0
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.
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.
