Functional amino acid supplementation postweaning mitigates the response of normal birth weight more than for low birth weight pigs to a subsequent Salmonella challenge.

Previous work has shown that dietary supplementation with key functional amino acids (FAA) improves growth performance and immune status of disease-challenged normal birth weight (NBW) pigs. It is not known whether FAA supplementation attenuates the effects of a subsequent disease challenge or whether this response is similar in low birth weight (LBW) pigs. The objective was to determine the effects of birth weight and FAA supplementation during the postweaning period in Salmonella-challenged pigs. Thirty-two LBW (1.08 ± 0.11 kg) and NBW (1.58 ± 0.11 kg) pigs were assigned to a nursery feeding program at weaning (25 d) for 31 days in a 2 × 2 factorial arrangement. Factors were birth weight category (LBW vs. NBW) and basal (FAA-) or supplemented FAA profile (FAA+; Thr, Met, and Trp at 120% of requirements). At d 31, pigs were placed onto a common grower diet and, after a 7-d adaptation period, were inoculated with Salmonella Typhimurium (ST; 2.2 × 109 colony-forming units/mL) and monitored for 7-d postinoculation. Growth performance, rectal temperature, fecal score, indicators of gut health, ST shedding score in feces, intestinal ST colonization and translocation, and blood parameters of acute-phase response and antioxidant balance were measured pre- and postinoculation. Inoculation with ST increased temperature and fecal score, and the overall rectal temperature was higher in LBW compared to NBW pigs (P < 0.05). Postinoculation (d 7), reduced:oxidized glutathione was increased in NBW compared to LBW pigs (P < 0.05). Salmonella shedding and translocation to spleen were lower in NBW-FAA+ compared to NBW-FAA- pigs (P < 0.05). Postinoculation average daily gain was higher in NBW-FAA+ (P < 0.05) compared to the other groups. Postinoculation haptoglobin, superoxide dismutase, and colonic myeloperoxidase were increased in LBW-FAA- pigs (P < 0.05). Ileal alkaline phosphatase was decreased in LBW compared to NBW (P < 0.05). Overall, FAA supplementation represents a potential strategy to mitigate the effect of enteric disease challenge in NBW, but not LBW pigs.

Evaluating the standardized ileal digestible lysine requirement of 7- to 15-kg weanling pigs fed corn-soybean meal-based diets.

Continued genetic improvement necessitates the verification of nutrient requirements for newly developed pig genotypes. Therefore, the objective of this research was to determine the standardized ileal digestible (SID) lysine (Lys) requirement of 7- to 15-kg weanling pigs (TN70 × TN Tempo; Topigs Norsvin) fed a corn-soybean meal-based diet. A total of 144 piglets with an initial BW of 6.51 ±â€¯0.56 kg (mean ±â€¯SD) were assigned to one of six diets using a randomized complete block design based on BW to give eight replicate pens with three pigs per pen. The six diets contained 1.00, 1.16, 1.32, 1.48, 1.64, and 1.80% SID Lys, achieved by adding crystalline l-Lys·HCl at the expense of cornstarch. Other indispensable amino acids were provided to meet the requirements. Piglets had free access to diets and water for 21 days. Individual BW of pigs and feed disappearance were recorded weekly and blood samples were collected on day 1, 14, and 21. Average daily gain (ADG) and average daily feed intake were not affected by dietary SID Lys content during the first 7 days. However, the addition of dietary SID Lys quadratically increased (P < 0.05) gain:feed (G:F) during the first 7 days of the experiment. A quadratic increase (P < 0.05) was found in both ADG and G:F when SID Lys content increased in the diets from day 14 to 21. During the overall experimental period, increasing dietary Lys content quadratically increased (P < 0.05) ADG and G:F, whereas plasma urea nitrogen quadratically decreased (P < 0.05) as SID Lys content increased. The SID Lys requirements were estimated for linear and quadratic broken-line models. In conclusion, the SID Lys requirement for optimal growth performance of 7- to 15-kg weanling pigs fed corn-soybean meal-based diets based on linear and quadratic broken-line models were 1.27% (95% confidence interval (CI): [1.01, 1.53]) and 1.30% (95% CI: [0.94, 1.66]) for ADG and 1.27% (95% CI: [1.14, 1.40]) and 1.43% (95% CI: [1.11, 1.75]) for G:F, respectively, thus giving an overall average value of 1.32%.

