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.     

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.     

Effect of fermentation of cereals on the degradation of polysaccharides and other macronutrients in the gastrointestinal tract of growing pigs

The main objective of the present investigation was to study the impact of fermentation of cereals on the degradation of polysaccharides and other macronutrients in the small intestine and total tract of growing pigs. Eight pigs (initial BW, 34.5 ± 0.9 kg) were used in a replicated 4 × 4 Latin square design. Pigs were cannulated and housed individually in metabolism pens during sample collection. The 4 cereal-based diets were nonfermented liquid barley (NFLB), nonfermented liquid wheat (NFLW), fermented liquid barley (FLB), and fermented liquid wheat (FLW). The fermented feeds were prepared by storing the dietary cereals (barley and wheat) and water [1:2.75 (wt/wt)] in a closed tank at 25 °C for 2 d, after which 50% of the volume was removed and replaced with an equal amount of fresh cereals and water after each afternoon meal. At the time of feeding (0730 and 1430 h), the remaining dietary ingredients were added. Water was added to the dry nonfermented feeds [1:1 (wt/wt)] immediately before feeding. The fermentation process reduced the amount of DM in both cereals (P<0.001), whereas the amount of DM was similar (P=0.626) between the fermented cereals. There was an interaction of cereal and treatment for ileal flow of DM (P=0.014), OM (P=0.013), and protein (P=0.006), which were less in pigs fed the NFLB than the FLB diets, but unchanged in pigs fed the NFLW and FLW diets. Conversely, the ileal flow of protein was similar (P=0.605) in pigs fed the barley diets (average, 47.5 ± 1.7 g/kg of DMI) and increased with the FLW diet compared with the NFLW diet (43 vs. 35 g/kg of DMI, respectively). Ileal fat and CH(2)O digestibilities were 7.6 (P=0.002) and 8.9% (P<0.001) greater, respectively, when pigs were fed wheat compared with the barley-based diets, and the ileal digestibility of CH(2)O was greater when pigs were fed the fermented than nonfermented diets (86.5 vs. 84.5%, respectively; P<0.001). Fermentation reduced (P<0.0001) the fecal excretion of DM, OM, and protein in pigs fed the barley diet, but not when fed the wheat-based diet (P=0.305). Fermentation had no effect (P=0.243) on the fecal digestibility of nonstarch polysaccharides in either of the cereals but their digestibility was 10.0% greater (P<0.001) in pigs fed wheat than the barley-based diets. In conclusion, fermentation of cereal before feeding altered the dietary composition and influenced flow and composition of polysaccharides and other macronutrients at the ileum and in feces to a larger extent for barley than wheat.     

Effect of common antinutritive factors and fibrous feedstuffs in pig diets on amino acid digestibilities with special emphasis on threonine

Most feedstuffs contain antinutritive factors (ANF) such as insoluble fibers, lignins, tannins, and lectins. Intake of these ANF has the ability to reduce nutrient digestibility and to increase endogenous protein losses, such as through increased intestinal mucus secretion. The objective of this experiment was to determine the apparent ileal digestibilities (AID) of AA of 6 ANF-enriched diets to estimate endogenous protein loss associated with these ingredients in diets for young pigs. Forty-two 10-kg BW pigs fitted with a simple T-cannula at the distal ileum were randomly assigned to 1 of 7 casein-based diets with: no supplement (control), 100 g/kg of canola meal (CM), 100 g/kg of wheat bran (WB), 150 g/kg of barley (BR), 22.5 g/kg of lignin (LG), 15 g/kg of kidney beans [as a lectin (LE) source], and 15 g/kg of tannins (TN). All diets were formulated to be similar in N, indispensable AA, and caloric contents. After a 7-d adaptation to the test diets, N balance was conducted for 5 d, followed by 24 h of collection of digesta for analyses of AA. Pigs fed BR had 17% lower ADG and 15% lower feed conversion ratio (P < 0.05) compared with control and CM pigs. Pigs fed diets containing WB and BR had lower N retention as a percentage of absorbed N compared with all other groups (P = 0.03). The AID for CP was lower in BR, WB, and LE pigs compared with control. Of the AA, AID of Thr was notably lowest in BR, WB, and TN pigs (P < 0.05). The standardized ileal digestibility was lower in WB and BR pigs for most indispensable AA. Altogether, these data suggest that hemicellulose fiber, at concentrations typical in commercial swine diets, reduces AID of AA by increasing endogenous losses. Understanding the differential effects of ANF on endogenous losses of individual dietary AA will improve the accuracy of diet formulation.     

