Effect of a lysine depletion–repletion protocol on the compensatory growth of growing-finishing pigs1

The effect of Lys restriction followed by a repletion period on the performance of growing pigs was studied during 3 feeding phases, each lasting 28 d. A total of 47 castrated male pigs (G Performer 8.0 × Fertilis 25 pigs; Genetiporc Inc., Saint-Bernard, QC, Canada; initial BW of 26.7 ± 2.7 kg) were given each d 70% or 100% of their Lys requirements according to 1 of the following 5 sequences: 70–70–70, 70–70–100, 70–100–70, 70–100–100, or 100–100–100 (for each sequence, numbers indicate the Lys supply percentage in phase 1, 2, and 3, respectively). Individual Lys requirements were estimated daily on the basis of each pig’s actual BW and feed intake and BW gain patterns obtained by regression using each pig’s historical data. At the end of phase 1, the pigs given 100% of their Lys requirements had higher ADFI (P = 0.01), ADG (P < 0.01), and average daily protein deposition (P < 0.01) than did the pigs given 70% of their requirements. Similar results were observed during phases 2 and 3. At the end of phase 2, the pigs in the 70–100 sequence did not display any compensatory response, given that their ADFI, ADG, and average daily protein deposition did not differ from those of the pigs in the 100–100 sequence. Similar results were observed during phase 3. Although no compensatory growth was observed during the growing phases, the fact that the pigs in the 70–100–100 treatment were able to catch up in terms of BW and body protein mass to the pigs in the 100– 100–100 sequence could indicate that a small degree of compensation did occur; these research results cannot ascertain that any compensatory growth occurred.