SUMMER STRESS MANAGEMENT IN LIVESTOCK
Babul Rudra Paul
Ph.D. Scholar, Veterinary Medicine, ICAR-Indian Veterinary Research Institute, Uttarpradesh-243122
Introduction
The high ambient temperature and humidity of a typical summer season combine to make a very uncomfortable environment which negatively affects the welfare and productivity of livestock. Considering the tropical climate of Indian subcontinent, the summer stress is a major problem in managing animals in India. During the extreme hot humid or hot dry weather, thermoregulatory capability of animals to dissipate heat by sweating and panting is compromised and Summer/heat stress occurs. Severe heat stress can further lead to rise in body temperature, increased pulse rate, increased peripheral blood flow, reduced feed intake, and increased water intake.
Different part of India have different stressful period for livestock
| Part of India | Stressful period |
| Northern India | May-September |
| Western India | May-September |
| Southern India | April-September |
| Eastern India | April-October |
https://www.pashudhanpraharee.com/summer-stress-management-in-livestock-4/
Summer stress in cattle and Buffalo
Cattle and buffalo are homoeothermic animals and need to maintain a constant body temperature of around 38.8°C +/- 0.5°C. They are sensitive to factors which influence their thermal exchange with the environment. These factors include air temperature, radiant temperature, air velocity and relative humidity. Crossbred and exotic breeds of cattle are highly sensitive to heat stress during summer, while indigenous cattle breed are more thermo-tolerant. Buffaloes are more prone to this owing to their black skin that absorbs more solar radiations and fewer sweat glands ( 1/6th that of cattle), compromising heat dissipation through evaporative heat loss.
When the environmental temperature goes beyond Upper critical temperature (24°-26°C for Exotic and crossbred cattle and 33°C for Zebu cattle and 36°C for buffaloes), body is unable to maintain the core body temperature through sweating and panting (evaporative heat loss mechanism). In India, the summer temperature goes beyond 45°C which is 18°C above the upper critical temperature of dairy cattle. When the temperature exceeds 27° even with low humidity, the temperature is above the comfort zone for the high producing dairy cows. Humidity plays significant role in heat stress. The most common index of heat stress (Temperature humidity index or THI) is calculated from the temperature and relative humidity (RH).
Economic importance: All the changes associated with summer stress lead to loss of productivity, reduced breeding efficiency and even loss of life in extreme cases. Every year in India severe loss in milk production incurred due to heat stress during summer causing huge financial loss. During hot summer weather, milk production may decrease by as much as 50 percent and reproductive proficiency of lactating dairy cows is greatly diminished by decreasing oestrus expression, conception rate and by increasing length of service and dry period.
Summer stress in swine
Because pigs cannot efficiently sweat, and they have small lungs, and thick layer of subcutaneous adipose tissue, make these difficult to self-regulate their body temperature, it is important to maintain their environmental temperature as low as possible during the warm months of summer.
During summer stress, by reducing feed intake they try to decrease internal heat production. During prolong heat stress, pigs start to drink excessive amounts of water which leads to a loss of electrolytes via the urine and accumulate acids produced within the body resulting in acid-base imbalance, which eventually leads to diarrhea or even death in severe condition.
Summer stress in sheep and Goat
Sheep and goats tend to be less susceptible to heat stress than swine, cattle, and buffalo. Hair sheep usually tolerate heat better than wooled sheep. This is why they are often used for training and trialing herding dogs. Fat-tailed sheep are also more heat tolerant.
Goats tend to tolerate heat better than sheep. Goats with loose skin and floppy ears may be more heat tolerant than other goats. Angora goats have a decreased ability to respond to heat stress as compared to sheep and other breeds of goats. Dark-colored animals are more susceptible to heat stress, while light-colored animals may be prone to sunburn. Females usually handle heat better than males. The heat is especially hard on fat animals.
Weight gains is very less in summer season due to heat stress. Due to sunstroke there is occurrence of diarrhea and concentrated urine in effected sheep and goat
Common symptoms of heat-stressed animal
- Animal moves to shade
- Water intake enhanced while feed intake reduced
- Prefers standing than lying down
- Increased respiration rate, body temperature
- Increased production of saliva
- Open-mouth panting
Strategies to combat summer stress
While stress during summer cannot be avoided entirely, it should be the goal to minimize stress. Methods to reduce summer stress are can be categories into two (1) Managemental practices (2) Feeding management
1) Managemental practices
Scientific management practice has a vast contribution in sustainable and profitable livestock farming. When summer stress become a constraint for animal welfare and profitability, farmers need to look the matter seriously and have to adopt good, scientific management practice to overcome negative impact of summer stress on animals. Under managemental practices, emphasis should be given on proper water supply, proper animal housing to reduce or to manage heat stress.
