Dietary galactooligosaccharides affect ileal and total-tract nutrient digestibility, ileal and fecal bacterial concentrations, and ileal fermentative characteristics of growing pigs

The objective of this study was to evaluate dietary galactooligosaccharide (Gal OS) addition on swine nutrient digestibility, ileal and fecal bacterial populations, and ileal short-chain fatty acid (SCFA) production, and to determine their impact on ileal fermentative characteristics in vitro. Twelve T-cannulated pigs (BW = 25 kg) were fed a diet free of Gal OS for 21 d. On d 22, ileal digesta samples were collected for an in vitro fermentation experiment (Exp. 1). Substrates included: raffinose/stachyose combination (R + S), soy solubles (SS), and transgalactooligosaccharides (TOS). Also included were the non-OS components of SS and TOS. Nine pigs (three donors per treatment) served as ileal effluent donors. Each substrate was fermented in vitro for 6 h, and pH and SCFA and gas production were determined. Pigs then were allotted to three treatments: a Gal OS-free control diet and the control diet with either 3.5% added Gal OS from SS or TOS. Diets, feces, and digesta samples collected weekly for 6 wk on d 6 (feces) and 7 (digesta) were analyzed for DM, OM, CP, and chromic oxide concentrations. Feces and ileal digesta were analyzed for bifidobacteria and lactobacilli populations. Ileal digesta samples were analyzed for SCFA. On d 64, a second in vitro fermentation experiment (Exp. 2) was conducted using ileal effluent from three pigs per treatment and the same substrates used in Exp. 1. In vivo results showed that ileal and total tract DM and OM digestion were decreased (P < 0.05) by addition of both SS and TOS to the diet. Ileal and total-tract N digestibilities were decreased (P < 0.05) by dietary addition of SS. Fecal bifidobacteria and lactobacilli were increased (P < 0.05) by addition of SS and TOS to the diet. Ileal propionate and butyrate concentrations were greater (P < 0.05) for pigs fed diets containing both sources of Gal OS. In vitro results showed that fermentation data were not affected by donor animal adaptation to treatment. For both in vitro experiments, gas and SCFA production were higher (P < 0.05) for R + S than for SS or TOS. Fermentation of R + S resulted in a higher pH (P < 0.05) than did SS or TOS. Fermentation of non-OS components of SS and TOS resulted in more (P < 0.05) gas and SCFA production, and pH values that did not differ (P > 0.05) compared to SS and TOS. The Gal OS used in this study were prebiotics, increasing beneficial bacteria in vivo and SCFA concentrations both in vivo and in vitro.     

Effects of individual or combined xylanase and phytase supplementation on energy, amino acid, and phosphorus digestibility and growth performance of grower pigs fed wheat-based diets containing wheat millrun

The objective of these studies was to determine if dietary enzymes increase the digestibility of nutrients bound by nonstarch polysaccharides, such as arabinoxylans, or phytate in wheat millrun. Effects of millrun inclusion rates (20 or 40%), xylanase (0 or 4,375 units/kg of feed), and phytase (0 or 500 phytase units/kg of feed) on nutrient digestibility and growth performance were investigated in a 2 x 2 x 2 factorial arrangement with a wheat control diet (0% millrun). Diets were formulated to contain 3.34 Mcal of DE/kg and 3.0 g of true ileal digestible Lys/Mcal of DE and contained 0.4% chromic oxide. Each of 18 cannulated pigs (36.2 +/- 1.9 kg of BW) was fed 3 diets at 3x maintenance in successive 10-d periods for 6 observations per diet. Feces and ileal digesta were collected for 2 d. Ileal energy digestibility was reduced (P < 0.01) linearly by millrun and increased by xylanase (P < 0.01) and phytase (P < 0.05). Total tract energy digestibility was reduced linearly by millrun (P < 0.01) and increased by xylanase (P < 0.01). For 20% millrun, xylanase plus phytase improved DE content from 3.53 to 3.69 Mcal/kg of DM, a similar content to that of the wheat control diet (3.72 Mcal/kg of DM). Millrun linearly reduced (P < 0.01) ileal digestibility of Lys, Thr, Met, Ile, and Val. Xylanase improved (P < 0.05) ileal digestibility of Ile. Phytase improved ileal digestibility of Lys, Thr, Ile, and Val (P < 0.05). Millrun linearly reduced (P < 0.05) total tract P and Ca digestibility and retention. Phytase (P < 0.01) and xylanase (P < 0.05) improved total tract P digestibility, and phytase and xylanase tended to improve (P < 0.10) P retention. Phytase improved Ca digestibility (P < 0.05) and retention (P < 0.01). The 9 diets were also fed for 35 d to 8 individually housed pigs (36.2 +/- 3.4 kg of BW) per diet. Millrun reduced (P < 0.05) ADFI, ADG, and final BW. Xylanase increased (P < 0.05) G:F; phytase reduced (P < 0.05) ADFI; and xylanase tended to reduce (P = 0.07) ADFI. In summary, millrun reduced energy, AA, P, and Ca digestibility and growth performance compared with the wheat control diet. Xylanase and phytase improved energy, AA, and P digestibility, indicating that nonstarch polysaccharides and phytate limit nutrient digestibility in wheat byproducts. The improvement by xylanase of energy digestibility coincided with improved G:F but did not translate into improved ADG.     

