Summer Stress Management in Livestock

Summer Stress Management in Livestock

Dr Jitendra kumar

(PhD Scholar)

Department of Veterinary Gynaecology & Obstetrics Jabalpur

College of Veterinary Science and Animal Husbandry Jabalpur,

NDVSU Jabalpur M.P-482001

 

Corresponding author:  jitendrasingh263@gmail.com

 

Abstract:

Summer stress affects the fertility and reproductive livestock performance by compromising the physiology reproductive tract, through hormonal imbalance, decreased oocyte quality and poor semen quality, and decreased embryo development and survival Stress is defined as a state of physiological or psychological imbalance resulting from the disparity between situational demand and the individual’s ability or motivation to meet those demands. It is inability of an animal to cope with its environment, a phenomenon that is revealed by a failure to achieve genetic potential, e.g. for growth rate, milk yield, disease resistance, or fertility. During summer when environmental temperatures move out of the thermo-neutral zone then dairy cattle begin to experience heat stress. Environmental (heat/cold), nutritional (feed/water deprivation), social and psychological (fear/restrain), internal (disease/toxin/pathogen), physiological (altitude/ pregnancy/ lactation), transportation/ training/ management are different types of stress in dairy animals. These conditions affect animal productivity and health status of animals.

Keywords: Summer stress, Animal housing, shed, design, width and size of shelter, cooling system, feeding management,

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Introduction:

                                In summer season Heat stress in dairy animals is one of the major causes of decreased productivity and fertility during summer months. The crossbred animals are more prone to heat stress. 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). At high ambient temperature the animals waste their feed energy in Panting and Sweating the nature’s way of cooling animals by evaporation. During summer the milk production is reduced to the extent of 50%. The crossbred / exotic animals are more susceptible to the heat stress losses as compared to indigenous cattle.

Armstrong (1994) reported that by evaporative cooling, the cow gives 7.5 kg more milk per day when the enviouremental temperature was about 40.5 C (RH less than 30%). Igono (1986) observed that cows shed cooled with spray and fans produced 2 kg more milk compared to the cows in shade alone.  Armstrong (1994) reported following responses in animals during heat stress.

 

• Reduced feed intake
• Increase water intake
• Change in the metabolic rate / maintenance requirement.
• Increased evaporative loss
• Changes in blood hormones concentrations.
• Increase body temperature.

There are many other factors, which influence the severity of heat stress. These include

• Environmental condition
• Level of production & feed consumed
• Stage of lactation
• Cooling management.
• Exercise requirements
• Breed and Body colour

All these factor influence heat production, degree of stress and effectively the low dissipate heat. These factors responsible for low in milk yield and reduce fertility. These losses during summer can be reduced substantially by adopting the following heat stress management.

• Proper summer oriented housing
• Animal cooling system
• Development of breeds tolerant to heat stress
• High energy feeding.

 

Summer stress:

                                       In summer season the stress for the dairy cow can be understood to indicate all high temperature-related forces that induce adjustments occurring from the sub cellular to the whole animal level to help the cow avoid physiological dysfunction and for it to better fit its environment. Heat stress is the significant burden to animal in most areas of world and subtropical and tropical parts of our country.  During summer heat stress is primarily by high air temperature, but intensified by high humidity, thermal radiation and low air movement.

 

Effects of summer stress on livestock:

 

• Body temperature is elevated due to disturbed heat dissipation mechanism.
• Panting and Increased respiration rate is first sign of heat stress (>70/min). It disturbs the calcium homeostasis and acid base balance, this leads to increased chances of hypocalcaemia and milk fever.
• Increased maintenance energy requirement through various mechanisms animal tries to dissipate the excess heat and maintain body temperature. Due to this the maintenance energy requirement may increase by 20- 30% in animals under heat stress. This decrease the energy available for production functions.
• During heat stress decreased blood flow to the rumen and intestines, Dry matter intake reduced by 8-12% or more, to avoid increased heat production from feed digestion, increased water intakes that fill the stomach (Saini and Chandrahas, 2013).
• Decreased milk production.
• Folliculogenesis and embryo development is affected due to heat stress. Redistribution of blood flow from the viscera to the periphery during heat stress, leads to reduced perfusion of placental vascular bed, retarded foetal growth (Alejandro et al., 2014).

