Effects of dietary supplementation of l-methionine vs. dl-methionine on performance, plasma concentrations of free amino acids and other metabolites, and myogenesis gene expression in young growing pigs

Abstract

Methionine (Met), the second or third limiting amino acid (AA) in typical swine diets, plays important roles in promoting swine health and growth, especially, muscle growth. Whereas dl-Met products have been used in swine industry for many years, l-Met products have been developed recently. This research was conducted to study the effects of supplemental l-Met or dl-Met on nutrient metabolism, muscle gene expression, and growth performance of pigs. Twenty crossbred young barrows (initial body weight [BW] 21.2 ± 2.7 kg) were randomly assigned to 20 individual pens and two dietary treatments according to a completely randomized design with pigs serving as the experiment unit (n = 10). Two corn and soybean meal-based diets (diets 1 and 2) were formulated to meet or exceed the recommended requirements for energy, AA, and other nutrients (NRC. 2012. Nutrient requirements of swine, 11th ed. Washington, DC: The National Academies Press; AMINODat 5.0). Crystalline l-Met and dl-Met were supplemented to diets 1 and 2 (both at 0.13%, as-fed basis), respectively. After 4 wk of an ad libitum feeding trial, BW and feed intake were measured to calculate average daily gain (ADG), average daily feed intake (ADFI), and gain-to-feed ratio (G:F). Blood samples were collected from the jugular vein for analyses of plasma AA and metabolite concentrations. The longissimus dorsi muscle samples were collected for analysis of myogenesis gene expression. Data were analyzed using Student’s t-test. There were no differences (P = 0.56 to 0.94) in ADG, ADFI, or G:F between pigs fed the two experimental diets and no differences between diets were observed in plasma free AA concentrations. No differences were observed between pigs fed the two diets in expression of mRNA for eight myogenesis-related genes, which were myogenic differentiation 1, myogenin, myogenic factors 5, muscle regulatory factor 4 (a.k.a. myogenic factors 6), and myocyte enhancer factors 2A, 2B, 2C, and 2D. In conclusion, results of this experiment indicate that the bioefficacy of l-Met is not different from that of dl-Met, which is likely because of an efficient conversion of d-Met to l-Met by pigs.

Effect of replacement different methionine levels and sources with betaine on blood metabolites, breast muscle morphology and immune response in heat-stressed broiler chickens

“…Therefore, L-Met has a greater advantage in broilers during heat stress. However, Yang et al (2019) indicated that there was not difference in the expression of myogenesis-related genes and muscle growth in pigs fed with L-Met and DL-Met.…”

Changes in growth performance, plasma metabolite concentrations, and myogenic gene expression in growing pigs fed a methionine-restricted diet

“…The myogenic gene expression was analyzed by following our previously reported protocols [24]. Briefly, the total RNA was extracted from approximately 50 mg of muscle sample per pig using TRIzol Reagent (Invitrogen Corporation, Carlsbad, CA, USA) following the manufacturer's instructions.…”

“…The semi-quantitative polymerase chain reaction (PCR) analysis was performed using the Rotor-Gene SYBR Green PCR Kit with the Rotor-Gene Q System (Qiagen), followed by melting curve analysis to verify the specificity and identity of the PCR products [24]. The thermal cycling parameters were 95 • C for 5 min, followed by 40 cycles of 95 • C for 5 s and 60 • C for 10 s. Primers for the selected myogenesis-related genes, as well the hypoxanthine phosphoribosyl transferase 1 (Hprft1; as the endogenous control) gene, were manufactured at Integrated DNA Technologies (Coralville, IA, USA) with the primer sequences being adopted from Yang et al [24]. The Hprft1 gene was used for normalization of the potential variations caused during the sample preparation [25].…”

“…The comparative ∆∆C T method was used for mRNA quantity calculation. Briefly, the raw quantity of a given gene was normalized against the raw quantity of Hprft1 reference gene of a given sample obtained from the Rotor-Gene Q System, and then the normalized level of the given gene of each sample in the Diet 1 group was expressed as a quantity relative to the mean of the normalized quantities of the given gene in the Diet 2 samples [24].…”

Maintaining the same ratio between standardized ileal digestible methionine and cysteine do not affect its requirements for starting pigs

“…An adequate dietary amino acid (AA) supply is often evaluated for pigs and most research has studied the requirements of a single AA; mainly the most limiting essential AAs in pig diets (Kiefer et al, 2005). There is much information about lysine requirements for different genetic groups, categories and sex of pigs (Santos et al, 2011), but there are few studies about the sulphur containing AAs (SAA) methionine (Met) and cysteine (Cys), mainly for starting pigs, since Met is typically the second or third limiting indispensable AA in grain-based swine diets (Yang et al, 2019).…”