(a) Proper water supply
Animals need to increase water intake during time of heat stress during hot summer to dissipate heat through respiration and sweating. Water consumption increases by as much as 50% as the environmental temperature rises.
- Water should be fresh, clean and cool (70- 86° F).
- Water should be available for 24 hours in a day
- It should be close to shed with enough water space.
- Provide at least two water locations per group of animal.
(b) Proper animal housing
The animal sheds should be designed to reduce the heat load because heat stress during hot summer cause more negative impact to animals compared to winter. Though animal can tolerate winter condition up to 150 C without any difficulty, while temprature above 30° C result in drop in milk production and breeding efficiency. The best type of animal shelter is a one where the microenvironment temperature remains within 15 to 25° C.
- Orientation- The East- West oriented shelters provides a better cooler environment compare to North-South orientation, which favours the animals for radiation exchange with cooler north sky. Floor temperature remain lower maximum period of the day.
- Height of the shelter- Minimum roof height should be 10.0 feet to reduce heat load. The height of shelter in hot climate should be between 3.0 – 5.0 m
- Shape and type of roof –The shape of the roof can be either flat, slopped or “A” shaped. “A” shaped roof is definitely better than a flat roof in hot climate.
- Roofing material– It may be Hay or Straw, Galvanised steel, Plywood and several types of plastics are the roofing material.
- Colour of roof and walls- It should be white outside and coloured inside. Reflectivity of white colour is around 75%.
- Ventilation– Proper ventilation at ridge level keep two or three walls open
(c) Cooling systems in the farm
- Use of water as cooling agent either directly on animal body or for cooling the shelter micro environment is as widely accepted practice.
- Fans in combination with water sprinkling facility provide the best cooling option. Excessive sprinkling should never be practised as it can result into wet bedding making animal prone to mastitis and other diseases.
- During summer, we can reduce heat load of animals artificially by spraying small quantity of water on their body at repeated interval of 15-30 minutes
- The farm should be well ventilated.
(d) Breeding Management
- Good heat detection program – As animal exhibit lesser heat symptoms during heat stress zones as compared to thermal comfort periods, it is necessary to adopt a good heat detection program to detect cows with marginal heat symptoms.
- Artificial insemination– It is always advisable to continue AI breeding instead of using bulls because in natural breeding both bull and cows suffers infertility due to summer stress.
- Genetic selection of heat tolerant animals– and inclusion of heat tolerance as a trait in selection programme will be a boon to the farms.
(2) Feeding Management
Heat stressed animals during summer are more likely to have lower reproductive and productive performance. Feeding high quality forages and balanced rations will combat negative effects of heat stress and will boost performance of the animals.
Some feeding and nutritional management tips to manage heat stress are:
- Provide high quality feeds like total mixed rations
- Increase the frequency of feedings
- Avoid feeding during the hottest period of the day (between 10.00am-4.00pm),
- Keep feed fresh as much as possible
- Provide high-quality forage
- Provide adequate fibre
- Use of by–pass proteins can enhance the milk yield and protein content.
- Intake of sufficient cool water is probably the most important strategy for animals to undertake during heat stress.
- Prefer grazing during early morning & late evening hours to avoid the scorching heat
Conclusion
Summer stress causes serious impact on variety of reproduction and growth parameters. It has direct (increased core temperature) and indirect (reduced nutrient intake, Summer infertility) effects on multiple physiological systems that ultimately compromise animal health and productivity. To combat potential problems with animal welfare, animal farmers need to recognize and monitors symptoms of heat stress during hot summer. Implementing all these managemnetal and feeding strategies to manage summer stress will do positive impact on sustainable and profitable livestock farming.
References
Rashamol, V.P., Sejian, V., Bagath, M., Krishnan, G., Archana, P.R. and Bhatta, R., 2020. Physiological adaptability of livestock to heat stress: an updated review. Journal of Animal Behaviour and Biometeorology, 6(3), pp.62-71.
Krishnan, G., Bagath, M., Pragna, P., Vidya, M.K., Aleena, J., Archana, P.R., Sejian, V. and Bhatta, R., 2017. Mitigation of the heat stress impact in livestock reproduction. Theriogenology, 8, pp.8-9.
Mittal, P.K., Gottam, G.S., Gupta, B. and Bilochi, D.R., 2019. The effect of climate change on productivity and reproductive and health performance of livestock: A review. J. Entomol, 7, pp.4-9.