 

Economic impacts of summer stress:

The economic loss is direct result from summer stress that affect the  reproductive activity and production of milk  as well as quality, heifer growth, increasing cow and calf mortalities and health care costs. Urdaz et al., (2006) conducted a study on dairy cows which reared under feed line sprinklers and feed line sprinklers with shade & fans.  He found that production  increased 60 days  milk yield in feed line sprinklers with shade & fans , decreased post parturient disorders and serum non-esterifies fatty acid concentrations and  gained annual profits by 8.92/cow.

 

 

Management of summer stress in livestock:

Physical modification of the every environment is based on two concepts

 

• Protecting the cows from the factors contributing to heat stress.
• Enhancing evaporative heat loss by the animal Heat abatement system such as shades, fans, for misters and sprinklers are use to alleviate heat stress of high producing cows during summers.

 

Temperature and humidity of animals housing:

                                                                                       The cow sheds in Indian conditions should be designed to reduce the heat load because heat stress because more damage to animals compared to winter.  Animal can tolerate winter condition up to 150 C without any difficulty. But the temperature above 30 ⁰C results in drop in milk production and breeding efficiency. Therefore our cattle’s especially crossbreds must be provided with proper housing. Theoretically speaking, the best type of animal shelter is a one where the microenvironment temperature remains within 15 to 250 C and humidity level around 10-12 mm Hg. Shades of trees provides an ideal protection from radiant heat, but do not fit because of other reasons.

 

Orientation of shed:

Shed with its long axis running East – West provides a cooler environment than one with a North-South orientation (Kelly et al, 1950). In the East- West oriented shelters animals get more opportunity to exchange radiation with cooler north sky. The shelter is shaded for a maximum part of the day resulting into lower floor temperature. Thus this orientation favours heat loss from animal body to environment both by radiation and its shadow. This helps in cutting down heat gain from roof. Roof – may be either single or double with both the roofs of same or different materials.

 

Design, width and sizeof shelter:

Open type of sheds are more effective than  closed type of  shed because  temperature in close type  shed was significantly higher than those of open type shed. The close type shed significantly contributed to higher ambient temperature during both hot dry and hot humid months i.e. from April to September. Slightly more shaded area than the minimum recommended floor space required for different species of livestock should be provided in hot dry climate. Floor space requirement for calf is 1.5 to 2 m2, Adult male 7.0 m2 and for adult female is 4.0-5.0 m2. Optimum width of the shelter is 5.0-6.0 m. although wide shelter results in lower ground temperature underneath it and thus the amount of radiation from ground to animal body is reduced. Yet is simultaneously restricts the radiation from animals to cooler sky during night. Length of shelter depends on requirements. Ensure minimum cow stand of 5.5 x 9.0 feet with Pacca and well drained floor.  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. A height less than 3.0 m interferes with proper ventilation resulting into reduced convective heat loss from animals.  The impedance of the total sun and sky radiation at 3.5 m height is 61% against 64% at 2.2 m height. A too high shelter without providing any significant additional benefit involves high cost of construction.

 

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. One side of “A” shaped roof saves the other half form direct solar radiation by casting its shadow. This helps in cutting down heat gain from roof. Roof – may be either single or double with both the roofs of same or different materials.

 

Roofing material its cooling system:

It may be Hay or Straw, Galvanised steel, Plywood and several types of plastics are the roofing material. On a typical summer day differences in radiant heat load under shades covered with straw and galvanised iron or plastics were of the order of 163 K cal/hour/ m2 of animal surface. A 4-6 inch thick hay thatch does not receive much heat from the upper surface by conduction. The surface convective co-efficient of the hay, because of its uneven surface is also high. Hay thatch is more suitable for hot dry climate than hot humid climate (need for frequent removal of thatch is limiting factor). Wood makes good shed material but in it cracks develops and it needs treatments frequently. Asbestos sheet are more effective as top layer in double roof shelter. If the roof is sprinkled, the temperature of the roof can be reduced upto 28 C by application of 1.5-1 water per hour and per square meter roof area. If a wall or a roof is wet, energy and therefore heat will be used to evaporate the water. Therefore radiated sun energy will be reduced.