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.     

The effects of thermal treatment of field peas (Pisum sativum L.) on nutrient and energy digestibility by growing pigs

An experiment was conducted to measure the effect of thermal treatment on the digestibility of CP, AA, starch, NDF, ADF, and energy in field peas fed to growing pigs. Five pea-containing diets were formulated. The peas included in these diets were either not heat-treated (control) or extruded at 75, 115, or 155 degrees C or pelleted at 75 degrees C. A N-free diet was also included in the experiment to measure basal endogenous losses of CP and AA. The 6 diets were fed to 6 growing pigs (initial BW: 69.3 +/- 2.9 kg) that were allotted to dietary treatments in a 6 x 6 Latin square design. A T-cannula was installed in the distal ileum of each pig, allowing for the collection of ileal digesta. Each experimental period lasted 9 d; fecal samples were collected on d 6 and 7, and ileal samples were collected on d 8 and 9 of each period. Apparent ileal digestibilities (AID) for CP, AA, starch, and energy and standardized ileal digestibility values (SID) for CP and AA were calculated. Apparent total tract digestibilities (ATTD) for NDF, ADF, starch, and energy were also calculated. As the extrusion temperature increased, the AID and SID for CP and all AA, except Pro, increased (quadratic, P < 0.05). In contrast, except for Arg and Pro, the peas that were pelleted at 75 degrees C had AID and SID for CP and AA that were similar to those obtained for the control peas but less (P < 0.05) than the AID for the peas that were extruded at 75 degrees C. The AID for starch and energy increased (linear, P < 0.001) as the extrusion temperature increased to 155 degrees C (from 89.8 to 95.9% and from 71.5 to 79.0%, respectively), but the AID for starch and energy in the pelleted diet was not different from the AID in the control diet (90.1 vs. 89.8% and 69.1 vs. 71.5%, respectively). The ATTD for starch varied from 98.6 to 99.7% and did not differ among treatments. Likewise, no differences were observed for the ATTD of NDF and ADF. However, the ATTD for energy in the diets increased from 89.0 to 93.3% (linear and quadratic, P < 0.05) as field peas were extruded, and the ATTD for energy in the pelleted diet was also greater (P < 0.05) than that of the control diet (91.6 vs. 89.0%). In conclusion, extrusion of field peas increases the AID of CP, AA, starch, and energy and the ATTD of energy. Pelleting field peas at 75 degrees C does not influence the AID of nutrients or energy but improves the ATTD of energy.     

The effect of source of fiber on ileal and fecal amino acid digestibility and bacterial nitrogen excretion in growing pigs.

Studies were carried out with six barrows (initial BW 50 kg) to determine the effect of two fiber sources on the apparent ileal and fecal N and amino acid digestibilities and bacterial N excretion in feces. The pigs, fitted with a simple T-cannula at the distal ileum, were fed three cornstarch-based diets formulated to contain 16% CP from soybean meal according to a repeated 3 x 3 Latin square design. Diet 1 did not contain additional fiber. Diets 2 and 3 contained 10% powdered cellulose and 10% barley straw (ground through a 2-mm mesh screen), included at the expense of cornstarch, respectively. The pigs were fed 900 g at each meal twice daily, 0800 and 2000. Feces were collected for 48 h after a 10-d adaptation period. Thereafter, ileal digesta were collected for 24 h. Chromic oxide was used as a digestibility marker. With the exception of leucine, the inclusion of fiber did not affect (P greater than .05) the ileal digestibilities of the indispensable amino acids. The values for the average of the ileal digestibilities of the indispensable amino acids were 85.3, 82.9, and 83.2% for diets 1, 2, and 3, respectively. On the other hand, the inclusion of fiber decreased (P less than .05) the fecal digestibilities of all the indispensable amino acids. The values for the average of the fecal digestibilities of the indispensable amino acids were 91.7, 87.4, and 89.1% for diets 1, 2, and 3, respectively. These decreases resulted from an increase (P less than .05) in the excretion of bacterial N, which was measured using 2,6-diaminopimelic acid as a marker. In conclusion, as measured with the ileal analysis method, the inclusion of fiber had little effect on the digestible amino acid supply.     

