cold stress ruminant

Cold stress in ruminant animal

Under Supervision of:Prof. Dr. Gamal Ashour

Professor of animal physiology

Presented By :Ahmed Hassan Amin

M.SC.

content

1.Introduction2.Definations3.physiological responses4.Feed Intake5.Protein Efficiency Ratio6.Digestibility of Nutrients7.Production8.References

IntroductionAnimals use behavioural means to

aid in body temperature regulation (Hafez, 1969; Cabanac, 1974).

Behavioural responses may, therefore, provide a useful index of the extent to which animals are able to sense changes in heat loss to the environment.

DEFINITIONS

There are a number of terms that need to be defined prior to examining the influence of cold stress.

These terms include:

Definations

•thermoneutral zone (TMZ),• the range of environmental

temperatures where normal body temperature is maintained and heat production is at the basal level

• lower critical temperature (LCT)

• the environmental temperature at which an animal needs to increase metabolic heat production to maintain body temperature.

Definations

Definations

• There are four primary ways in which animals can lose heat to the environment. These are:

• Evaporation. The body heat is used to evaporate water mainly from the skin and hair.

• Conduction. This is heat loss that occurs as result of direct contact by the animal with items such as bedding or stall surfaces.

Definations

• Radiation. This is the transfer of heat through the air from a warm object.

• Convection. This loss occurs when air passes over the body. Exposure to wind increases the heat lost by this mechanism.

Definations

physiological responses

• However, a point of maximum heat production (summit metabolism) is reached as a consequence of extreme cold, and continual exposure to even lower temperatures results in hypothermia and reduced capacity of the animal to produce metabolic heat and, if the situation is not reversed, death of the animal.

Effects Of Cold Temperature On Some Aspects Of physiological responses

Each steer was exposed in an environmental chamber to temperatures of 20,O and - 20°C in September and again in December. After 16 h in the chamber the frequency of biphasic reticular contractions was recorded using a fluid filled balloon placed in the reticulum and connected via a pressure transducer to a physiological recorder

Gonyou et al. 1979

Feed Intake• The dry matter intake of the animals in general is

increased during very cold weather. (Graham et al. 1982).

• increased voluntary feed intake in cold stressed animals which was attributed to the activity of the thyroid gland (Gale 1973).

• The elevation of thyroid activity resulted in increased ruminoreticulum motility and higher rate of passage of digesta (Gonyou et al. 1979).

• Addition of fibrous ingredients in the diet can also reduce the effects of cold temperatures.

Effect Of Temperature On Lamb Performance And Protein Efficiency Ratio

Exposure of livestock to thermal stress (effective temperature above or below the thermal neutral zone) affects voluntary food intake and increases maintenance requirements Protein efficiency ratio (PER) was reduced when temperature and diet were such that maximum food intake would not meet demands for maintenance and growth

Ames, et al. 1979

Ames, et al. 1979

Digestibility of Nutrients

Cold stress

Reducing D.M

Digestibility

1.8% for

each 10C belo

w 20C

Increase

passage rate

feed efficiency

increase fecal and urinary

energy

diverting nutrients to

heat generation

Production

• If cows are not fed additional feed does not allow them to eat enough to meet their additional energy requirements

• In this condition • increased neonatal mortality• reduced growth rate in surviving calves• cows usually have delayed return to estrus• poorer reproductive success

lower milk production

• Cold exposure may directly limit the synthetic capacity of the mammary gland by reducing mammary gland temperature (Johnson 1976), or may act indirectly affecting the udder’s blood supply

Health Of Neonatal Calves Reared In Warm And Cold Environments

Calf Health

electrolyte

Antibiotic costs

pneumonia

NEVA

cold environments

Mean Values For Body Weight, Food Intake, And Rectal Temperature

ReferencesAmes, D. R. and D. Brink (1977). "Effect of temperature on lamb performance and protein efficiency ratio." Journal of Animal Science 44(1): 136-144.

Fuquay, J. W., et al. (2011). Encyclopedia of Dairy Sciences 2nd Edition, Four-Volume set, Academic Press.

Sejian, V., et al. (2012). Environmental stress and amelioration in livestock production, Springer.

Webster, A., et al. (1969). "Cold climate and cold temperature induced changes in the heat production and thermal insulation of sheep." Canadian journal of physiology and pharmacology 47(6): 553-562.

Young, B. (1981). "Cold stress as it affects animal production." Journal of Animal Science 52(1): 154-163.

Webster, A., A. Hicks and F. Hays (1969). "Cold climate and cold temperature induced changes in the heat production and thermal insulation of sheep." Canadian journal of physiology and pharmacology 47(6): 553-562.