Tropical Animal Health and Production

, Volume 36, Issue 7, pp 685–692 | Cite as

Effect of Heat Stress on Milk Production, Rectal Temperature, Respiratory Rate and Blood Chemistry in Holstein, Jersey and Australian Milking Zebu Cows

  • A. Srikandakumar
  • E.H. Johnson


The effect of heat stress on changes in milk production, rectal temperature, respiratory rate and blood chemistry was evaluated in three groups of six mature Holstein, Jersey and Australian Milking Zebu (AMZ) dairy cows. These animals were subjected to a cool environment when the mean temperature–humidity index (THI) was 72±1.4 (dry bulb temperature of 22.2–24.4°C and relative humidity of 100–60%) during the month of December. This experiment was repeated during the hotter month of July of the following year, when the mean THI was 93±3.1 (dry bulb temperature of 35.6–43.9°C and relative humidity 95–35%). Holstein cows produced more (p<0.01) milk than AMZ and Jersey cows during the cooler months of the year and all the cows were dry during the hotter months from June until September. Heat stress increased (p<0.01) rectal temperature and respiratory rate in all three breeds. Heat stress had no effect on blood pH in Holstein and AMZ cows but lowered (p<0.01) blood pH from 7.42 to 7.34 in Jersey cows. In addition, heat stress lowered (p<0.01) blood pCO2 (kPa), bicarbonate (HCO3, mmol/L), base excess (BE, mmol/L) and plasma chloride (Cl, mmol/L) in all three breeds. The total haemoglobin (THb, g/dl) was elevated (p<0.01) in all three breeds when they were subjected to heat stress. Heat stress increased (p<0.01) oxygen saturation (O2SAT, %) in Jersey and AMZ cows but lowered it (p<0.01) in Holstein cows. On the other hand, heat stress increased (p<0.01) pO2 (kPa) in Holstein and Jersey cows but lowered it (p<0.01) in AMZ cows. Heat stress increased (p<0.01) plasma potassium (K, mmol/L) and calcium (Ca, mmol/L) only in Holstein and Jersey cows but lowered them (p<0.01) in AMZ cows. The plasma glucose (GLU, mmol/L) increased (p<0.01) with heat stress in Holstein and AMZ cows but decreased (p<0.01) in Jersey cows. Heat stress increased (p<0.01) plasma creatinine (CR, (mol/L) but lowered (p<0.01) plasma creatinine phosphokinase (CPK, IU/L), aspartate aminotransferase (AST, IU/L) and blood urea nitrogen (BUN, mmol/L) in all three breeds. These results indicate that heat-stressed Holstein and AMZ cows were able to maintain their acid–base balance with a marginal change in their pH of 0.02 when their rectal temperatures increased by 0.47 and 0.38°C, respectively. When heat stress increased the rectal temperature in Jersey cows by 0.70°C, the pH decreased (p<0.01) from 7.42 to 7.34. However, even with this decrease 0.08 the pH is still within the lower physiological limit of 7.31.

blood chemistry dairy cows heat stress milk production rectal temperature respiratory rate 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Anderson, B.E., 1989. Temperature regulation and environmental physiology. In: M.J. Swenson (ed.), Dukes' Physiology of Domestic Animals, (Cornell University Press, Ithaca, NY), 719–727Google Scholar
  2. Benjamin, M.M., 1978. Fluids and electrolytes. In: M.M. Benjamin (ed.), Outline of Veterinary Clinical Pathology, (Iowa State University, Ames, IA), 213–214Google Scholar
  3. Bianca, W., 1962. Relative importance of dry and wet bulb temperatures in causing heat stress in cattle. Nature (London), 195, 251CrossRefGoogle Scholar
  4. Duncan, J.R. and Prasse, K.W., 1994. Veterinary Laboratory Medicine, 3rd edn., (Iowa State University Press, Ames, IA)Google Scholar
  5. Finch, V.A., Bennet, I.L. and Holmes, C.R., 1982. Sweating response in cattle and its relation to rectal temperature, tolerance of sun and metabolic rate. Journal of Agricultural Science (Cambridge), 99, 479–487CrossRefGoogle Scholar
  6. Fraser, C.M., 1991. Acid–base balance. In: The Merck Veterinary Manual, (Merck & Co., Inc., Whitehouse Station, NJ)), 1361–1367Google Scholar
  7. Fuquay, J.W., 1981. Heat stress as it affects animal production. Journal of Animal Science, 52, 164–169PubMedGoogle Scholar
  8. Ganong, W.F., 1977. Energy balance, metabolism and nutrition. In: W.F. Ganong (ed.), Review of Medical Physiology, 8th edn., (Lange Medical Publications, Los Altos, CA), 199–235Google Scholar
  9. Hales, J.R.S., 1974. Physiological responses to heat. In: D. Robertshaw (ed.), International Review of Science, (Butterworths, London), 107–162Google Scholar
  10. Houpt, T.R., 1989. Water, electrolytes and acid–base balance. In: M.J. Swenson (ed.), Dukes' Physiology of Domestic Animals, (Cornell University Press, Ithaca, NY), 486–506Google Scholar
  11. Kibler, H.H., 1964. Thermal effects of various temperature–humidity combinations on Holstein cattle as measured by eight physiological responses, (Missouri Agricultural Experiment Station Research Bulletin no. 862)Google Scholar
  12. Nienaber, J.A., Hahn, G.L. and Eigenberg, R.A., 1999. Quantifying livestock responses for heat stress management: a review. International Journal of Biometeorology, 42, 183–188PubMedCrossRefGoogle Scholar
  13. Ott, R.L., 1993. Analysis of variance in some standard experimental designs. In: R.L. Ott (ed.), An Introduction to Statistical Methods and Data Analysis, (Duxbury Press, Belmont, CA), 842–928Google Scholar
  14. Ravagnolo, O., Misztal, I. and Hoogenboom, G., 2000. Genetic component of heat stress in dairy cattle: development of heat index function. Journal of Dairy Science, 83, 2120–2125PubMedCrossRefGoogle Scholar
  15. Riek, P.M. and Srikandakumar, A., 1994. Breeding and management of dairy cattle in the Sultanate of Oman. Proceedings of the Australian Society of Animal Production, 20, 224–231Google Scholar
  16. SAS, 1993. SAS/STAT User's Guide, Volume 2, Version 6, (SAS Institute, Cary, NC)Google Scholar
  17. Srikandakumar, A., Riek, P.M. and Horton, G.M.J., 1993. The effect of spray cooling on respiratory rate, rectal temperature in Australian Milking Zebu, Jersey and Holstein cows in a desert environment. Proceedings of the Fourth International Livestock Environment Symposium, 4, 922–928Google Scholar
  18. West, J.W., Mullinix, B.G. and Sandifer, T.G., 1991. Changing dietary electrolyte balance for dairy cows in cool and hot environments. Journal of Dairy Science, 74, 1662–1674PubMedCrossRefGoogle Scholar

Copyright information

© Kluwer Academic Publishers 2004

Authors and Affiliations

  • A. Srikandakumar
    • 1
  • E.H. Johnson
    • 1
  1. 1.Department of Animal and Veterinary Sciences, College of AgricultureSultan Qaboos UniversitySultanate of Oman

Personalised recommendations