Standardized Total Tract Digestibility Research Articles

Dependence of the hindgut disappearance of phosphorus in pigs on the quantity of phosphorus entering the hindgut based on a Meta-analysis

The objectives of the current study were to compare the difference between standardized ileal digestibility (SID) and standardized total tract digestibility (STTD) of phosphorus (P) in pigs using published data and investigate the factors that affect the hindgut disappearance of P in pigs. A total of 156 observations from 32 experiments that determined the apparent ileal digestibility and total tract digestibility of P in pigs were collected. SID and STTD of P were calculated by accounting for basal endogenous losses of P. Standardized hindgut disappearance (SHD) of P was determined by subtracting the STTD of P from the SID of P. The chi-square test was performed to investigate the association between SHD of P and categorical variables, including the use of phytase, the use of inorganic P sources, the use of corn-soybean meal-based diets, and body weight (BW) of pigs. To determine the effects of the SID of P on the SHD of P, a linear equation for the SHD of P was developed using the SID of P as an independent variable. The BW of pigs ranged from 10.0 to 104.8 kg and the SHD of P ranged from –22.8% to 39.8%. The STTD of P was greater than the SID of P (47.1% vs. 49.7%; P = 0.019). Based on the chi-square analysis, the supplementation of inorganic P sources tended to result in a higher occurrence of a positive value for the SHD of P (P = 0.079). In addition, the occurrence of a positive value in the SHD of P was lower when the BW of pigs was below 30 kg. However, as the BW of pigs increased, the occurrence of a positive value in the SHD of P increased (P = 0.061). A regression analysis of the SHD of P against the SID of P in pigs indicated that the SHD of P decreased as the SID of P increased in pigs (r2 = 0.17; P < 0.001). In conclusion, the STTD of P is greater than the SID of P in pigs, and the SHD of P depends on the diet composition, the amount of P entering the large intestine, and the BW of the pigs.

Standardized total tract digestibility of phosphorus in canola meal fed to gestating or lactating sows without or with a multi-enzyme complex

An experiment was conducted to determine coefficients of standardized total tract digestibility (CSTTD) of P in canola meal (CM) fed to gestating and lactating sows without or with a multi-enzyme complex (MC). Eight sows cannulated on day 40 of gestation were assigned at random to the 4 dietary treatments in a replicated 4 × 4 Latin square design. The 4 diets included 2 cornstarch-based diets with 313 g/kg solvent-extracted CM as the only source of P, without or with MC, a casein-cornstarch diet to determine ileal endogenous amino acid losses (amino acid digestibility data reported elsewhere), and a P-free diet to determine the endogenous P losses. All diets contained 3 g/kg titanium dioxide as an indigestible marker. Gestating sows were fed 3.0 kg/day, whereas, during lactation, sows had ad libitum access to diets. Samples were collected over 3 phases; mid-gestation, late-gestation, and lactation. Each phase had 4 experimental periods lasting 8 days. In each period, after 5-day acclimation to the experimental diets, fecal samples were collected by grab sampling via rectal palpation on day 6. Results indicated no differences in total tract digestibility of nutrients between mid-gestation, late-gestation, and lactation. Enzyme supplementation improved (P < 0.05) the apparent total tract digestibility of dry matter and P, and CSTTD of P during lactation. The CSTTD of P in CM was 0.445 (without MC) and 0.504 (with MC) in mid-gestation, 0.455 (without MC) and 0.492 (with MC) in late-gestation, and 0.442 (without MC) and 0.489 (with MC) in lactation. In conclusion, the average CSTTD for P in CM fed to sows was 0.447 and MC significantly improved the CSTTD of P in CM during lactation.

Standardized total tract digestibility of phosphorus in field peas fed to growing pigs is increased by microbial phytase, but particle size and origin of field peas do not affect digestibility of phosphorus

Two experiments were conducted to test the hypothesis that particle size or origin of field peas does not influence apparent total tract digestibility (ATTD) or standardized total tract digestibility (STTD) of P, but that increasing levels of phytase will increase ATTD and STTD of P in field peas when fed to growing pigs. In experiment 1, one source of field peas was obtained from the U.S., and two sources were obtained from Canada (i.e., Canada 1 and Canada 2). The U.S. field peas were ground to 265, 457, or 678 µm, whereas the Canada 1 peas were ground to 253 µm, and the Canada 2 source was ground to 411 µm. The five batches of field peas were each included in one diet and fed to 50 growing pigs (16.36 ± 1.19 kg) with 10 replicate pigs per diet. In experiment 2, six diets based on the U.S. field peas ground to 678 µm were formulated to contain 0, 250, 500, 1000, 2000, or 4000 units per kg of microbial phytase and fed to 48 pigs (15.26 ± 0.91 kg) with eight replicate pigs per diet. In both experiments, field peas were the only source of P in the diets. Pigs were housed individually in metabolism crates and feces were collected for four days. Results of experiment 1 indicated that the ATTD and STTD of P were not affected by source of peas or by particle size of the field peas and it was concluded that growing location and variety do not influence STTD of P in field peas. Results of experiment 2 indicated that the ATTD of Ca and P and the STTD of P increased (linear, P < 0.001) as phytase increased in the diets, and fecal excretion of Ca and P was reduced as the concentration of dietary phytase increased (linear, P < 0.001). It was, therefore, concluded that if microbial phytase is included in diets containing field peas, the inclusion of feed phosphate can be reduced, and manure concentration of P will also be reduced. In conclusion, the hypotheses that neither growing location nor particle size influences STTD of P were confirmed, and the hypothesis that increased concentration of dietary phytase increases STTD of P was also confirmed.