Effect of dietary protein content on ileal amino acid digestibility, growth performance, and formation of microbial metabolites in ileal and cecal digesta of early-weaned pigs

Diarrhea incidence in weaned pigs may be associated with the concentration of intestinal microbial metabolites (ammonia, amines, and VFA) that are influenced by dietary CP content. Three experiments were conducted to determine effects of a low-protein, AA-supplemented diet on ileal AA digestibility, growth performance, diarrhea incidence, and concentration of microbial metabolites in ileal and cecal digesta of pigs weaned at 14 d of age. In Exp. 1, 8 pigs fitted with a simple T-cannula at the distal ileum were assigned in a crossover design to 2 diets containing 24 or 20% CP using wheat, corn, full-fat soybeans, whey powder, fish meal, and blood plasma as the main ingredients. Supplemental AA were added to the diets to meet the AA standards according to the 1998 NRC recommendations. Chromic oxide was used as an indigestible marker. Diets were fed at 2.5 times the ME requirement for maintenance. The reduction of dietary CP decreased (P < 0.05) the apparent ileal digestibility of most AA, except Lys, Met, Thr, Val, and Pro. Dietary CP content did not affect the pH of ileal digesta or ileal concentrations of ammonia N, cadaverine, putrescine, or VFA. In Exp. 2, 8 pigs fitted with a simple T-cannula in the cecum were assigned to 2 diets, similar to Exp. 1. Dietary CP content did not affect the pH of cecal digesta. The reduction in CP content decreased (P < 0.05) cecal ammonia N, acetic acid, isobutyric acid, isovaleric acid, total VFA, and putrescine concentrations by 28 to 39%. In Exp. 3, 32 pigs were assigned to 2 diets, similar to Exp. 1, according to a randomized complete block design. Pigs had free access to feed and water. Dietary CP content did not affect growth performance or fecal consistency scores during the 3-wk study, and diarrhea was not observed. The results of these experiments indicate that lowering the dietary CP content combined with supplementation of AA markedly reduced the production of potentially harmful microbial metabolites in cecal digesta of early-weaned pigs without affecting growth performance.     

Use of carbohydrases in corn-soybean meal-based nursery diets

Three experiments were conducted to test the hypothesis that supplementing nursery pig diets with a mixture of carbohydrases (CS) will improve pig performance and nutrient digestibility. The CS used in these experiments contained 7 units/g of alpha-1,6-galactosidase, 22 units/g of beta-1,4-mannanase, beta-1,4 mannosidase, and trace amounts of other enzymes. In Exp. 1, 108 pigs weaned at d 21 of age were fed one of three diets containing 0 (control), 0.1, or 0.2% CS for 5 wk, based on a three-phase feeding program (1, 2, and 2 wk). Over the entire 35-d period, ADG was not affected (P > 0.05) by treatment, but supplementing 0.1% CS increased (P < 0.05) gain:feed by 9%. Experiment 2 used 10 gilts fitted with simple T-cannula in the terminal ileum at 3 wk of age. After cannulation, pigs were fed the same control Phase I and II diets, but the Phase III diet contained either 0 or 0.1% CS. Ileal samples were collected for the 3 d following the 5-d adjustment period during Phase III. Apparent ileal digestibility of GE, lysine, threonine, and tryptophan was greater (P < 0.05) in the CS diet. In Exp. 3, 90 pigs weaned at 21 d of age were fed the same control Phase I and II diets, but the Phase III diet contained either 0 or 0.1% CS. Phase III diets were fed for 3 wk. Average daily gain of the CS group was greater (P < 0.05) than the control group during wk 3. Gain:feed ratio was greater (P < 0.05) for the carbohydrase group during the entire Phase III period. Four pigs per treatment were killed at the end of Exp. 3 to measure villus height and to determine the concentration of raffinose and stachyose in different parts of the gastrointestinal tract. Average villus height was greater (P < 0.05) in pigs fed the CS diet. Carbohydrase supplementation decreased (P < 0.05) the concentration of stachyose in freeze-dried digesta from the proximal and distal small intestine. Raffinose concentration, on the other hand, was decreased (P < 0.05) by CS supplementation only in the distal small intestine. These lower concentrations suggest that CS improved the digestibility of carbohydrate in soybean meal. In conclusion, the addition of CS to Phase I and Phase II nursery diets containing low levels of soybean meal did not improve pig performance, but its addition to corn-soybean meal-based Phase III nursery diets improved gain:feed ratio and energy and AA digestibility.     

The influence of xylanase on the fermentability,digestibility, and physicochemical properties of insoluble corn-based fiber along the gastrointestinal tract of growing pigs

In theory, supplementing xylanase in corn-based swine diets should improve nutrient and energy digestibility and fiber fermentability, but its efficacy is inconsistent. The experimental objective was to investigate the impact of xylanase on energy and nutrient digestibility, digesta viscosity, and fermentation when pigs are fed a diet high in insoluble fiber (>20% neutral detergent fiber; NDF) and given a 46-d dietary adaptation period. A total of 3 replicates of 20 growing gilts were blocked by initial body weight, individually housed, and assigned to 1 of 4 dietary treatments: a low-fiber control (LF) with 7.5% NDF, a 30% corn bran high-fiber control (HF; 21.9% NDF), HF + 100 mg xylanase/kg (HF + XY [Econase XT 25P; AB Vista, Marlborough, UK]) providing 16,000 birch xylan units/kg; and HF + 50 mg arabinoxylan-oligosaccharide (AXOS) product/kg (HF + AX [XOS 35A; Shandong Longlive Biotechnology, Shandong, China]) providing AXOS with 3–7 degrees of polymerization. Gilts were allowed ad libitum access to fed for 36-d. On d 36, pigs were housed in metabolism crates for a 10-d period, limit fed, and feces were collected. On d 46, pigs were euthanized and ileal, cecal, and colonic digesta were collected. Data were analyzed as a linear mixed model with block and replication as random effects, and treatment as a fixed effect. Compared with LF, HF reduced the apparent ileal digestibility (AID), apparent cecal digestibility (ACED), apparent colonic digestibility (ACOD), and apparent total tract digestibility (ATTD) of dry matter (DM), gross energy (GE), crude protein (CP), acid detergent fiber (ADF), NDF, and hemicellulose (P < 0.01). Relative to HF, HF + XY improved the AID of GE, CP, and NDF (P < 0.05), and improved the ACED, ACOD, and ATTD of DM, GE, CP, NDF, ADF, and hemicellulose (P < 0.05). Among treatments, pigs fed HF had increased hindgut DM disappearance (P = 0.031). Relative to HF, HF + XY improved cecal disappearance of DM (162 vs. 98 g; P = 0.008) and NDF (44 vs. 13 g; P < 0.01). Pigs fed xylanase had a greater proportion of acetate in cecal digesta and butyrate in colonic digesta among treatments (P < 0.05). Compared with LF, HF increased ileal, cecal, and colonic viscosity, but HF + XY decreased ileal viscosity compared with HF (P < 0.001). In conclusion, increased insoluble corn-based fiber decreases digestibility, reduces cecal fermentation, and increases digesta viscosity, but supplementing xylanase partially mitigated that effect.     

