Apparent Total Tract Digestibility Research Articles

PSI-11 Determination of standardized total tract phosphorus digestibility in expeller-pressed Canadian prairie grown soybean meal fed to growing pigs

Abstract The objectives of this study were 1) to determine the apparent total tract digestibility (ATTD) of calcium (Ca) and phosphorous (P) and standardized total tract digestibility (STTD) of P in soybean expeller (SBE), and 2) to examine the effects of microbial phytase supplementation on ATTD and STTD of P in SBE. A total of 48 growing barrows (body weight = 15.5 ± 0.7 kg, mean ± SD) were assigned to 1 of 8 dietary treatments (4 with 500 phytase units/kg and 4 without phytase) in a completely randomized design to give 6 replicates per treatment. SBE was the only source of P in diets. Four SBEs were used in the experiment, with three derived from soybeans grown in Manitoba (MB1, MB2, and MB3) whereas the fourth was derived from soybeans grown in Ontario. The experiment was conducted over 3 consecutive 12-d periods; within each period the initial 7 d were for adaptation followed by 5 d for total fecal collection (marker to marker procedure). Data were analyzed using the MIXED procedure of SAS. Fixed effects were the type of SBE and phytase whereas period was included as a random effect in the model. Dry matter (DM), Ca and P content was analyzed in diets and feces. The ATTD and STTD of P were not affected by the source of SBE and averaged 63.0% and 69.9%, respectively. Phytase supplementation significantly increased (P < 0.001) P digestibility in all SBE types. The ATTD and STTD values of P with phytase supplementation averaged 72.8% and 79.7%, respectively. There was no interaction effect between type of SBE and phytase supplementation. The ATTD of Ca (P < 0.001) in MB2 was significantly less (55.7%) than in the other SBEs whose values averaged71.6%. Ca digestibility was not affected by phytase inclusion. In conclusion, the ATTD and STTD of P were not different among the SBE types. Phytase supplementation increases the P digestibility in SBE irrespective of source.

PSI-18 Effects of heat treatment and multi-carbohydrase supplementation on the digestibility of phosphorus in field peas fed to growing pigs

Abstract Most plant-based feed ingredients contain about two-thirds of their total P as phytate. Mineral elements are chelated to phytate or entrapped in plant cell walls, and microbial or enzymatic breakdown of cell walls may be able to release entrapped P, thus leading to improvement of the apparent total tract digestibility (ATTD) of P in pigs. Heat treatment is one of the processing methods that improve the digestibility of fiber in various feedstuffs for pigs. Therefore, this study aimed to determine the effects of heat treatment and multi-carbohydrase supplementation on the ATTD and standardized total tract digestibility (STTD) of P in peas fed to growing pigs. A total of 18 pigs (23.9 ± 1.3 kg) were assigned to 1 of 3 diets in a completely randomized design to give 6 replicates per diet. Three experimental diets were formulated: 1) non-heated or 2) heat-treated (pelleted) peas as the sole source of P, and 3) heat-treated peas with multi-carbohydrase supplementation. Pigs were individually housed in metabolism crates for 12 d, including 7 d for adaptation and 5 d for total collection of feces. Pigs were offered their daily ration at 2.8 times their maintenance energy requirement. Samples of ingredients, diets, and feces were analyzed for dry matter, Ca, and P. Fecal samples were analyzed for mixed bacterial mass (MBM) and volatile fatty acids (VFA) concentrations. Data were analyzed using the PROC MIXED of SAS. The statistical model included diet as fixed effect and replicate as random effect. An alpha level of 0.05 was used to determine statistical significance and P ≤ 0.10 was considered a trend. Pigs fed the diet that contained heat-treated peas with carbohydrase supplementation tended to have greater (P < 0.10) ATTD and STTD of P than pigs fed the diet containing heat-treated peas without enzyme. The values of STTD of P were 54.4, 47.3, and 55.0% for diets containing raw peas, heat-treated peas, and heat-treated peas with carbohydrase supplementation, respectively. Heat treatment and enzyme supplementation did not affect the ATTD of Ca in peas fed to growing pigs. No significant differences were observed in fecal MBM-P and VFA concentrations. In conclusion, carbohydrase supplementation tended to increase the digestibility of P in heat-treated peas fed to growing pigs, however, there was no difference in P digestibility between raw and heat-treated peas. Heat treatment and carbohydrase supplementation did not affect fecal MBM-P and VFA concentrations in growing pigs.

247 Evaluating the use of soybean hulls on growth performance, carcass composition, and digestibility when fed to grow-finish pigs

Abstract The addition of fiber to grow-finish diets is commonly utilized in swine production formulation as energy costs increase. The objective of this study was to determine the effects of feeding soybean hulls (SBH) at increasing levels to grow-finish pigs on growth performance, carcass characteristics, and apparent total tract digestibility (ATTD) of nutrients. Utilizing 192 grower pigs [PIC 337×1050, initial body weight (BW) = 21.99 ± 2.75 kg] that were randomly assigned to split sexed pens (n = 12 pens/treatment), pens were assigned to one of four dietary treatments and fed over three feeding phases for the estimated BW ranges of 22 to 50 kg, 50 to 86 kg, and 86 to 127 kg. Diets were formulated to represent conventional corn and soybean meal diets, containing increasing levels of SBH at: 1) 0% SBH (0%); 2) 7.5% SBH (7.5%); 3) 15% SBH (15%); and 4) 22.5% SBH (22.5%). Within phase, diets had equal SID Lys:ME and energy was allowed to float. Individual BW and pen feed disappearance were collected for each phase to calculate pen average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency gain to feed ratio (G:F). On d 56 of study and during phase 2, 32 gilts (n = 8) were placed into individual metabolism crates, where total urine and feces were collected for 72 h to measure ATTD of gross energy (GE), nitrogen (N), neutral detergent fiber (NDF), and acid detergent fiber (ADF), then returned to original pens. At the completion of study, carcass weight, backfat depth, and loin depth were collected. Data were analyzed with the fixed effects of dietary treatment by ANOVA, linear, and quadratic contrasts. Pen served as the experimental unit for performance and carcass characteristics and pig as the experimental unit for ATTD analyses. Overall, as SBH increased from 0% to 22.5%, ADG tended to decrease (linear P = 0.060) with no difference in ADFI (P > 0.05), resulting in an overall decrease in G:F (0.38, 0.37, 0.36, 0.35; linear P < 0.001; 0, 7.5, 15 and 22.5% SBH, respectively). Final BW tended to decrease (linear P = 0.069) and carcass weight decreased (102.9, 102.7, 99.7, and 96.5 kg, linear P < 0.001) as SBH increased in diet. Carcass fat depth (P = 0.014) and loin depth (P = 0.006) linearly decreased with increasing levels of SBH in the diet. Increasing levels of SBH from 0% to 22.5% decreased ATTD of GE and N (linear P < 0.001) and tended to increase ATTD NDF and ADF (linear P = 0.056 and P = 0.073, respectively). Altogether, these data suggest increasing dietary SBH in grow-finish pig diets decreases growth efficiency and the digestibility of GE and N. Further, feeding high inclusion rates of SBH negatively impacts carcass yield, backfat and loin depth.

