Effect of L‐lysine on expression of selected genes, serum concentration of amino acids, muscle growth and performance of growing pigs

Abstract

Lysine (Lys) is the first limiting amino acid (AA) in most feed formulations for pigs and most abundant, along with leucine, in muscle proteins. An experiment was conducted with 17 pigs (17.7 ± 0.05 kg initial BW) to identify a role of dietary Lys in the control of protein synthesis in pigs. Fourteen pigs were randomly assigned to one of the two wheat-based dietary treatments: Lys-deficient, 3.0 g/kg (DEF) and Lys-adequate, 10.8 g/kg (ADE). Samples from jejunum mucosa, liver, Longissumus and Semitendinosus muscles, and blood were collected. The other three pigs were sacrificed at the beginning of the trial to measure basal carcass composition. Weight gain, gain:feed ratio, Lys intake and loin eye area were greater in ADE than in DEF pigs (p < 0.01). Muscle-related carcass characteristics were better, and myosin heavy chain IIb expression (MyHC IIb) in Semitendinosus was higher in ADE than in DEF pigs. Expression of AA transporters CAT-1 was lower (p < 0.05), serum Lys was higher and serum Val was lower in pigs fed the ADE diet. The higher muscularity, MyHC IIb expression in Semitendinosus muscle and Lys serum of pigs fed the ADE diet suggest that Lys increases growth rate not only by functioning as protein construction unit but also as potential control of the protein synthesis process.

Research Article Expression of lipid metabolism and myosin heavy chain genes in pigs is affected by genotype and dietary lysine

“…Lysine is the most abundant amino acid in muscle proteins of the pig (Bikker et al, 1994). The greater mRNA expression of MyHC IIb in Logissimus muscle observed in gilts fed with different dietary digestible lysine contents support the hypothesis that lysine may stimulate, either direct or indirectly, the transcription of MyHC IIb (Morales et al, 2015).…”

“…The higher mRNA expression of MyHC IIb in Logissimus muscle caused by dietary DL content suggests that lysine stimulates the synthesis of skeletal muscle proteins at a transcriptional level (Morales et al, 2015). Lysine is the most abundant amino acid in muscle proteins of the pig (Bikker et al, 1994).…”

“…The oxidative fibers may be associated to increased IMF content (Guo et al, 2011). Furthermore, low dietary lysine content decreases the transcription of fibers IIB, but there is no available report showing the mechanism by which lysine causes this effect (Morales et al, 2015) and increased IMF content (Katsumata et al, 2012;Madeira et al, 2013).…”

Dietary levels of protein and free amino acids affect pancreatic proteases activities, amino acids transporters expression and serum amino acid concentrations in starter pigs

“…() and Morales et al. (). Hence, the results of the present experiment indicate that the presence of free Lys in duodenal digesta stimulates the expression of b 0,+ AT in the mucosa of duodenum.…”

iTRAQ-based proteomic analysis reveals key proteins affecting muscle growth and lipid deposition in pigs

“…Myosin heavy chain 4 (MYH4 or MyHC IIb) fibres are the most prominent in pigs and contribute to differential growth of muscles32. Furthermore, mRNA abundance of MyHC IIb can be used as an indicator of muscle protein synthesis and muscle growth rate3334. MyHC IIb is a type of fast fibre, and some studies have shown that the proportion of IIb glycolytic fibres is about 75–86% in commercial pig breeds that have a rapid growth rate35.…”