SUMMER STRESS MANAGEMENT IN DAIRY COWSIntroduction
The thermoregulatory capability of animals to dissipate heat by sweating and panting is compromised during hot humid and dry weather. Summer stress in livestock occurs when the heat load of an animal is greater than its capacity to lose heat. High air temperature, humidity, solar radiation and low air movement contribute to increased risk of summer stress. Though indigenous breeds of cattle are more thermotolerant, crossbred and exotic breeds of cattle are highly sensitive to summer stress. Thus it is imperative to manage summer stress in livestock to avoid ill health and production loss.
How to prevent summer stress in Cows
Strategies to manage summer stress in livestock
It is necessary to minimize the effects of summer stress through an integrated solution of management, animal comfort, nutrition and breeding. The following strategies are important in managing summer stress.
Cooling systems in the farm and creating shed areas
The farm should be well ventilated. Fans in combination with water sprinkling facility provide the best cooling option. Excessive sprinkling should be avoided to prevent wet bedding making the animal prone to mastitis. Plantation around the farm helps in alleviating stress load from the animals. Provision of artificial shade area by shade cloth or a naturally well ventilated structure with open sidewalls keep the animals away from direct solar radiation. Open end of the shed should be covered with thatched bamboo or jute curtains. Sheet roof should be covered with a thatch. The top of the roof can be painted white and the under surface black. Shady trees should be planted around the sheds especially at the southern wall/boundary for further cooling. Additional environmental control measures typical in modern barns include automated sprinkler systems and fan forced air that help to increase evaporative cooling for the cows. Animals must be kept under shades. The most effective source of shade is trees. Thatched roof of a minimum height of 9 feet should be provided. Agri-nets with 20% perforation are useful. If facilities are not available with the individual farmers, facilities available at the village can be used by the community. Thatching the roof with materials like paddy straw, painting the roof with white paint and providing a false ceiling insulation provide a cooler environment. Barriers against hot wind using thatched wall or wet gunny cloth/ gunny bags and one ventilator of 3 x 1 feet per cow in covered shed can be created. In these sheds, heavy duty fan is best option to facilitate ventilation. Misting in the microenvironment of the animal at least thrice in an hour, wet screen and provision of fan is useful in hot dry weather. Auto mister, fogger with mini pumps and cyclic timers are preferable. Summer stress can be managed by spraying/ sprinkling water directly on the body of animals for a period of 1 to 5 minutes at an interval of 10- 30 minutes. Fans and blowers should be used to induce evaporation from the skin of animals. The most effective way of combating summer stress in buffalo is wallowing in the water pond.
Livestock are more likely to have lower reproductive and productive performance in summer stress. Feeding high quality forages and balanced rations decrease summer stress and enhance performance of the animals. Adequate round the clock drinking water to animals should be provided under shade. Feeding should be practiced during early morning, evening and night. Rescheduling feeding times and feeding 40% of the daily ration early in the morning and 60% late in the afternoon/evening yields benefits including giving cows access to fresh feed when they are more likely to consume it.
Preference for grazing during early morning and late evening hours is needed to avoid the sun exposure. Ration density may be increased so as to provide same nutrients at reduced dry matter intake. Diets with low fibre and high fermentable carbohydrate have lower dietary heat increment compared to high fibre diets. Increased mineral supplementation must be ensured during hot weather to meet the increased demand of minerals. Potassium rich mineral mixture should be preferred. Some nutritional management tips to manage heat stress include feeding of green fodders/silage/hay and green fodder mixed with dry fodder. The feed must be fresh including high-quality forage, adequate fibre and use of by–pass proteins enhance the milk yield and protein content. Intake of sufficient cool water ad libitum is necessary. Proper pre-partum feeding of advance pregnant heifers is important. The frequency of feedings must be increased instead of a large meal.
The supplementation of autolyzed yeast n to the diet stabilizes rumen pH and thus support gastrointestinal comfort. To meet the energy requirements of summer stressed cows with a reduced feed intake, besides increasing the concentrate-to-forage ratio, other solutions that can help to increase nutrient digestibility are also important. It enhances rumen efficiency by getting more nutrients from the same amount of feed. It maintains ruminal and digestive comfort and to minimize feed consumption losses and improves digestibility in cows and efficient feed utilization, even under non-optimal environmental conditions. This supplies high quality nutrients to rumen microbiota like B-vitamins, peptides, amino acids and functional components like nucleotides, enzymes and cell-wall carbohydrates. They help to maintain ruminal and intestinal comfort and health under summer stress. phytogenic feed additives, support dry matter intake by stimulating feed intake and rumination. Feed additives are available in market which support dry matter intake, increase digestibility and gastrointestinal comfort and minimize the adverse effects of summer stress.
Genetic selection of heat tolerant animals
Cows exhibit lesser heat symptoms during summer stress as compared to thermal comfort periods. It is necessary to adopt a good heat detection program to detect cows with marginal heat symptoms. It is advisable to continue artificial insemination 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 are typical selection traits. Selection based on specific molecular genetic markers for heat tolerance is a boon to alleviate summer stress in cattle and buffaloes by identifying the heat tolerant animals. Summer stress in dairy animals can challenge the reproductive and production potential of the animals.
There should be provision of thermal comfort to heifers, buffaloes and bulls to improve heat detection efficiency. Observation for estrus thrice in a day and at least once during night hours is needed. Close observation of all non-pregnant buffaloes for cervical mucus discharge and its characteristics is important. Artificial insemination during cooler parts of the day and night can be done. Insemination between mid and late estrus with good quality semen should be done. Repetition of insemination in case of prolonged estrus can be done. Cooler environment must be provided for first 15 days after artificial insemination. Breeding of underweight heifers needs to be avoided.
Availability of water is another important issue when minimizing the effects of summer stress. Water must be clean and easily accessible. Water troughs should be cleaned regularly and placed at multiple locations in the barns, holding pens, travel alleys and feeding area. Cows should have water easily available right after milking.
First aid Treatment
Immediate veterinary aid should be provided to the suffering animal. The animal should be moved to a cooler place, given bath with cold water or wrapped in wet sheets and provided with fan.
An integrated solution should be applied to minimize production and profitability losses associated with the effects of summer stress in livestock. This should include cow comfort, by providing animals with a comfortable environment and access to water, adjusted feeding management and necessary diet modifications. Implementing proper breeding programs, cooling strategies at farm with better feeding programs can help to minimize some of the adverse effects of summer stress in livestock.