PSV-14 Determination of optimal digestible phosphorus level in lactating sows

Abstract Optimal dietary phosphorus (P) is important for sows, not only to maintain P homeostasis and prevent premature culling due to lameness and locomotion, but also to support growth of their offspring. The objective of this experiment was to determine the optimal level of digestible P in lactating sows for the best reproductive performance and piglet growth. A total of 550 gestating sows were enrolled using a randomized block design with sow parity and group as blocks. Sows with an entry body weight of 247.5 ± 29.1 kg were allotted to one of the five levels of digestible P (similar as standard total tract digestibility of P with consideration of phytase released P): 0.2%, 0.3%, 0.4%, 0.5% and 0.6%. A corn-soy-wheat middling based lactation diet was formulated with phytase inclusion (550 FTU/kg) and a fixed ratio between calcium (Ca) and digestible P of 2.5. All diets were formulated to have the same nutrient levels except 69 kcal net energy difference between 0.6% and 0.2% digestible P treatments due to slight difference in the ingredient composition. Experimental diets were fed approximately 4 d before farrowing and throughout the entire lactation (21 d). Feces were collected from 20 sows per treatment around 14 d of lactation to measure apparent total tract digestibility (ATTD) of Ca and P. Using R (version 4.0.0), performance and digestibility data were analyzed using a general linear model and a generalized linear model specifying a binomial distribution was deployed for count data. Dietary treatments did not impact sow average daily feed intake or piglet birth and weaning weights (Table 1). However, dietary treatments affected piglet livability (P < 0.05) and pre-weaning morality (P < 0.01), with 0.5% digestible P having the greatest livability and 0.4% digestible P having the least pre-weaning mortality. There was a positive linear dose effect of digestible P on probability of weaned pigs (P < 0.05). Dietary digestible P affected ATTD Ca (88.8 ± 3.1%, P < 0.01) and ATTD P (64.4 ± 6.5%, P < 0.01) in sows on d14 of lactation, with greater digestible P leading to decreased ATTD Ca and P. In conclusion, dietary digestible P level affected ATTD Ca and P during lactation. Digestible P level of 0.4% and greater led to greater piglet livability and resulted in greater probability of weaned pigs.

172 Effects of post-MSC DDGS inclusion in gestation diets on total tract nutrient and energy digestibility compared with other fiber sources

Abstract The high fiber content of corn dried distiller grains with solubles (DDGS) make it an ideal candidate for inclusion in gestation sow diets. Gestating sows, however, have greater utilization of fibrous ingredients, and nutrient values attained in grower pigs are not representative of nutrient metrics for gestating sows. The objective of this study was to evaluate apparent total tract digestibility (ATTD) of energy and nutrients from post-protein separation (post-MSC) DDGS provided to gestating sows in comparison with soyhulls and sugar beet pulp; two commonly used fiber sources in gestation diets. Pregnant sows [n = 22; parity 0 to 1; initial body weight (BW) = 190 ± 10 kg] were allocated to 1 of 6 dietary treatments in a crossover design with two collection periods (period 1 from d 40-59 of gestation and period 2 from d 60-79 of gestation) to attain at least 7 observations per treatment. Two of the six diets were practical corn-soybean meal-based gestation diets with either soyhulls (17.5% inclusion) or post-MSC DDGS (15% inclusion) to determine ATTD of energy and nutrients in complete diets. The remaining four diets included a corn-basal diet and the basal diet plus 30% inclusion of post-MSC DDGS, soyhulls, or sugar beet pulp. Titanium dioxide was included as an indigestible marker to calculate ATTD. Sows were fed experimental diets (2.2 kg/d in a single feeding) in two 20-d collection periods where the initial 14 d considered a diet adaptation period followed by 5 d for total collection of urine (collected using urine catheters inserted on d 14) and grab fecal samples. Energy values for the post-MSC DDGS, soyhulls, and sugar beet pulp in the corn-basal diets were calculated using differential procedure. Data were analyzed with ANOVA and fixed to a mixed linear model using treatment as the main effect and collection period as a random variable. The ATTD of the post-MSC DDGS practical diet was 8% greater in ATTD of crude protein and 13% greater in ATTD of ether extract than the practical soyhull diet (P < 0.01). The ATTD of gross energy of post-MSC DDGS was 16% greater than soyhulls (P < 0.01). This resulted in an 800 and 750 kcal/kg greater digestible energy and metabolizable energy content, respectively on an as-fed basis in post-MSC DDGS compared with soyhulls and sugar beet pulp (P < 0.01). The post-MSC DDGS also had a net energy value (as-fed basis) 700 kcal/kg greater than soyhulls and sugar beet pulp. In conclusion, post-MSC DDGS is suitable for inclusion in gestating sow diets as a fiber source while meeting the energy needs of the gestating sow.

