Heat stress effect assessment on milk yield in dairy herds of the Tunisian northern west area

Yosra Ressaissi, Mohamed Ben Hamouda


Dairy herds are raised under dry climate in Tunisia which make them subject to heat stress which is known to considerably decline their milk yield. This paper aimed to evaluate heat stress impact on the dairy performances of the Tunisian North West cows. We used 4789 test-day recorded between 2008 and 2011 on 585 Holstein cows in their first three parities, calved between 2007 and 2011 and belong to 10 herds from the Tunisian North-West area. Temperature and humidity data were associated to each test-day and Thermal Humidity Indexes (THI) were calculated. First, the effect of temperature and humidity factors were assessed separately, then the effect of their interaction and finally the effect of their THI using three statistical models. For model 2 and 3, all fixed factors were significant (P<0.001) while for model 1 the humidity didn’t show a significant on the milk performances. The highest milk yield was 51 kg and was found to be reached during the lowest daily temperature and the highest humidity; corresponding to the lowest THI index. The lowest milk yield was 1 kg and was found to be recorded during the hottest temperature and the lowest humidity; resulting in the highest THI; which have significantly exceeded the THIThreshold. Our analysis has showed that Tunisian dairy cows in the North West area undergo moderate heat stress during one third of the year and that the average milk yield decline is about 5 kg/day.


Temperature, Humidity, Milk yield, Dairy cows, dry region.


Aguilar I 2010. Genetic components of heat stress for dairy cattle with multiple lactations. Journal of Dairy Science, 92 : 1754-1758.

ALCOR-TEC- SNCC 2012. Stratégie Nationale sur le Changement Climatique Rapport de la stratégie.http://www.environnement.gov.tn/fileadmin/medias/pdfs/dgeqv/chang_climatique_3.pdf.

Bohmanova J. Misztal I. Cole JB. 2007. Temperature-Humidity Indices as Indicators of Milk Production Losses due to Heat Stress. Journal of Dairy Science, 90: 1947-1956.

Bouraoui R. Lahmar M. Majdoub A. Djemali M. Belyea R 2002. The relationship of temperature-humidity index with milk production of dairy cows in a Mediterranean climate. Animal Research, 51: 479-491.

Bray RD. Bucklin R 1996. Recommendations for Cooling Systems for Dairy Cattle.Fact Sheet DS-29. University of Florida Cooperative Extension Service, Gainesville, Florida 32611.

Das R, Sailo L. Verma N. Bharti P. Saikia JI. Kumar R 2016. Impact of heat stress on health and performance of dairy animals: A review, Veterinary World, 92: 60-268.

Du Preez JH. Hatting PJ Giesecke WH. Eisenberg BE 1990. Heat stress in dairy cattle and other livestock under Southern African conditions. III. Monthly temperature-humidity index mean values and their significance in the performance of dairy cattle, Onderstepoort. Journal of Veterinary Research, 5: 183.

Hao LY. Wang J. Sun P. Bu DP 2016. The Effect of Heat Stress on the Metabolism of Dairy Cows: Updates & Review. Austin Journal NutrMetab, 3: 1036.

Her E. Wolfenson D. Flamenbaum I. Folman Y. Kaim M. Berman A 1988. Thermal, productive and reproductive responses of high yielding cows exposed to short-term cooling in summer. Journal of Dairy Science, 71: 1085-1092.

Igono MO. Bjotvedt G. Sanford CHT 1992. Environmental profile and critical temperature effects on milk production of Holstein cows in desert climate. Int. J. Biometeorol, 36: 77-87.

Lang B. 2011. Dairy Cattle Production Systems Specialist. Ministère de l’Agriculture, de l’Alimentation et des Affaires Rurales.http://www.omafra.gov.on.ca/french/livestock/dairy/facts/stressthres.htm.

Louhichi R 2013. Présentation de la filière laitière Tunisienne.www.pole-competitivite-bizerte.com.tn/image.php?id=106.

Mallonee PG. Beede DK. Collier RJ. Wilcox CJ 1985. Production and physiological responses of dairy cows to varying dietary potassium during heat stress. Journal of Dairy Science, 68.

Mitsunori K. Shigeru S 2003. Dairy cattle management in hot environment. Food and Fertilizer Technology Center.http://www.agnet.org/library.php?func=view&id=20110801153254&type_id=4.

Ohnstad I 2017. Managing Heat Stress in Dairy Cows. The Dairy Group, NADIS, Animal Health Skills. http://www.nadis.org.uk/bulletins/managing-heat-stress-in-dairy-ows.aspx?altTemplate=PDF.

Ravagnolo O. Misztal I. Hoogenboom G 2000. Genetic component of heat stress in dairy cattle, development of heat index function. Journal of Dairy Sciences, 83: 2120-2125.

Ravagnolo O. Misztal I 2000.Genetic component of heat stress in dairy cattle, parameter estimation. Journal of Dairy Science, 83: 2126-2130.

West J W 2003. Effects of Heat-Stress on Production in Dairy Cattle. Journal of Dairy Sciences, 86: 21-35.

Full Text: PDF


  • There are currently no refbacks.

Creative Commons License
This work is licensed under a Creative Commons Attribution 3.0 License.

Department of Biology, Faculty of Natural Sciences and Life, Earth Sciences and the UniverseUniversity of Tlemcen PO.Box 119,  13000 Tlemcen, Algeria. E-mail: gen.biodv.journal@gmail.com

Copyright © 2017 University of Tlemcen - ALGERIA