PSI-16 Effect of HiPhorius phytase on finishing pig growth performance and bone mineralization with the use of two diet formulation strategies

Abstract Two experiments were conducted to determine the effect of HiPhorius (dsm-firmenich, Parsippany, NJ) phytase on finishing pig growth performance, serum chemistry, bone mineralization, and carcass characteristics. In Exp. 1, 1,161 pigs (PIC 337 × 1050, initially 36.7 ± 0.48 kg) were used in a 105-d trial. There were 27 pigs per pen and 10 or 11 replications per treatment. Treatments consisted of: 1) Control diet with no added phytase and formulated to NRC (2012) requirement estimates for standardized total tract digestible (STTD) P; 2) 600 FYT/kg added phytase formulated to the same STTD P as the control diet considering a release of 0.13% STTD P and 0.095% STTD Ca; 3) 1,000 FYT/kg added phytase formulated to the same STTD P as the control diet considering release of 0.16% STTD P and 0.107% STTD Ca, and 4) high STTD P (no phytase; approximately 22% above NRC requirement estimates). All diets were formulated to a 1.30:1 STTD Ca:STTD P ratio, but analysis suggested all phases were greater than the formulated target. Overall, pigs fed NRC (2012) or increased STTD P had increased average daily gain (ADG) and hot carcass weight (HCW; P &amp;lt; 0.05) compared with pigs fed the treatments with added phytase. Pigs fed NRC (2012) STTD P had greater (P &amp;lt; 0.05) gain to feed ratio (G:F) compared with those with 1,000 FYT/kg with other treatments intermediate. In Exp. 2, 1,160 pigs (PIC 337 × 1050, initially 75.9 ± 1.32 kg) were used in a 58-d trial. There were 27 pigs per pen and 11 replications per treatment. Treatments were the same as in Exp.1 except diets were formulated to the same total Ca:P ratio [1.15:1 from 75 to 100 kg and 1.12:1 from 100 to 136 kg body weight (BW)] without a STTD Ca release consideration from phytase; however, diets analyzed with a wider Ca:P compared with the expected value (Table 1). Overall, there were no differences in ADG, average daily feed intake (ADFI) or G:F among treatments (P &amp;gt; 0.10). For pigs fed NRC or increased STTD P, there was an increase (P &amp;lt; 0.05) in metacarpal bone density, and a tendency for increased (P &amp;lt; 0.10) bone ash weight and percentage bone ash compared with pigs fed treatments containing phytase. In conclusion, regardless of diet formulation strategy, pigs fed diets with phytase had decreased growth performance (Exp.1) and bone mineralization (Exp.2), which was unexpected and could be a result of the nutrient release values attributed to the phytase being overestimated, not enough phytate-bound P that is phytase-sensitive present in the diets, or too wide of a Ca:P ratio leading to reduced phytase activity in the analyzed diet samples compared with the intended ratio based on diet formulation.

248 Effects of feeding finishing pig diets differing in Ca:P ratio, added phytase and 25(OH)D3 on growth performance, serum 25(OH)D3, carcass characteristics, and bone characteristics

Abstract A total of 2,160 pigs [337 × 1050, PIC; initial body weight (BW) = 33.2 ± 1.4 kg] were used in a 114-d trial to determine the effects of feeding diets differing in Ca:P ratio and added phytase or phytase and 25(OH)D3 (Hy-D, DM Nutritional Products, Parsippany, NJ) on growth performance, carcass characteristics, serum 25(OH)D3, and bone characteristics. Pigs were housed in mixed sex pens with 27 pigs per pen and 20 pens per treatment. The four treatments were assigned to pens in a randomized complete block design and consisted of 1) a high phosphorus (HP) diet with standardized total tract digestibility (STTD) P at 115% of NRC (2012) requirement estimate without added phytase and formulated to a 1.25:1 Ca to P ratio; 2) low phosphorus (LP) diet with STTD P at 80% of NRC requirement without added phytase and formulated to a 1.25:1 Ca to P ratio; 3) HP with phytase (HP+phytase) diet with STTD P at 115% of NRC requirement using 0.125% STTD P release from 600 FYT/kg HiPhorius and 1.1:1 Ca to P ratio; and 4) Diet 3 except 25(OH)D3 replaced most of the vitamin D3 in the diet (HP+25(OH)D3). Diets were fed in 4 phases from 32 to 50, 50 to 75, 75 to 100, and 100 to 133 kg. For overall growth performance, source of vitamin D had no impact on performance. Pigs fed HP diets had improved (P &amp;lt; 0.05) average daily gain (ADG), average daily feed intake (ADFI) and gain to feed ratio (G:F) compared with those fed LP diets, and increased ADFI compared with those fed the HP+phytase diets (Table 1). For 25(OH)D3 measured on d 50, pigs fed the HP diets had increased (P &amp;lt; 0.05) serum 25(OH)D3 compared with pigs fed the LP diets and pigs fed the HP+25(OH)D3 diets had increased (P &amp;lt; 0.05) serum 25(OH)D3 compared with pigs fed the HP+phytase diets. Pigs fed the HP diets had greater (P &amp;lt; 0.05) HCW and percentage lean than those fed LP diets. For bone analysis, pigs fed HP diets had greater (P &amp;lt; 0.05) bone ash (g) and breaking strength than pigs fed LP or HP+phytase and 1.1:1 Ca to P ratio. In conclusion, compared with pigs fed LP diets, HP-fed pigs had improved performance and HCW. Dietary 25(OH)D3 replacing D3 did not impact performance but increased circulating 25(OH)D3.