Amino acid digestibility in soybean meal sourced from different regions of the United States and fed to pigs.

An experiment was conducted to determine the apparent ileal digestibility (AID) and the standardized ileal digestibility (SID) by growing pigs of AA in soybean meal (SBM) produced in different regions of the United States. Twenty-two growing barrows (25.5 ± 1.73 kg) were fitted with a T-cannula near the distal ileum and allotted to a 22 × 8 Youden square design. Twenty-two sources of SBM were procured from soybean crushing plants located throughout the United States. For analysis, the crushing plant locations were separated into the following 3 zones: 1) Michigan, Minnesota, and South Dakota ( = 4); 2) Georgia, Illinois, Indiana, and Ohio ( = 11); and 3) Iowa, Missouri, and Nebraska ( = 7). Dietary treatments included 22 diets based on a mixture of cornstarch, sucrose, and each source of SBM as the sole source of CP. Results indicated that the concentration of most indispensable and dispensable AA in SBM were not different among zones. However, SBM from zone 2 had a greater ( < 0.05) concentration of Thr than SBM from zone 3 and a greater ( < 0.05) concentration of Gly than SBM from zone 1. The concentration of Tyr in SBM from zone 2 was also greater ( < 0.05) than in SBM from zones 1 and 3. However, if concentrations of AA were calculated as a percent of CP, there were no differences in the concentrations of indispensable and dispensable AA among SBM from the 3 zones. Likewise, the AID of CP and the AID of indispensable and dispensable AA were not different among SBM from the 3 zones. The SID of CP and most AA was also not different among SBM from the 3 zones. However, SBM from zone 3 had a greater ( < 0.05) SID of His, Asp, and Cys than SBM from zone 2, and SBM from zone 1 had a greater ( < 0.05) SID of Lys than SBM from zone 2. There was also a tendency ( < 0.10) for SBM from zone 3 to have a greater SID of Ile, Leu, Phe, Val, Ala, and Tyr than SBM from zone 2. If the concentrations of SID CP and AA were calculated as grams per kilogram, SBM among the 3 zones were not different with the exception that there was a tendency ( = 0.07) for SBM from zone 2 to contain more SID Thr and SID Tyr than SBM from zone 3. In conclusion, only a few differences in concentrations and digestibility of CP and AA exist among sources of SBM from different zones in the United States. These observations indicate that the protein value is not different among SBM produced in the United States regardless of the location of the crushing plants.

Requirement for digestible calcium by eleven- to twenty-five-kilogram pigs as determined by growth performance, bone ash concentration, calcium and phosphorus balances, and expression of genes involved in transport of calcium in intestinal and kidney cells.

Two experiments were conducted to determine the requirement for standardized total tract digestible (STTD) Ca by 11- to 25-kg pigs based on growth performance, bone ash, or Ca and P retention and to determine the effect of dietary Ca on expression of genes related to Ca transport in the jejunum and kidneys. Six diets were formulated to contain 0.36% STTD P and 0.32, 0.40, 0.48, 0.56, 0.64, or 0.72% STTD Ca by including increasing quantities of calcium carbonate in the diets at the expense of cornstarch. Two additional diets contained 0.72% STTD Ca and 0.33% or 0.40% STTD P to determine if 0.36% STTD P had negative effects on the Ca requirement. The same batch of all diets was used in both experiments. In Exp. 1, 256 pigs (11.39 ± 1.21 kg initial BW) were randomly allotted to the 8 diets with 4 pigs per pen and 8 replicate pens per diet in a randomized complete block design. On the last day of the experiment, 1 pig from each pen was euthanized and the right femur and intestine and kidney samples were collected. Results indicated that ADG and G:F started to decline (linear and quadratic, < 0.05) at 0.54 and 0.50% STTD Ca, respectively. In contrast, bone ash increased (quadratic, < 0.05) as dietary Ca increased and reached a plateau indicating that the requirement for STTD Ca to maximize bone ash was 0.48%. Bone ash, but not ADG or G:F, increased (linear, < 0.01) as STTD increased in the diets. The mRNA expression of genes related to transcellular Ca transport decreased (linear, < 0.01) in the jejunum and in kidneys (linear and quadratic, < 0.01) as dietary Ca increased. In Exp. 2, 80 pigs (13.12 ± 1.79 kg initial BW) were placed in metabolism crates and randomly allotted to the 8 diets with 10 replicate pigs per diet in a randomized complete block design. Fecal and urine samples were collected using the marker-to-marker approach. Results indicated that the requirement for STTD Ca to maximize Ca and P retention (g/d) was 0.60 and 0.49%, respectively. In conclusion, the STTD Ca requirement by 11- to 25-kg pigs to maximize bone ash was 0.48%; however, ADG and G:F declined if more than 0.54 or 0.50% STTD Ca, respectively, was fed, and the minimum concentration of Ca needed to maximize ADG and G:F could not be determined under the conditions of this experiment. Increasing dietary Ca decreased the mRNA expression of several genes related to transcellular Ca transport in the jejunum and the kidneys.