159 Concentrations of energy in pistachio shell powder fed to gestating sows and lactating sows

Abstract Two experiments were conducted to test the hypothesis that apparent total tract digestibility (ATTD) of gross energy (GE), digestible energy (DE), and metabolizable energy (ME) in pistachio shell powder are not different from those in soybean hulls when fed to gestating sows. The second hypothesis was that the ATTD of GE and DE in pistachio shell powder are not different from those in soybean hulls when fed to lactating sows. In Exp. 1, gestating sows (n = 24) were housed in metabolism crates and were fed a corn-based control diet or two diets that included corn and 20% pistachio shell powder or 20% soybean hulls. Sows were fed the experimental diets for 13 d with feces and urine being quantitatively collected for 4 d, after a 6 d of adaptation. Concentrations of DE and ME were calculated. In Exp. 2, lactating sows (n = 24) were housed in farrowing crates and fed a diet based on corn and soybean meal (SBM) or two diets that contained corn, SBM and 20% of either pistachio shell powder or soybean hulls. All diets contained corn and SBM at a ratio of 2.87:1.00 and 0.40% TiO2 as the digestibility marker. Lactating sows were allowed ad libitum access to the experimental diets and feces were collected for 6 d after a 7 d of adaptation to the diets. The DE in each diet and in pistachio shell powder and soybean hulls was calculated. Each experiment was conducted as a randomized complete block design and each experiment used two blocks of 12 sows, with 4 sows per diet in each block. The statistical model in both experiments included diet or ingredient as the fixed effect and block and replicate within block as the random effects. Results from Exp. 1 indicated that the ATTD of GE and DE and ME on an as-fed basis as well as on a dry matter basis were less (P < 0.05) in pistachio shell powder compared with corn and soybean hulls and DE and ME in soybean hulls were less (P < 0.05) than in corn (Table 1). Results from Exp. 2 indicated that the ATTD of GE and DE in pistachio shell powder were less (P < 0.05) than in soybean hulls. In conclusion, pistachio shell powder has a high concentration of fiber and energy digestibility and concentrations of energy in pistachio shell powder were, therefore, less than in soybean hulls when fed to gestating or lactating sows, but gestating sows appear to be better at digesting pistachio shell powder than lactating sows. This is likely due to the restricted feed intake of gestating sows that allows more time for nutrient and energy digestion and absorption in the intestinal tract compared with lactating sows.

PSI-14 Effect of dietary xylanase supplementation on growth performance, nutrient digestibility, and digesta viscosity of weaned pigs fed wheat-soybean meal-based diets

Abstract Xylanase supplementation can improve nutrient digestibility in pig diets by degrading cell wall non-starch polysaccharides and reducing digesta viscosity as well as promoting intestinal health of pigs after weaning. This study determined the effects of dietary xylanase supplementation on growth performance, apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of nutrients, and digesta viscosity in different digestive sites of weaned pigs. A total of 312 weaned pigs [body weight (BW) = 5.1 ± 0.9 kg] were weaned into 48 pens and assigned to one of six dietary treatments, each treatment with 8 pens, 6 to 7 pigs per pen, and sex ratios maintained within BW blocks. Experimental diets were formulated in a 3-phase nursery feeding program: Phase 1 (d 0 - d 7), Phase 2 (d 8 - d 21), and Phase 3 (d 22 – d 42). Experimental diets consisted of a wheat/soybean meal-based diet formulated to meet pig requirements (positive control, PC), the PC diet with reduction of 100 kcal of ME (negative control, NC), and the NC diet supplemented with either 900, 1,800, 3,600, or 7,200 units of xylanase. Feed disappearance and body weight were measured at d 7, 14, 21, and 42. Pen fecal score was assessed daily during d 0 to 14 and three times a week during d 15 to 28. On d 21 to 24 of the experiment (12 pigs per day), one pig per pen was selected for sample collection: ileal, cecal, and mid-colon digesta for viscosity and ileal digesta and feces for nutrient digestibility. Orthogonal polynomial contrasts were used to determine the linear and quadratic effects of increasing levels of xylanase in NC diets. Contrast analysis was used to compare PC and NC groups with xylanase-supplemented groups. Fecal score data were analyzed using the PROC FREQ procedure. Supplementing xylanase to NC diets did not improve pig growth performance (P > 0.05) through the nursery period. In wk 2 and wk 3, pigs fed the PC and NC diets had a greater (χ2 < 0.05) incidence of fecal scores 3 & 4 (diarrhea) than the xylanase-supplemented pigs. The AID of DM and ATTD of crude protein, gross energy, and NDF were greater (P < 0.05) in the PC and 900-xylanase supplemented diets than in the other dietary treatments. In addition, the ATTD of NDF and ADF increased linearly (P < 0.1) in response to xylanase supplementation. Xylanase supplementation (900 to 7,200 U) decreased digesta viscosity in colon when compared with PC and NC diets. Overall, xylanase supplementation can improve nutrient digestibility, particularly at total tract level, and reduce viscosity in the hindgut, which could be related with decreasing the occurrence of looseness. However, the effects on growth performance were not expressive when xylanase was supplemented to wheat-soybean meal-based diets with reduction of 100 kcal of ME.

246 The effect of trypsin inhibitor unit concentrations from raw soybeans in grower pig performance and protein digestibility

