BackgroundDuring processing in a desolventizer/toaster (DT), rapeseed meal (RSM) is heated to evaporate the hexane and to reduce the level of heat-labile anti-nutritional factors such as glucosinolates (GSL). However, excessive heat treatment may reduce amino acid (AA) content in addition to lower AA digestibility and availability in RSM. The objective of the present study was to produce from one batch of a 00-rapeseed variety (17 μmol GSL/g dry matter (DM), seed grade quality) five differently processed RSM under standardized and defined conditions in a pilot plant, and to determine the impact of these different treatments on protein solubility and chemical composition, in particular with regard to contents of AA including reactive Lys (rLys) and levels of total and individual GSL.MethodsFour RSM were exposed to wet toasting conditions (WetTC) with increasing residence time in the DT of 48, 64, 76, and 93 min. A blend of these four RSM was further processed, starting with saturated steam processing (< 100 °C) and followed by exposure to dry toasting conditions (DryTC) to further reduce the GSL content in this RSM.ResultsThe contents of neutral detergent fiber and neutral detergent fiber bound crude protein (CP) increased linearly (P < 0.05), as residence time of RSM in the DT increased from 48 to 93 min, whereas contents of total and most individual GSL and those of Lys, rLys, Cys, and the calculated ratio of Lys:CP and rLys:CP decreased linearly (P ≤ 0.05). The combination of wet heating and DryTC resulted in the lowest GSL content compared to RSM produced under WetTC, but was associated with lowest protein solubility.ConclusionsIt can be concluded that by increasing residence time in the DT or using alternative processing conditions such as wet heating combined with DryTC, contents of total and individual GSL in RSM can be substantially reduced. Further in vivo studies are warranted to elucidate if and to which extent the observed differences in protein quality and GSL content between RSM may affect digestibility and bioavailability of AA in monogastric animals.

Five rapeseed meals (RSM) were produced from a single batch of rapeseed in a large-scale pilot plant under standardized conditions. The objective was to evaluate the effect of residence time in the desolventizer/toaster (DT) on chemical composition and standardized ileal digestibility (SID) of AA in RSM. Four RSM, with 48, 64, 76, and 93 min residence time and using unsaturated steam in the DT, referred to as RSM48, RSM64, RSM76, and RSM93, respectively, and 1 low-glucosinolate RSM, which was subjected to sequential treatment with unsaturated steam, saturated steam, and dry heat in the DT, referred to as low-GSL RSM, were assayed. Six barrows (average initial BW = 22 ± 1 kg) were surgically fitted with a T-cannula at the distal ileum. Pigs were allotted to a 5 × 6 row × column design with 5 diets and 5 periods. The 5 RSM were included in a cornstarch-casein-based basal diet. In addition, basal ileal endogenous losses and SID of AA originating from casein were determined at the conclusion of the experiment in 2 additional periods by means of the regression method and using 3 graded levels of casein. The SID of AA in the 5 RSM was determined in difference to SID of AA originating from casein. The glucosinolates (GSL) were efficiently reduced, whereas NDF, ADF, ADL, and NDIN contents increased and reactive Lys (rLys) and Lys:CP ratio decreased as the residence time in the DT was increased from 48 to 93 min. The SID of most AA in RSM linearly decreased (P < 0.05) as the residence time in the DT increased from 48 to 93 min. Moreover, there was a linear decrease (P < 0.05) in SID of AA with increasing NDF, ADF, ADL, and NDIN contents in these RSM, whereas SID of AA linearly decreased (P < 0.05) with decreasing levels of GSL and rLys and a decreasing Lys:CP ratio. The decrease (P < 0.05) in SID of AA amounted from 3 up to 6 (percentage units) for most AA, except for SID of Cys and Lys, which decreased by 10 and 11%-units (P < 0.05), respectively, as the residence time in the DT was increased from 48 to 93 min. The SID in low-GSL RSM was for CP and most AA similar to RSM93 but lower ( < 0.05) compared to RSM48. It can be concluded that time and energy-intensive heat treatment results in lower contents of SID AA in RSM together with a reduction in GSL levels. The feed industry would most likely benefit from a rapid and accurate prediction of SID of AA, for example, based on content of NDIN, GSL, rLys or on Lys:CP ratio, in different batches of RSM used for feed manufacturing.

Dairy cows are customarily given grains and highly digestible byproduct ingredients as additions to forage to support milk production. In many parts of the world growing seasons are short, and the grain crops that can be grown may not provide adequate yields. Sugar beets, on the other hand are relatively hardy, and dry matter yields surpass the yields of most grain crops. There are however, perceptions that beets may not be suitable as a feed ingredient due to the fact that the storage form of carbohydrate is sugar rather than starch. With little analytical support, sugar has been rejected in many feeding programs with the view that sugar reduces rumen pH, fiber digestion and microbial yield. This review explores available facts revolving around these concerns. Information regarding the feeding of sugar beets is provided and the use of sugar beets as a partial replacement for grain is proposed.

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A study with growing barrows was conducted to evaluate of variations in particle size and degree of heat treatment during processing on standardized ileal digestibility (SID) of AA in soybean (Glycine max) meal (SBM). A commercial SBM batch was visually identified as being overtoasted due to its brownish color and was separated into small and large particles using a 1-mm sieve. In addition, 3 SBM were produced from 1 batch of soybean and exposed to different processing conditions (temperature and direct steam contact) referred to as mild (105°C; 34 min), medium (115°C; 45 min), and strong (139°C; 7 min). In total, 5 SBM-corn (Zea mays) starch-based diets were formulated to contain SBM as the sole protein source. This experiment was conducted according to a 6 × 6 Latin square design using 6 barrows (23 kg initial BW) fitted with a T-cannula at the distal ileum. With increasing particle size, SID of His and some dispensable AA increased (P < 0.05). Lower SID values in small compared to large SBM particles indicate more pronounced heat damage possibly due to increased surface area. The SID of CP and AA was lowest in the mild, intermediate in the strong, and highest in the medium toasted SBM (P < 0.001). These differences in SID are reflected in varying contents of trypsin inhibitors, Lys, reactive Lys, and NDF. In conclusion, both differences in particles size and variations in thermal processing conditions of SBM may affect SID of CP and AA.