Effects of production area and microbial phytase on the apparent and standardized total tract digestibility of phosphorus in soybean meal fed to growing pigs.

An experiment was conducted to determine if the area in which soybeans are grown influences the concentration of P, phytate, and macro- and microminerals in the soybean meal (SBM) produced from the beans and, therefore, also influences the apparent total tract digestibility (ATTD) and the standardized total tract digestibility (STTD) of P in SBM. The second objective was to test the hypothesis that inclusion of microbial phytase will increase the ATTD and STTD of P in SBM regardless of where the beans were grown. Twenty sources of SBM were procured from crushing facilities located in different regions of the United States that were separated into 3 zones: 1) the northern growing area (Michigan, Minnesota, and South Dakota), 2) the eastern growing area (Georgia, Illinois, Indiana, and Ohio), and 3) the western growing area (Iowa, Missouri, and Nebraska). For each source of SBM, 2 diets based on cornstarch and SBM were formulated; one of these diets contained no microbial phytase and the other diet contained 500 units/kg of microbial phytase. Two hundred growing barrows (16.90 ± 1.79 kg initial BW) were individually placed in metabolism crates and allotted to a randomized complete block design with 40 diets and 5 replicate pigs per treatment. Feces were collected for 4 d after a 4-d adaptation period using the marker-to-marker procedure. Results indicated that there were no differences in concentration of Ca, P, phytate, and macro- and microminerals among SBM from the different zones. However, there was a tendency ( = 0.055) for an increase in concentration of nonphytate P in SBM from the western growing area (0.25%) compared with SBM from the northern growing area (0.23%) and the eastern growing area (0.23%). There were no differences in feed intake, absorbed P, ATTD of P, STTD of P, Ca intake, Ca output, or ATTD of Ca for pigs fed SBM from the 3 zones. However, there was a tendency (P = 0.066) for an increase in P intake and P output from pigs fed SBM from the western growing area compared with pigs fed SBM from the northern growing area. There was an increase ( < 0.05) in absorbed P, ATTD and STTD of P, and ATTD of Ca if microbial phytase was included in the diets, but the quantity of P and Ca that was excreted in the feces decreased ( < 0.001) if microbial phytase was used. Overall, no differences in ATTD and STTD of P exist among SBM produced in different areas of the United States, but microbial phytase will increase the digestibility of P in SBM.

Requirement for digestible calcium by 25 to 50 kg pigs at different dietary concentrations of phosphorus as indicated by growth performance, bone ash concentration, and calcium and phosphorus balances.

