Whole-body growth, carcass growth and primal mass as indices of lysine adequacy in high lean growth pigs
ME Johnston, RD Boyd, B Fields, C Booher, CE Fralick, CE Zier-Rush, and AA Sosnicki, 2010. Journal of Animal Science, 87 (E-Suppl. 3):54.
06-Oct-2010 (15 years 8 months 1 days ago)This experiment was conducted to determine if the lysine level that is required to maximize whole-body (WB) growth is comparable to that needed for carcass growth and primal mass. Second, to determine if the metabolism modifier ractopamine (PLN) improved primal mass and (or) primal distribution. 320 castrates were used in a growth assay from 22.9 kg (± .9 kg) to 131.5 (± 1.4 kg) in pens of 10 pigs/ pen. Pigs were blocked by weight and randomly allotted to diet regimens (8 pens/diet). Treatments consisted of 4 diet treatments, administered in 5 phases. Three involved feeding to different lysine curves (88, 100, 112% specification). The fourth treatment involved feeding PLN to pigs having received the standard diet (100%) until 28 d pre-slaughter.
PLN was provided at 7.2 ppm (14 d, 1.05% SID Lysine) followed by 8.8 ppm (15 to 28 d, 0.95% SID Lysine). The assay was time constant (105 d). WB ADG averaged 1.035 ± 0.015 kg/d (P=0.154) for the Lysine curves (88, 100, 112% Lysine specification). However, carcass yield declined linearly (P<0.05; 76.5, 76.2, 74.4%) as specification increased. Thus, carcass ADG tended to decline (0.796, 0.775, 0.778 kg/d) and total carcass weight declined (P<0.02) as Lysine increased. WB G:F ratio improved (P<0.005) in a linear manner (0.422, 0.431, 0.439) with increasing Lysine. PLN improved (P<0.001) WB ADG (1.218 kg/d) and WB G:F ratio (0.398), during the final 28 d period, when compared to the 100% counterpart (1.059, 0.341). FOM Lean was improved with PLN(P<0.001, 54.9% vs 52.7). Carcasses were cut into primal and subprimal parts and related to a constant carcass end-weight (99.5 kg). Total primal weight did not differ for Lysine curves (avg. 79.1 g/carcass), but PLN treatment improved primal weight (81.4 kg, P<0.15) and primal percent of carcass (81.7 vs 79.4%).
We conclude that a Lysine specification that is based only on WB growth may conflict with carcass growth, because yield is adversely affected by a high level. PLN increased the total primal and sub-primal mass by more than 2 kg.
PLN was provided at 7.2 ppm (14 d, 1.05% SID Lysine) followed by 8.8 ppm (15 to 28 d, 0.95% SID Lysine). The assay was time constant (105 d). WB ADG averaged 1.035 ± 0.015 kg/d (P=0.154) for the Lysine curves (88, 100, 112% Lysine specification). However, carcass yield declined linearly (P<0.05; 76.5, 76.2, 74.4%) as specification increased. Thus, carcass ADG tended to decline (0.796, 0.775, 0.778 kg/d) and total carcass weight declined (P<0.02) as Lysine increased. WB G:F ratio improved (P<0.005) in a linear manner (0.422, 0.431, 0.439) with increasing Lysine. PLN improved (P<0.001) WB ADG (1.218 kg/d) and WB G:F ratio (0.398), during the final 28 d period, when compared to the 100% counterpart (1.059, 0.341). FOM Lean was improved with PLN(P<0.001, 54.9% vs 52.7). Carcasses were cut into primal and subprimal parts and related to a constant carcass end-weight (99.5 kg). Total primal weight did not differ for Lysine curves (avg. 79.1 g/carcass), but PLN treatment improved primal weight (81.4 kg, P<0.15) and primal percent of carcass (81.7 vs 79.4%).
We conclude that a Lysine specification that is based only on WB growth may conflict with carcass growth, because yield is adversely affected by a high level. PLN increased the total primal and sub-primal mass by more than 2 kg.