Abstract Soybeans contain two major protease inhibitors, Kunitz trypsin and Bowman-Birk protease inhibitors, both of which are anti-nutritional components that can be directly linked to a reduction in amino acid bioavailability and growth performance in swine. Therefore, the objective of this study was to determine the level at which trypsin inhibitor units (TIU, expressed as TIU/mg of complete feed), coming from raw soybeans, in pig diets result in reduction in growth performance and digestibility. This study used 45 grower gilts initial body weight (BW) = 39.7 ± 2.1 kg] that were individually penned and fed one of five dietary TIU treatments (n = 9 pigs/trt) in a complete randomized design. Diets were representative of a commercial corn-soybean meal diet and formulated to have ranging TIU/mg of complete feed of 0.89, 1.77, 3.55, 6.99, and 11.54 TIU/mg utilizing raw ground soybeans and soybean meal at incremental levels. Analyzed diets contained 0.99, 2.23, 3.07, 6.49, and 9.38 active TIU/mg. Diets were balanced to the same grams of SID Lys:ME of 2.85 and NDF concentration of 7.4% utilizing soybean oil and soybean hulls, respectively. Individual feed intake was recorded throughout, and pig BW were collected on d 0, 21, and 27 to calculate average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency gain to feed ratio (G:F). All pigs were placed into metabolism crates on d 21 for 6 d to determine apparent total tract digestibility (ATTD) of nitrogen (N), N excretion and N balance. Growth performance and ATTD data were analyzed with pig as the experimental unit and diet TIU level as a fixed effect using ANOVA, linear, and quadratic contrast models. Overall, ADG decreased as diet TIU increased (1.07, 1.03, 1.02, 0.91, and 0.83 kg/d, respectively, linear P < 0.001). However, no differences in ADFI (P > 0.10) were reported and this resulted in a decrease in G:F (0.48, 0.45, 0.43, 0.41, 0.36, respectively, linear P < 0.001) as dietary TIU concentrations increased from 0.99 to 9.38 TIU/mg. Compared with 0.99 TIU/mg, pigs fed 9.38 TIU/mg had a 9.32% reduction in final BW (68.7 vs. 62.3 kg, linear P < 0.001). Apparent total tract digestibility of N decreased when pigs were fed 9.38 TIU/mg compared with 0.99 and 2.23 TIU/mg (83.26% vs. 90.29% and 89.57%, respectively, P < 0.001). In conclusion, as total trypsin inhibitor units increase in complete feed of grower pigs, digestibility of protein, growth rates and feed efficiency are reduced in a linear manner.

PSI-12 Dietary isoacids modulate nutrient digestibility and fermentation products in ileal digesta and feces of growing pigs fed corn-soybean meal diets

Abstract Branched-chain fatty acids, or isoacids, are the product of branched-chain amino acid fermentation and have been associated with benefits on the productivity of ruminants, primarily by positively modulating gut microbes and promoting gastrointestinal health. The objective of this study was to determine the optimal inclusion level of isoacid blend product based on apparent ileal digestibility (AID), apparent total tract digestibility (ATTD) of nutrients, and fermentation products in growing pigs fed corn-soybean meal diets. Twelve cannulated pigs [body weight (BW) = 20.9 + 0.6 kg] were used in a 5-period switch-back design with 6 diets and 2 replicate pigs in each period (n = 10 observations per dietary treatment). Experimental diets consisted of increasing levels (0%, 0.5%, 0.75%, 1%, 1.25%, and 1.5%) of an isoacid blend (isobutyrate, isovalerate, and 2-methyl butyrate, 1:1:1) added to a corn-soybean meal basal diet containing titanium dioxide as an indigestible marker. Each experimental period lasted 14 d: 10 d for acclimatization to the diets, 2 d for fecal collection, and 2 d for digesta collection. Diets, fecal, and ileal digesta samples were analyzed for gross energy (GE), crude protein (CP), fiber composition, amino acids (AA), and titanium. The concentration of short-chain fatty acids and ammonia were analyzed in digesta and fecal samples. Orthogonal polynomial contrasts were used to determine the linear and quadratic effects of increasing levels of isoacids. Dietary supplementation of isoacids improved (P < 0.1, linear and/or quadratic) AID of crude fiber and hemicellulose and most of the indispensable AA (except Met+Cys, Trp, and Val) as well as ATTD of CP, GE, neutral detergent fiber, and hemicellulose. In addition, ATTD of Arg, His, Ile, Leu, Met+Cys, Phe, Thr, Trp, and Val increased quadratically (P < 0.1). Collectively, 1% isoacid inclusion promoted the greatest responses in most measured variables (% increase: unsupplemented vs. 1%): AID of Lys (9.3%), Met (5.7%), Thr (17.8%), Leu (7.4%), Ile (9.2%), Phe (7.8%), His (5.9%), Arg (4.9%); ATTD of CP (2.1%), GE (1.3%), NDF (3.9%), hemicellulose (>50%), overall indispensable AA (9.5%), overall dispensable AA (8.6%). On the other hand, the inclusion of isoacids quadratically increased (P = 0.071) the concentration of ammonia and decreased (P < 0.1) the concentration of acetic acid, iso-valeric acid, and total VFA in ileal digesta samples. In fecal samples, the proportion of acetic acid decreased (P < 0.05) quadratically while the proportion of propionic, valeric, and caproic acids increased (P < 0.1). In conclusion, dietary supplementation of isoacids at 1% can improve dietary nutrient digestibility, particularly ileal AA digestibility. Based on the changes in fermentation products, the modulation of intestinal microbiota through the gastrointestinal tract could be potentially related to the effects of isoacids on nutrient digestibility. However, the effects of isoacids supplementation on intestinal microbiota must be determined.

260 Effect of different doses of phytase (HiPhorius) and two primary calcium sources on nutrient digestibility, retention and blood parameters in weaned piglets