Two experiments were conducted to determine the requirement for standardized total tract digestible (STTD) Ca by 25 to 50 kg pigs at different concentrations of STTD P. Twenty corn-soybean meal based diets were formulated with diets containing 4 concentrations of STTD P (0.15, 0.31, 0.39, or 0.47%) and 5 concentrations of STTD Ca (0.13, 0.27, 0.42, 0.57, or 0.72%). Diets were mixed in 1 batch and were used in both experiments. In Exp. 1, 240 pigs (initial average BW: 24.70 ± 1.27 kg) were randomly allotted to the 20 diets in 6 blocks with 1 pen per diet in each block using a 4 × 5 factorial design. There was 1 gilt and 1 barrow in each pen. At the conclusion of the 28 d experiment, all barrows were euthanized and the right femur was collected. Results indicated that there were interactions ( < 0.001) between concentration of STTD Ca and concentration of STTD P in diets for ADG, G:F, and bone ash. The predicted maximum ADG at STTD P concentrations of 0.15, 0.31, 0.39, and 0.47% were 0.76, 0.87, 0.90, and 0.92 kg at STTD Ca concentrations of 0.12, 0.36, 0.47, and 0.59%, respectively, which correspond to STTD Ca:STTD P ratios of 0.80:1, 1.16:1, 1.21:1, and 1.26:1. The predicted maximum G:F ratio at the 4 STTD P concentrations were 0.43, 0.46, 0.48, and 0.50 kg/kg at STTD Ca concentrations of 0.09, 0.38, 0.52, and 0.67%, respectively, and these values correspond to STTD Ca:STTD P ratios of 0.60:1, 1.23:1, 1.33:1, and 1.43:1. The predicted maximum bone ash at the 4 STTD P concentrations were 14.5, 21.0, 23.1, and 24.5 g at STTD Ca concentrations of 0.41, 0.56, 0.64, and 0.72%, respectively, which correspond to STTD Ca:STTD P ratios of 2.73:1, 1.81:1, 1.64:1, and 1.53:1. In Exp. 2, 120 pigs (initial average BW: 29.45 ± 2.15 kg) were placed in metabolism crates and randomly allotted to the 20 diets in 6 blocks with 1 pig per diet in each block. Fecal and urine samples were collected. Results indicated that the predicted maximum retention of Ca in the body at STTD P concentrations of 0.15, 0.31, 0.39, and 0.47% were 4.7, 7.1, 8.6, and 10.2 g/d at STTD Ca concentrations of 0.77, 0.96, 1.06, and 1.15%, respectively, which correspond to STTD Ca:STTD P ratios of 5.13:1, 3.10:1, 2.72:1, and 2.45:1. These observations indicate that if STTD P meets or exceeds the requirement, the STTD Ca:STTD P ratio needed to maximize ADG and G:F by 25 to 50 kg pigs is between 1.16:1 and 1.43:1. However, a greater ratio may be needed to maximize bone ash or Ca retention.

Concentrations of digestible, metabolizable, and net energy in soybean meal produced in different areas of the United States and fed to pigs.

An experiment was conducted to determine concentrations of DE, ME, and NE in soybean meal (SBM) produced in different areas of the United States if fed to growing pigs. Twenty-two sources of SBM were procured from crushing facilities located throughout the soybean growing area of the United States. For analysis, crushing plant locations were separated into 4 zones: 1) MI, MN, and SD ( = 4); 2) GA, IN, and OH ( = 6); 3) IA, MO, and NE ( = 7), and 4) IL ( = 5). Dietary treatments included a corn-based diet and 22 diets based on a mixture of corn and each source of SBM. Twenty-three growing barrows (initial BW: 26.4 ± 1.8 kg) were allotted to a 23 × 8 Youden square design with 23 diets and 8 periods. Pigs were placed in individual metabolism crates that were equipped with a feeder, a cup waterer, slatted floors, and a urine tray. Feces and urine were collected for 5 d after a 7-d adaptation period. The GE was 4,165, 4,209, 4,162, and 4,198 kcal/kg (as-fed) for SBM from Zones 1, 2, 3, and 4, respectively, and the GE in SBM from Zone 2 tended ( = 0.08) to be greater than the GE in SBM from Zones 1 and 3. The apparent total tract digestibility (ATTD) of GE for SBM was not different among zones. The DE and ME were 4,343 and 4,098; 4,319 and 4,117; 4,135 and 3,926; and 4,248 and 4,039 kcal/kg DM for SBM from Zones 1, 2, 3, and 4, respectively. The DE and ME of SBM from Zones 1 and 2 were greater ( < 0.05) than the DE and ME of SBM from Zone 3, but the DE and ME of SBM from Zone 4 were not different from that of the other zones. Net energy was calculated for each source of SBM using a published prediction equation based on DE, ether extract, starch, CP, and ADF. The NE of SBM from Zones 1 and 2 (2,534 and 2,497 kcal/kg DM) was greater ( < 0.05) than the NE of SBM from Zone 3 (2391 kcal/kg DM), but the NE of SBM from Zone 4 (2448 kcal/kg DM) was not different from the NE of SBM from the other zones. Regardless of growing area, values for DE, ME, and NE of SBM determined in this experiment are greater than values published by and indicate that DE, ME, and NE values for SBM may be underestimated by . In conclusion, regardless of growing area, GE, DE, ME, and NE were not different for SBM from the northern or eastern growing area or from Illinois, but DE, ME, and NE were less in SBM from the western growing area.