The nutritional value of degermed,dehulled corn for pigs and its impact on the gastrointestinal tract and nutrient excretion

Three experiments were designed to assess the feeding value and potential environmental benefits of feeding degermed, dehulled corn, a low fiber by-product originating from the corn dry milling process, to pigs. Twelve 27-kg (SE = 0.8) barrows were used in Exp. 1 to measure the apparent fecal digestibility of DM, GE and N of degermed, dehulled corn compared with corn grain. Two diets were formulated to contain either 96.4% of degermed, dehulled corn or corn grain plus supplemental vitamins and minerals. Digestibilities of DM, GE, and N were greater in degermed, dehulled corn (96.2, 96.0, and 93.6%, respectively) compared with corn grain (89.0, 89.0, and 78.4%, respectively) (P < 0.01). Overall, a 67 and 29% reduction in DM and N excretion, respectively, was observed. In Exp. 2, eight 70-kg (SE =1.8) barrows were surgically fitted with ileal cannulae and fed the same diets as in Exp. 1, to measure the ileal digestibility of nutrients in degermed, dehulled corn. Ileal digestibility of DM, energy, and N was 13, 15, and 7% greater in degermed, dehulled corn (P < 0.05). Apparent ileal digestibility coefficients of leucine, methionine, and phenylalanine were greater in degermed, dehulled corn compared with corn grain (P < 0.05) while a trend for a lower tryptophan digestibility in degermed, dehulled corn was observed (P = 0.067). In Experiment 3, 96 nursery pigs with an initial average BW of 8.8 kg (SE = 0.08), fed a starter diet formulated with degermed, dehulled corn or corn grain as the major grain source, were used in a 28-d growth performance study. At the end of the study, 24 pigs (1 pig per pen) were sacrificed and gastrointestinal tract measurements were taken. Daily growth rates of pigs were the same between diets (0.64 kg/d). A trend for reduced feed intake (P = 0.073) in pigs fed degermed, dehulled corn led to a 4% improvement in gain to feed (P < 0.05). Feeding degermed, dehulled corn had no effect on gut fill, gastrointestinal tract weight, or liver weight (P > 0.05). Ileal villus lengths and crypt depths were not affected by feeding degermed, dehulled corn although ileal villus widths were greater in pigs fed corn grain. Results from these trials suggest that corn processed to remove poorly digestible fiber fractions provides more digestible nutrients than corn grain. As a result, degermed, dehulled corn reduces fecal and N excretion, thus providing a means to reduce nutrient excretion.     

Effects of xylanase supplementation on the apparent digestibility and digestible content of energy, amino acids, phosphorus, and calcium in wheat and wheat by-products from dry milling fed to grower pigs

Wheat by-products are feedstuffs that vary in nutritional value, partly because of arabinoxylans that limit nutrient digestibility. Millrun is a byproduct from dry milling wheat into flour and contains varying amounts of the bran, middlings, screening, and shorts fractions. The digestible nutrient content of mill-run is not well known. Effects of xylanase supplementation (0 or 4,000 units/kg of diet) on energy, AA, P, and Ca digestibilities were studied in a wheat control diet and 5 diets containing 30% of a by-product (mill-run, middlings, shorts, screening, or bran) in a 2 x 6 factorial arrangement of treatments. The wheat control diet was formulated to contain 3.34 Mcal of DE/kg and 3.0 g of standardized ileal digestible Lys/Mcal of DE. Diets contained 0.4% chromic oxide. Each of 12 ileal-cannulated pigs (32.5 +/- 2.5 kg) was fed 6 or 7 of 12 diets at 3 times the DE requirement for maintenance in successive 10-d periods for 6 or 7 observations per diet. Feces and ileal digesta were each collected for 2 d. Xylanase tended to increase (P < 0.10) ileal energy digestibility by 2.2 percentage units and the DE content by 0.10 Mcal/kg of DM and increased (P < 0.05) ileal DM digestibility by 2.8 percentage units; a diet x xylanase interaction was not observed. Xylanase increased (P < 0.05) total tract energy and DM digestibilities and the DE content. A diet x xylanase interaction was observed; xylanase increased (P < 0.05) total tract energy digestibility of the millrun diet from 72.1 to 78.9%, DE content from 3.19 to 3.51 Mcal/kg of DM, and DM digestibility from 71.5 to 78.6%. Diet affected (P < 0.05) and xylanase improved (P < 0.05) digestibility and digestible contents of some AA in diets and by-products, including Lys, Thr, and Val. Xylanase increased (P < 0.05) Lys digestibility by 13.8, 5.0, 5.2, 6.0, and 14.1 percentage units in millrun, middlings, shorts, screening, and bran, respectively. Diet affected (P < 0.01) total tract P and Ca digestibilities. Xylanase increased (P < 0.05) digestible P and Ca contents. In summary, nutrient digestibility varies among wheat by-products. Millrun contained 2.65 Mcal of DE/kg of DM, which xylanase increased to 3.56 Mcal of DE/kg of DM. Xylanase improved nutrient digestibility and DE content in wheat by-products; and the extent of improvement depended on the by-product. Xylanase supplementation may maximize opportunities to include wheat byproducts in swine diets and ameliorate reductions in nutrient digestibility that may be associated with arabinoxylans.     