Effects of Xylanase and Protease Supplementation on Nutrient Digestibility in Diets Based on Peas and Wheat Fed to Weaned Pigs

This experiment was conducted to determine the effects of a commercial enzyme mixture providing xylanase and protease activities on the di gesfibility of dietary nutrients when added to diets based on peas and wheat and fed to 9.5 to 15 kg pigs.Pigs were weaned at 18 to 21 days of age and fitted with a simple T-cannula at the distal ileum,6 to 7 days after weaning.After 5 to 7 days for adaptation to their diets,ileal digesta,and feces were collected.Enzyme supplementation had no effect on the apparent ileal or fecal digestibility of any dietary nutrient.There Was a numerical improvement(P＞0.05)in the ileal digestibility of fiber.In conclusion.xylanase and protease appeared to be ineffective in improving nutrient digestibility when supplemented in diets based on peas and wheat fed to weaned pigs.     

Estimating equivalency values of microbial phytase for amino acids in growing and finishing pigs fitted with steered ileo-cecal valve cannulas

Ten crossbred barrows (48.3 +/- 2.3 kg of initial BW) fitted with steered ileo-cecal valve cannulas were used to investigate the effects of supplemental microbial phytase on the apparent ileal digestibilities (AID) of AA, Ca, P, N, and DM, and the apparent total tract digestibilities of Ca, P, N, and DM. All diets were corn-soybean meal-based, and contained 0.44% Ca and 0.40% total P. Diets 1, 2, and 3 contained 12.0, 11.1, and 10.2% CP, respectively. Diets 4 and 5 had the same ingredient composition as diet 3, plus 250 and 500 U/kg phytase (Natuphos), respectively. Pigs were randomly allotted to 1 of 5 dietary treatments in a paired 5 x 5 Latin square with an extra period to test for carryover effects. Each 14-d period consisted of a 7-d adjustment followed by a 3-d total collection, a 12-h ileal digesta collection, a 3-d readjustment, and a second 12-h ileal digesta collection. Pigs were housed individually in metabolism pens (1.2 x 1.2 m). Water was supplied ad libitum, and feed was supplied at a level of 9% of the metabolic BW (BW(0.75)) per day in 2 equal daily feedings. As the dietary CP concentration increased, the AID of CP and all AA measured increased linearly (P < 0.05) with the exception of proline. In addition, the apparent total tract digestibilities (grams per day) and retention of N (grams per day) increased linearly (P < 0.01) with increasing CP levels. Supplementing diets with phytase increased the AID of Ca (P < 0.01), P (P < 0.001), CP (P = 0.07), and the AA (P < 0.10) Gly, Ala, Val, Ile, Thr, TSAA, Asp, Glu, Phe, Lys, and Arg. Protein and phytase response equations were generated for those AA affected (P < 0.10) by both CP level and phytase supplementation. Based on these equations, 500 U/kg of phytase can replace 0.52 percentage units of the dietary CP, which includes a 0.03 percentage unit improvement in Lys AID. The results of this study show that supplementing pig diets with microbial phytase improves CP and AA digestibilities in addition to Ca and P digestibilities.     