Effect of phytate, microbial phytase, fiber, and soybean oil on calculated values for apparent and standardized total tract digestibility of calcium and apparent total tract digestibility of phosphorus in fish meal fed to growing pigs.

Two experiments were conducted to determine the effects of phytate, phytase, fiber, and soybean oil on apparent total tract digestibility (ATTD) and standardized total tract digestibility (STTD) of Ca and on ATTD of P in fish meal fed to growing pigs. In Exp. 1, 40 growing pigs (initial average BW: 19.16 ± 2.04 kg) were randomly allotted to 1 of 5 diets with 8 pigs per treatment and placed in metabolism crates. Four diets were used in a 2 ´ 2 factorial design with 2 levels of phytate (0 or 0.7%) and 2 levels of microbial phytase (0 or 500 phytase units/kg). The diet containing no phytate was based on sucrose, cornstarch, fish meal, casein, and soybean oil, and the diet containing 0.7% phytate was based on corn, corn germ, fish meal, casein, and soybean oil. A Ca-free diet was used to determine basal endogenous losses of Ca. Feces were collected from d 6 to 13 after a 5-d adaptation period. Results indicated that the ATTD and STTD of Ca in fish meal and the ATTD of P increased ( < 0.001) if phytase was used and were greater ( < 0.05) in the diets based on corn and corn germ. Experiment 2 was conducted to determine the effects of fiber and soybean oil on the ATTD and STTD of Ca and the ATTD of P in fish meal. Fifty growing pigs (initial average BW: 19.36 ± 0.99 kg) were randomly allotted to 1 of 5 diets with 10 pigs per treatment. Two diets contained sucrose, cornstarch, fish meal, casein, and either 0 or 8% of a synthetic source of fiber. Two additional diets contained fish meal, casein, corn, and either 1 or 7% soybean oil. A Ca-free diet was also used. Pigs were housed individually in metabolism crates and fecal samples were collected. Results indicated that fiber increased ( < 0.001) the ATTD and STTD of Ca and the ATTD of P, but the ATTD and STTD of Ca or the ATTD of P were not affected by soybean oil. In agreement with the results of Exp. 1, the ATTD and STTD of Ca and the ATTD of P in the corn-based diet were greater ( < 0.05) than those in the cornstarch-based diet. In conclusion, phytase and fiber increased the ATTD and STTD of Ca and the ATTD of P in fish meal, but inclusion of soybean oil did not affect digestibility of Ca or P. The observation that values for the ATTD and STTD of Ca and ATTD of P are greater in corn-based diets than in cornstarch-based diets indicates that values for the digestibility of Ca and P obtained in cornstarch-based diets may not always be representative for the digestibility in practical corn-based diets.

Effects of microbial phytase on apparent and standardized total tract digestibility of calcium in calcium supplements fed to growing pigs.