Abstract An 18-d study evaluated the effect of increasing phytase levels in diets with limestone or Ca-formate on Ca and P digestibility, P retention, and blood inositol, Ca, and P in weaned piglets. At weaning, male piglets [n = 60; 29.8 ± 1.10 d of age; initial body weight (BW) = 8.8 ± 0.31 kg) were randomly allocated to ten diets formulated as a 2 × 5 factorial design with 2 primary Ca sources (limestone or Ca-formate) and 5 Ca/P levels. There was a positive control diet (PC; 0.76% Ca, 0.34 dP) and 4 negative control diets (NC; 0.56% Ca, 0.34% dP) supplemented with phytase at 0, 750, 1,500, and 3,000 FYT/kg. At d 10, piglets were individually housed in metabolism crates and fed 3.2 x metabolic weight. On d 14 to 18, fecal and total urine samples were collected. Apparent total tract digestibility (ATTD) was calculated for dry matter (DM), organic matter (OM), crude protein (CP), ash, Ca, and P using TiO2 as marker. Urinary P was measured to calculate P retention. These data were analyzed as a 2-way interaction. On d 0 (baseline), 8 and 18, blood samples were collected to analyze serum Ca and P, and plasma inositol. Blood data were analyzed as a 3-way interaction. Results indicated that piglets fed Ca-formate had greater ATTD of Ca (75.0% vs. 71.4%, P < 0.01) but decreased ATTD of P (66.4% vs. 68.8%, P < 0.01), than piglets fed limestone. Phytase supplementation improved ATTD of DM, ash, OM, CP, P, and Ca compared with the NC and PC. An interaction between Ca/P levels and Ca-sources was observed for urinary P (P = 0.03), as there were no differences between Ca sources in piglets fed the NC or the 750 FYT diets, but piglets fed the PC diet and the NC+1,500 or 3,000 FYT with limestone had greater urinary P compared with Ca-formate. A 2-way interaction between Ca/P levels and d was observed for plasma inositol (P = 0.012). On d 8 and 18, there was no difference between the NC and PC;, however, phytase supplementation at 750, 1,500, and 3,000 FYT increased plasma inositol on d 8 (58.2, 80.7, and 89.5 μmol) and d 18 (70.2, 85.4, and 106.4 μmol). There was only a main effect of Ca/P levels in serum P. Compared with the NC (73.7 mg/L), the PC and the NC+750, 1,500, and 3,000 FTU/kg increased serum P (90.3, 89.1, 87.6, and 93.2 mg/L, respectively, P < 0.01). There was no effect of Ca source on blood inositol and P. No significant dietary treatment effects were observed in serum Ca. In conclusion, using Ca-formate instead of limestone increases Ca digestibility but reduces P digestibility, likely due to a greater Ca solubility of Ca-formate. This suggests that diets should be formulated based on digestible Ca instead of total Ca.

49 Effects of xylanase or a stimbiotic on growth performance and total tract digestibility of nutrients by pigs weaned from sows fed a lactation diet without or with xylanase

Abstract Two hypotheses were tested 1) the offspring of sows fed xylanase in lactation have greater growth performance after weaning than offspring of sows fed no xylanase, and 2) xylanase and a stimbiotic (i.e., xylanase in combination with xylo-oligosaccharides) improve growth performance, apparent total tract digestibility (ATTD) of gross energy (GE) and total dietary fiber (TDF), and digestible energy (DE) of diets for weanling pigs. A total of 120 newly weaned pigs from sows fed a lactation diet without xylanase and 120 pigs from sows fed a lactation diet containing 16,000 beechwood xylanase units (BXU) per kg of an exogenous xylanase were used [initial body weight (BW) = 5.81 ± 0.50 kg]. Pigs were allotted to a 2 × 3 factorial with two sow groups (lactation diet without or with xylanase) and three dietary treatments (i.e., control, control plus 100 g/t of xylanase, or control plus 100 g/t of stimbiotic). The xylanase (Econase XT) and the stimbiotic (Signis) were procured from AB Vista, Marlborough, UK. Pigs were weaned in 4 blocks and allotted to 12 pens per block, with 5 pigs per pen for a total of 8 replicate pens per treatment. Pigs were fed phase 1 diets from d 1 to 14, phase 2 diets from d 15 to 28, and phase 3 diets from d 29 to 42 post-weaning. Average daily gain (ADG), average daily feed intake (ADFI), and gain to feed ratio (G:F) were calculated. Fecal samples were collected at the end of phases 2 and 3. Data were analyzed using the MIXED procedure of SAS. Sow group, diet, and the interaction between sow group and diet were fixed effects, and block and replicate within block were random effects. Results indicated that for the overall experiment, there were no interactions between sow group and diet, and sow lactation diet treatment did not impact any post-weaning growth or digestibility parameters in the weaned pigs (Table 1). However, weaned pigs had greater (P < 0.05) ADG, G:F, ATTD of GE and TDF, and DE in phase 2 if fed the diet with stimbiotic than if fed the xylanase diet or the control diet, but pigs fed the xylanase diet had greater (P < 0.05) ADG, G:F, ATTD of GE and TDF, and DE than pigs fed the control diet (Table 2). In phase 3, pigs fed the diet with xylanase or stimbiotic had greater (P < 0.05) ADG, ATTD of GE and TDF, and DE than pigs fed the control diet. In conclusion, pigs fed diets containing xylanase or stimbiotic had greater nutrient digestibility and DE, resulting in greater overall ADG, G:F, and final body weight on d 42 post-weaning, but feeding sows xylanase in lactation did not influence post-weaning growth performance.

153 Standardized ileal digestibility of amino acids and concentration of metabolizable energy in three sources of corn protein fed to weanling pigs

Abstract Two experiments were conducted to test the hypothesis that the standardized ileal digestibility (SID) of amino acids (AA), apparent total tract digestibility (ATTD) of gross energy (GE), and concentrations of digestible energy (DE) and metabolizable energy (ME) are not different among three sources of corn protein (i.e., new corn protein, ANDVantage 50Y, ANDVantage 40Y) when fed to weanling pigs. In Exp. 1, ileal-cannulated barrows [n = 8; initial body weight (BW) = 11.09 kg; SD = 0.46] were fed an N-free diet or three diets containing each corn protein as the sole source of AA. Pigs were allotted to a replicated 4 × 4 Latin square design with 4 diets and 4 periods of 7 d in each square. Ileal digesta were collected for 2 d and the SID of AA was calculated. In Exp. 2, weanling pigs (n = 32; initial BW = 18.0 kg; SD = 1.21) were fed a corn-based basal diet or three diets containing corn and each source of corn protein. Pigs were housed individually in metabolism crates and feces and urine were quantitatively collected for 5 d after 7 d of adaptation. Concentrations of DE and ME in all diets were calculated and DE and ME in the three sources of corn protein were calculated by difference. Data from both experiments were analyzed using the MIXED procedure of SAS with pig as the experimental unit. In Exp. 1, the statistical model included diet as the fixed effect and square, pig, and period as random effects. In Exp. 2, the model included ingredient as the fixed effect. Results from Exp. 1 demonstrated that the SID of all indispensable AA except Arg and His in ANDVantage 40Y and ANDVantage 50Y were greater (P < 0.05) compared with the new corn protein, but no differences were observed between ANDVantage 50Y and ANDVantage 40Y (Table 1). Results from Exp. 2 indicated that on a dry matter basis, concentration of DE in ANDVantage 50Y was greater (P < 0.05) than in ANDVantage 40Y, the new corn protein, and corn, but ME in ANDVantage 50Y was not different from the ME in the new corn protein (Table 2). Concentration of ME in the new corn protein was not different from ME in corn, ANDVantage 40Y, or ANDVantage 50Y. In conclusion, the new source of corn protein had concentrations of AA that were not different from ANDVantage 50 Y, but this new corn protein had decreased digestibility of AA compared with other corn proteins. The new corn protein also had less DE compared with ANDVantage 50Y, but ME in the new corn protein was not different from corn, ANDVantage 40Y, or ANDVantage 50Y.

