Relationships between heat stress and metabolic and milk parameters in dairy cows in southern Brazil

Alejandra Barrera Garcia, Natalia Angeli, Letícia Machado, Felipe Cardoso de Cardoso, Félix Gonzalez

Research output: Contribution to journalArticlepeer-review


This study approached the relationships between heat stress and metabolic and milk parameters in a commercial herd of Holstein cows located in southern Brazil. A total of 50 multiparous cows at different lactations and lactation stages were selected in order to obtain 450 samples during two consecutive years (2011 and 2012). The animals were fed a partial mixed ration along with ryegrass pasture in a semi-confinement system. Blood, milk, and urine samples were taken during the summer and winter for a total of eight samples. Three intervals of temperature-humidity index (THI) were established during the summer months (January and February) as follows: low group (LOW), THI between 75 and 81 (N = 100); moderate group (MOD), THI between 81 and 82 (N = 150); and severe group (SEV), THI between 83 and 90 (N = 150). The group of cows sampled during winter (July) constituted the control group (CON; THI = 59, N = 50). Increased total protein, albumin, glucose, and cholesterol occurred in heat-stressed cows. Increased AST activity was also observed in heat-stressed cows, but triglycerides and beta-OH-butyrate did not show any difference among groups. Lower lactate and higher pO2 were seen in cows with heat stress than CON. Cows in SEV had a 21 % milk yield decrease, while lactose and protein decreased with fat not being affected. Heat stress had strong effects on metabolic, clinical, and performance parameters in Holstein cows.

Original languageEnglish (US)
Pages (from-to)889-894
Number of pages6
JournalTropical Animal Health and Production
Issue number5
StatePublished - Jun 1 2015


  • Acid-base balance
  • Metabolism
  • Milk quality
  • THI index

ASJC Scopus subject areas

  • Food Animals
  • Animal Science and Zoology

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