Modeling dairy cow thermoregulation during warm and hot environmental conditions 1: Model development

C. R. Nelson, K. A. Janni

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

A steady-state heat transfer model developed by McGovern and Bruce (2000) and modified by Berman (2005) was modified more to model thermoregulatory responses of lactating Holstein cows to heat stress. The new model describes metabolic heat generation and heat exchange to the surrounding environment. Heat exchanges included respiratory latent and sensible heat exchange, evaporative heat loss via the skin, solar radiation heat gain, and convective and long-wave radiative heat exchanges. In McGovern and Bruce (2000) four mechanisms cows have to mitigate heat stress effects were implemented in a step-wise manner. Reported cow responses to heat stress indicate that mitigation mechanisms such as increased respiration and sweat rate, and body temperature overlap rather than activate in sequence. The model was modified to allow overlap in animal responses to given environmental conditions. Tissue insulation and body temperature were related to respiration rate. Sweat rate was related to skin temperature. Metabolic heat production was related to daily milk production and respiratory cooling was based on data for Holstein cows. Model inputs include cow size, daily milk production, dry-bulb and dew-point temperatures and air velocity. These variables impact which mechanisms and the levels a cow needs to employ to achieve thermal balance. Model results compared favorably to information reported in the literature. The modified model can be used to determine what thermal conditions (ex. temperature, humidity, solar gain and air velocity) a cow can be in and maintain thermal balance for given physiological responses (i.e., respiration rate, sweat rate and body temperature).

Original languageEnglish (US)
Title of host publication2016 American Society of Agricultural and Biological Engineers Annual International Meeting, ASABE 2016
PublisherAmerican Society of Agricultural and Biological Engineers
ISBN (Electronic)9781510828759
DOIs
StatePublished - Jan 1 2016
Event2016 ASABE Annual International Meeting - Orlando, United States
Duration: Jul 17 2016Jul 20 2016

Other

Other2016 ASABE Annual International Meeting
CountryUnited States
CityOrlando
Period7/17/167/20/16

Keywords

  • Dairy cow
  • Heat stress
  • Model
  • THI
  • Thermoregulation

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    Nelson, C. R., & Janni, K. A. (2016). Modeling dairy cow thermoregulation during warm and hot environmental conditions 1: Model development. In 2016 American Society of Agricultural and Biological Engineers Annual International Meeting, ASABE 2016 American Society of Agricultural and Biological Engineers. https://doi.org/10.13031/aim.20162462138