PSI-15 Effect of feeding intact protein from soybean meal instead of crystalline amino acids on energy and nitrogen balance by growing pigs

Abstract The objective was to test the hypothesis that feeding intact protein from soybean meal (SBM) to growing pigs instead of crystalline amino acids (AA) increases nitrogen (N) retention, digestible energy (DE), and metabolizable energy (ME). A control corn-SBM diet and three diets, in which the inclusion rate of SBM was reduced and 3, 4, or 5 crystalline AA (i.e., Lys, Met, Thr, Trp, Val) were added, were formulated. The concentration of standardized ileal digestible AA was constant among diets, but crude protein was reduced as crystalline AA were added. Pigs were limit fed at 3.2 times the ME requirement for maintenance. Forty pigs (initial body weight = 20.5 kg; SD = 2.4) were allotted to the 4 diets using a randomized complete block design with 2 blocks of 20 pigs with five pigs per diet in each block. Pigs were housed in metabolism crates with pans and screens that allowed for quantitative collection of feces and urine for 4 d after 5 d of adaptation. Samples of diets, feces, and urine were analyzed for gross energy (GE) and N. The statistical model included diet as fixed effect and block as random effect, and pig was the experimental unit. Contrasts coefficients were used to determine linear and quadratic effects of reducing dietary protein. Results indicated that apparent total tract digestibility (ATTD) of dry matter (DM) decreased (quadratic, P = 0.027) and ATTD of GE tended to decrease (quadratic, P = 0.076; Table 1) as SBM inclusion was reduced in the diets. Absorbed N, retained N (g/d), and ATTD of N were decreased (linear, P < 0.001) as SBM decreased in diets, but retention of N (% of intake and % of absorbed) increased (linear, P < 0.001) as SBM decreased in diets. The DE decreased (linear, P = 0.007) as SBM decreased in diets, whereas SBM had no effect on ME. Dietary SBM also had no effect on ME to GE ratio, but ME to DE increased (linear, P = 0.008) by reducing SBM in diets. In conclusion, diets containing intact protein from SBM had greater ATTD of GE and N, and greater DE, but reduced N retention rate when compared with diets containing crystalline AA. However, daily protein retention could not be maintained when crystalline AA rather than SBM were used to furnish the digestible AA in the diets, which may have negative consequences on carcass quality.

168 Effects of feeding barley-based diets differing in fermentable starch and fiber on nutrient digestion and body composition in weaned pigs

Abstract Hulled and hull-less barley grains containing low insoluble fiber are alternative energy sources in weaning diets but are typically not part of weaned pig diets. The range in fermentable starch and fiber content among barley cultivars presents opportunities to investigate whether these fermentable carbohydrates of barley grain do influence nutrient digestion, gut short chain fatty acid (SCFA) profile and body composition. To explore, pigs [n = 40; body weight (BW) = 8.6 kg; 1-wk post-weaning] were housed individually and fed 1 of 4 diets containing 600 to 705 g of cereal grain/kg: 1) low-fermentable wheat (LFW); 2) high β-glucan, hull-less barley (HFBB); 3) high amylose, hull-less barley (HFAB); or 4) low-fermentable hulled barley (LFB). Diets provided 10.2 and 9.8 MJ NE/kg, and 1.32 and 1.21 g standardized ileal digestible (SID) lysine/MJ NE for phase 1 (d 0–14) and phase 2 (d 15–28), respectively. At the end of the trial, feces were collected, and pigs were slaughtered to collect digesta and the carcass that was subsequently ground. Subsamples of feces, digesta, and carcasses were freeze-dried and analyzed. The apparent ileal digestibility (AID) of crude protein (CP) and gross energy (GE) did not differ among diets. The AID of β-glucan was 3 times greater (P < 0.05) for LFW than HFBB and HFAB, while AID of starch was 12% less (P < 0.05) for HFAB than the other diets. Apparent total tract digestibility (ATTD) of GE and CP was 4.2 and 8.9% less (P < 0.05), respectively, for the 3 barley diets than the wheat diet. The apparent hindgut fermentation (AHF) of β-glucan was 2.6 times greater (P < 0.05) for HFAB and HFBB than LFW, while AHF of starch was 7.5 times greater for HFAB than LFW. The calculated NE value was greatest (P < 0.05) for LFW, intermediate for HFBB and HFAB, and least for LFB. Among diets, HFAB increased (P < 0.05) the concentration of butyrate (indicator of gut health) and propionate in cecal and colonic digesta, with butyrate up to 50% more (P < 0.05) than that of LFW. Carcass protein and lipid concentration did not differ among pigs fed the 4 diets. In conclusion, feeding barley instead of wheat grain to weaned pigs reduced diet nutrient digestibility but did not affect carcass protein and lipid concentration. Feeding high amylose barley increased gut SCFA concentration. Barley grain with increasing fermentable carbohydrates can thus be included as alternative ingredient in diets of young pigs.

