Introduction How to manage heat stress in Dairy cattle
The following information about “How To Manage Heat Stress In Dairy Cattle“.
India is able to produce almost 78 million tonnes of milk from different varieties of dairy cattle. This huge production is possible only due to cross breeding the local breeds with other non descript varieties of cattle. It is estimated that a total of 9 to 11% of the dairy cattle found in the country are cross breed varieties. These cross breed animals are found to be more susceptible to the heat stress condition, which leads to decreased production and infertility during summer months.
When the temperature of the region exceeds 27˚C, even with low humidity causes discomfort to the dairy cattle. Humidity is an important factor for heat stress and is measured in terms of temperature humidity index (THI). It is believed that as the temperature rise, the cattle use their feed energy in panting and sweating (for cooling the body temperature). Therefore, the milk production is reduced by 50% and this is severe in cross breed cattle when compared to indigenous cattle.
Symptoms of heat stress in cattle
The animals prone to heat stress responded in the following way:
- Low feed intake
- High water consumption
- Altered metabolic rate
- Increased evaporation loss
- Change in the level of blood hormone concentration
- Higher body temperature
The symptoms of the heat stress are worsened by the following factors, such as:
- Environmental conditions (atmospheric temperature, relative humidity, air movement and solar radiation)
- Feed intake
- Production level
- Stage of lactation
- Cooling management
- Exercise requirements
- Colour of the cattle and type of breed
Reducing or managing heat stress in cattle
The management of heat stress in cattle requires a multi-disciplinary approach, i.e. a combination of breeding cattle for improved heat tolerance, proper nutrition and designing a proper structure for controlling environmental factors within the housing system. One major thing that is important during the heat stress period is that the animals need to consume more water to dissipate heat through respiration and sweating. Providing sufficient water troughs with at least 3 inches deep water level is necessary during the summer. Apart from this there are some other management techniques to combat the heat stress management.
- The orientation of the cattle sheds should be in the East-West direction, so that the shed has a lower floor temperature.
- Open type shed is more advantageous than closed ones because mean and minimum temperature is lower for the open shed type when compared to closed type.
- Each calf in the shed should have minimum shed space of 1.5 to 2 m² and an adult female should have minimum space of 4-5 m². The average width of the shelter should be 5 to 6 m. The cow stand dimensions should be 5.5 x 9 ft (minimum). Similarly, there has to a shaded rest area for the cattle (30-40 sq ft/animal).
- The minimum roof height should be 10 ft to reduce heat load on the shed. Height of the roof less than 3 m is not suitable for the cattle.
- The shape of the roof of the cattle shed could possibly be flat, slopped or ‘A’ shaped.
- The roof of the shed can be made with hay, straw, galvanized steel or plywood.
- Proper ventilation is provided in the shed by keeping the walls open at the ridge level.
- The roof or the walls should be painted white outside and coloured on the inside so that the heat is reflected by 75% from the white surface of the walls and roof.
Feed and nutrition management
- Avoid extra feeding.
- Provide adequate feed during the cooler time of the day with plenty of water.
- Providing more digestible ration decreases forage to concentrate ratio and also minimizes the drop in milk production.
- Avoid feeding the animals with extra fat or highly degradable protein during the hot climate.
- Provide high quality forage and by-pass proteins.
- Use water to directly cool the animal body or the surrounding temperature.
- Spraying the water in the shed region and on the roof during periodic intervals can help lower the temperature of the region.
Tips to keep the farm area cool
The main aim of keeping the area cool is to reduce the heat stress in animals and mentioned below are some constructional tips for maintaining a farm during summer.
- The proper design of the cattle shed such that too much heat can be avoided during the peak hours of the day.
- Use paints or colours on the outer surface of the shed to reflect the sunlight, thereby reducing the temperature of the region.
- Plant more trees around the shed to protect the animals from direct sunlight.
- Installing ceiling fans or oscillating fans within the cattle shed can keep the animals comfortable.
- Installing sprinklers outside the shed or on the roof top and foggers or misters inside the shed is an economical way of reducing the temperature of the region.
- Creating a cooling effect by installing misting rings in the cattle shed area.
- Washing the animals in the afternoon can also be effective in managing heat stress.
- Fixing gunny bags as curtains and sprinkling water over them can be effective in cooling the shed area to a maximum extent.
- Late evening grazing is preferred in some regions to keep the cattle safe.
- Another important way of reducing heat stress is by delaying afternoon milking by almost 1 or 2 hours.
- Providing sufficient water in the shed area is highly important to manage heat stress in animals.
- Breeding during summer is carried out by artificial insemination rather than the natural way so as to get good fertility rates.