Effect of heat stress on the endogenous intestinal loss of amino acids in growing pigs1

Abstract

Heat stress (HS) increases the death of intestinal cells in pigs, which, in turn, may elevate the endogenous intestinal loss (EIL) of proteins and AA. An experiment was conducted to analyze the effect of HS on the AA composition of intestinal endogenous proteins and the EIL of AA in pigs. Eight pigs (25.2 ± 1.2 kg initial BW) were surgically implanted with T-type cannulas at the end of the small intestine. After surgery recovery, during the subsequent 7 d, all pigs were adapted to a protein- and AA-free diet and trained to consume the same amount of feed twice a day. All pigs were housed under thermoneutral (TN) conditions (22 ± 2°C) during this time. The following day, all pigs were still under TN conditions and ileal content was collected during 12 consecutive hours, at the end of which and for the following 8 d the pigs were exposed to natural HS conditions (31 to 37°C). Ileal content was collected again on d 2 (HS at d 2 [HSd2]) and 8 (HS at d 8 [HSd8]). Body temperature (BT) was measured in another group of 8 pigs every 15 min during the whole study. The average BT at HSd2 (39.6°C) was higher ( < 0.05) compared with both TN conditions (38.6°C) and HSd8 (38.8°C), but it did not differ between TN conditions and HSd8. The AA composition of endogenous intestinal protein was not affected by HS. The EIL of Arg and His were greater ( < 0.05) and the EIL of Thr and Phe tended to be greater ( ≤ 0.10) at HSd2 than in TN conditions; the EIL of Pro was greater ( = 0.01) at HSd8. The EIL of the remaining AA was not affected by HS. Although HS increased the EIL of Arg and His within the first 2 d, it appeared that normal EIL was shortly reestablished. These data show that acute HS does not affect the AA composition of intestinal endogenous proteins in growing pigs and that the EIL of AA may not be critical in growing pigs acclimated to high ambient temperature. Nevertheless, the increased EIL of Arg and Thr at HSd2 indicate that HS might affect the integrity of the intestinal epithelium of pigs during the first day of their exposure to high ambient temperature.

Effect of feed intake level and dietary protein content on the body temperature of pigs housed under thermo neutral conditions

“…At low AT, pigs generate heat through basal metabolism (Adair & Black, ) and feed‐related thermogenesis (Levine, ), but at high AT, they use a well‐regulated mechanism to dissipate heat to the environment (Morera, Basirico, Hosoda, & Bernabucci, ). At thermo neutral (TN) conditions, the BT of healthy pigs varies between 38.0 and 39.5°C (Morales et al., ; Pearce, Sanz‐Fernandez, Hollis, Baumgard, & Gabler, ; Pearce et al., ). However, at high AT, the BT of pigs exceeds 40°C (Pearce et al., ) and even get as high as 42°C (Morales et al., ).…”

Effect of Heat Stress on the Expression of HSP70, UCP3 and CYP450 Genes in Liver; Longissimus Dorsi and Semitendinosus Muscle of Growing Pigs

“…The expression of HSP70, UCP3 and P450 in muscles and liver of pigs exposed to natural HS or TN conditions and different feed intake is part of a large data set obtained in the present experiment. Performance, mRNA expression for amino acid transporters and serum amino acids are published already (Morales et al, 2016).…”

“…Immediately after slaughter, samples (0.5 g) of liver, Longissimus Dorsi (LD) and Semitendinosus (ST) muscles were collected into 2 ml micro tubes. Also, samples of blood and intestinal epithelia were collected to analyse the expression of amino acid transporters in the small intestine and the concentration of free AA in serum; these data are already published (Morales et al, 2016). All samples were immediately frozen in liquid nitrogen and stored at -80°C until lab analysis.…”

“…Heat stress pigs increase their respiratory frequency and heart rate to dissipate more body heat (Wilson and Crandall, 2011) and consume less feed to decrease body heat production (Bernabucci et al, 2010). Nonetheless, pigs exposed to severe HS increase Body Temperature (BT) up to 2.0°C (Pearce et al, 2013;Morales et al, 2016), which might result in cell death (Rhoads et al, 2013).…”

Beyond Heat Stress: Intestinal Integrity Disruption and Mechanism-Based Intervention Strategies

“…Nutrition deprivation experiments proved that amino acids are critical to the gut barrier and the gut microbiota [183,184]. In the last decade, awareness of the nutritional relevance of some amino acids has been broadened from nutritional-only to therapeutically-important agents, due to their ability to modify cell signaling and to modulate gut-associated disorders [185][186][187]. Functional amino acids, including arginine and glutamine enhance intestinal mucosal immunity, abolish the oxidative damage, trigger proliferation of enterocytes and enhance gut barrier function.…”