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A total of 45 gilts and 45 castrated males (57.8 ± 0.8 kg of BW, 3 gilts or 3 castrated males/pen) were assigned to finisher-1 diets. At an average pen BW of 81.0 ± 1.4 kg were assigned to finisher-2 diets. Corn-SBM, positive control (PC) diets were formulated to contain 6.1g and 4.7g of apparent ileal digestible (AID) Lys/kg, respectively. Corn-FM negative control (NC) diets were formulated to be iso-N to the PC diets. The NC diets were supplemented further with the third limiting AA, Thr (40+3AA; NC + Lys, Trp, and Thr), and fourth and fifth limiting AA, His and Ile (40+5AA; NC + Lys, Trp, Thr, His, and Ile), based on the assumption that the apparent ileal digestibility of all indispensable AA in FM is 40%. Blood samples were collected at the end of the study to analyze urea N, total protein, albumin, glucose, triglycerides and cholesterol. Pigs were slaughtered to collect samples of heart, liver and kidneys and to measure backfat thickness.
During the finisher-1 phase and finisher-2 phase pigs fed the PC diet consumed more feed (P=0.041) (P=0.005) and their AID Lys intake was considerably greater than those fed the NC diet (P<0.001). Pigs fed the PC diet grew faster and had greater G:F than those fed the NC diet (P<0.001). During the finisher-1 phase BW gain to AID Lys intake (G:LysI) was greater in the pigs fed the NC diet than those fed the PC diet (P<0.001). However, pigs fed the PC diet had greater G:LysI (P=0.015) than those fed the NC diet during the finisher-2 phase. Pigs fed the NC diet had less fat-free lean percentage (P=0.005), fat-free lean gain (LG) (P<0.001) and LG to feed intake (P<0.001) than those fed the PC diet. Pigs fed the NC diet had less serum total protein and albumin concentrations (P<0.001) but greater glucose (P=0.031) and cholesterol (P<0.001) concentrations than those fed the PC diet.
The results indicated that the corn-FM diets were not as effective as the corn-SBM diet in supporting BW gain of finisher pigs and seemed to indicate that pigs fed the corn-FM diet supplemented with the necessary AA can utilize feed and AA for BW gain and lean BW gain as efficiently as those fed the corn-SBM diet.
KC Divakala, LI Chiba, RB Kamalakar, SP Rodning, EG Welles, KA Cummins, J Swann, F Cespedes, and R. Payne. 2009. Journal of Animal Science, 87:1270-1281
