title: Short-term exposure to heat stress attenuates appetite and intestinal integrity in growing pigs.
abstract: Acute heat stress (HS) and heat stroke can be detrimental to the health, well-being, and performance of mammals such as swine. Therefore, our objective was to chronologically characterize how a growing pig perceives and initially copes with a severe heat load. Crossbred gilts (n=32; 63.8±2.9 kg) were subjected to HS conditions (37°C and 40% humidity) with ad libitum intake for 0, 2, 4, or 6 h (n=8/time point). Rectal temperature (Tr), respiration rates (RR), and feed intake were determined every 2 h. Pigs were euthanized at each time point and fresh ileum and colon samples were mounted into modified Ussing chambers to assess ex vivo intestinal integrity and function. Transepithelial electrical resistance (TER) and fluorescein isothiocyanate-labeled dextran (FD4) permeability were assessed. As expected, Tr increased linearly over time (P<0.001) with the highest temperature observed at 6 h of HS. Compared to the 0-h thermal-neutral (TN) pigs, RR increased (230%; P<0.001) in the first 2 h and remained elevated over the 6 h of HS (P<0.05). Feed intake was dramatically reduced due to HS and this corresponded with significant changes in plasma glucose, ghrelin, and glucose-dependent insulinotropic peptide (P<0.050). At as early as 2 h of HS, ileum TER linearly decreased (P<0.01), while FD4 linearly increased with time (P<0.05). Colon TER and FD4 changed due to HS in quadratic responses over time (P=0.050) similar to the ileum but were less pronounced. In response to HS, ileum and colon heat shock protein (HSP) 70 mRNA and protein abundance increased linearly over time (P<0.050). Altogether, these data indicated that a short duration of HS (2-6 h) compromised feed intake and intestinal integrity in growing pigs.
authors.affiliation: Department of Animal Science.
authors.forename: S C
authors.initials: SC
authors.lastname: Pearce
authors.affiliation: Department of Animal Science.
authors.forename: M V
authors.initials: MV
authors.lastname: Sanz-Fernandez
authors.affiliation: Department of Food Science and Human Nutrition, Iowa State University, Ames 50011.
authors.forename: J H
authors.initials: JH
authors.lastname: Hollis
authors.affiliation: Department of Animal Science.
authors.forename: L H
authors.initials: LH
authors.lastname: Baumgard
authors.affiliation: Department of Animal Science ngabler@iastate.edu.
authors.forename: N K
authors.initials: NK
authors.lastname: Gabler
mesh_terms: D000469:Alkaline Phosphatase / Q000097:blood; D000818:Animals; D001066:Appetite / Q000502:physiology*; D001831:Body Temperature; D003911:Dextrans; D017097:Electric Impedance; D004591:Electrophoresis, Polyacrylamide Gel / Q000662:veterinary; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives; D005453:Fluorescence; D005749:Gastric Inhibitory Polypeptide / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006652:Histological Techniques / Q000662:veterinary; D006358:Hot Temperature; D006813:Humidity; D007422:Intestines / Q000502:physiology*; D016018:Least-Squares Analysis; D009113:Muramidase / Q000097:blood; D056152:Respiratory Rate; D013312:Stress, Physiological / Q000502:physiology*; D013552:Swine / Q000502:physiology*
chemical_list: D003911:Dextrans; D018840:HSP70 Heat-Shock Proteins; C015219:fluorescein isothiocyanate dextran; D005749:Gastric Inhibitory Polypeptide; D000469:Alkaline Phosphatase; D009113:Muramidase; D016650:Fluorescein-5-isothiocyanate
keywords: appetite; heat stress; intestinal integrity; swine