256 Anchor Talk: Accounting for effects of microbial phytase on digestibility of calcium and phosphorus

Abstract Inclusion of increasing levels of microbial phytase in diets for weanling and growing pigs results in a linear increase in the standardized total tract digestibility (STTD) of Ca and P. In many experiments, maximum effects on STTD of Ca and P were obtained with inclusion of around 1,200 phytase units (FTU) per kg of diet, although some of the newer phytases appear to release Ca and P until at least 2,000 FTU is included in the diets. In most individual feed ingredients and most practical diets, the maximum standardized total tract digestibility (STTD) of P that is obtained by using between 500 and 1,000 FTU per kg diet is around 70%, whereas the STTD of Ca for some ingredients can be over 80% if microbial phytase is used. One reason for the decreased STTD of P than of Ca in diets with maximum dosages of phytase is that dietary Ca prevents some P from being absorbed, and the STTD of P in practical diets, therefore, will never be 100% regardless of phytase inclusion. It is, however, important that the increased STTD of dietary Ca that is caused by phytase is taken into account in diet formulation because of the negative effects of Ca on STTD of P. In addition, at low dietary phytase there is release of more Ca than P, whereas at greater inclusion levels of phytase, there may be a similar release of Ca and P. Release of Ca and P by phytase is also impacted by ingredient composition in the diets because phytase does not have the same effect on all ingredients. In general, ingredients with low concentration of phytate have greater STTD of P if no phytase is used than ingredients with greater concentrations of phytate P, but the response to phytase is greater for ingredients with high concentrations of phytate. Sows also have lower digestibility of Ca and P than growing pigs and the response to phytase in diets for sows is less than in diets for growing pigs. Likewise, there is a linear reduction in phytase effects on STTD of both Ca and P as pigs get older. In contrast, in diets for newly weaned pigs there are specific advantages to using high concentrations of phytase (at least 2,000 FTU) because gastric pH is reduced in diets with phytase, which results in less diarrhea. This effect may be related to increased concentrations of plasma inositol in pigs fed diets with phytase, which may positively impact the immune status of the pigs. In conclusion, use of phytase in diets for pigs results in increased STTD of Ca and P and may have other benefits as well.

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 &amp;lt; 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 &amp;lt; 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.

263 Effects of source of calcium carbonate and microbial phytase on standardized total tract digestibility of calcium by growing pigs

Abstract The objective of this experiment was to test the hypothesis that there are differences in the standardized total tract digestibility (STTD) of Ca and in response to microbial phytase among sources of calcium carbonate obtained from different regions of the world. Barrows [n = 320; average body weight (BW) = 17.47 kg; SD = 1.28] were allotted to 40 diets using a completely randomized block design with eight blocks of 40 pigs for a total of eight replicate pigs per diet. All diets were based on corn and potato protein concentrate. Twenty sources of calcium carbonate were obtained from different regions of the world, including the United States, Europe, Asia, and South Africa. Each source of calcium carbonate was used in two diets, one diet without microbial phytase and one diet that contained 1,000 phytase units/kg diet. Pigs were housed individually in metabolism crates. Pigs were provided feed at 3.0 times the maintenance requirement for energy. Feces were collected for 4 d following the adaptation period after 5 d of adaptation. Fecal samples were dried, ground, and analyzed for Ca to calculate the digestibility. The initial statistical model included calcium carbonate source, phytase, and the Ca-source × phytase interaction as fixed effects; however, no interactions between Ca source and phytase were observed. Therefore, the final statistical model included only Ca source and phytase as fixed effects. A second analysis was performed to compare the digestibility of Ca in calcium carbonate obtained from different regions of the world (i.e., Europe, Asia, the United States, and South Africa). In this model region, phytase, and the region × phytase interaction were fixed effects. However, no interactions between region and phytase were observed and therefore, the final statistical model included only region and phytase as fixed effects. Concentrations of Ca in the 20 sources of calcium carbonate ranged from 32.1 to 40.9% (Table 1). Differences in the STTD of Ca were observed among pigs fed diets containing different sources of calcium carbonate (P &amp;lt; 0.001). Pigs fed diets containing 1,000 units of phytase had greater (P &amp;lt; 0.001) STTD of Ca compared with pigs fed diets containing no phytase. The STTD of Ca in calcium carbonate from the United States was less (P &amp;lt; 0.001) than in calcium carbonate from Europe, Asia, or South Africa. In conclusion, the use of microbial phytase increases the STTD of Ca in calcium carbonate, but the STTD of Ca varies among different sources and among sources from different regions. Therefore, consideration should be given to differences in analyzed concentrations of Ca, values for STTD of Ca, and response to microbial phytase among different sources of Ca carbonate to ensure Ca is not being oversupplied when formulating diets.

