PSIII-10 Effects of Mitoquinol During an Acute Heat Stress in Growing Gilts

Abstract

Abstract Objectives were to evaluate the effects of mitoquinol (MitoQ) on production parameters, gastrointestinal (GIT) contents, GIT mass, and circulating leukocytes during acute heat stress (HS). Crossbred gilts [49.1±2.4 kg body weight (BW)] were blocked by BW and randomly assigned to 1 of 4 therapeutic-environmental treatments: 1) thermoneutral (TN) control (TNCON; n = 8), 2) TN and MitoQ (TNMitoQ; n = 8), 3) HS control (HSCON; n = 8), or 4) HS and MitoQ (HSMitoQ; n = 8). The study consisted of two experimental periods (P). During P1 (2 d) pigs were fed ad libitum and housed in TN conditions (20.6±1.5°C). During P2 (24 h) pigs were fed ad libitum and exposed to either TN or constant HS (37.3±1.3°C). In MitoQ fed pigs, MitoQ (20 mg) was administered twice daily (0700 and 1800 h; 40 mg/d) during both P1 and P2. Rectal temperature (TR), skin (TS), respiration rate (RR), and feed intake (FI) were recorded every 4 h during P2. Following P2, all pigs were euthanized, and organs were weighed. As expected, pigs exposed to HS had increased TR, TS, and RR (1.5°C, 8.7°C, and 86 bpm, respectively; P < 0.01) relative to TN. Compared with TN, HS pigs had decreased FI (67%; P < 0.01). Additionally, HS pigs lost BW compared with TN (-1.9 vs. +1.5 kg, respectively; P < 0.01). Despite consuming 67% less feed, stomach contents were similar in TN and HS pigs (P > 0.54), regardless of environment. Large and small intestine contents were decreased in HS pigs relative to TN (23 and 49%, respectively; P ≤ 0.01). Total GIT luminal contents (stomach, small and large intestines) were decreased in HS relative to TN pigs (2.43 vs. 3.26 kg; P = 0.01); however, MitoQ fed pigs tended to have increased GIT contents regardless of the environment (3.05 vs. 2.63 kg; P = 0.08). Total empty GIT and liver weights decreased in HS relative to TN pigs (3.21 vs. 3.48 and 1.16 vs. 1.22 kg, respectively; P ≤ 0.03). In addition, liver weight was decreased in MitoQ relative to CON pigs (1.13 vs. 1.24 kg; P = 0.01). Further, total GIT weight (tissue and contents) was decreased in HS relative to TN pigs (5.63 vs. 6.70 kg; P = 0.01). Environment nor therapeutic treatment affected circulating leukocytes (P > 0.16); however, HS pigs tended to have decreased lymphocytes relative to TN (16%; P = 0.07). Based upon the changes in GIT content, it appears HS decreases gastric emptying while increasing intestinal passage rate. Overall, acute HS increased body temperature indices, and decreased FI, GIT mass and BW; however, MitoQ administration did not appear to ameliorate these metrics.