Daily Adaptive Changes in Blood Chemistry of Pigs Exposed to Heat Stress

Abstract

Animals and humans exposed to heat stress (HS) conditions may modify their physiology and metabolism to maintain homeostasis. In the dessert regions of the world, they have to adapt to great changes in ambient temperature (AT) within 24‐h periods, from thermo neutral (TN) AT early in the morning to stressful high AT in the afternoon. An experiment was conducted with six pigs (45 kg BW), individually housed, during the summer of Northwestern Mexico to analyze the impact of HS as well as the diurnal changes in AT on their blood chemistry. First, the pigs were housed under natural HS conditions (30.4 – 41.1° C, HS) during 14 d. Then, the pigs were moved to an air‐conditioned room (22.6–25.1 °C, TN) for two weeks. Blood samples were collected from the jugular vein of pigs at 0600, 1200 and 1600 h, during the last three days under HS, and again on the last day under TN conditions. Samples were processed to obtain serum in which blood chemistry parameters were analyzed. Heat stress reduced the serum concentration of cholesterol, total proteins, albumin, globulin, phosphorus, and Ala‐amino‐transferase (P<0.05); indirect bilirubin tended to reduce (P<0.10), and calcium tended to increase (P<0.10). As for the diurnal changes in AT, Ca SC decreased at 1200 and 1600 h (P<0.001) as compared with that at 0600; cholesterol also reduced at 1600 h compared to 0600 h (P<0.05). These changes indicate that HS animals modify their physiology and that some factors such as blood proteins, cholesterol and calcium are modified along the day in order to maintain pig homeostasis.Support or Funding InformationCONACYT, México. Ciencia básica 2012, 00181348.