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 &amp;lt; 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.

283 Identification of new or existing risk factors associated with the development of sow pelvic organ prolapse

Abstract A survey was conducted between March and December of 2022 to examine the variation between farms that had high and low pelvic organ prolapse (POP) rate. The objective was to identify new or existing risk factors associated with the development of POP, which could open new avenues for further investigation. Sow farms (n = 53) across 26 production systems located in the US, Canada, and Mexico were used. Sampling of farms was not random. High and low POP systems were selected within each region as well as high and low POP farms within each system. Over 800 variables related to general farm information and management, performance traits, reproductive management, replacement gilt management, gestation and farrowing practices, labor and health management, and nutrition were collected during farm visits. To be included in the analysis, at least 70% of observations were needed for continuous variables with at least 10% of observation for each category for categorical variables. Univariable models were fitted to identify variables associated with annualized POP rate for 2021. Variables with P ≤ 0.10 were selected for further analysis, with 94 predictor variables selected for principal components analysis (PCA). A factor analysis of mixed data was conducted, and results were then fitted into a hierarchical clustering on PCA, which segregated the data into three clusters: 2 with low POP (2.5%) and 1 with high POP (6.1%) prevalence (low vs high P &amp;lt; 0.05). The resulting clusters explained 33.7% of the variability in annualized 2021 POP rate. Differences between clusters were evaluated by Kruskall-Wallis test for numerical variables and chi-square test for categorical variables. High POP cluster farms had greater total piglets born over the years, greater number of sows per worker, greater annual gestation feed usage, and a lower mean body condition score at 16 wk of gestation compared with low POP cluster farms. High POP cluster farms had a decreased proportion of farms using conventional artificial insemination, a greater proportion of farms utilizing cup waterers in gestation for sows in group housing and in farrowing, and greater proportion of farms with a routine sleeving practice. High POP cluster farms compared with low POP cluster farms had greater gestation distillers dried grains with solubles (DDGS) inclusion level (14.6% vs 4.0%, SE 3.02), greater levels of standardized total tract digestibility (STTD) P% (0.49% vs 0.39%, SE 0.014), narrower analyzed Ca to STTD P ratio (1.7 vs 2.2, SE 0.06), and lower phytase inclusion and release (0.16% vs 0.09%, SE 0.014). These variables were also the predictors with the greatest R2 values in the univariable models. These observations suggest further research is needed to evaluate the connection between dietary Ca and P and pelvic organ prolapse.

Effects of added 25(OH)D3 with varying standardized total tract digestible phosphorus concentrations on nursery pig performance, bone characteristics, and serum vitamin D status.

A total of 360 pigs (DNA 600 × 241; initially 5.8kg) were used in a 45-d growth study to evaluate the effects of adding 25(OH)D3 with 3 levels of standardized total tract digestible (STTD) P on nursery pig growth performance, bone and urine characteristics, and serum vitamin D. Pigs were weaned at 19 d of age and randomly allotted to 1 of 6 dietary treatments with 5 pigs per pen and 12 replications per treatment. Dietary treatments were arranged in a 2 × 3 factorial with main effects of 25(OH)D3 (0 or 50 µg/kg equivalent to 2,000 IU/kg of vitamin D3; Hy-D, dsm-firmenich, Plainsboro, NJ) and STTD P (70%, 100%, or 130% of the NRC [NRC 2012. Nutrient requirements of swine. 11th rev. ed. Natl. Acad. Press, Washington, DC) requirement estimate on a dietary percentage basis]. All diets contained 1,653 IU/kg of vitamin D3. On day 45, 1 pig per pen was euthanized to collect the right fibula, metacarpal, and 2nd and 10th ribs. Overall, increasing STTD P increased (quadratic, P ≤ 0.003) ADG, ADFI, and G:F with minimal improvement above 100% of the NRC STTD P requirement estimate. Added 25(OH)D3 had no effect on growth performance. Increasing STTD P decreased urinary Ca concentration (linear, P < 0.001) and increased urinary P concentration (quadratic, P < 0.001). When pigs were fed added 25(OH)D3, serum 25(OH)D3 increased (quadratic, P = 0.005) as STTD P increased but no differences were observed when 25(OH)D3 was not added and STTD P increased (25(OH)D3 × STTD P interaction, P = 0.032). When pigs were fed 25(OH)D3, serum 1,25(OH)2D3 increased (quadratic, P < 0.001) as STTD P decreased but the increase was not significant when no 25(OH)D3 was fed (STTD P × 25(OH)D3 interaction, P = 0.002). Bone ash percentage and weight increased (quadratic, P ≤ 0.065) in all bones as STTD P increased. Added 25(OH)D3 had no effect on bone density or bone ash weight; however, the reduction in bone ash percentage observed with reducing STTD P level tended to be less when 25(OH)D3 was provided (linear interaction, P = 0.098). Increasing STTD P decreased the likelihood of abnormal histologic bone lesions in the 10th rib. In summary, added 25(OH)D3 had limited effect on growth performance; however, an increase in serum concentrations of 25(OH)D3 and 24,25(OH)2D3 was observed. The addition of 25(OH)D3 to P-deficient diets increased percentage bone ash. Increasing STTD P to 100% of NRC [NRC 2012. Nutrient requirements of swine. 11th rev. ed. Natl. Acad. Press, Washington, DC] requirement estimate increased growth and 130% of NRC maximized bone ash.