Growth performance, gastrointestinal microbial activity, and nutrient digestibility in early-weaned pigs fed diets containing flaxseed and carbohydrase enzyme

The effects of ground flaxseed (FS) and a multicarbohydrase enzyme (C) supplement on piglet performance, gastrointestinal microbial activity, and nutrient digestibility were investigated in a 28-d trial. The enzyme supplement provided 500 units of pectinase, 50 units of cellulase, 400 units of mannanase, 1,200 units of xylanase, 450 units of glucanase, and 45 units of galactanase per kilogram of diet. Ninety-six pigs were weaned at 17 d of age (BW, 6.1 +/- 0.4 kg, mean +/- SD) and assigned to treatments based on a 2 x 2 factorial arrangement in a completely randomized design, with 6 pens per diet (4 pigs per pen). The diets contained wheat, barley, peas, soybean meal, and canola meal with 0 or 12% FS, and were fed without or with C. Flaxseed was included by changing the levels of the other ingredients to balance the diets for DE and nutrients. Diets had similar nutrient contents and met the NRC (1998) nutrient specifications, with the exception of DE, CP, and AA, which were 95, 94, and 97% of the NRC requirements, respectively. Diets were fed in a 2-phase feeding program (2 wk/phase). Feed intake and BW were measured weekly, and 1 pig per pen with a BW nearest the pen average was bled weekly to evaluate plasma urea nitrogen. On d 28, fresh fecal samples were collected from each pen and 1 pig per pen with a BW nearest the pen average was killed to evaluate intestinal microbial activity and nutrient digestibility. A dietary effect on piglet performance was observed only in wk 3, when the FS diets decreased (P = 0.005) ADG and G:F, tended to decrease (P = 0.070) ADFI, and increased (P = 0.027) plasma urea nitrogen. An interaction between FS and C was observed for ileal digesta viscosity (P = 0.045), such that C increased viscosity in the FS diet but had no effect in the non-FS diet. Flaxseed and C interacted to affect ileal ammonia content (P = 0.049), such that in the absence of FS, pigs fed the diet with C had lower ammonia than those on the diet without C. Flaxseed and C affected other ileal parameters independently. Pigs fed the FS diets had decreased (P = 0.003 to 0.033) anaerobic spore counts, organic acid, DM, CP, and nonstarch polysaccharide (NSP) digestibility compared with pigs fed the non-FS diets, whereas pigs fed the C-supplemented diets had greater (P = 0.009 to 0.061) lactobacilli counts, lactate, DM, and NSP digestibility than pigs fed the unsupplemented diets. In conclusion, FS reduced ileal microbial activity, nutrient digestibilities, and piglet performance in wk 3. The multicarbohydrase supplement increased ileal DM and NSP digestibilities as well as lactobacilli counts and lactate.     

Glycemic index of starch affects nitrogen retention in grower pigs

Three studies were performed to examine the effect of starch and protein digestion rates on N retention in grower pigs. In Exp. 1, the glycemic index (GI) of corn, a malting barley, and a slow-rumen-degradable barley (SRD-barley) were measured using 6 barrows (BW = 18.0 ± 0.5 kg). The GI of malting barley was greater (P < 0.05) than that of SRD-barley (71.1 vs. 49.4), and the GI of both barley cultivars was less (P < 0.05) than that of corn (104.8). In Exp. 2, the standardized ileal digestibility of AA and DE content of the 3 ingredients were determined using 5 ileal-cannulated barrows (BW = 20.7 ± 2.3). The apparent total-tract energy digestibility values of corn (86.1%) and malting barley (85.7%) were greater (P < 0.05) than that of SRD-barley (82.3%). The standardized ileal digestibility of Lys was 94.0, 92.6, and 92.4% for corn, malting barley, and SRD-barley, respectively, and did not differ among grains. In Exp. 3, 6 diets were formulated to equal DE (3.40 Mcal/kg), standardized ileal digestibility of Lys (8.6 g/kg), starch (424.9 g/kg), and digestible CP (180.0 g/kg) using the values obtained in Exp. 2. Three GI [high (corn), medium (malting barley), and low (SRD-barley)] and 2 rates of protein digestion [rapid (soy protein hydrolysate) and slow (soy protein isolate)] were tested in a 3 × 2 factorial arrangement with 36 barrows (BW = 32.2 ± 2.5 kg). Pigs were fed 3.0 times the maintenance energy requirement daily in 2 meals for 2 wk and were housed in metabolic crates to collect feces and urine separately. At the end of the study, intestinal contents were collected from 4 equal-length segments of the small intestine. The percentage of unabsorbed CP in segment 1 relative to dietary CP was greater (P < 0.05) for the soy protein isolate diet than for the soy protein hydrolysate diet (170.3 vs. 116.5%). The percentages of unabsorbed starch in segments 1 and 2 were greater (P < 0.05) for the SRD-barley diet than for the malting barley or corn diet. Nitrogen intake and fecal N excretion were greater (P < 0.05) for pigs fed the malting barley and SRD-barley diets than for pigs fed the corn diet. Urinary N excretion was greater (P < 0.05) for pigs fed the SRD-barley diet than for pigs fed the corn or malting barley diet. Pigs fed slowly digestible starch (SRD-barley; 46.6%) had less (P < 0.05) net N retention than pigs fed corn or malting barley (54.7 and 54.1%, respectively). In conclusion, slowly digestible starch sources such as SRD-barley may not be suitable to support maximum protein deposition in restricted-fed grower pigs.     