PSI-20 Isobutyrate supplementation improved energy and nitrogen digestibility in prepubertal gilts fed a high insoluble, but not soluble, fiber diet

Abstract Isoacids are short, branched-chain volatile fatty acids produced by microbial degradation of branched-chain amino acids. While there is a lack of information on isoacids supplementation in monogastric animals, in ruminants, isoacids are growth factors for cellulolytic bacteria which leads to improved digestibility of fibrous ingredients. The objective was to determine if feeding isoacids to prepubertal gilts could improve digestibility of high fiber diets. Two groups of 45 prepubertal gilts (body weight = 139.10 ± 0.68 kg) were individually housed and allotted to 1 of 9 dietary treatments for a 28-d trial (n = 10 per treatment). Dietary treatments consisted of a 3 × 3 factorial arrangement with factors of diet type [corn-soybean meal (CSBM), CSBM with 40% inclusion of distiller’s dried grains with solubles (DDGS), or CSBM with 40% inclusion of sugar beet pulp (SBP)] and isoacids inclusion [no isoacid (NO), 0.50% inclusion of isobutyrate (IB), or 0.88% inclusion of an isoacid mixture (isobutyrate, 2-methylbutyrate, isovalerate; 1:1:1 ratio; MX). Isobutyrate inclusion was the same between IB and MX diets. Gilts were limit fed approximately 2.2 kg per day. Overall growth performance, apparent total tract digestibility (ATTD) of energy and nitrogen (N), and fecal volatile fatty acids (VFA) profile (d 26) were determined. Average daily feed intake (ADFI) was reduced and gain:feed ratio (GF) was increased in gilts fed DDGS (2.14 ± 0.07 kg/d and 0.20 ± 0.02 kg/kg, respectively) or SBP (2.07 ± 0.07 kg/d and 0.19 ± 0.02 kg/kg, respectively) compared with gilts fed CSBM (2.30 ± 0.07 kg/d and 0.15 ± 0.02 kg/kg, respectively), regardless of isoacids inclusion (P < 0.05). Gilts fed DDGS-IB had increased energy (86.5 vs. 83.5 ± 0.42%) and N (84.7 vs. 81.3 ± 0.85%) ATTD compared with gilts fed DDGS-NO (P < 0.05). Gilts fed CSBM-MX had reduced energy (86.9 vs. 88.3 ± 0.50%) and N (75.4 vs. 78.7 ± 0.39%) ATTD compared with gilts fed CSBM-NO (P < 0.05). Moreover, gilts fed SBP-NO had increased energy (85.9 vs. 83.6 ± 0.44%) ATTD compared with the other groups and increased N (71.8 vs. 67.2 ± 0.51%) ATTD compared with SBP-IB (P < 0.05). Fecal content of isobutyrate was decreased in NO compared with the other groups (2.10 vs. 3.00 ± 0.31 mM/L), while fecal content of heptanoate was increased in MX compared with NO (0.06 vs. 0.03 ± 0.01 mM/L), regardless of diet type (P < 0.05). Gilts fed SBP-MX had increased fecal content of total VFA compared with gilts fed SBP-NO (108.90 vs. 67.60 ± 11.50 mM/L; P < 0.05). These results suggest that IB may positively impact the digestibility of diets with a high content of insoluble fiber.

236 The effects of replacing dried distiller’s grains with solubles with heat-treated soybean meal on nutrient intake and digestibility in forage-based diets

Abstract Cattle growth is calculated through dry matter intake, average daily gain and gain:feed measures that assume performance and digestibility are correlated. Hence, evaluating nutrient digestibility and flow provides additional explanations for subsequent growth performance. Therefore, five fistulated Jersey steers [Initial body weight (BW) = 288 ± 22 kg) fitted with ruminal, duodenal, and ileal cannulas were utilized in a 4 × 5 row-column design to determine intake and total tract nutrient digestibility when replacing dried distiller’s grains plus solubles (DDGS) with heat-treated soybean meal (TSBM) in forage-based growing diets. The 56-d study contained 4 periods, each period lasting 14 d [9 d of adaptation and 5 d of collection (d 0 to 4)]. Dietary treatments partially replaced DDGS, included at 16% diet dry matter (DM), with TSBM at increasing inclusion levels of 0 (TSBM0), 4 (TSBM4), 8 (TSBM8), and 12% (TSBM12) DM. Basal diets contained 43.5% corn silage, 36.5% oat hay, and 4% meal supplement (DM). Chromic oxide was incorporated into the diet daily at 0.25% DM as a digesta marker. Steers were housed in individual tie stalls during the 5-d collection period. Treatment diets were fed daily at 0800 h with orts being weighed at 0730 h and subsampled on d 0 to d 4 each period. Fecal collection bags were harnessed to each steer from d 0 to d 4 to collect fecal weight and subsampled twice daily (0700 and 1900 h). Digestibility and feed intake were analyzed utilizing the MIXED procedure of SAS with treatment and period as fixed effects and animal as a random effect. There were no differences (P ≥ 0.14) in DM, organic matter (OM), neutral detergent fiber (NDF), starch and nitrogen (N) intakes among treatments. Fecal DM, OM, NDF, starch, and N output resulted in no treatment effects (P ≥ 0.24). Subsequently, total tract apparent digestibility differences (P ≥ 0.32) were not detected for DM, OM, NDF, and starch content. However, N total tract apparent digestibility was significantly different (P < 0.03) with TSBM0 resulting in less N digestibility than TSBM12 (65.54% and 71.59%, respectively). Replacing a portion of DDGS with TSBM does not result in deleterious digestive effects in forage-based growing diets. As a result, the utilization of DDGS or TSBM as the primary protein source will depend on growth performance, feedstuff availability and economics.