Effect of different protein sources on growth and carcass traits in growing-finishing pigs

Crossbred gilts (n = 180) and barrows (n = 180) from the Louisiana State University (LSU) Agricultural Center and the University of Illinois (UI) were used to compare the effect of soybean meal in swine diets, relative to other protein sources, on growth performance and carcass traits of growing-finishing pigs. Four replications with five pigs each at each location were allotted to nine dietary treatments: soybean meal control (SBM), crystalline AA (corn-AA), extruded soybeans (ESB), canola meal (CAN), peanut meal (PNT), sunflower meal (SFLR), ground peas, meat and bone meal (MBM), and poultry by-product meal (PLTY). The diets were formulated to meet or exceed NRC nutrient requirements and to have equal Lys:ME according to dietary phase and sex. Corn was the grain source in all diets and the protein sources were the sole source of supplemental protein in all diets except when AA were added to meet the requirement. Pigs (three per pen at each location) were killed at an average final BW of 114 kg in the LSU or UI Meat Science Laboratories. Pigs fed SBM had greater (P < 0.05) ADG than pigs fed the corn-AA, CAN, SFLR, MBM, or PLTY and greater (P < 0.05) ADFI relative to pigs fed the corn-AA, ESB, MBM, or PLTY. Gain:feed was decreased (P < 0.05) in pigs fed corn-AA or SFLR but increased (P < 0.05) in pigs fed ESB compared with pigs fed the SBM diet. Loin muscle area was decreased (P < 0.05) in pigs fed the corn-AA or MBM diets compared with pigs fed the SBM diet. Tenth-rib backfat thickness was greater (P < 0.10) in pigs fed corn-AA, peas, or MBM than in those fed SBM. The NPPC percentage acceptable quality lean and kilograms of lean were decreased (P < 0.10) in pigs fed corn-AA, peas, or MBM compared with those fed SBM. Results from this experiment suggest that pigs fed SBM have equal or better growth performance and carcass traits than pigs fed other protein sources.     

The effect of microbial phytase on true and apparent ileal amino acid digestibilities in growing-finishing pigs

Ten 56-d-old, 15-kg barrows were surgically fitted with a postvalvular T-cecum cannula at the ileo-cecal junction to evaluate the effect of microbial phytase on apparent and true ileal AA digestibility and N utilization. A semipurified cornstarch- and soybean meal-based diet was formulated to contain 3.4 Mcal of DE/kg, 17.0% CP, 0.8% Ca, and 0.6% P but had a low phytate-P concentration (0.13%; all on an as-fed basis). Chromic oxide and dysprosium chloride were used as indigestible markers. The basal diet was supplemented with 0 or 1,000 phytase units/kg of microbial phytase. Postprandial plasma urea N and alpha-amino N concentrations, excretion of Ca, P, and N in feces and urine, and ileal AA digestibilities were determined 3 times at 4-wk intervals beginning at 70 d of age. The homoarginine (HA) method was used to determine endogenous AA flow by replacing 50% of the basal protein with guanidinated protein. Microbial phytase had no effect on apparent ileal digestibility (AID) or on true ileal digestibilities of N and most AA but did increase AID for arginine (P = 0.006) and methionine (P = 0.037). However, in HA diets, phytase increased the AID of CP (P = 0.01) and several AA. Addition of microbial phytase had no effect on the postprandial alpha-amino N concentrations in plasma but increased overall plasma urea N concentrations (P = 0.035). Barrows fed phytase-supplemented diets had decreased P in feces (P = 0.003) and greater P in urine (P = 0.001) but comparable total P excretion compared with barrows fed no phytase-supplemented diets. In conclusion, the addition of phytase to a semi-purified soybean meal-based diet did not affect the AID of several AA. In addition, differences between the basal and HA diets in N digestibilities indicated that that guanidination may limit the use of the HA method in determining endogenous protein losses.     