The influence of soy oligosaccharides on apparent and true ileal amino acid digestibilities and fecal consistency in growing pigs

Fourteen ileally cannulated pigs (BW = 35 +/- 2 kg) were randomly allotted to a replicated 7 x 7 Latin square design experiment to evaluate the influence of the soybean oligosaccharides (OS), raffinose and stachyose, on ileal nutrient digestibility and fecal consistency. Semipurified diets containing soy protein concentrate (SPC) or soybean meal (SBM) as the sole protein sources were fed. Soy solubles (SS), a by-product of SBM processing containing 3.5% raffinose and 11.5% stachyose, were used to increase dietary raffinose and stachyose concentrations. The seven dietary treatments were SPC, SPC + 9% SS, SBM, SBM + 9% SS, SBM + 18% SS, SBM + 24,000 U alpha-galactosidase enzyme preparation/kg diet, and a low-protein casein (LPC) diet used to calculate true digestibility. Diets, with the exception of the LPC diet, were formulated to contain 17% CP. All diets contained 0.5% chromic oxide as a marker for ileal digestibility determination. The experimental periods were divided into a 5-d diet adaptation followed by 2-d of ileal digesta collection. Diets and digesta were analyzed for DM, N, Cr, amino acids (AA), raffinose, and stachyose. Fecal consistency was determined on d 6 and 7 of each experimental period. The apparent and true ileal AA digestibilities were not different (P < 0.05) for the SPC and SBM control diets. When SS was added to the SPC diet, apparent and true N and AA digestibilities were depressed (P < 0.05) with the exception of Trp and Pro. The apparent and true ileal N and AA digestibilities were not different (P > 0.05) between the SBM control and SBM + 9% SS diets with the exception of Glu. There was a linear decrease (P < 0.05) in apparent and true DM, Val, Gly, and Tyr digestibilities when increasing levels of SS were added to the SBM diet. The addition of alpha-galactosidase did not improve apparent or true ileal N or AA digestibilities except for apparent and true Val and Tyr. Ileal raffinose digestibility was improved (P < 0.05) by addition of a-galactosidase, but was not affected by any other dietary treatment. Ileal stachyose digestibility was not affected (P > 0.58) by treatment. Fecal consistency likewise was not affected (P > 0.36) by dietary treatment. In conclusion, soy OS reduced nutrient digestibilities, but the reductions were small, ranging from approximately 1.1 to 7.4 percentage units. This suggests that other factors may be negatively impacting SBM digestibility.     

Determination of the ileal amino acid and energy digestibilities of corn distillers dried grains with solubles using grower-finisher pigs

An experiment evaluated the ileal apparent and standardized AA and apparent energy digestibilities in grower-finisher pigs of 5 sources of distillers dried grains with solubles (DDGS) from corn. The 5 DDGS sources were analyzed for AA, GE, NDF, ADF, and color score. Diets were formulated to contain 15% CP from the test DDGS sources (approximately 60% of the diet). A low-protein (5% casein) diet was used to estimate basal endogenous AA losses. The experiment was conducted in 2 replicates of a 6 x 6 Latin Square design, with 6 treatments and six 1-wk periods. The experiment used 12 crossbred barrows [(Yorkshire x Landrace) x Duroc], averaging 28 kg of BW and 60 d of age, and surgically fitted with a T-cannula in the distal ileum. After a 10-d recovery period, treatment diets were fed in meal form, initially at 0.09 kg . BW(0.75). Feed intake was equalized between pigs within each period and increased for each subsequent period. Periods included 5 d of diet acclimation followed by two 12-h ileal digesta collections, one on d 6 and one on d 7. Apparent and standardized digestibility of AA was calculated using chromic oxide (0.4%) as an indigestible marker. The results demonstrated that apparent and standardized lysine digestibilities ranged from 24.6 to 52.3% and 38.2 to 61.5%, respectively. Average apparent essential AA digestibility was lower (P < 0.05) in sources 1 and 5, the 2 sources that were darkest in color. Apparent and standardized digestibility of the averaged nonessential AA were lower (P < 0.05) in source 5 than in all other sources. Source 5, the darkest colored DDGS, had a 10% lower (P < 0.05) average apparent and standardized essential AA digestibility and was more than 15% lower (P < 0.05) in lysine digestibility than the 3 lightest colored sources. Apparent ileal energy digestibility did not differ among the 5 sources. Lysine content and digestibility seemed to be reduced to a greater extent by the darker colored DDGS than the other essential AA, suggesting that the Maillard reaction reduced total lysine content and lowered its digestibility. These results, therefore, imply that darker colored DDGS sources may have lower (P < 0.05) analyzed lysine contents, as well as lower (P < 0.05) lysine and essential AA digestibilities, than lighter colored DDGS sources.     

Chromic oxide and acid‐insoluble ash as markers in digestibility studies with growing pigs and sows

The results of three experiments, focused on the determination of endogenous ileal flow (EIF) of amino acids (AA) and nitrogen (N) (Exp. 1), apparent ileal digestibility (AID) of AA and N (Exp. 2), and apparent total tract digestibility (ATTD) of dry matter (DM), organic matter (OM), N, calcium (Ca) and phosphorus (P) (Exps. 2 and 3), were used to compare chromic oxide (Cr₂O₃) and acid‐insoluble ash (AIA) as digestibility markers. In Exps. 1 and 2, a total of six gilts fitted with T‐cannula in terminal ileum, and in Exp. 3, a total of 24 pregnant sows were used. In Exps. 1 and 2, the pigs were assigned into four dietary treatments according to 4 × 6 crossover design (Exp. 1; diets with 0%, 4%, 8% and 12% of casein; Exp. 2 basal diet with different levels of phytase). In Exp. 3, the sows were assigned to four dietary treatments (basal diet with different levels of phytase) of six sows. In Exps. 1 and 2 ileal digesta and in Exps. 2 and 3 faeces were collected for the determination of EIF, AID and ATTD. Differences in EIF of AA determined by Cr₂O₃ and AIA ranged (p ? 0.05) from ?4.62 to 4.54%. The lowest EIF was for methionine and the greatest one for proline, determined by both markers. Apparent ileal digestibility determined by Cr₂O₃ was slightly greater (p ? 0.05) in comparison with AIA. Differences ranged from 1.88% (Arg) to 7.08% (Gly). The greatest AID was for arginine and the lowest one for glycine, determined by both Cr₂O₃ and AIA. Similarly for ATTD of DM, OM, N, Ca and P, there were no differences in digestibility determined by Cr₂O₃ and AIA. Both, Cr₂O₃ and AIA, are suitable and comparable markers for digestibility studies in pigs.     