PSII-13 Effects of benzoic acid, bromelain, adipic acid, and humic substance supplementation on nitrogen balance, urine pH, slurry pH, and manure odorous compounds in pigs

Abstract The objective of the present study was to evaluate the effects of benzoic acid, bromelain, adipic acid, and humic substance supplementation on nitrogen balance, urinary pH, slurry pH, and manure odorous compounds in pigs. Fifteen barrows with an initial body weight of 37.9 kg (standard deviation = 4.1) were individually housed in metabolism crates. The animals were allocated to a triplicated 5 × 2 incomplete Latin square design with 15 animals, 5 experimental diets, and 2 periods. The basal diet mainly consisted of corn, soybean meal, and rapeseed meal. Four experimental diets were prepared by supplementing each additive at a concentration of 10 g/kg at the expense of corn starch to the basal diet. Each period consisted of a 4-d adaptation period and a 24-h collection period for slurry, followed by a 4-d collection period for feces and urine. On d 5, feces and urine were collected for 24 h, and the feces and urine were mixed in a ratio of fecal weight to urine weight at the end of the collection to obtain slurry samples. The fecal nitrogen (N) output was greatest (P < 0.05) in pigs fed the diet supplemented with humic substances. The apparent total tract digestibility of N in pigs fed the humic substance diet was less (P < 0.05) than other groups. The urinary pH in pigs fed the adipic acid diet was less (P < 0.05) than that in other groups except the benzoic acid group. The slurry pH tended to differ among the treatment groups (P = 0.074) with the least value in pigs fed the adipic acid diet. The concentrations of indole in slurry (P = 0.084) and isovalerate in feces (P = 0.062) tended to differ among the groups with the least values in the pigs fed the humic substance diet. In conclusion, benzoic acid supplemented has the potential to increase N utilization in pigs, and adipic acid supplemented to pig diets can decrease urinary pH and slurry pH. Although benzoic acid and adipic acid have limited effects in reducing odorous compounds, humic substances have potential to reduce some odorous compounds.

PSVI-5 Extruded blend of Nannochloropsis oculata microalgae and flaxseed and its effects on ruminal fermentation and nutrient digestion

Abstract Omega-3 fatty acids are essential nutrients for mammals, and are required for cellular growth and synthesis of numerous cellular signaling molecules. NBO3 Technologies, LLC (Manhattan, KS) has developed an omega-3 supplement consisting of an extruded blend of flaxseed and Nannochloropsis oculata microalgae (GreatOplus; GOP). Our objective was to evaluate effects of GOP on dry matter intake (DMI), water intake (WI), ruminal metabolism, and apparent total tract nutrient disappearance in cannulated Holstein steers (n = 11; initial body weight 586.4 ± 49.7 kg). Treatments consisted of backgrounding diets (40% roughage, 60% concentrate) containing 0% (CON) or 10% GOP (dry basis). Feed and water intake were recorded using an Insentec Roughage and Water monitoring system (Hokofarm Group; Emmeloord, The Netherlands). Steers were utilized in a cross-over design with two 19-d periods. Each period consisted of a 15-d adaptation phase and a 4-d collection phase. Ruminal contents, duodenal digesta, and feces were collected at 8-h intervals for 4 d starting at 1000 h on d 16. The sampling schedule was advanced by 2 h with each subsequent sampling day, thus generating a 24-h profile at 2-h intervals post-feeding over the 4-d sampling phase. Titanium dioxide (15 g) was dispensed directly into the rumen of each steer 15 min before feeding and to estimate apparent ruminal flow and fecal excretion of nutrients. There was a Treatment X Day interaction for DMI (P < 0.001); DMI was greater for steers fed GOP some of the days during the adaptation phase compared with steers fed the control diet, but intakes were similar during the collection phase. Ruminal fluid pH, ruminal ammonia concentration, and WI were not affected by treatment (P > 0.10). As expected, ruminal outflows of total fatty acids (195.6 vs 338.1 g/d for CON and GOP, respectively) and α-linolenic acid (ALA; 1.6 vs 6.3 g/d, respectively) were greater for steers fed GOP compared with steers fed CON (P < 0.05); however, ruminal disappearance (i.e., biohydrogenation) of ALA was extensive, with only 8% and 4.7% of ALA intake exiting the rumen for CON and GOP, respectively. Apparent total tract digestion of organic matter was not impacted by diet (P > 0.20; 78.1 and 76.8% for CON and GOP, respectively). Supplementing an extruded blend of flaxseed and microalgae can effectively increase the amount of α-linolenic acid available for absorption in the small intestine, but overall recovery of dietary α-linolenic acid is relatively low due to extensive biohydrogenation by microbes within the rumen.

PSII-12 Dose-dependent effects of supplemental benzoic acid on nitrogen balance, urinary pH, slurry pH, and manure odorous compounds in pigs

Abstract The objective of this study was to determine the effects of supplemental benzoic acid (BA) at 0.5% to 2.5% in diets on nitrogen (N) utilization, urinary pH, slurry pH, and manure odorous compounds in pigs. Fifteen barrows with an initial body weight of 56.2 kg (standard deviation = 2.6) were individually housed in metabolism crates. The animals were allocated to a replicated 6 × 4 incomplete Latin square design with 12 animals, 6 experimental diets, and 4 periods, resulting in 8 observations per dietary treatment. The basal diet mainly consisted of corn, soybean meal, and rapeseed meal. Benzoic acid was supplemented to the basal diet at 0.0%, 0.5%, 1.0%, 1.5%, 2.0%, or 2.5% BA at the expense of corn starch. Each period consisted of a 4-d adaptation period and a 24-h collection period for slurry followed by a 4-d collection period for feces and urine. On d 5, feces and urine were collected for 24 h, and the feces and urine were mixed in a ratio of fecal weight to urine weight at the end of the collection to obtain slurry samples. The apparent total tract digestibility of N tended to linearly increase (P = 0.071) and the daily digested N linearly increased (P < 0.05) with increasing BA supplementation. In contrast, the urinary N output and retained N were not affected by inclusion of BA. The urinary and slurry pH were quadratically decreased (P < 0.05) with increasing BA supplementation. In the fecal samples, the concentrations of acetate, propionate, butyrate, and skatole linearly decreased (P < 0.05) and isovalerate concentration tended to linearly decrease (P = 0.099) by supplemental BA. In the slurry samples, the concentrations of isovalerate and skatole decrease linearly (P < 0.05), and butyrate concentration tended to linearly decrease (P = 0.054) by supplemental BA. In conclusion, supplemental benzoic acid has the potential to improve the N digestibility in a dose-dependent manner for pigs. In addition, increasing benzoic acid supplementation decreased urinary pH, slurry pH, and concentrations of some odorous compounds in pig feces and slurry.

Apparent total tract digestibility of calcium and phosphorus from partially defatted Hermetia illucens larvae meal in pigs

Apparent total tract digestibility of calcium and phosphorus from partially defatted Hermetia illucens larvae meal in pigs