Amino acid utilization and body composition of growing pigs fed processed soybean meal or rapeseed meal with or without amino acid supplementation

Feed ingredients used in swine diets are often processed to improve nutritional value. However, (over-)processing may result in chemical reactions with amino acids (AAs) that decrease their ileal digestibility. This study aimed to determine effects of (over-)processing of soybean meal (SBM) and rapeseed meal (RSM) on post-absorptive utilization of ileal digestible AAs for retention and on body AA composition of growing pigs. Soybean meal and RSM were processed by secondary toasting in the presence of lignosulfonate to obtain processed soybean meal (pSBM) and processed rapeseed meal (pRSM). Four diets contained SBM, pSBM, RSM or pRSM as sole protein source. Two additional diets contained pSBM or pRSM and were supplemented with crystalline AA to similar standardized ileal digestible (SID) AA level as the SBM or RSM diet. These diets were used to verify that processing affected AA retention by affecting ileal AA digestibility rather than post-absorptive AA utilization. The SID AA levels of the protein sources were determined in a previous study. In total, 59 pigs were used (initial BW of 15.6±0.7 kg) of which five were used to determine initial body composition at the start of the experiment. In total, 54 pigs were fed one of six experimental diets and were slaughtered at a BW of 40 kg. The organ fraction (i.e. empty organs plus blood) and carcass were analyzed separately for N and AA content. Post-absorptive AA utilization was calculated from AA retention and SID AA intake. An interaction between diet type, comprising effects of processing and supplementing crystalline AA, and protein source was observed for CP content in the organ fraction, carcass and empty body and for nutrient retention. Processing reduced CP content and nutrient retention more for SBM than for RSM. Moreover, processing reduced (P<0.001) the lysine content in the organ fraction for both protein sources. Supplementing crystalline AA ameliorated the effect of processing on these variables. Thus, the data indicated that processing affected retention by reducing digestibility. Correcting AA retention for SID AA intake was, therefore, expected to result in similar post-absorptive AA utilization which was observed for the RSM diets. However, post-absorptive AA utilization was lower for the pSBM diet than for the SBM diet which might be related to an imbalanced post-absorptive AA supply. In conclusion, processing negatively affected nutrient retention for both protein sources and post-absorptive utilization of SID AA for retention for SBM. Effects of processing were compensated by supplementing crystalline AA.

Processing of soybean meal and 00-rapeseed meal reduces protein digestibility and pig growth performance but does not affect nitrogen solubilization along the small intestine

An experiment was conducted to determine the effects of processing of soybean meal (SBM) and 00-rapeseed meal (RSM) on N solubilization in chyme, CP digestibility along the small intestine, metabolic load as determined by organ weight, body composition, and growth performance in growing pigs. The SBM and RSM were processed by secondary toasting (at 95°C for 30 min) in the presence of lignosulfonate, resulting in processed SBM (pSBM) and processed RSM (pRSM) as a model for overprocessed protein sources. Fifty-four growing pigs were each fed 1 of the 6 experimental diets. Four of the diets contained SBM, pSBM, RSM, or pRSM as the sole protein source. The remaining 2 experimental diets contained pSBM or pRSM and were supplemented with crystalline AA to the same standardized ileal digestible AA levels as the SBM or RSM diet. Pigs were slaughtered at 40 kg, and organ weights were recorded. The organs plus blood and empty carcass were analyzed for CP content. The small intestine was divided into 3 segments, and chyme samples were taken from the last meter of each segment. Chyme of the SBM, pSBM, RSM, and pRSM diets was centrifuged to separate the soluble and insoluble fractions, and N content was determined in the latter. The amount of insoluble N as a fraction of N in chyme at each small intestinal segment was not affected by processing. Diet type, comprising effects of processing and supplementing crystalline AA, affected ( < 0.05) the G:F and standardized ileal digestibility (SID) of CP. Processing reduced G:F from 0.56 to 0.38 for SBM and 0.49 to 0.40 for RSM, whereas supplementing crystalline AA increased G:F to the level of the SBM and RSM diets. Processing reduced the SID of CP from 87.2% to 69.2% for SBM and 71.0% to 52.2% for RSM. Diet type affected ( < 0.05) the CP content in the empty body, with processing reducing this content from 170 to 144 g/kg empty BW for SBM and 157 to 149 g/kg empty BW for RSM and supplementing crystalline AA restoring this content. Processing reduced ( < 0.05) the weight of several organs, and supplementing crystalline AA restored organ weight. In conclusion, processing increased the amount of N in the chyme, reduced organ weight, body CP content, and G:F. These effects were caused by a reduction in available AA as supplementing crystalline AA restored organ weight, body CP content, and G:F.

Assessment of protein quality of soybean meal and 00-rapeseed meal toasted in the presence of lignosulfonate by amino acid digestibility in growing pigs and Maillard reaction products

An experiment was conducted to determine protein quality in processed protein sources using the content of AA, -methylisourea (OMIU)-reactive Lys, Maillard reaction products (MRP), and cross-link products; the standardized ileal digestibility (SID) of CP and AA; and growth performance in growing pigs as criteria. Differences in protein quality were created by secondary toasting (at 95°C for 30 min) of soybean meal (SBM) and rapeseed meal (RSM) in the presence of lignosulfonate resulting in processed SBM (pSBM) and processed RSM (pRSM). The processing treatment was used as a model for overprocessed protein sources. Ten growing pigs were each fed 1 of the 4 diets containing SBM, pSBM, RSM, or pRSM in each of 3 periods. Ileal chyme was collected at the end of each period and analyzed for CP, AA, and OMIU-reactive Lys. Diets were analyzed for furosine and carboxymethyllysine (CML) as an indicator for MRP and lysinoalanine (LAL), which is a cross-link product. The SBM and RSM diets contained furosine, CML, and LAL, indicating that the Maillard reaction and cross-linking had taken place in SBM and RSM, presumably during the oil extraction/desolventizing process. The amounts of furosine, CML, and LAL were elevated in pSBM and pRSM due to further processing. Processing resulted in a reduction in total and OMIU-reactive Lys contents and a decrease in G:F from 0.52 to 0.42 for SBM and 0.46 to 0.39 for RSM ( = 0.006), SID of CP from 83.9 to 71.6% for SBM and 74.9 to 64.6% for RSM ( < 0.001), and SID of AA ( < 0.001), with the largest effects for total and OMIU-reactive Lys. The effects of processing could be substantial and should be taken into account when using processed protein sources in diets for growing pigs. The extent of protein damage may be assessed by additional analyses of MRP and cross-link products.