 

Colour of roof and walls:

It should be white outside and coloured inside Reflectivity of white colour is around 75%. The reflectivity of the underneath surface should be less at it determines the quantity of incidental energy from the ground which will be reflected back down to the animals. Radiant heat load on the under surface of an aluminium roof having white paint on top and velvet – black inside was observed to be about 13 BTU/ feet2 / hour less than unpainted roof made of the same material. Painting of side walls white from outside reduces the surface temperature of the walls inside by 12 to 220 C in comparison to unpainted walls at air temperature of the walls inside by 12 to 220 C in comparison to unpainted walls at air temperature above 370 C.Water troughs should be kept under shade ensuring 24 hours water availability.

 

 

 

Sprinklers:

Sprinkler cooling is a process whereby water droplets are applied to wet the cow’s hair coat to the skin, and fans are used to force dry the cow. Sprinkling does not attempt to cool air as in the case of fogging and misting but instead uses large water droplet size to wet the hair coat to skin. Cooling is accomplished as water evaporates from hair and skin. In combination with forced air, sprinkling increases the loss of body heat over that possible by sweating alone (Nagpal et al., 2005). Sprinklers cows before entering a shade reduced respiration rate by 65-81% and body temperatures by 46-50% over shade alone. Using sprinklers in combination with supplemental air flow proved to be superior to a fan alone or sprinkling. A combination of fans and misters is as effective as fans and sprinklers at maintaining intake and milk yield. However, the fan/sprinkler system used about 10-fold more water than did the fan/mist system (Urdaz et al., 2006). It is found that cooling using fans and sprinklers improved DM intake by 7 to 9%, milk yield by 8.6 to 15.8%, reduced rectal temperature by 0.8-1.0°C.

Feeding management during summer:

Points to be consider while feeding animals during hot weather, as feeding frequency, (extra feeding) time of feeding, (cooler time of a day, adequate feeding space and plenty of cool water. Modification in ration can help to minimize the drop in milk production, decreasing forage to concentrate ratio, result in more digestible rations. Feeding buffers such as sodium bicarbonate and magnesium oxide allow higher concentrate rations and can help in low fat milk syndrome also. Hot weather increases the need of certain minerals. Do not over feed highly degradable protein during hot weather it should be 18% or less. Supplemental fat can be added in ration to increase energy in take. Also avoid feeding excess fat, over feeding causes problem with rumen function supplementing extra vitamins during summer has no.

 

Conclusion:

 The summer stress affects the animal reproductive performance and profitability, by lowering feed intake, nutrient utilization and production. We cannot control the weather in case of heat related stress, but we can do everything reasonably possible to reduce various kinds of the stress effects on animals.

 

Reference:

 

Armstrong, D. V. (1994). Heat stress interaction with shade and cooling J. Dairy Sci. 77: 2044-2050.

 

Alejandro, C.I., Abel, V.M., Jaime, O.P. and Pedro, S.A. (2014). Environmental stress effect on animal reproduction. scientific research, 2014, 4, 79-84.

 

Igono, M. O. (1986). Effect of humid temperate climate and environmental modifications with shed, spray and fan. on milk production, thermal balance and hormone functions of dairy cows. Dissertation

Abstracts. International J. (Sciences & Engineering) 46: 3645

 

Kelly, C. F.; Bond, T. E, and Ittner N. R. (1950). Thermal design livestock sheds. Agric. Engg., 36, 173- 80.

 

Nagpal SK, Pankaj PK, Ray B and Talaware MK. (2005). Shelter Management for dairy (a review). Indian J. of Anim. Sci, 75(10): 1199-1214.

 

Saini AL and Chandrahas (2013). Shelter Management in Modern Dairying. In: Prasad S, Kumerasan A, Lathwal SS, Bhakat M, Manimaran A (Ed.) New Paradigms in LivestockProduction from traditional to commercial farming and beyond. 196-207. Agrotech Publishing Academy, India.

 

Urdaz JH, Overton MW, Moore DA and Santos JEP. (2006). Technical Note:

Effects of adding shade and fans to a feedbunk sprinkler system for preparturient cows on health and performance. J. Dairy Sci. 89: 2000-2006.

https://www.dairynz.co.nz/animal/cow-health/heat-stress/