Effect of protein source and fumaric acid supplementation on apparent ileal digestibility of nutrients by young pigs

Two experiments were conducted to determine the apparent ileal digestibility of DM and N by young pigs fed diets supplemented with different protein sources or organic acids. Pigs were surgically fitted with silicone cannulas at 2 wk of age. Following surgery, pigs were allowed to recuperate with their dams while suckling normally. After weaning at 24 d, pigs were assigned to treatment diets at 28 d of age. A 3-d adjustment and 4-d collection sequence was followed for the duration of the 4-wk experiment. Four treatment diets were fed in each experiment in a weekly rotation until each diet had been fed to each pig. Diet samples and digesta collected through the ileal cannulas were analyzed for chromic oxide (used as an indigestible marker), DM, and N. Pigs in Exp. 1 were fed isolysinic (1.0%) corn-based diets supplemented with casein, soybean meal, soy protein concentrate, or isolated soy protein. Casein addition resulted in improved DM (P less than .001) and N (P less than .05) digestibility but reduced gain (P less than .05) compared with the average of the soy protein sources. Nitrogen from diets formulated with soybean meal was digested more completely (P less than .05) than N from diets based on soy protein concentrate and isolated soy protein. Experiment 2 was an evaluation of the effect of dried skim milk (25%) and fumaric acid (2%) addition on apparent ileal digestibility of N and DM in corn-soybean meal diets. Addition of dried skim milk improved DM (P less than .01) and N (P less than .05) digestibility and daily gain (P less than .001). Fumaric acid supplementation did not affect nutrient digestibility or gain (P greater than .10).     

Effect of phytase addition and dietary calcium and phosphorus levels on plasma metabolites and ileal and total-tract nutrient digestibility in pigs

Two experiments were conducted to determine the effect of phytase on plasma metabolites and AA and energy digestibility in swine. In Exp. 1, eight barrows (surgery BW = 52 kg) were fitted with steered ileocecal cannulas. The experiment was a Latin rectangle and the treatments were 1) corn-soybean meal diet adequate in Ca and P (0.5% Ca, 0.19% available P [aP]), 2) corn-soybean meal diet with reduced Ca and P (0.4% Ca, 0.09% aP), 3) Diet 1 with 500 phytase units/kg, or 4) Diet 2 with 500 phytase units/kg. Pigs were fed twice daily to a total daily energy intake of 2.6 x maintenance (106 kcal of ME/kg of BW(0.75)). For each ileal digesta sample, digesta samples were collected for two 24-h periods and combined for each pig. The combination of supplementing with phytase and decreasing the concentration of dietary Ca and P increased average ileal AA (P < 0.02), starch (P < 0.02), GE (P < 0.04), and DM (P < 0.03) digestibilities. In Exp. 2, a feeding challenge was conducted with barrows (eight per treatment; average BW of 53 kg). The treatments consisted of a corn-soybean meal diet or corn-soybean meal diet + 500 phytase units per kilogram of diet. In the diet with no phytase, Ca and aP were at 0.50% and 0.19%, respectively, and, in the diet with phytase, Ca and aP were each decreased by 0.12%. A catheter was surgically inserted into the anterior vena cava of each pig 6 d before the start of the feeding challenge. The barrows were penned individually, and the diets were fed for 3 d before the challenge. The pigs were held without feed for 16 h, and blood samples were obtained at -60, -30, and 0 min before the pigs were fed (2% of BW). Blood samples were then collected at 10, 20, 30, 40, 50, 60, 75, 90, 105, 120, 150, 180, 210, 240, 270, and 300 min after feeding. Glucose area under the response curve and plasma glucose, insulin, urea N, and total alpha-amino N concentrations were increased (P < 0.05) in pigs fed the diet with reduced Ca and P and the phytase addition. Area under the response curve for insulin, urea N, and total alpha-amino N; insulin:glucose; and plasma NEFA concentration, clearance, and half-life were not affected by diet. In conclusion, the combination of Ca and P reduction and phytase addition increased nutrient and energy digestibility in diets for pigs and increased plasma concentrations of glucose, insulin, urea N, and alpha-amino N.     

Energy, phosphorus, and amino acid digestibility of high-protein distillers dried grains and corn germ fed to growing pigs

Three experiments were conducted to measure energy, P, and AA digestibility in 2 novel co-products from the ethanol industry [i.e., high-protein distillers dried grains (HP DDG) and corn germ]. These products are produced by dehulling and degerming corn before it enters the fermentation process. Experiment 1 was an energy balance experiment conducted to measure DE and ME in HP DDG, corn germ, and corn. Six growing pigs (initial BW, 48.9 +/- 1.99 kg) were placed in metabolism cages and fed diets based on corn, corn and HP DDG, or corn and corn germ. Pigs were allotted to a replicated, 3 x 3 Latin square design. The DE and ME in corn (4,056 and 3,972 kcal/kg of DM, respectively) did not differ from the DE and ME in corn germ (3,979 and 3,866 kcal/kg of DM, respectively). However, HP DDG contained more (P < 0.05) energy (4,763 kcal of DE/kg of DM and 4,476 kcal of ME/kg of DM) than corn or corn germ. Experiment 2 was conducted to measure apparent total tract digestibility (ATTD) and true total tract digestibility of P in HP DDG and corn germ. Thirty growing pigs (initial BW, 33.2 +/- 7.18 kg) were placed in metabolism cages and fed a diet based on HP DDG or corn germ. A P-free diet was used to measure endogenous P losses. Pigs were assigned to treatments in a randomized complete block design, with 10 replications per treatment. The ATTD and the retention of P were calculated for the diets containing HP DDG and corn germ, and the endogenous loss of P was estimated from pigs fed the P-free diet. The ATTD was lower (P < 0.05) in corn germ (28.6%) than in the HP DDG (59.6%). The retention of P was also lower (P < 0.05) in pigs fed corn germ (26.7%) than in pigs fed HP DDG (58.9%). The endogenous loss of P was estimated to be 211 +/- 39 mg per kg of DMI. The true total tract digestibility of P for HP DDG and corn germ was calculated to be 69.3 and 33.7%, respectively. In Exp. 3, apparent ileal digestibility and standardized ileal digestibility values of CP and AA in HP DDG and corn germ were measured using 6 growing pigs (initial BW, 78.2 +/- 11.4 kg) allotted to a replicated, 3 x 3 Latin square design. The apparent ileal digestibility for CP and all AA except Arg and Pro, and the standardized ileal digestibility for CP and all AA except Arg, Lys, Gly, and Pro were greater (P < 0.05) in HP DDG than in corn germ. It was concluded that HP DDG has a greater digestibility of energy, P, and most AA than corn germ.     