Effect of graded levels of niacin supplementation of a semipurified diet on energy and nitrogen balance, growth performance, diarrhea occurrence, and niacin metabolite excretion by growing swine

Thirty-six crossbred barrows with an average initial age of 42 d and BW of 13.8 kg were placed in individual metabolism crates in a 35-d experiment to evaluate the supplementation of a semipurified diet with graded levels of crystalline niacin. Response criteria were energy and N balance, growth performance, occurrence of niacin deficiency diarrhea, and urinary excretion of the niacin metabolite N(1)-methyl-2-pyridone-5-carboxylamide (PYR). The basal diet met the true ileal Trp requirement of growing swine, and supplementation with 6, 10, 14, 18, 22, or 44 mg of niacin/kg made 6 treatments. Pigs were observed for scours twice daily, and pig BW and feed consumption were determined weekly. Total urine collections and fecal grab samples were made twice daily from each pig from d 28 to 35. Pigs fed the diet containing 14 mg of niacin/kg absorbed and retained more (P < 0.05) grams of N/d, had a greater N digestibility (%, P < 0.05), a greater ADFI and ADG (P < 0.10), and no diarrhea (P < 0.05) compared with pigs fed the diet containing 6 mg of niacin/kg, and pigs fed the diet containing 10 mg of niacin/kg were intermediate in ADG. There were no additional improvements in the response criteria with niacin supplementation greater than 14 mg/kg. Urinary PYR criteria (mg/L and mg/d) were greater (P < 0.001) for pigs fed the diet containing 44 mg of niacin/kg than for pigs fed the diets containing 6 to 22 mg of niacin/kg. However, urinary PYR criteria for pigs fed the diets containing 6 to 22 mg of niacin/kg did not differ from each other, indicating that PYR was not a sensitive indicator of niacin status for growing swine. Niacin treatment did not affect the percentages of N retained/N absorbed, N retained/N intake, DE, or ME. In conclusion, 14 mg of crystalline niacin/kg of semipurified diet adequate in Trp was the minimum concentration of niacin that maximized N utilization and growth performance, and prevented niacin deficiency diarrhea of growing swine in the current experiment. Because practical feed ingredients may be sources of available endogenous niacin, supplementation of practical diets with 100% of the current NRC requirement for niacin should provide adequate niacin for growing swine.     

Evaluation of the homoarginine technique for measuring true ileal amino acid digestibilities in pigs fed a barley-canola meal-based diet

The homoarginine technique has been suggested as a means to determine true ileal amino acid digestibilities in nonruminant animals fed protein-containing diets. Conditions for guanidinating lysine to homoarginine in barley and canola meal and the effect of this process on nutrient composition and ileal digestibilities in the resulting material were investigated. Conditions tested were methylisourea concentration (0.4, 0.5, or 0.6 M) and reaction time (4 or 6 d) at pH 10.5. Using 0.4 methylisourea M solution for 4 or 6 d gave guanidination rates of 72.5 and 78.5% for barley and 72.3 and 75.2% for canola meal, respectively. Using 0.5 M gave 88.0 and 84.6% guanidination rates in barley and canola meal, respectively, after a 6-d reaction time. Under these conditions, guanidination did not change the nutrient composition of barley (P > 0.10), whereas it increased CP (38.4 vs 49.0%), crude fiber (10.2 vs 16.0%), acid detergent fiber (30.0 vs 43.4%) and neutral detergent fiber (29.8 vs 49.4%) levels in canola meal (P < 0.05). Four 33.6-kg barrows fitted with a simple T-cannula at the terminal ileum were fed a 16% CP unguanidinated barley and canola meal-based diet for four consecutive 14-d periods. Ileal digesta were collected continuously for 24 h on d 12 and 14 to determine apparent nutrient digestibilities. On the morning of d 14, pigs were fed a diet in which half of the barley and canola meal was replaced with guanidinated material for determining true ileal amino acid digestibilities. Digesta samples were pooled by pig and by 24-h period to give 16 observations per diet. Apparent ileal digestibilities of DM, CP, and AA in the unguanidinated and guanidinated barley-canola meal diet were similar (P > 0.10) despite the changes observed in canola meal. Apparent ileal lysine digestibility was 73.9 and 74.5% in the unguanidinated and guanidinated diet, respectively. The true ileal lysine digestibility was 88.1%. The present results show that guanidination does not interfere with digestion and further support the use of the homoarginine method for determining true ileal amino acid digestibilities in pigs fed practical diets. A methylisourea solution of 0.5 M and a 6-d reaction time are recommended for converting lysine to homoarginine in barley and canola meal.     

