Abstract
Feeding oxidized lipids compromises growth performance of pigs, but the metabolic events contributing to this adverse effect are not well defined. In this study, oxidized corn oil (OCO) was prepared by heating control corn oil (CCO) at 185 oC for 12 h. Weanling pigs (initial BW = 6.3 ± 1.4 kg) were fed 4 isocaloric diets containing 9% CCO, 6% CCO + 3% OCO, 3% CCO + 6% OCO, and 9% OCO, respectively. Pigs were provided ad libitum access to experimental diets in 3 phases (phase 1 = 4 d, phase 2 = 10 d and phase 3 = 21 d) for 35 d. Pig body weight (BW) and feed disappearance were determined at the d 0, 4, 14 and 35 to calculate average daily gain (ADG), average daily feed intake (ADFI) and gain to feed (G:F) ratio. Serum and liver samples collected on d 35 of feeding were analyzed by the liquid chromatography-mass spectrometry (LC-MS)-based metabolomics analysis. Growth performance data were analyzed using the MIXED procedure of SAS and metabolomics data were analyzed by two-tailed student’s t test for comparison between different doses of OCO and CCO treatments. The result showed that dietary OCO decreased G:F ratio (P < 0.05) dose-dependently, but did not ADFI. Metabolomics analysis showed that OCO fed pigs decreased the levels of serum alanine (P < 0.01), tryptophan (P < 0.05), carnosine (P < 0.01), and glutamic acid (P < 0.05), while the levels of threonine (P < 0.05) was increased compared to CCO. Moreover, consuming OCO decreased the hepatic metabolites from threonine catabolism pathways, including α-ketobutyrate (P < 0.01), α-amino-butyrate (P < 0.05), and propionic acid (P < 0.05), compared to CCO treatment. In addition, OCO increased hepatic NAD level by activating tryptophan-NAD+ metabolic pathway. Overall, OCO selectively modulated amino acid metabolism in nursery pigs, which may further affect growth performance.
Quantitative metabolomics analysis of amino acid metabolism in recombinant Pichia pastoris under different oxygen availability conditions