Effect of bone and analytical method on assessment of bone mineralization in response to dietary phosphorus, phytase, and vitamin D in finishing pigs.

A total of 882 pigs (PIC TR4 × [Fast LW × PIC L02]; initially 33.2 ± 0.31kg) were used in a 112-d study to evaluate the effects of different bones and analytical methods on the assessment of bone mineralization response to changes in dietary P, phytase, and vitamin D in growing pigs. Pens of pigs (20 pigs per pen) were randomized to one of five dietary treatments with nine pens per treatment. Dietary treatments were designed to create differences in bone mineralization and included: 1) P at 80% of NRC (2012) standardized total tract digestible (STTD) P requirement, 2) NRC STTD P with no phytase, 3) NRC STTD P with phytase providing an assumed release of 0.14% STTD P from 2,000 FYT/kg, 4) high STTD P (128% of the NRC P) using monocalcium phosphate and phytase, and 5) diet 4 with additional vitamin D3 from 25(OH)D3. On day 112, one pig per pen was euthanized for bone, blood, and urine analysis. Additionally, 11 pigs identified as having poor body condition which indicated a history of low feed intake (unhealthy) were sampled. There were no differences between treatments for final body weight, average daily gain, average daily feed intake, gain to feed, or bone ash measurements (treatment × bone interaction) regardless of bone ash method. The response to treatment for bone density and bone mineral content was dependent upon the bone sampled (density interaction, P = 0.053; mineral interaction, P = 0.078). For 10th rib bone density, pigs fed high levels of P had increased (P < 0.05) bone density compared with pigs fed NRC levels with phytase, with pigs fed deficient P, NRC levels of P with no phytase, and high STTD P with extra 25(OH)D3 intermediate, with no differences for metacarpals, fibulas, or 2nd ribs. Pigs fed extra vitamin D from 25(OH)D3 had increased (P < 0.05) 10th rib bone mineral content compared with pigs fed deficient P and NRC levels of P with phytase, with pigs fed industry P and vitamin D, and NRC P with monocalcium intermediate. Healthy pigs had greater (P < 0.05) serum Ca, P, vitamin D concentrations, and defatted bone ash than those unhealthy, with no difference between the two health statuses for non-defatted bone ash. In summary, differences between bone ash procedures were more apparent than differences between diets. Differences in bone density and mineral content in response to dietary P and vitamin D were most apparent with 10th ribs.

149 Effects of Microbial Phytase on Standardized Total Tract Digestibility of Phosphorus in Feed Phosphates Fed to Growing Pigs