Effect of fumaric acid and dietary buffering capacity on ileal and fecal amino acid digestibilities in early-weaned pigs

Experiments were conducted to determine the effect of fumaric acid supplementation and buffering capacity of the diet on ileal and fecal digestibilities of CP, GE, and amino acids in early-weaned pigs. In two experiments, 12 pigs each were weaned at 14 d of age and fitted with a simple T-cannula at the distal ileum between 15 and 17 d of age. In both experiments, the pigs were fed four diets, based on wheat and soybean meal without (control) or with 1, 2, or 3% fumaric acid according to a balanced two-period change-over design. In Exp. 2, the buffering capacity of the diets was increased by supplementation of 3% sodium bicarbonate. The pigs were fed three times daily: equal amounts at 8-h intervals. The diets were supplied at a rate of 5% (wt/wt) of body weight. The inclusion of fumaric acid to the diet with a low buffering capacity increased (P < .05) the ileal digestibilities of CP, GE, and the majority of amino acids. The highest responses were found at an inclusion level of 2% fumaric acid. The improvements in apparent ileal amino acid digestibilities ranged from 4.9 to 12.8 percentage units. Supplementation of fumaric acid to a diet with a high buffering capacity led only to numerical increases in ileal digestibilities of CP, GE, and amino acids. In both studies, fumaric acid supplementation had no effect (P > .05) on the fecal digestibilities of CP, GE, and amino acids, except histidine. A high buffering capacity of the diet decreased the ileal amino acid digestibilities by 1 to 10 percentage units compared with diets with the low buffering capacities. In both experiments, ileal and fecal digestibilities were higher (P < .05) in Period 2 (on d 24 after weaning) than in Period 1 (on d 11 after weaning). A positive correlation (P < .05) between ileal digestibilities and fumaric acid supplementation to the diets with the low buffering capacities was observed in Period 1 (on d 11 after weaning), but not in Period 2 (on d 24 after weaning). No relationship (P > .05) between ileal digestibilities and fumaric acid supplementation to the diets with a high buffering capacity could be established. In conclusion, supplementation of fumaric acid to starter diets during the first 3 to 4 wk after weaning increases the ileal digestibilities of GE, CP, and amino acids.     

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).     

Digestibility of nitrogen and amino acids in soybean meal with added soyhulls

This study was designed to quantify the effect of soyhulls on N and AA digestibilities of soybean meal for growing pigs. Soyhulls were incorporated into 17% CP diets containing 33.25% soybean meal (SBM) at 0, 3, 6, or 9% (as-fed basis) and fed to 35-kg barrows to determine their effect on apparent and true digestibility of DM, GE, N, and AA measured at the terminal ileum. Positive and negative control diets containing 1.05% lysine were formulated with 35% SBM and 27% soy protein concentrate (SPC), respectively. A low-protein, casein-based diet was used to estimate endogenous AA losses. Soyhulls were incorporated into experimental diets at the expense of cornstarch, and SBM levels were adjusted to accommodate the contribution of CP from soyhulls. Fourteen pigs were surgically fitted with simple T-cannula at the distal ileum and fed the seven semipurified cornstarch diets based on a replicated 7 x 7 Latin square design. Each period lasted 7 d, with diet acclimation from d 1 to 5 and ileal sample collection for 12 h on d 6 and 7. Feed was offered at a level of 90 g/kg BW(0.75) in two equal portions at 0800 and 2000. Apparent ileal digestibilities of DM and GE decreased approximately six percentage units with the addition of soyhulls (linear, P < 0.05), whereas N was not affected. Both apparent and true ileal digestibilities of arginine, histidine, lysine, phenylalanine, aspartic acid, serine, and tyrosine also exhibited a decrease (linear, P < 0.05) of up to five percentage units with the addition of soyhulls. True ileal lysine digestibility of SBM decreased from 90.3 to 87.7% with the addition of 9% soyhulls. The endogenous nutrient fraction measured at the distal ileum was rich in proline, glutamic acid, and glycine, with losses greater than 1,000 mg/kg of DMI for each AA, and contained minimal amounts of tryptophan, methionine, and cystine. The current data suggest that a 0.2% decrease in some true ileal indispensable AA digestibilities may result with each 1% increase in soyhull inclusion in semipurified diets containing SBM as the sole source of AA as fed to growing pigs.     

