171 Effect of Supplemental DL-Ethionine or DL-Methionine-Hydroxy Analogue on Performance, Gene Expression and Serum Antioxidant Activity in Heat Stressed Pigs

Abstract

Abstract Heat stress (HS) increases body temperature and production of reactive-oxygen-species in pigs. Because HS-pigs redirect blood flow to the periphery to maintain normal body temperature, less blood reaches internal organs that, combined with decreased feed intake, nutrients supply to the small intestine reduces causing intestinal damage. Methionine functions as intracellular antioxidant thus HS-pigs may increase its requirement. An experiment with 36 individually housed pigs (27.4±4.3 kg BW) was conducted to evaluate the effect of supplementing DL-Methionine or the calcium-salt of DL-Methionine-hydroxy-analogue (MHA-Ca) on performance, intestinal histology, serum antioxidant enzymes, and expression of genes coding for amino acid transporters B0 and b0,+. The basal wheat-soybean meal diet met 100% methionine and exceeded at least 20% the other essential AA requirements. Pigs were exposed to HS and randomly assigned to 3 treatments: basal-diet (Met100); and basal-diet plus 0.12% methionine as DL-Methionine (Met120) or MHA-Ca (MHA-Ca120). Feed and water were freely available during the 21-d trial. At completion, blood samples, and samples from duodenum, jejunum, and ileum were collected. Serum antioxidant activity, and villi-height, crypt-depth, their ratio (villi:crypt), and expression of B0 and b0,+ in intestinal segments were analyzed. Weight gain tended to increase (P < 0.10) and gain:feed increased (P < 0.05) in Met120 and MHA-Ca120 pigs compared with Met100 pigs. Crypt-depth in duodenum and jejunum decreased but villi:crypt in duodenum, jejunum, and ileum increased (P < 0.01) in Met120 and MHA-Ca120 pigs, compared with Met100 pigs. Jejunum and ileum villi-height increased in Met120 and MHA-Ca120 pigs compared with Met100 pigs (P < 0.01). Serum superoxide-dismutase increased in Met120 and MHA-Ca120 pigs compared with Met100 pigs; glutathione increased in Met120 pigs compared with Met100 or MHA-Ca120 pigs (P < 0.05). Expression of mRNA coding for b0,+ was higher in Met120 pigs than in MHA-Ca120 pigs (P < 0.05). These results indicate that supplying Met at 20% above the requirement, as DL-Methionine or DL-Methionine-hydroxy-analogue, ameliorates the negative effects of HS on pigs, as evidenced by increased weight-gain, gain:feed, and activity of serum superoxide-dismutase and glutathione.