Abstract The objective of this experiment was to determine the effect of increased microbial phytase on total tract digestibility of P in feed phosphates when fed to growing pigs. A source of monocalcium phosphate (MCP), monosodium phosphate (MSP), and magnesium phosphate (MgP) were procured. Three basal diets were formulated to contain 0, 500, and 4,000 units of microbial phytase (FTU) and no addition of feed phosphates. Nine phosphate-containing diets were formulated by adding each of the 3 feed phosphates and 3 levels of phytase. A P-free diet was formulated to determine the basal endogenous P loss. A total of 117 growing barrows (BW = 15.56 kg; SD = 1.68) were divided into 3 blocks of 39 pigs and allotted to the 13 diets for a total of 9 pigs per diet. During the experiment, pigs were housed individually in metabolism crates equipped with a slatted floor, a feeder, and a nipple drinker. Fecal samples were quantitatively collected for 4 days after 5 days of adaptation using the marker-to-marker approach. Fecal samples were dried and ground before analysis. Fecal samples, feed ingredients, feed phosphates, and diet samples were analyzed for P, Ca, and dry matter and the apparent total tract digestibility (ATTD) and standardized total tract digestibility (STTD) were calculated. The ATTD and STTD of P in the 3 feed phosphates were calculated using difference procedure. The statistical model included the level of phytase and the P source as the fixed effects and the random effects of period and replicate within period. Contrast statements were used to test for linear and quadratic effects of increasing phytase in diets and the model included diet as the fixed effect and period and replicate as the random effects. Pig was the experimental unit. Results indicated that the ATTD and STTD of P in all diets increased (P &amp;lt; 0.05) with the inclusion of 500 or 4,000 FTU, but the ATTD and STTD of P in feed phosphates were not affected by the inclusion of phytase (Table 1). This indicates that the increases in ATTD and STTD of P that were observed in the mixed diets when phytase was used were due to the release of P from phytate in corn and soybean meal and not from an increase in digestibility of P in feed phosphates. However, MgP had a lower (P &amp;lt; 0.05) STTD of P than MCP and MSP. In conclusion, microbial phytase does not increase the digestibility of P in MCP, MSP, or MgP, but the digestibility of P in MgP is less than in MCP and MSP.

PSIII-18 Effect of Microbial Phytase on Digestibility of Phosphorus in Seven Sources of Sunflower co-Products Fed to Growing Pigs

Abstract An experiment was conducted to test the hypothesis that there are no differences among sources of sunflower co-products on the apparent total tract digestibility (ATTD) of P and Ca and on the standardized total tract digestibility (STTD) of P regardless of where the ingredients were produced. Six sources of sunflower meal (SFM) were obtained from the U.S. (2 sources), Ukraine (2 sources), Hungary, and Italy. A source of sunflower expellers (SFE) from the U.S. was also used. Seven diets were formulated by mixing each source of sunflower co-product with cornstarch; therefore, the sunflower co-product was the only source of P in these diets. Seven additional diets that were similar to the previous seven diets with the exception that 300 units per kg of microbial phytase were added were also formulated. A total of 112 barrows (initial body weight = 17.95 kg ± 1.37 kg) were allotted to the 14 diets using 4 blocks, 2 pigs per diet in each block, and a total of 8 replicate pigs per diet. Pigs were placed in individual metabolism crates to allow for the total collection of fecal materials for 4 days after 7 days of adaptation to the diets. Diets and dried fecal samples were analyzed for dry matter, Ca, and P. Data for Ca and P digestibility were analyzed in a randomized complete block design in a 7 × 2 factorial arrangement using the PROC MIXED function in SAS. Results indicated that diets containing phytase had greater (P &amp;lt; 0.01) ATTD of Ca and P and greater (P &amp;lt; 0.01) STTD of P than diets without phytase (Table 1). Digestibility of P was also greater in one of the sources of SFM from Ukraine compared with the other sources except for the SFM from Hungary (Table 2). Pigs fed the diet containing one of the sources of SFM from the U.S. had greater (P &amp;lt; 0.05) ATTD of Ca compared with pigs fed diets containing the other source of SFM from the U.S. or one of the Ukraine SFM sources. In conclusion, some variability in the ATTD and STTD of P and the ATTD Ca was observed among SFM of different origins, but the ATTD and STTD of P and ATTD of Ca in SFM and SFE were greater if microbial phytase was used.

123 Effects of Different Protein Sources Containing Highly Digestible Phosphorus on the Basal Endogenous Loss of Phosphorus

Abstract The objective of this experiment was to test the hypothesis that the basal endogenous loss of P from pigs fed a diet containing blood plasma, casein, or potato protein concentrate is not different from that of pigs fed a diet containing gelatin. Pigs (n = 40; body weigh =: 19.34 kg) were housed in metabolism crates and were randomly allotted to four low-P diets containing 20% gelatin, 20% blood plasma, 18.5% casein, or 20% potato protein concentrate. With the exception of Ca and P, diets were formulated to meet the requirements for 11 to 25 kg pigs. Feces and urine samples were collected separately for 4 d following a 5-d adaptation period. Feces samples were dried, ground, and analyzed for Ca and P, and urine samples were also analyzed for Ca and P. Data were analyzed using a model that included diet as fixed effect and replicate as random effect. Results indicated that feed intake and fecal excretion of dry matter were greater (P &amp;lt; 0.05) in pigs fed diets containing blood plasma, casein, and potato protein concentrate compared with pigs fed the gelatin diet, with pigs fed potato protein concentrate having the greatest (P &amp;lt; 0.05) excretion (Table 1). The apparent total tract digestibility of dry matter was least (P &amp;lt; 0.001) in pigs fed the diet containing potato protein concentrate, but there were no differences among gelatin, blood plasma, and casein diets. No differences were observed in the standardized total tract digestibility of P among diets. Basal endogenous loss of P was not different between the gelatin and casein diets, but pigs fed diets containing blood plasma or potato protein concentrate had greater (P &amp;lt; 0.001) basal endogenous loss of P compared with pigs fed gelatin or casein diets. In conclusion, the basal endogenous loss of P was greater in diets containing blood plasma and potato protein concentrate compared with gelatin. However, casein could be an alternative to gelatin to estimate the basal endogenous loss of P because casein provides a greater amount of P compared with gelatin that compensates for the deficient level of P in gelatin, but does not affect values for the basal endogenous loss of P.