Nutritional evaluation of egg byproducts in diets for early-weaned pigs

A total of 272 Cotswold pigs (17 +/- 1 d) were utilized in three experiments to evaluate the nutritive value of spray-dried egg proteins for early-weaned pigs. In all experiments, pigs were stratified by sex and initial BW and then assigned randomly to experimental diets. In Exp. 1, four corn-soybean meal-based diets containing 7% of either spray-dried porcine plasma (SDPP), spray-dried technical albumen (SDTA), SDTA stored at 70 degrees C for 3 d (SDTA-ht), or spray-dried whole egg (SDWE) were assigned to five pens each with four pigs for a 3-wk study period. Average daily gain, ADFI, and gain:feed ratio (G:F) were determined. At the end of wk 3, five pigs per treatment were killed to determine ileal AA and energy digestibilities, as well as Enterobacteriaceae counts. Compared with the SDPP diet, ADG and G:F were lower (P < 0.05) for SDTA-, SDTA-ht- and SDWE-containing diets. Apparent ileal digestibilities of cystine, histidine, isoleucine, methionine, and threonine in the SDPP diet were lower (P < 0.05) than in diets containing spray-dried egg products. Ileal digestible energy content did not differ (P > 0.05) in all diets (3.1 to 3.2 Mcal/kg). Enterobacteriaceae counts were lower in the SDTA-ht diet than in either the SDTA or SDWE diets (P < 0.05). In Exp. 2, the effect of substituting SDPP with varying levels of SDTA was investigated. Diets were randomly assigned to five pens (except for the 100% SDTA diet, which had four pens), each with four pigs. Average daily gain, ADFI, and G:F decreased linearly as the level of SDTA was increased in the diet (P < 0.05). Replacing SDPP with SDTA at 25 or 50% had no effect on pig performance (P > 0.10). In Exp. 3, phase I diets containing 0, 25, or 50% SDTA in place of SDPP (7% of the diet) were each assigned at random to eight pens each with four pigs for a 14-d period, after which all pigs were switched to a common phase II diet lacking both SDPP and SDTA for another 14 d. Average daily feed intake and ADG did not differ among all diets in phase I and II and overall (d 0 to 28). Pigs fed the diet containing 50% SDTA in phase I had lower (P < 0.05) G:F than those fed the SDPP diet. The results indicate that technical albumen can replace 25 to 50% of SDPP in early-weaned pig diets without compromising performance, and further suggest that heat-treated SDTA may affect intestinal microbial population in pigs.     

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.     

True ileal digestible tryptophan to lysine ratios in ninety- to one hundred twenty-five-kilogram barrows

