Barley (Hordeum vulgare) and wheat (Triticum aestivum) are often stored dry with 14% or less moisture, which during rainy periods may require that grains are dried after harvest. The hypothesis is that air-tight storage of high-moisture barley and wheat will increase nutrient digestibility due to chemical conversions prior to feeding. The objective was to evaluate the effect of high moisture compared to dry storage of barley and wheat on digestibility of P and CP. The crops were grown on 1 field keeping other factors constant. Half of the grains was harvested in the morning after a rainy day and stored in air-tight silos (DM, %: barley, 85.2; wheat, 82.8) and the other half was harvested later the same day (windy and sunny) and stored dry (DM, %: barley, 89.8; wheat, 88.3). After 6 mo of storage, 1 low- and 1 high-moisture diet were prepared with a barley:wheat ratio of 1:1 mixed with soybean (Glycine max) meal and rapeseed cake to produce a compound diet without inorganic P and microbial phytase. Sixteen 45-kg pigs housed in metabolism crates were fed either the low- or the high-moisture diet for 5 d for adaptation and 7 d for total collection of feces. Digestibility of P was 12% higher (P < 0.01) and of CP was 4% higher (P = 0.08) in the high-moisture diet. Phytase activity of dry-stored grain was lower (P < 0.01) and phytate P was 4% higher in the high-moisture stored grain vs. the grains stored dry. Overall, high-moisture storage increased digestibility of P and CP when the grain was fed to finishing pigs. Therefore, high-moisture air-tight storage saved energy (without drying) and at the same time enhanced P digestibility and increased the nutritional value of grain probably through enzymatic activity during storage.

Soybean meal (SBM) contains anti-nutritional factors (ANF) that may limit kinetics and total extent of protein digestion in pigs. This study evaluated effects of thermo-mechanical and enzyme-facilitated (TE) processing on in vitro kinetics of crude protein (CP) digestion and CP and amino acid (AA) digestibility in weaned pigs. Each batch of SBM (48% CP) was divided into 2 parts: non-processed SBM as control vs. thermo-mechanical and enzyme-facilitated processed soybean meal (TES) as experimental group. For digestion kinetics, samples (3 batches of non-processed SBM vs. TES) were incubated in triplicate sequentially with pepsin at pH 3.5 for 1.5 h (stomach phase), and subsequently with pancreatin and bile extract at pH 6.8 for 0, 0.5, 1, 2, 4, or 6 h (small intestine phase). Protein was classified into CPfast, CPslow, and CPresistant corresponding to CP digested within the first 0.5 h, from 0.5 to 4 h, and after 4 h plus undigested CP, respectively. Eight weaned barrows (Large White × Duroc, 9.43 ± 0.40 kg) were surgically fitted with a T-cannula at the terminal ileum. Pigs were randomly assigned to a Youden square with 3 diets over 4 periods. The 3 diets were an N-free diet and 2 diets using 40% SBM or TES as sole source of AA with Cr2O3 as an indigestible marker. Each period included sequentially a 5-d adaptation, 2-d collection of feces, and 2-d collection of ileal digesta. The TE processing reduced ANF content in TES by 91% for lectin, 22% for trypsin inhibitor activity, 75% for β-conglycinin, and 62% for glycinin compared to SBM. In vitro, TE processing increased (P &lt; 0.05) digested CP by 5.6% and enhanced kinetics of CP digestion by tending to increase (P = 0.056) CPfast by 25% and reducing (P &lt; 0.05) CPslow and CPresistant by 48 and 11%, respectively. In pigs, TE processing increased (P &lt; 0.05) apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of CP in TES by 2.3 and 2.1%, respectively. The TE processing increased (P &lt; 0.05) AID and SID of all AA up to 3.3%, except for AID of Pro and SID of Pro, Gly, and Cys. The TE processing did not change reactive Lys or Lys:CP but increased (P &lt; 0.05) SID of Lys and reactive Lys by 3%. Combined, the greater in vitro digestion kinetics matched the greater in vivo AID and SID of CP in TES and lower ANF compared to SBM. Thus, TE processing created a protein source that is digested faster and to a greater extent than SBM, thereby lowering the chance of protein fermentation.

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The objective of the study was to evaluate the effect of screen size (1, 2 and 3 mm) and microbial phytase (0 and 1000 FTU/kg as-fed) on phytate degradation in maize (100% maize), soybean meal (100% SBM) and maize-SBM (75% maize and 25% SBM) incubated in water for 0, 2, 4, 8 and 24 h at 38°C. Samples were analysed for pH, dry matter and phytate phosphorus (P). Particle size distribution (PSD) and average particle size (APS) of samples were measured by the Laser Diffraction and Bygholm method. PSD differed between the two methods, whereas APS was similar. Decreasing screen size from 3 to 1 mm reduced APS by 48% in maize, 30% in SBM and 26% in maize-SBM. No interaction between screen size and microbial phytase on phytate degradation was observed, but the interaction between microbial phytase and incubation time was significant ( P < 0.001). This was because microbial phytase reduced phytate P by 88% in maize, 84% in maize-SBM and 75% in SBM after 2 h of incubation ( P < 0.05), whereas the reduction of phytate P was limited (<50%) in the feeds, even after 24 h when no microbial phytase was added. The exponential decay model was fitted to the feeds with microbial phytase to analyse the effect of screen size and feed on microbial phytase efficacy on phytate degradation. The interaction between screen size and feed affected the relative phytate degradation rate ( R d ) of microbial phytase as well as the time to decrease 50% of the phytate P ( t1 = 2 ) ( P < 0.001). Thus, changing from 3 to 1 mm screen size increased R d by 22 and 10%/h and shortened t1 = 2 by 0.4 and 0.2 h in maize and maize-SBM, respectively ( P < 0.05), but not in SBM. Moreover, the screen size effect was more pronounced in maize and maize-SBM compared with SBM as a higher phytate degradation rate constant (K d ) and R d , and a shorter t1 = 2 was observed in maize compared with SBM in all screen sizes ( P < 0.05). However, a higher amount of degraded phytate was achieved in SBM than in maize because of the higher initial phytate P content in SBM. In conclusion, reducing screen size from 3 to 1 mm increased K d and R d and decreased t1 = 2 in maize and maize-SBM with microbial phytase. The positive effect of grinding on improving microbial phytase efficacy, which was expressed as K d , R d and t1 = 2 , was greater in maize than in SBM.