Impact of dietary analyzed calcium to phosphorus ratios and standardized total tract digestible phosphorus to net energy ratios on growth performance, bone, and carcass characteristics of pigs.

A total of 2,184 pigs (337 × 1,050, PIC; initially 12.4 ± 0.17 kg) were used in a 143-d study to evaluate the effects of feeding varying analyzed calcium to phosphorus ratios (Ca:P) at two standardized total tract digestible (STTD) phosphorus to net energy ratios (STTD P:NE). Pens of pigs (26 pigs per pen) were assigned to 1 of the 6 dietary treatments in a 2 × 3 factorial with main effects of STTD P:NE and Ca:P ratio. Diets consisted of two levels of STTD P:NE; High (1.80, 1.62, 1.43, 1.25, 1.10, and 0.99 g STTD P/Mcal NE from 11 to 22, 22 to 40, 40 to 58, 58 to 81, 81 to 104, and 104 to 129 kg, respectively); or Low (75% of the High levels), and three analyzed Ca:P ratios (0.90:1, 1.30:1, and 1.75:1). There were 14 pens per treatment. Diets were corn-soybean meal-based and contained a constant phytase concentration within each dietary phase with levels decreasing throughout the trial (phases 1 through 3, 500 FTU/kg, assumed release of 0.13% STTD P; phase 4, 400 FTU/kg, assumed release of 0.11% STTD P; phase 5, 290 FTU/kg, assumed release of 0.09% STTD P; and phase 6, 210 FTU/kg, assumed release of 0.07% STTD P). Overall, there was a Ca:P × STTD P:NE interaction (P < 0.05) observed for average daily gain (ADG), feed efficiency (G:F), final body weight (BW), hot carcass weight (HCW), bone mineral density, bone mineral content, and bone-breaking strength. When feeding Low STTD P:NE levels, increasing the analyzed Ca:P ratio decreased (linear, P < 0.001) ADG final BW, HCW, and tended to worsen G:F, bone mineral density, and bone mineral content (linear, P < 0.10). However, when feeding High STTD P:NE levels, increasing the analyzed Ca:P ratio significantly improved bone mineral content and bone mineral density (linear, P < 0.05), and tended to improve ADG and final BW (linear, P < 0.10) and G:F (quadratic P < 0.10). Additionally, increasing the analyzed Ca:P ratio worsened ADG, G:F, and bone mineralization with Low STTD P:NE but had marginal impacts when adequate STTD P:NE was fed.

The impact of the interaction between dietary total phosphorus level and efficacy of phytase on the performance of growing-finishing pigs

Two experiments were conducted to investigate the interaction between dietary total phosphorus (P) level and phytase on the performance of growing-finishing pigs. In experiment 1, a total of 96 growing pigs [Duroc × Landrace × Yorkshire (barrows, initial body weight (BW) = 39.1 ± 0.5 kg), 8 pigs per treatment] were used in a 5-d total fecal and urine collection study to determine the apparent total tract digestible (ATTD) P release value of phytase in 2 dietary standardized total tract digestible (STTD) P levels (1.49 vs 2.87 g/kg of STTD P) with 0, 250, 500, 750, 1000, and 1250 FTU/kg of phytase. The results indicated that there was an interaction between P level and phytase in the determination of coefficient of apparent total tract digestibility of P (P < 0.01). The determined P release curves were STTD P = −1.4 phytase2 × 10−6 + 20.8305 phytase × 10−3 + 6.88392 × 10−2, R² = 0.9766 [1] in low-P diets, and STTD P = −1.2 phytase2 × 10−6 + 20.2754 phytase × 10−3 + 1.86325 × 10−2, R² = 0.9965 [2] in high-P diets. In experiment 2, a total of 1344 growing pigs [Duroc × Landrace × Yorkshire (initial BW = 69.4 ± 0.6 kg), 28 pigs per pen] were used in a 35-d growth performance study. The study had 4 dietary treatments which included low-P (1.0 g/kg of STTD P) diet group, high-P (1.9 g/kg of STTD P) diet group, low-P diet + 1100 FTU/kg phytase group, and high-P diet + 250 FTU/kg phytase group. The two treatments with phytase were formulated to the same STTD P level using the P release value of phytase determined by equation [1] from Experiment 1. The results showed that the treatment with 1100 FTU/kg phytase had greater gain to feed ratio compared to the treatment with 250 FTU/kg phytase, 1.0 g/kg total STTD P group and 1.9 g/kg total STTD P group (P < 0.05). In conclusion, the determination of P release of phytase may be impacted by the total P level in the diet. The P release value determined in low-P diets may not be accurate for the diet formulation when dietary total P level is greater.

