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Cold stress: calves
Synonym(s): hypothermia, calf, calves, neonatal, thermoneutral zone
Introduction
- Cause:
- Harsh winter conditions. Cold climatic conditions are further exacerbated by wind and precipitation, with the latter having a negative effect on calf survival.
- Within a range of environmental temperatures known as the “thermoneutral zone,” animals do not have to expend any additional energy to maintain their body temperature.
- At the lower end of this range, normal metabolic processes supply enough heat to maintain body core temperature.
- Within their thermoneutral zone, animals may modify their behavior to stay warm, but will not require additional nutrition.
- If, however, temperatures drop below the lower limit of the thermoneutral zone then the animal experiences cold stress.
- To combat cold stress, the animal must increase its metabolic rate to supply more body heat.
- As a result of these increased maintenance energy requirements, productivity is compromised.
- Hypothermia occurs when the body temperature drops below normal.
- Mild hypothermia: body temperature of 30°C-32°C, (86°F-89°F)
- Moderate hypothermia: body temperature at 22°F-29°C, (71°F-85°F).
- Once rectal temperature drops below 28°C (82°F), cows are not able to return to normal temperature without human assistance.
- Severe hypothermia: body temperature below 20°C (68°F).
- Signs: See below.
- Diagnosis: Clinical signs consistent with disease, core body temperature, blood gas analysis.
- Treatment: See below.
- Prognosis: Guarded.
Age predisposition
- Neonatal animals are more susceptible, as they are dependent upon shivering of skeletal muscle and non-shivering thermogenesis by brown adipose tissue.
Pathogenesis
Etiology
- Extreme climatic conditions that cannot be compensated by thermoregulatory mechanisms result in thermic stress.
- Thermoregulatory responses for heat generation include shivering and non-shivering thermogenesis such as an increased metabolic rate, piloerection and peripheral vasoconstriction.
- Moisture and wind/draughts will severely exacerbate the effects of cold conditions.
- In neonatal calves metabolism of brown fat reserves and ingestion of colostrum plays an important role in thermoregulation.
- Healthy calves are physically active, which increases heat production and cold resistance. However, newborn calves are prone to heat loss under cold conditions because of their low surface/mass-ratio and poor insulation.
- Inclement weather and cold stress will also reduce immune competence in neonatal calves. Cold stress decreases neutrophil chemotaxis and vasoconstriction reduces leukocyte distribution to peripheral tissues.
Predisposing factors
General
- Adverse weather conditions.
Specific
- Inclement weather conditions exacerbated by wind, drafts and precipitation.
- Anorexia or lack of provision of sufficient or appropriate feed to support metabolic demand for heat generation and maintenance.
- Failure of passive transfer and concurrent sepsis.
Timecourse
- Hours to days.
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed Papers
- Recent references from PubMed and VetMedResource.
- Roland L, Drillich M, Klein-Jobstl & Iwersen M (2016) Invited review: Influence of climatic conditions on the development, performance and health of calves. J Dairy Sci 99, 2438-2452 PubMed.
- Mader T L & Griffin D (2015) Management of Cattle Exposed to Adverse Environmental Conditions. Vet Clin North Am Food Anim Pract 31 (2), 247-258 PubMed.
- Brumbaugh G W (2003) Neonatal Adjustments. Vet Clin North Am Food Anim Pract 19 (3), 551-556 PubMed.
- Olson D P, Papasian C J & Ritter R C (1980) The Effects of Cold Stress on Neonatal Calves 1. Clinical Condition and Pathological Lesions. Can J Comp Med 44, 11-18 PubMed.
Other sources of information
- www.omafra.gov.on.ca/english/livestock/beef/facts/07-001.htm
- House J K, Smith G W, McGuirk S M, Gunn A A, Izzo M (2015) Manifestations and Management of Disease in Neonatal Ruminants. In: Large Animal Internal Medicine. Ed: Smith B P. 5th edn. pp 302-338.
- White M E & Fecteau S L (2015) Alterations in body temperature. In: Large Animal Internal Medicine. Ed: Smith B P. 5th edn. pp 39.