Effect of micronized pea and enzyme supplementation on nutrient utilization and manure output in growing pigs

An experiment was done to determine manure output, N and P excretion, and apparent digestibilities of AA, CP, P, and DM in growing pigs fed barley-based diets containing micronized or raw peas with or without supplementation with enzyme containing primarily beta-glucanase and phytase (Biogal S+). Eight barrows (21.5 +/- 1.2 kg of initial BW) fitted with T-cannulas at the distal ileum were used in a 40-d trial and housed in metabolism cages. Pigs were assigned in a replicated 4 x 4 Latin square design to 4 experimental diets: 1) barley-raw peas control (BRP), 2) barley-micronized peas (BMP), 3) BRP plus enzyme, and 4) BMP plus enzyme (BMP+E). Pigs received 2.6 times maintenance energy requirements based on BW at the beginning of each experimental period. During each experimental period, pigs were acclimatized to their respective diets for 5 d followed by a 3-d period of total fecal and urine collection and another 2-d period of ileal digesta collection. Samples were analyzed for DM, AA (diets and digesta only), N, and P. Wet fecal output of BRP plus enzyme-fed pigs tended to be lower (P = 0.07) than the amount produced by BMP-fed pigs. The amounts of dry feces and urine produced were not different among treatments (P > 0.10). Supplementing the BRP and BMP diet with enzyme increased (P = 0.002) the daily P retained per pig. Pigs fed the enzyme-supplemented diets tended to have lower (P = 0.06) fecal P excretion and greater urinary P excretion (P = 0.001) compared with pigs fed the nonsupplemented diets, but total P excretion was not influenced by diet (P > 0.10). Pigs fed the BMP+E diet retained more (P = 0.006) N per day than pigs fed the BMP diet. However, N excretion was not influenced by dietary treatment (P > 0.10), although BMP+E-fed pigs excreted 13.2% less N in the feces compared with those fed the nonenzyme supplemented controls. Inclusion of micronized peas with or without enzyme supplementation did not affect urinary or fecal N excretion (P > 0.10) compared with the BRP. Dietary treatment had no effect (P > 0.10) on ileal or fecal DM or CP digestibilities. Apparent ileal digestibilities of AA were usually lower (P < 0.05) in the BRP diet compared with the other diets. Enzyme supplementation improved P digestibility at the ileal and fecal level. The current results indicate that utilizing micronized peas in barley-based pig grower diets enhances P retention.     

Dietary supplementation with multienzyme preparations improves nutrient utilization and growth performance in weaned pigs

Two experiments with young pigs (25 d of age) were conducted to investigate the effect of multienzyme preparations on nutrient digestibility, growth performance, and P utilization and excretion. In Exp. 1, 24 pigs (six pigs per treatment) were used in a 28-d performance and digestibility trial using four diets: control (no enzyme) and control supplemented with enzyme preparation A, B, or C. The control diet was formulated to meet 95% of NRC (1998) nutrient specifications (except for available P, which was at 44% NRC) and composed of corn, wheat, wheat by-products, barley, soybean meal, canola meal, and peas. All three enzyme preparations contained xylanase, glucanase, amylase, protease, invertase, and phytase activities and differed in the type of plant cell wall-degrading activities; Enzyme A contained cellulase, galactanase, and mannanase; Enzyme B contained cellulase and pectinase; and Enzyme C contained cellulase, galactanase, mannanase, and pectinase. Pigs fed enzyme-supplemented diets had higher ADG (P = 0.02) and G:F (P = 0.01) than those fed the control diet. On average, and when compared with control diet, enzyme supplementation improved (P = 0.001 to 0.04) ileal digestibility of DM (60 vs. 66%), GE (62.8 vs. 70.4%), CP (62 vs. 72%), starch (86.7 vs. 94.2%), nonstarch polysaccharides (NSP; 10.1 vs. 17.6%), and phytate (59 vs. 70%). Compared with the control, total-tract digestibility of nutrients was increased (P = 0.001 to 0.01) owing to enzyme supplementation, with Enzyme C showing the highest improvement in DM, GE, CP, starch, NSP, phytate, and P utilization. Pigs fed enzyme-supplemented diets had decreased (P = 0.04) fecal P excretion. The benefit from improved nutrient utilization with enzyme supplementation was further substantiated in a 38-d growth performance study with 48 pigs. The control and Enzyme C-supplemented diets (same as Exp. 1) were assigned to six replicate pens (four pigs per pen). The study was conducted in three phases (Phase 1 = d 0 to 7; Phase 2 = d 7 to 21; Phase 3 = d 21 to 38). Individual BW and pen feed disappearance were monitored. Average daily gain and G:F were 231 and 257 g (P = 0.01), and 0.56 and 0.63 (P = 0.001) for the control and enzyme-supplemented diets, respectively. It is evident from this study that the use of enzyme preparations may allow for cost-effective and environmentally friendly formulation of young pig diets.     

