Effects of energy or protein restriction followed by realimentation on the composition of gain and meat quality characteristics of Musculus longissimus dorsi in pigs.

The effect of realimentation of fattening pigs on gain composition and intramuscular fat content in the longissimus dorsi muscle and their relationship to meat tenderness was investigated in 60 gilts. From day 90 to 168 of age, Group C (control) was fed according to the requirements, while from day 90 to 118 of age, Group R was fed restrictively (protein and energy) and Group P was fed restrictively with protein alone. This period was followed by adequate feeding. Comparative slaughter techniques were used; animals were slaughtered at the beginning of the study (day 90), at the end of the restriction period (day 118), and after two periods of realimentation (day 146 and day 168). Interactions between experimental treatments indicated that muscle protein gain (p < 0.05), muscle fat gain (p < 0.01), and shear force (p < 0.01) differed depending on period of realimentation. Muscle protein deposition differed only during the second period of realimentation, where Group R deposited more protein compared with Groups C and P (6.0, 4.5 and 5.0 g/d, respectively). Muscle fat deposition during the first period of realimentation was lower in Groups R and P than in Group C (0.73, 0.74 and 1.20 g/d, respectively) while in the second period Group R deposited considerably more fat than Groups C and P (2.39, 1.20 and 1.23 g/d, respectively). At the end of the first period, the shear force of Groups R and P was lower when compared with Group C (2.44, 2.79 and 3.22 kg, respectively); however, at final age it did not differ between treatments.