An experiment was conducted to test the hypothesis that differences in the apparent total tract digestibility (ATTD) and standardized total tract digestibility (STTD) of Ca exist among Ca supplements and that inclusion of microbial phytase increases the ATTD and STTD of Ca. One hundred and four growing barrows (average initial BW of 17.73 ± 2.53 kg) were allotted to a randomized complete block design with 13 dietary treatments and 8 pigs per treatment. A basal diet containing corn, cornstarch, potato protein isolate, soybean oil, calcium carbonate, monosodium phosphate, vitamins, and minerals was formulated. Five additional diets were formulated by adding monocalcium phosphate (MCP), dicalcium phosphate (DCP), calcium carbonate, Lithothamnium calcareum Ca, or a high-Ca sugar beet co-product to the basal diet at the expense of cornstarch. Six additional diets that were similar to the previous 6 diets with the exception that they also contained 500 units per kilogram of microbial phytase were also formulated. A Ca-free diet was used to determine basal endogenous losses of Ca. Feces were collected using the marker-to-marker approach. Results indicated that regardless of inclusion of microbial phytase, MCP had the greatest (P < 0.05) ATTD and STTD of Ca. The ATTD and STTD of Ca in DCP were greater (P < 0.05) than in calcium carbonate, L. calcareumC a, or in the sugar beet co-product, but no differences were observed among the ATTD and STTD of Ca in calcium carbonate, L. calcareum Ca, or sugar beet co-product. Inclusion of microbial phytase increased (P < 0.05) the ATTD and STTD of Ca in the diets, but this was not the case in the Ca supplements. Regardless of inclusion of microbial phytase, the ATTD of P was greater ( P< 0.05) in pigs fed basal, MCP, or DCP diets than in pigs fed calcium carbonate, L. calcareum Ca, or the sugar beet co-product, but pigs fed calcium carbonate diets had greater ( P< 0.05) ATTD of P than pigs fed L. calcareumCa or the sugar beet co-product. Regardless of Ca source, inclusion of microbial phytase increased (P < 0.001) the ATTD of P. In conclusion, MCP has the greatest ATTD and STTD of Ca among the calcium supplements used in this experiment, followed by DCP. Basal, MCP, and DCP diets had greater ATTD of P than the other diets, and inclusion of microbial phytase increased the ATTD and STTD of Ca and the ATTD of P in the diets.

Energy concentration and amino acid digestibility in high-protein canola meal, conventional canola meal, and soybean meal fed to growing pigs.

Two experiments were conducted to determine DE and ME and the standardized ileal digestibility (SID) of CP and AA in 2 sources of high-protein canola meal (CM-HP1 and CM-HP2), conventional canola meal (CM-CV), and soybean meal (SBM) fed to growing pigs. In Exp. 1, 40 barrows (51.5 ± 4.0 kg initial BW) were housed in metabolism cages and randomly allotted to 1 of 5 diets with 8 replicate pigs per diet. A corn-based diet (97.4% corn) and 4 diets that contained both corn and each of the 3 sources of canola meal or SBM were formulated. Feces and urine were collected for 5 d after a 5-d adaptation period. The DE and ME were 3,347 and 3,268 kcal/kg in corn, 3,312 and 2,893 kcal/kg in CM-HP1, 3,627 and 3,346 kcal/kg in CM-HP2, 2,798 and 2,492 kcal/kg in CM-CV, and 4,000 and 3,796 kcal/kg in SBM, respectively. Values for DE and ME were greater (P< 0.05) in SBM than in all other ingredients, but DE and ME were greater (P < 0.05) in corn and the 2 high-protein canola meals than in CM-CV. The DE and ME were also greater (P< 0.05) in CM-HP2 than in CM-HP1. In Exp. 2, 10 barrows (65.3 ± 10.4 kg initial BW) were equipped with a T-cannula in the distal ileum and randomly allotted to a replicated 5 × 5 Latin square design with 5 diets and 5 periods in each square. A N-free diet and 4 corn starch-based diets that contained CM-HP1, CM-HP2, CM-CV, or SBM as the sole source of AA were formulated. Each period lasted 7 d and ileal digesta were collected on d 6 and 7 of each period. The SID of CP and all AA except Pro were greater (P < 0.05) in SBM than in the 3 sources of canola meal. With the exception of His and Lys, no differences in SID of indispensable AA were observed among the 3 sources of canola meal. The SID of His and Lys were greater (P < 0.05) in CM-HP1 and CM-HP2 than in CM-CV and the SID of CP was greater (P < 0.05) in CM-HP2 than in CM-CV, but no differences in the SID of indispensable AA were observed between CM-HP1 and CM-HP2. In conclusion, the 2 high-protein canola meals used in this experiment have ME values that are not different from corn but greater than in CM-CV. The SID of most AA is greater in SBM than in canola meals, but SID of His and Lys are greater in high-protein canola meals than in CM-CV. As a consequence, high-protein canola meals supply more ME and SID of AA for growing pigs than CM-CV.