Effects of different fermented soy protein and apparent ileal digestible lysine levels on weaning pigs fed fermented soy protein‐amended diets

Two experiments were conducted to evaluate the effect of different fermented soybean proteins and the apparent ileal digestible lysine levels on weaning pigs fed fermented soy protein (FSP)‐amended diets. In Exp. 1, 70 crossed piglets (6.25 ± 0.40 kg) were used in a 5‐week trial to evaluate two different FSP. In Exp. 2, 20 weaning barrows (6.15 ± 0.45 kg) were used in a metabolism trial to determine the effects of the apparent ileal digestible (1.2, 1.3, 1.4 and 1.5%) lysine levels in weaning pigs fed FSP (5%) diet. In Exp. 1, pigs fed the diet containing Lactobacillus spp. FSP showed higher nitrogen (N) digestibility (P < 0.05), lower blood urea nitrogen and serum creatinine levels (P < 0.05) than those fed the Aspergillus oryzae FSP diet. In Exp. 2, increasing dietary lysine levels increased the average daily gain, apparent dry matter, N digestibility, N retention and essential amino acids in the current study (P < 0.05), with the 1.5% showing the highest value. In conclusion, pigs fed Lactobacillus spp. FSP had a higher N digestibility than those fed A. oryzae FSP. The optimal apparent ileal digestibility lysine level in fermented soy protein diets (3550 kcal/kg metabolizable energy) for maximizing growth performance and N utilization in the first 7 days (6.25 kg) was 1.5%.     

Performance, digesta characteristics, nutrient flux, plasma composition, and organ weight in pigs as affected by dietary cation anion difference and nonstarch polysaccharide

Two dietary cation anion difference (CAD) levels (-100 and 200 mEq/kg) and two dietary nonstarch polysaccharide (NSP) levels (10 and 15%) were used in a 2 x 2 factorial arrangement in two randomized blocks (trials) to evaluate performance, digesta pH and buffer capacity, apparent digestibility, plasma composition, and organ weight in pigs. Seven pigs with a mean initial weight of 7.5 kg were used in each treatment. Pigs had free access to feed and water during the 3-wk experimental period. At the end of the experiment, all pigs were killed approximately 2.5 h after addition of fresh feed. Liver, kidneys, and small and large intestine were removed and weighed immediately. Gastric and small intestinal (divided into two equal parts) digesta were collected. Dry matter, pH, buffering capacity, viscosity, acid insoluble ash, mineral content (Na+, K+, and Cl-), nitrogen, and gross energy content (only in the second part of the small intestine) of the digesta were measured. An interaction (P < 0.05) between dietary CAD and dietary NSP was observed for feed intake, growth, apparent digestibility of DM and gross energy in the distal small intestine, and chloride in the stomach and duodeno-jejunal part of the small intestine. Increasing dietary NSP content increased apparent digestibility of DM and chloride in the stomach and increased apparent digestibility of DM, chloride, sodium, and potassium in the first part of the small intestine. Lowering dietary CAD levels significantly increased apparent digestibility of DM in the first part of the small intestine and decreased chloride influx in the stomach and the small intestine. No significant differences were found for pH, buffering capacity, and viscosity of digesta, except the buffering capacity in the second part of the small intestine, which was higher (P < 0.05) in the 200 mEq/kg CAD group than in the -100 CAD mEq/ kg group. Plasma urea decreased in the low dietary CAD groups and plasma ammonia increased in the high NSP groups. Large intestine weight was significantly less for the -100 mEq/kg CAD groups than for the 200 mEq/kg CAD groups. In conclusion, the effect of CAD on feed intake and growth in pigs depends on dietary NSP levels.     

Effects of feed enzymes on nutritive value of soyabean meal fed to broilers

1. The effects of two enzyme products on the nutritive value of soyabean meal (SBM) were investigated with the emphasis on changes in composition of non-starch polysaccharides (NSP) along the digestive tract. Enzyme A was a commercially available product containing mainly hemicellulase, pectinase, beta-glucanase and some protease activities and Enzyme B was an experimental product with mainly beta-galactanase activity. 2. Enzymes were added at the recommended dosage (normal) and at 5 times the recommended dosage (high) to a semi-purified diet based on maize with SBM as the sole protein source. 3. The enzymes had no effect on digesta viscosity in the jejunum or ileum. 4. Enzyme A at the high dosage significantly (P<0.05) improved AMEN, reduced excreta moisture content and improved ileal protein digestibility. The addition of the same enzyme at the recommended dosage had no effect on any of the above parameters. 5. Analysis of the monosaccharide composition revealed that Enzyme A tended to reduce the amounts of rhamnose and galactose in the soluble and insoluble NSP fractions in thejejunal and ileal digesta. The reduction was significant (P<0.05) when the same enzyme was added at the high dosage. 6. Enzyme B significantly (P<0.05) improved AMEN of the diet but not the growth or the feed conversion ratio (FCR) of the birds. Enzyme B at the high dosage significantly reduced (P<0.05) ileal protein digestibility. 7. Enzyme B significantly (P<0.05) increased the amount of free sugars in thejejunum and reduced (P<0.05) the concentration of soluble NSP in the ileum. 8. Analysis of the monosaccharide composition in the jejunal and ileal digesta showed that this enzyme was highly effective in releasing galactose from both the soluble and insoluble NSP fractions. 9. It is concluded that glycanases with galactanase and pectinase activities supplemented at appropriate dosages can improve the digestibility of the NSP in SBM and increase the metabolisable energy content of the diet containing high levels of SBM. 10. Furthermore, the addition of Enzyme B at the high dosage significantly (P<0.05) reduced protein digestibility without any measurable reduction in growth performance.