Complete Replacement of Soybean Meal in Pig Diets with Hydrolyzed Feather Meal with Blood by Amino Acid Supplementation Based on Standardized Ileal Digestibility
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The current study was conducted to examine the possibility of completely replacing soybean meal (SBM) with hydrolyzed feather meal with blood (FM) by supplementing with appropriate AA based on standardized ileal digestible (SID) AA in FM. Corn-SBM, positive control (POS) diets were formulated to contain 6.6 and 5.2 g true ileal digestible (TID) Lys/kg to satisfy the requirements during the finisher-1 and finisher-2 phases, respectively. Corn-FM negative control (NEG) diets were formulated to be iso-N and iso-caloric to the POS diets. The NEG diets were supplemented with Lys and Trp to alleviate AA deficiencies based on TID AA values in FM reported by the 1998 NRC (NRC). In addition, the NEG diets were supplemented with Lys and Trp to alleviate AA deficiencies based on the determined SID of AA in FM (SID). Thirty-two gilts and 32 castrated males were selected for the study. When they weighed 50.0 ± 2.9 kg, pigs (2 gilts or 2 castrated males/pen) were randomly assigned to 1 of 4 finisher-1 phase diets with 4 gilt pens and 4 castrated male pens/diet. When average pen weight was 79.0 ± 2.0 kg, pigs were switched to finisher-2 phase diets. Pigs had ad libitum access to feed and water throughout the study. At the end of the finisher-2 phase (107.7 ± 3.3 kg), blood samples were collected and analyzed for serum metabolites. Overall growth performance indicated that total Lys intake (P = 0.029) increased and ADFI tended to increase (P = 0.083) in pigs fed the POS diets compared with those fed the SID diets, which may have resulted in the tendency for POS pigs to have slightly greater ADG (P = 0.094). No differences were observed between the treatments in the efficiency of feed or Lys utilization for BW gain. Pigs fed the SID diets tended to have greater G:F (P = 0.057) and had greater gain:total Lys intake (P < 0.001) than those fed the NRC diets. As expected, pigs fed the POS diets performed better than those fed the NEG diets in terms of ADG (P < 0.001) and G:F (P < 0.001), consumed more total Lys (P < 0.001), and tended to have greater ADFI (P = 0.079) than pigs fed the NEG diets. However, pigs fed the NEG diets had increased BW gain:Lys intake (P < 0.001) compared with pigs fed the POS diets. Dietary treatments had no effect on dressing percentage, last rib backfat, fat-free lean gain:Lys intake, or subjective meat quality scores. Pigs fed the POS diets had greater fat-free lean accretion (P = 0.020) than SID pigs, but there were no differences between the treatments for LM area, fat-free carcass %, or the efficiency of feed and Lys utilization for lean gain. Pigs fed the POS diets had increased LM areas (P = 0.012), rates (P < 0.001) and proportion (P = 0.03) of carcass lean, and lean gain:feed (P < 0.001) than those fed the NEG diets. Dietary treatments had no effect on serum glucose concentrations. Pigs fed the POS diets had greater urea-N (P = 0.003), but lower cholesterol (P = 0.002) concentrations than those fed the SID diets. Pigs fed the NEG diet had reduced total protein (P < 0.001), and increased urea-N (P = 0.001), triglycerides (P < 0.001), and cholesterol (P < 0.001) concentrations compared to those fed the POS diets. The results indicated that pigs fed the corn-FM diets supplemented with AA based on the SID of AA in FM utilized feed and Lys for BW gain as efficiently as pigs fed corn-SBM diets. However, pigs fed the SID diets had slightly reduced BW gain and lean gain compared with those fed the POS diets, perhaps because of slightly reduced feed and Lys intake.