Effects of heat treatment on the nutritional value of raw soybean selected for low trypsin inhibitor activity

Abstract

1. Two broiler experimentss and a layer experiments were conducted on Kunitz trypsin inhibitor (Kti) soybeans (SB) of low trypsin inhibitor (TI) activity to determine their nutritive value when included as mash in least-cost poultry diets. 2. Experiment 1 compared chick performance on the Kti or raw SB using a commercial full-fat SB meal (FFSBM) and a solvent extracted SB meal (SBM) as controls during a 20 d experimental period. Broiler experiment 2 compared Kti and raw SB, non-steamed, or steam-pelleted with and without DL-methionine supplementation added to every treatment containing 170 g SB/kg. For each broiler experiment the levels of each SB were 70, 120 and 170 g/kg with the control birds fed only 170 g SB/kg. 3. The layer experiment, compared steam-pelleted Kti and raw SB against a non-steamed Kti and raw SB each fed at two levels (70 and 110 g/kg) x 30 replicates from 29 weeks of age for 19 weeks in a completely randomised design. Production parameters were measured when diets were formulated to contain minimum required specifications and calculated apparent metabolisable energy (AME). At the completion of each trial, 2 broiler birds from each cage and 5 layer birds per treatment were killed, weighed, and their liver and pancreas weighed. 4. Both broiler experiments indicated that production parameters on the Kti SB treatments were significantly lower (P<0.05) than on the two commercial control SB treatments. However, the Kti treatments were superior to the raw SB treatments. 5. Pancreas weight increased with increasing inclusion of both raw and Kti SB, suggesting that a TI was causing the depression in performance. The AME of the Kti SB was similar to that of commercial FFSB meal. After steam conditioning, the raw SB meal AME value of 9.5 MJ/kg dry matter (DM) was improved to 14.1 MJ/kg DM by reduced TI activity, but this AME improvement with TI activity reduction, plus the supplementation with DL-methionine on birds fed the raw SB had no effect (P>0.05) on any parameter evaluated in experiment 2. 6. The layer experiment showed that hens on the Kti SB treatments had significantly greater live weight gain (LWG), egg weight and daily egg mass than birds given raw SB. A reduced food intake (FI) was observed in the Kti treatments but egg mass was generally similar to that on the FFSB control diet, indicating that Kti SB supported excellent egg production at an inclusion of 110 g/kg. The depressed performance observed for broiler chicks suggest that younger birds are more susceptible to the effects of SB TI.

The effect of soybean meal replacement with raw full-fat soybean in diets for broiler chickens

“…Although the trypsin activity increased with increasing dietary inclusion of RFFS, this did lead to improved animal performance. TI activity, according to Ruitz et al (2004), is significantly correlated with BW, and FCR and pancreas weight increase with increasing dietary inclusion of raw soybean (Perez-Maldonado et al 2003). Similar results were achieved in our study.…”

Effect of extruded full-fat soybeans on performance, amino acids digestibility, trypsin activity, and intestinal morphology in broilers

“…Pancreas weight increases with increasing inclusion of both raw and Kunitz trypsin inhibitor SB, suggesting that TI is causing the depression in performance (Perez-Maldonado et al, 2003). Minimum pancreas weight was observed when chickens were fed FFSB extruded at 140°C (Perilla et al, 1997).…”

Reduction of protease inhibitor activity by expression of a mutant Bowman-Birk gene in soybean seed

“…This inhibition acts to reduce the activity of intestinal enzymes, and that is considered to lead to a reduction in nutrient absorption. Both KTI and BBI have been linked to pancreas hypertrophy and hyperplasia in animals that consume the inhibitors (Perez-Maldonado et al 2003).…”

“…Protease inhibitors are major contributors to the anti-nutritional properties of soybean meal (Clarke and Wiseman 2000;Perez-Maldonado et al 2003). The two principle protease inhibitors in soybean are the Kunitz trypsin inhibitor (KTI) and Bowman-Birk (BBI) family of isoinhibitors (Birk 1985).…”