may be seen in broilers and layers. In heat stressed birds blood flow increases to upper respiratory tract, skin and abdominal muscles for relieving heat, however, blood flow to intestinal tract is decreased. As a result there is reduction in appetite leading to lower feed intake. Concurrently water intake is increased resulting in fluid contents in intestinal tract. This further cause’s diarrhea that results in loss of electrolytes needed to maintain acid base balance.

1.2 CLINICAL SIGNS OR SYMPTOMS

The following clinical signs will be observed in heat stressed birds:

Panting/rapid respiration
More intake of water
Reduced appetite.
Reduction of egg production
Poor egg shell quality
Less body weight gain in broilers
Reduced feed efficiency
Increase in body temperature
Death

1.3 POST MORTEM LESIONS

Dehydrated carcass
Mucoid exudates in mouth and nostrils
Pale/cyanotic combs
Pale breast muscles
Congestion of liver, spleen, kidney and lungs.
Fluid contents in intestines.
Rapid decomposition of carcass

2.0 STEPS TO COMBAT HEAT STRESS

The aim of adopting measures to combat heat stress is not only to keep birds alive but also to get production out of them to achieve targeted figures i.e. number of egg from layers and a better body weight at particular age with specific FCR in broilers.

Following steps will help to combat heat stress in birds:

Housing Management
Water Management
Feed Management
General Management

2.1 HOUSING MANAGEMENT

Orient the long axis of poultry house in an east-west direction to minimize solar heating and direct access to sunlight.
Poultry houses in tropics should have good roof insulation (if possible with false roof to reduce the conduction of heat) with support of foggers and cooler systems.
In open sided houses, width of house will be a limiting factor so keep the optimum width (24-32 ft) based on temperature, humidity and wind velocity, type of house and nature of bird for effective cross ventilation.
Increased air movement over the birds by cooler fans/exhaust to produce a wind chill effect which will cool birds even without drop in the house temperature.
Shed design and construction should not allow direct sunlight on birds.
Thatching of roof with paddy straw or sugar cane leaves will reduce temperature inside the shed.
The roof should be painted with white wash to reflect light.
Shades from tall trees and plantation around the sheds can reduce the radiant heat. The plantation of trees should be such that trees will be leafy during summer and bald during winter.
Roof overhangs should be sufficient (3-5 ft) to protect the birds from strong sunrays.

2.2 WATER MANAGEMENT

Practically water is the most important criteria of these four managemental factors during summer. In summer water consumption is 3-4 times more. Even a slight shortfall of water can lead to heat stroke and mortality. Normally feed and water consumption ratio is 1:2 but when temperature shoots beyond 95^oF, this ratio may increase up to 1:4 or more.

Points to be taken into consideration:

Supply of plenty of clean and cool water (60-70^oF) must be ensured during summer months.
Use good quality sanitizers in water to control infections through water.
For day old chicks provide cool water and electrolytes on their arrival to farm before offering feed to avoid dehydration after transportation.
Cover water tanks with wet gunny bags to avoid direct exposure to sun.
Increase number of waterers by 25%.
Increase frequency of watering.
In case of nipple drinkers, insulate nipple pipe with wet gunny cloth.
Provide electrolyte (1-2 gm/liter) in water during hot hours.
Addition of 0.25% of salt to drinking water increases water consumption.
Adjust the amounts of medications and volumes of water used for water vaccination to reflect the increase water consumption of the flock during hot weather.
Do not withhold drinking water from the flock when vaccine is provided through drinking water.
Use good quality sanitizers in water to control infections through water.
For day old chicks provide cool water and electrolytes on their arrival to farm before offering feed to avoid dehydration after transportation.
Cover water tanks with wet gunny bags to avoid direct exposure to sun heat.
Increase frequency of watering.

2.3 FEED MANAGEMENT

During summer consumption of feed by birds is reduced considerably leading to reduced body weight, egg production and shell quality.
Increase the frequency of feeding.
Do not offer feed during day time in broilers.
Certain changes in feed formulations are necessary.
Increase nutrient density of feed to compensate for depressed feed intake.
Energy of feed should be reduced. Crude protein content should not be increased because heat generated by one gram of fat is 16.5% or one gram of fat is 22.5%.
Similarly 20-30% extra vitamins and trace minerals should be added to feed.
Available phosphorus content of feed should be increased.
Vitamin C is necessary to maintain integrity of blood vessels. Supplementation of vitamin C @ 200-500 gm /ton feed will be beneficial.
Vitamin E @ 50 gm /ton feed will also be beneficial.
Pelleted feeding is beneficial where low energy fiber diets are used
Add soda-bicarbonate @ 0.1% for improvement of shell quality.
Since hot humid climate favors growth of moulds/fungi in feed, so constant use of anti-fungal is recommended.
The diet should be balanced with limiting amino-acids, methionine and lysine which will give better results.
Increase the calcium level from 3-3.5% in layer diet.
Inclusion of vitamin A 8000 IU and vitamin E 250mg /kg diet for better performance and combat heat stress.

