title: Thermoregulatory responses during thermal acclimation in pigs divergently selected for residual feed intake.
abstract: The objective of this study was to evaluate the performance and thermoregulatory responses during acclimation to high ambient temperature (Ta) of pigs from two lines selected for high (RFI(+)) or low (RFI(-)) residual feed intake with the hypothesis that RFI(-) pigs producing less heat would better tolerate high Ta. Pigs (50 kg initial body weight; 17 per line among which 10 of them were catheterized) were individually housed in a climatic-controlled room where Ta was maintained at 24.2 ± 0.4 °C during 7 days and thereafter at 30.4 ± 0.7 °C during 14 days. Irrespective of Ta, RFI(-) pigs had lower feed intake (ADFI) and similar average daily gain (ADG) than RFI(+) pigs. Whatever the line, ADFI, ADG, and feed efficiency decreased with increased Ta. Overall, the Ta increase resulted in an increase in rectal temperature (RT), skin temperature (ST), and respiratory rate (RR) within the first 24-48 h and, subsequently, in a decrease followed by stabilization. The RT decrease during acclimation occurred 24 h earlier in RFI(-) pigs than in RFI(+). Thyroid hormones and cortisol decreased at high Ta and it was similar in both lines. Based on performance and RT, ST, and RR responses, it seems that selection for low RFI tends to ameliorate pigs' tolerance to high Ta. Nevertheless, this selection does not induce significant differences between lines in endocrine and metabolite responses during thermal stress.
authors.affiliation: INRA, UMR 1348 PEGASE, 35590, Saint-Gilles, France.
authors.forename: Paulo Henrique Reis Furtado
authors.initials: PH
authors.lastname: Campos
authors.forename: Jean
authors.initials: J
authors.lastname: Noblet
authors.forename: Yolande
authors.initials: Y
authors.lastname: Jaguelin-Peyraud
authors.forename: Hélène
authors.initials: H
authors.lastname: Gilbert
authors.forename: Pierre
authors.initials: P
authors.lastname: Mormède
authors.forename: Rita Flavia Miranda de Oliveira
authors.initials: RF
authors.lastname: Donzele
authors.forename: Juarez Lopes
authors.initials: JL
authors.lastname: Donzele
authors.forename: David
authors.initials: D
authors.lastname: Renaudeau
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D000821:Animal Feed; D000818:Animals; D001831:Body Temperature; D001833:Body Temperature Regulation / Q000502:physiology*; D004435:Eating; D006358:Hot Temperature / Q000009:adverse effects*; D006854:Hydrocortisone / Q000097:blood; D008297:Male; D056152:Respiratory Rate; D013552:Swine / Q000502:physiology*; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood
chemical_list: D014284:Triiodothyronine; D013974:Thyroxine; D006854:Hydrocortisone