- invited review - calcium digestibility and metabolism in pigs.

Calcium (Ca) and phosphorus (P) are minerals that have important physiological functions in the body. For formulation of diets for pigs, it is necessary to consider an appropriate Ca:P ratio for an adequate absorption and utilization of both minerals. Although both minerals are important, much more research has been conducted on P digestibility than on Ca digestibility. Therefore, this review focuses on aspects that are important for the digestibility of Ca. Only values for apparent total tract digestibility (ATTD) of Ca have been reported in pigs, whereas values for both ATTD and standardized total tract digestibility (STTD) of P in feed ingredients have been reported. To be able to determine STTD values for Ca it is necessary to determine basal endogenous losses of Ca. Although most Ca is absorbed in the small intestine, there are indications that Ca may also be absorbed in the colon under some circumstances, but more research to verify the extent of Ca absorption in different parts of the intestinal tract is needed. Most P in plant ingredients is usually bound to phytate. Therefore, plant ingredients have low digestibility of P due to a lack of phytase secretion by pigs. During the last 2 decades, inclusion of microbial phytase in swine diets has improved P digestibility. However, it has been reported that a high inclusion of Ca reduces the efficacy of microbial phytase. It is possible that formation of insoluble calcium-phytate complexes, or Ca-P complexes, not only may affect the efficacy of phytase, but also the digestibility of P and Ca. Therefore, Ca, P, phytate, and phytase interactions are aspects that need to be considered in Ca digestibility studies.

Endogenous intestinal losses of calcium and true total tract digestibility of calcium in canola meal fed to growing pigs.

An experiment was conducted to test the hypothesis that values for apparent total tract digestibility (ATTD) of Ca in pigs are influenced by endogenous Ca lost from the gastrointestinal tract. The objective was to determine the endogenous loss of Ca, the ATTD of Ca, and the true total tract digestibility (TTTD) of Ca in canola meal without and with microbial phytase. The second objective was to determine the balance of Ca in pigs fed diets based on canola meal without or with microbial phytase. Forty-eight growing barrows (initial BW: 16.72 ± 2.52 kg) were allotted to 8 dietary treatments in a randomized complete block design with 6 pigs per treatment. Diets were based on sucrose, cornstarch, potato protein isolate, corn gluten meal, and canola meal. Diets were formulated to contain 0.08, 0.16, 0.24, or 0.32% Ca from canola meal. All diets were formulated with 0 or 1,500 units/kg of microbial phytase and contained 0.32% digestible P. Feces and urine samples were collected from d 6 to 11. Total endogenous losses of Ca were determined using the regression procedure. Results indicated that ATTD of Ca and Ca retention increased (P < 0.05) if dietary Ca increased and also increased (P < 0.01) when phytase was added to the diets. The estimated total endogenous loss of Ca was 0.160 and 0.189 g/kg DMI for canola meal without and with microbial phytase, respectively, and these values were not different. The TTTD of Ca increased (P < 0.01) if phytase was used but was not affected by the level of dietary Ca. As dietary Ca increased, the amount of Ca absorbed and retained increased (P < 0.01) to a greater extent if phytase was used than when no phytase was included in the diet (interaction, P < 0.05). Fecal P excretion increased (P < 0.01) as dietary Ca increased but was reduced (P < 0.01) by the use of phytase. The ATTD of P decreased (P < 0.01) with increasing dietary Ca to a lesser extent if phytase was used than when no phytase was used (interaction, P < 0.01). In conclusion, endogenous Ca is lost from the gastrointestinal tract of growing pigs, and values for TTTD of Ca are, therefore, different from values for ATTD of Ca. Values for ATTD of Ca are influenced by level of dietary Ca, but that is not the case for values for TTTD of Ca. The ATTD of P decreases as dietary Ca increases, but microbial phytase increases Ca and P digestibility and Ca retention in pigs fed diets based on canola meal whereas it does not influence endogenous losses of Ca.

