Reduced dietary lysine enhances proportion of oxidative fibers in porcine skeletal muscle
2008
Katsumata, Masaya | Matsumoto, Mitsuhito | Kobayashi, Shu-ichi | Kaji, Yuji
The present study was conducted to elucidate the effects of dietary lysine levels on the proportion of oxidative muscle fibers in porcine muscle. Two 6-week-old barrows from each of five litters were used. Each littermate was assigned to one of two diets, control (lysine content: 1.16%) or low lysine (LL) diet (lysine content: 0.73%). The diets were iso-energetic and iso-protein, and contained all essential amino acids (apart from lysine) in the recommended amounts. The pigs were fed these diets for 3 weeks. Citrate synthase (EC 4.1.3.4) activity in longissimus dorsi and rhomboideus muscles was higher in the LL group (P < 0.05). In both muscles, pigs fed the LL diet had a higher proportion of muscle fiber with activities of reduced nicotinic amide adenine dinucleotide dehydrogenase (EC 1.6.5.3, P < 0.01). The abundance of mRNA of peroxisome proliferator-activated receptor γ coactivator 1α in rhomboideus muscle was higher in the LL group (P < 0.05), and those of peroxisome proliferator-activated receptor γ2 were higher in both longissimus dorsi and rhomboideus muscles in the LL group (P < 0.05). We conclude that reduced intake of dietary lysine enhances proportion of oxidative muscle fiber, and hence oxidative capacity of porcine muscle.
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