The feeding causes complex physiological and biochemical responses in animals. The circulating hormones (e.g., insulin) and nutritional metabolites (e.g., glucose and amino acids) are relatively elevated even with no food intake in pigs, and therefore ameliorate the whole-body nutritional metabolic status. Although with some differences in response to different dietary treatments (Deng et al. 2009; Deng et al. 2010), the postprandial circulating concentrations of glucose, amino acids, and insulin raised and are maintained at relatively high levels for 4 h after the meal and then returned to the baseline whatever pigs consumed their daily allowance under the feeding procedures of “six-time intake per day” (Yin et al. 2010; 2011; Deng et al. 2009; Deng et al. 2010), “three-time intake per day” (Liu et al. 2007), or “two-time intake per day” (Regmi et al. 2010) (Tables 8.1 and 8.2, Figs. 8.2 and 8.3). Therefore the whole-body fractional protein syntheses rate may be higher within the postprandial 4 h than during the time from postprandial 4th hour till next meal. In young pigs, the feeding stimulates protein synthesis in most tissues, and the efficiency by which dietary amino acids are used for protein deposition is high (Burrin et al. 1992). Notably, the most profound postprandial increase in protein synthesis occurs in skeletal muscle, which is of high metabolic significance, because skeletal muscle comprises a large proportion of the body mass in pigs. Feeding promotes the protein synthesis largely through glucose-, amino acid-, or insulin-induced formation of the active eukaryotic translation initiation factor (eIF) 4E.eIF4G complex or mTOR pathways (Kimball et al. 2000; Avruch et al. 2006; Jeyapalan et al. 2007; Suryawan et al. 2007). The phosphorylation of mTOR peaked within 30 min after starting the feeding, followed by the phosphorylation of the downstream targets of mTORC1, 4E-BP1, eIF4G, and S6 (Fig. 8.4), and then regulation of the binding of the mRNA with the 43S pre-initiation complex (Wilson et al 2009). These physiological and biochemical processes paralleled the stimulation of skeletal muscle protein synthesis and led to the enhancement of protein synthesis in pigs. In addition, the rate of translation initiation is up-regulated earlier than elongation after feeding. Although the elongation is also increased after meal consumption, this increase is delayed relative to the change in initiation. Interestingly, increased rates of elongation did not further increase muscle protein synthesis in response to feeding, which therefore indicates that initiation is the rate-limiting step in translation (Wilson et al. 2009). Therefore, the increased rates of initiation, but not elongation, are responsible for the increase in muscle protein synthesis in response to feeding in pigs.