Effect of the degree and duration of early dietary amino acid restrictions on subsequent and overall pig performance and physical and sensory characteristics of pork

The objective of this study was to in- vestigate the effect of the degree and duration of early dietary AA restrictions on subsequent and overall pig performance and physical and sensory characteristics of pork. For the grower (G) and finisher-1 (F1) phases, 3 corn-soybean meal diets were formulated to contain 100, 80, or 60% of the 1998 NRC total Lys recom- mendations (100G, 80G, or 60G, and 100F1, 80F1, or 60F1, for the G and F1 phases, respectively). For the finisher-2 (F2) phase, a common corn-soybean meal diet was formulated to satisfy the 1998 NRC total Lys recommendation. Thirty gilts and 30 castrated males (2 gilts or 2 castrated males/pen) were randomly assigned to 5 dietary treatments (100G-100F1, 80G-100F1, 80G- 80F1, 60G-100F1, and 60G-60F1) when BW was 22.7 ± 0.3 kg. Pigs were switched to F1 and F2 diets at 50.7 ± 0.4 and 79.9 ± 0.5 kg of BW, respectively. Pigs had ad libitum access to feed and water. All pigs were slaughtered at 110.7 ± 0.5 kg of BW, and LM samples were collected. Pigs fed the 60G diet had less (P ≤ 0.05) ADG during the G phase and greater (P ≤ 0.05) ultrasound backfat (UBF) at the end of the G phase than those fed the 100G diet. The ADG decreased lin- early (R 2 = 0.70; P < 0.001) as the degree of AA re- strictions became more severe. Although serum total protein (TP) and albumin concentrations in pigs fed the 60G-100F1 diets were less (P ≤ 0.05) than those