2.4 GENERAL MANAGEMENT

Litter preferably fresh litter of 2 inches thickness with racking or stirring of litter 2-3 times a day during cool hours is recommended.
10% extra floor space should be provided in summer.
Overcrowding of birds should be avoided.
Shifting, transportation, de-beaking and vaccination should be done during night or cool hours of the day.
Birds severely heat stressed may be dipped in cold water for 2-3 minutes keeping their neck and head above water level.
Provide proper cross ventilation.
Fans (pedestal, ceiling or exhaust) may be fitted in sheds.
Use foggers in the shed which could reduce the shed temperature up to 5-10^oC depending upon quality.
Use of paint ,white lime etc practically reduces the shed temperature up to 2^oC
Use side curtain in shed which should be sprinkled with water.
Provide 3 exhaust fans on one side and pad cooling on other side (200ft) which completely seals the shed sides and brings down temperature below 8^oC.
Use sprinklers on the top or inside shed.
Surround the house with tall trees.
Thatched roof is suitable for hot areas.
The house should be situated away from other buildings in order to facilitate free movement of air.
High altitude of roof is ordinarily 2.6 to 3.3 m from foundation to the roof line to provide maximum ventilation.
Provide 1meter overhang to cut the direct sun and rain into the house.

3.0 MANAGEMENT OF POULTRY DURING WINTER

Winter season has great effect on poultry production by lowering the temperature of surrounding. During winter when temperature goes down below 55^o F, various problems like reduction in egg production, reduction in water intake, reduction in fertility and hatchability etc occurs. Therefore, the management of poultry during winter is an important concern for poultry farmer. Following points should be considered to get better production from poultry during winter season:

Orientation of house
Ventilation
Litter management
Feed management
Water management

1.1 ORIENTATION OF HOUSE

Poultry house should be designed in such a way to provide all the comfort required by birds during winter. Orientation of a building with respect to wind and sun consequently influence temperature, and light on different external surfaces. In winter the arc of the sun’s visible path is shortened, an east west alignment of a rectangular house provides a maximum gain of solar energy in winter. House should be designed in a way that maximum sun light enters the shed during day time. Birds should be protected from chilled winds, for this gunny bags should be hanged at the places from where the cold air enters. These gunny bags should be hanged down as soon as sunlight goes in the evening till the arrival of sunlight next morning.

1.2 VENTILATION

During winter season it is necessary to keep the hose draft free but with plenty of ventilation. Birds release a lot of moisture in their breath and droppings which adversely affects their health, if there is restricted ventilation it causes ammonia build up in the air which causes respiratory problems. So, they need plenty of fresh air circulating around the house. For the purpose sliding windows are useful as they can be opened during day and closed during night. There should also be arrangement of exhaust fans to remove impure air.

1.3 LITTER MANAGEMENT

Prior to chick being placed in house, the surface of floor should be covered with a bedding material called litter. It gives comfort to the birds. A good quality litter serves as an insulator in maintaining uniform temperature, also absorbs moisture and promotes drying. It dilutes faecal material thus reducing contact between birds and manure. It also insulates the chicks from the cooling effects of the ground and provides protection cushion between bird and floor. Around 6 inches of litter is needed in houses during winter. The litter gives warmth to the birds during winter. If litter management is proper, it will be felt quite warm when taken in hand.

1.4 FEED MANAGEMENT

Poultry uses food for two main purposes i.e., as an energy source to maintain body temperature and to carry on normal physiological activities and as building material for development of bones, flesh, feather, egg etc.
The variation in feed consumption is smaller for each degree Fahrenheit change in temperature when the weather is cold than when it is hot. Low temperature causes more feed intake and higher oxygen demand. Therefore, when the weather gets colder, it is essential to give the chicken plenty of food as they require extra energy for maintaining body temperature.
Consumption of calories of ME/bird/day varies as the ambient temperature changes. Normally these differences are as follows:

When bird eat more feed, along with energy, other nutrients are also consumed more which are actually not needed and they become a waste. To avoid this wastage during winter energy rich sources like oil/fat should be added to the diet or level of other nutrients may be reduced keeping the energy at same level
In winter number of feeders should be increased as compared to summer.
Feed should be available to the bird whole of the day. It has been experimentally proved that for proper growth of broiler during summer, diet containing 23% protein and 3100 Kcal ME/kg diet is needed. While in winter 3400 Kcal/kg ME and 23% protein is needed.

1.5 WATER MANAGEMENT

During winter season birds take less water so far maintenance of water in the body, it is necessary to give continuous supply of fresh water which can be taken by the bird.
Water must be fresh and clean. If water is cold enough, then it should be given to chicken after adding hot water to it, so that the water comes to normal temperature.
In ice falling areas, blockage of pipe is a big problem due to freezing of water during winter season. When temperature goes below 0^°C routine inspection of pipe line should be done to avoid blockage of water.
Many of vaccines/ medicine/ antis tress vitamins are given to poultry through water. As water consumption of bird is reduced during winter season. Therefore, care should be taken that waterers are removed few hours prior to water medication and medicine/vaccine is given in less amount of water so that birds can consume total water and each bird get benefit of medicine/vaccine or other supplements.