Amino acid digestibility in heated soybean meal fed to growing pigs1

Abstract

Heat treatment of soybean meal (SBM) is necessary to reduce the concentration of trypsin inhibitors, but excessive heat treatment may reduce AA concentration and digestibility because AA can be destroyed by the Maillard reaction. The objective of this experiment was to determine the effects of heat treatment of SBM on apparent ileal digestibility and standardized ileal digestibility (SID) of AA by growing pigs. A source of conventional dehulled SBM (48.5% CP) was divided into 4 batches. One batch was not additionally heated, 1 batch was autoclaved at 125°C for 15 min, 1 batch was autoclaved at 125°C for 30 min, and 1 batch was oven-dried at 125°C for 30 min. Four SBM-cornstarch diets were formulated, and each of the 4 batches of SBM was used as the sole source of dietary AA in 1 diet. A N-free diet was used to estimate basal endogenous losses of AA. Ten growing barrows with an initial BW of 25.3 ± 2.0 kg were individually fitted with a T-cannula in the distal ileum. Pigs were allotted to treatments in a replicated 5 × 5 balanced Latin square design with 5 diets and 5 periods. Each period lasted 7 d, and ileal digesta were collected on d 6 and 7 of each period. Results of the experiment indicated that the apparent ileal digestibility and SID of CP and all AA decreased linearly (P < 0.01) as the time of autoclaving increased from 0 to 30 min. The concentration of furosine and the color of samples of SBM indicated that autoclaving resulted in a Maillard reaction in the SBM. However, oven drying at 125°C for 30 min did not change (P > 0.10) the SID of CP and AA in the SBM or the furosine concentration, and the color in the oven-dried sample indicated that this sample was not heat damaged. In conclusion, the digestibility of all AA in autoclaved SBM is linearly reduced as the autoclaving time increases from 0 to 30 min. The reason for these changes is most likely that autoclaving at 125°C results in Maillard reactions in SBM.

Effects of balancing crystalline amino acids in diets containing heat-damaged soybean meal or distillers dried grains with solubles fed to weanling pigs

“…The concentrations of dry matter, CP and indispensable amino acids in the non-autoclaved SBM used in this experiment are in agreement with values reported by Fontaine et al (2007) and González-Vega et al (2011). Based on Evonik's database (AminoDat ® 4.0) an SBM with an HDI around 12 represents an average quality SBM.…”

“…In contrast, the autoclaved SBM had an HDI of 40, which confirms that this SBM was heat damaged. Likewise, a lysine : CP ratio in SBM above 6.0 indicates that the SBM has not been heat damaged, whereas a lysine : CP ratio of <6.0 indicates heat damage (González-Vega et al, 2011). The fact that lysine : CP ratios of 6.09 and 5.40 were calculated for Adjusting diet formulations to weaned pigs the non-autoclaved and autoclaved SBM used in this experiment clearly indicates that the autoclaved SBM was severely heat damaged, whereas the non-autoclaved SBM was not heat damaged.…”

“…Ingredients and diets were analysed for dry matter by drying in an oven at 103°C for 4 h (Method 935.29; AOAC International, Gaithersburg, MD, USA), ADF (Method 973.18;AOAC International, 2007), NDF (Holst, 1973), CP according to the Dumas procedure (Method 968.06;AOAC International, 2007), and amino acids as previously described (González-Vega et al, 2011). Diets were also analysed for gross energy using bomb calorimetry (Model 6300; Parr Instruments, Moline, IL, USA).…”

“…The concentration and the digestibility of amino acids by growing pigs in feed ingredients decrease gradually with increasing degree of heat treatment (Fontaine et al, 2007;Pahm et al, 2008;González-Vega et al, 2011). Whereas amino acid analysis of raw materials by rapid methods such as near-IR spectroscopy (NIRS) can identify amino acid losses in heat-damaged ingredients, which may be considered in diet formulation, rapid estimations of changes in amino acid digestibility in different sources of ingredients is more challenging.…”

Energy content and amino acid digestibility of extruded and dehulled-extruded corn by pigs and its effect on the performance of weaned pigs

“…This may have caused increased damage to the protein and AA thus causing the reduction of AA digestibility in dehulled-extruded corn and dehulled-extruded corn diet. Finally, dehulled-extruded corn had a much lower Lys : CP ratio compared with raw and extruded corn in this experiment, which is the best method for assessing heat damage and, therefore, a reduction in the AID and SID of AA in dehulled-extruded corn and diet containing dehulled-extruded corn was observed (González-Vega et al, 2011).…”