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A FLOW CHART EXPLAINING THE EFFECTS OF

HOSTILE ENVIRONMENTS

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ON DIETARY ELECTROLYTE BALANCE (D.E.B.) INCREASING ENVIRONMENTAL TEMPERATURE AND RELATIVE HUMIDITY

HEAT REGULATING MECHANISMS BECOME INADEQUATE

Rise in Deep Body

Temperature e.g. to 40oC

ZONE OF COMFORT Bos taurus 4oC - 24oC Bos indicus 10oC - 27oC

Detected by

HYPOTHALAMUS

RESPIRATORY RATE INCREASES (from 20-120/minute)

HEAT STRESS

RH >50% EXACERBATES HEATSTRESS by reducing evaporative cooling

Increases dietary energy requirements (by 40% at 41oC) (VantHoffs Law)

Panting and drooling

MANIPULATION OF DEB IN DAIRY CALVES * increases feed intake * increases average daily weight gains

REDUCED FEED INTAKE

Less anti-diuretic hormone secreted Conduction Convection Radiation

Are less important routes of heat loss

INCREASED URINE OUTPUT WITH INCREASED LOSS OF K+ Na+ HCO3In order to maximise evaporative cooling (via respiratory passages)

SWEATING

Towards respiratory alkalosis where blood pH and HCO 3 and CO2 increase

UNLESS DEB IS Increased end products INCREASED of metabolism BLOOD WILL NOT BE BUFFERED Metabolic acidosis

PHYSIOLOGICAL RESPONSES

H2O consumption rises e.g. to 130 litres/day

HYPERVENTILATION

NORMAL RECTAL TEMPERATURE Dairy Cattle 38oC - 39.3oC Beef Cattle 36.7oC - 39.1oC

TO MINIMISE AN INCREASE IN DEEP BODY TEMPERATURE, STOPS EATING DURING THE DAY

LOSS OF ELECTROLYTE + ACID/BASE BALANCE

ACID-BASE BALANCE IS LOST LOSS OF HOMEOSTASIS

Loss of H2O from skin is 2.5 times greater at 30oC than at 20oC Unshaded animals lose 5 times more K+ than shaded In hot conditions the demand for Cl- is halved Heat stress is acidogenic and is related (linearly) to DEB

LOST PRODUCTION IS SEVERE IF THIS CONTINUES

DEB is expressed and measured as mEq/Kg of feed and water intake.

MANIPULATION OF DEB IN LACTATING COWS, THE LOSS OF DEB AND ACID/BASE BALANCE WITH HEAT STRESS IN DAIRY CATTLE THE INFLUENCE OF DEB IN THE MANAGEMENT OF PERIPARTURIENT COWS DURING THE TRANSITIONALPERIOD

BIOCHEMICAL and PHYSIOLOGICAL RESPONSES The Invisible Signs - detectable by biochemistry. * Heat stress reduces the rate of blood flow from the mammary gland (12-16%) Therefore there is a reduction in the supply of nutrients and energy upon which the synthesis of milk is dependent.* * 70% of body heat is produced in skeletal muscles * pH of blood plasma rises * pH within cells falls * Urine output increases and so losses of electrolytes * Bicarbonate (HCO3-) is lost * Stress hormones appear in the blood * Resources being diverted into unproductive efforts to restore the balance * Gene function is disturbed * Heat shock proteins are activiated to shut down metabolic sections and to protect heat-sensitive tissues. * Responses to intercurrent diseases or pathogens decline rapidly * All production is stopped - growth, etc. * HOMEOSTASIS IS LOST

HOW TO REDUCE PRODUCTION WASTAGE

*

Attain best practice animal husbandry

*

Ensure good shed design

*

Restore key electrolytes lost in Heat Stress

*

Add ANIGANE to the drinking water to improve appetite

*

* Improve stockmanship

ACID/BASE BALANCE pH OF PLASMA AND BODY FLUIDS

ACID

1

* Adequate ventilation, good water supply, and avoid overcrowding * Sodium, Potassium, Bicarbonate

and feed conversion. Cattle stay alert even when appetite and feed consumption normally drops.

Add SELECTOLYTE to the drinking water at 1-2 grams per litre

SELECTOLYTE contains the electrolytes Sodium, Potassium and Bicarbonate.

DESIRABLE RANGE

7

EXCESS OF BASE ALKALI

14

ENZYME ACTIVITY SLOWS RESOURCES ARE STRAINED TO RESTORE THE DESIRABLE RANGE PRODUCTION FALLS RAPIDLY WHEN pH IS OUTSIDE THE DESIRED RANGE

pH

SWITCH TO THE RCI PROGRAMME * Reduces mortalities Improves resistance to disease * Improves appetite * Improves feed conversion ratio * Restores and maintains DEB* (Dietary Electrolyte Balance) DEB* refers to the balance of the electrolytes, Sodium, Potassium, Chlorine and Sulphur in the diet. It is expressed and measured as mEq/Kg of feed and water intake.

RUR AL CHEMICAL INDUSTRIES (AUST.) PTY.LTD.

ABN 16003842402

Unit 4, 26 Kent Road, Mascot NSW 2020 Australia Mailing Address: PO Box 6316, The Sth. Sydney Business Hub, 154 Bourke Road, Alexandria, NSW 2015 Australia Phone: +61 2 9667 0700 Fax: +61 2 9669 0430 Email: info@rci.com.au

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Physiology of heat stress in beef and dairy cattle