Amino acid digestibility in canola, cottonseed, and sunflower products fed to finishing pigs.

Our objective was to determine the standardized ileal digestibility (SID) of CP and AA in soybean meal (SBM) and canola, cotton, and sunflower products fed to finishing pigs. Each of 8 barrows (average initial BW = 106.6 ± 5.5 kg) were surgically fitted with a T-cannula in the distal ileum. Pigs were allotted to an 8 × 8 Latin square design with 8 diets and 8 periods. The 7 protein ingredients were canola seeds (CS), canola meal (CM), cottonseed meal (CSM), sunflower seeds (SFS), sunflower meal (SFM), dehulled sunflower meal (SFM-DH), and SBM, with each ingredient included as the sole source of AA in the diet. A N-free diet was used to estimate basal endogenous losses of AA. Among tested ingredients, SBM had the greatest (P < 0.05) SID of Lys, and CS had the least (P < 0.05) SID of Phe, Thr, and Tyr. The SID of all indispensable AA except Trp was less (P < 0.05) in CS than SBM, and CM had a greater (P < 0.05) SID of all indispensable AA except Arg, His, Lys, and Trp than CS. However, the SID of all indispensable AA except Arg and Trp were less (P < 0.05) in CM than in SBM. The SID of all indispensable AA except Arg and Trp also were less (P < 0.05) in CSM than in SBM, and the SID of Met was less (P < 0.05) in CSM than in all other ingredients. Among sunflower products, the SID of His, Leu, Phe, and Thr were less (P < 0.05) in SFM-DH than in SFS and SFM, and the SID of Ile, Met, and Val were less (P < 0.05) in SFM-DH than in SFS; however, for CP, Arg, Lys, and Trp, no differences among SFS, SFM, and SFM-DH were observed. The SID of all indispensable AA except Trp were less (P < 0.05) in SFM-DH than SBM, and the SID of His, Ile, Lys, Thr, and Val in SFM were also less (P < 0.05) than in SBM. Except for Lys, no differences between SBM and SFS were observed. In conclusion, the SID of most AA in CS, CM, CSM, SFM, and SFM-DH are less than in SBM.

Amino acid digestibility in heated soybean meal fed to growing pigs.

Heat treatment of soybean meal (SBM) is necessary to reduce the concentration of trypsin inhibitors, but excessive heat treatment may reduce AA concentration and digestibility because AA can be destroyed by the Maillard reaction. The objective of this experiment was to determine the effects of heat treatment of SBM on apparent ileal digestibility and standardized ileal digestibility (SID) of AA by growing pigs. A source of conventional dehulled SBM (48.5% CP) was divided into 4 batches. One batch was not additionally heated, 1 batch was autoclaved at 125°C for 15 min, 1 batch was autoclaved at 125°C for 30 min, and 1 batch was oven-dried at 125°C for 30 min. Four SBM-cornstarch diets were formulated, and each of the 4 batches of SBM was used as the sole source of dietary AA in 1 diet. A N-free diet was used to estimate basal endogenous losses of AA. Ten growing barrows with an initial BW of 25.3 ± 2.0 kg were individually fitted with a T-cannula in the distal ileum. Pigs were allotted to treatments in a replicated 5 × 5 balanced Latin square design with 5 diets and 5 periods. Each period lasted 7 d, and ileal digesta were collected on d 6 and 7 of each period. Results of the experiment indicated that the apparent ileal digestibility and SID of CP and all AA decreased linearly (P < 0.01) as the time of autoclaving increased from 0 to 30 min. The concentration of furosine and the color of samples of SBM indicated that autoclaving resulted in a Maillard reaction in the SBM. However, oven drying at 125°C for 30 min did not change (P > 0.10) the SID of CP and AA in the SBM or the furosine concentration, and the color in the oven-dried sample indicated that this sample was not heat damaged. In conclusion, the digestibility of all AA in autoclaved SBM is linearly reduced as the autoclaving time increases from 0 to 30 min. The reason for these changes is most likely that autoclaving at 125°C results in Maillard reactions in SBM.