Three experiments were conducted to determine the optimal true ileal digestible (TID) Trp:Lys ratio for 90- to 125-kg barrows. Basal diets contained 0.55% TID Lys and were either corn-based (Exp. 1) or corn- and soybean meal-based (Exp. 2 and 3) diets supplemented with crystalline AA. In addition, each experiment contained a corn-soybean meal control diet. The number of pigs per pen progressively increased, with pigs housed in 2 (n = 82; initial and final BW of 88.5 and 113.6 kg, respectively), 7 (n = 210, initial and final BW of 91.2 and 123.3 kg, respectively), or 20 to 22 (n = 759; initial and final BW of 98.8 and 123.4 kg, respectively) pigs per pen for each successive experiment. Pigs in Exp. 1 were fed 6 incremental additions of L-Trp, equating to TID Trp:Lys ratios of 0.109, 0.145, 0.182, 0.218, 0.255, and 0.290. For the 28-d period, there was a quadratic improvement in G:F (P = 0.05) and ADG (P = 0.08) with increasing TID Trp:Lys, characterized by an improvement in performance of pigs fed the basal diet compared with those consuming diets with a 0.145 TID Trp:Lys ratio, with a plateau thereafter as TID Trp:Lys increased. Pigs fed the control diet had less increase in backfat depth than the average of pigs fed the titration diets (1.30 vs. 4.09 mm, respectively; P = 0.02), but pork quality was unaffected by dietary treatment. Pigs in Exp. 2 were fed 4 incremental additions of L-Trp, equating to TID Trp:Lys ratios of 0.130, 0.165, 0.200, and 0.235. Average daily gain and ADFI increased in a linear fashion with increasing TID Trp:Lys for the 29-d trial (P < 0.01), with quadratic improvements in d-29 BW (P = 0.06) and G:F (P = 0.05). Pigs fed the diet containing a TID Trp:Lys ratio of 0.165 had greater d-29 BW, ADG, G:F, and lower serum urea N concentration than pigs fed the basal diet (P < 0.05), but were similar to pigs fed TID Trp:Lys ratios of 0.200 and 0.235 for all criteria measured. In Exp. 3, TID Trp:Lys ratios of 0.13, 0.15, 0.17, 0.19, and 0.21 were evaluated. The response to increasing TID Trp:Lys was limited to a quadratic (P < 0.10) improvement in G:F with increasing TID Trp:Lys ratios. Maximum G:F was noted at a TID Trp:Lys ratio of 0.17. No relationship was noted between TID Trp:Lys and carcass characteristics. These experiments demonstrate that the minimum TID Trp:Lys ratio for pigs from 90 to 125 kg of BW is at least 0.145, but not greater than 0.17.     

The effect of feeding low-phytate barley-soybean meal diets differing in protein content to growing pigs on the excretion of phosphorus and nitrogen

An experiment was conducted with growing pigs to determine the excretion of P and N in 4 barley-based diets formulated to contain 18 or 15% CP by using a normal barley (NB) or a low-phytate barley (LPB). The NB contained 0.31% total P and 0.19% phytate P; the LPB contained 0.32% total P and 0.01% phytate P. The diets were supplemented, when so required, with lysine, methionine, threonine, and tryptophan to meet their apparent ileal digestible supplies according to the NRC (1998). The diets containing NB were supplemented with inorganic P to meet the NRC (1998) recommendation for available P (0.23%). The diets containing LPB were not supplemented with inorganic P because these contained sufficient available P (0.27%). Eight barrows with an average BW of 20.9 kg were assigned to the 4 dietary treatments according to a repeated 4 x 4 Latin square design. The diets were fed at a rate of 2.5 times the ME requirement for maintenance. The barrows were fed twice daily, at 0800 and 1500, equal amounts each meal. Water was added to the feed at a ratio of 2.5:1. Each experimental period consisted of a 7-d adaptation period followed by a 5-d collection of feces and urine. The substitution of NB with LPB decreased (P < 0.001) the total P excretion by 38 and 43% for the 18 and 15% CP diets, respectively. Reducing the CP content from 18 to 15% decreased (P < 0.001) the N excretion by 29 and 32% for the NB and LPB diets, respectively. With the reduction in CP content, there was a decrease (P < 0.001) in the amount of N retained. The N:P ratio in manure of pigs fed the LPB diets was greater (P < 0.001) than from pigs fed the NB diets. These data indicate that P and N excretion can be greatly reduced by substitution of NB by LPB, and also by the reduction of the CP content, in diets for growing pigs.