Effect of increasing dietary fermentable fiber on diet nutrient digestibility and estimation of endogenous phosphorus losses in growing pigs.

Fermentable fiber may increase endogenous losses of phosphorus (EPL) and amino acids (AA), thereby reducing apparent nutrient digestibility. Acacia gum with medium-to-high fermentability and low viscosity was increasingly included in diets to investigate its effect on apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of nutrients, gross energy (GE), and standardized total tract digestibility (STTD) of P in growing pigs. A control diet (49% cornstarch; 18% bovine plasma protein) was formulated to measure basal EPL. Three additional diets were formulated to include 2.5%, 5.0%, or 7.5% acacia gum at the expense of cornstarch. Diets contained 16.1% to 17.4% CP and 0.31% to 0.33% total P (DM-basis). The four diets were fed to eight ileal-cannulated barrows (initial BW, 54.6 kg) for four 9 d periods in a double 4 × 4 Latin square. Apparent hindgut fermentation (AHF) was calculated as ATTD minus AID. Feeding increasing acacia gum quadratically affected (P < 0.05) AID of DM, GE, linearly decreased (P < 0.05) ATTD of DM, crude protein (CP), GE, digestible (DE) and predicted net energy (NE) value of diets, and linearly increased (P < 0.001) AHF of DM and GE. Increasing acacia gum did not affect AID and standardized ileal digestibility (SID) of CP and AA. Basal EPL was 377 mg/kg DM intake (DMI) and increasing acacia gum linearly increased (P < 0.05) total tract EPL. Increasing acacia gum linearly decreased (P < 0.05) diet ATTD of P, and STTD of P based on either the calculated EPL or NRC (2012) recommended value (190 mg P/kg DMI). Increasing acacia gum did not affect AID and ATTD of Ca of diets. In conclusion, feeding increasing dietary fermentable, low-viscous acacia gum decreased diet AID and ATTD of DM and GE, but did not affect AID or SID of CP and AA. Increasing acacia gum decreased ATTD of P, which might have been due to increased specific endogenous losses of P in the total tract of growing pigs.

Inclusion of spray dried plasma in diets based on different ingredient combinations increases the digestibility of energy, fiber, Ca, and P by young pigs.

An experiment was conducted to test the hypothesis that inclusion of spray dried plasma (SDP) in diets increases apparent total tract digestibility (ATTD) and/or the standardized total tract digestibility (STTD) of gross energy (GE) and nutrients in diets for young pigs, and that ATTD of energy and nutrients or STTD of P in individual ingredients are additive in diets containing SDP. Eighty barrows (body weight: 9.30 ± 0.97 kg) were housed in individual metabolism crates and allotted to 1 of 10 diets in a randomized complete block design with 8 replicate pigs per diet. Four diets were prepared without SDP and contained ingredients commonly used in the United States, Canada, the European Union, or Asia. Four additional diets were prepared by mixing 94% of the previous four diets and 6% SDP. A diet containing SDP as the sole source of P and a P-free diet were also formulated. The ATTD of GE and nutrients and the STTD of P were calculated in all diets except the P-free diet and for the four regional diets containing 6% SDP, values were also predicted from the digestibility obtained in SDP alone and the regional diets without SDP. Differences between measured and predicted values for digestibility of GE and nutrients were also calculated. An interaction was observed between SDP and region for the ATTD of soluble dietary fiber where the digestibility decreased (P < 0.05) for pigs fed the U.S. diet with 6% SDP compared with 0% SDP, but that was not the case for the other regional diets. There was no interaction for the ATTD of GE, N, insoluble dietary fiber (IDF), total dietary fiber (TDF), Ca, and P or the STTD of P, but the ATTD and STTD values were greater (P < 0.05) or tended to be greater (P < 0.10%) when 6% SDP was included in the diet compared with diets with 0% SDP. The ATTD of GE, IDF, TDF, and P, and the STTD of P was greater (P < 0.05) for the Asia diet compared with the other diets regardless of inclusion of SDP. The measured ATTD of IDF and TDF was greater (P < 0.05) than the predicted values for the U.S. and European Union diets, and the measured ATTD of GE, N, Ca, and P and the STTD of P was greater (P < 0.05) than the predicted values for the Asia diet. In conclusion, addition of 6% SDP to a diet will increase the ATTD of energy and nutrients and the STTD of P in diets for weanling pigs, and in some cases, the measured ATTD of energy and nutrients or the STTD of P by pigs fed diets containing SDP is greater than predicted from individual ingredients.

- Invited Review - Mineral composition and phosphorus digestibility in feed phosphates fed to pigs and poultry.

Phosphorus (P) is a macro mineral needed for bone mineralization and cell membrane structure and P is also involved in several fundamental pathways of metabolism in the body. Because of the low concentration and digestibility of P in plant ingredients that are the main components of diets for poultry and pigs, feed phosphates are usually included in diets in addition to the P contributed by plant ingredients. The most widely used feed phosphates in poultry and swine diets are dicalcium phosphate (DCP) and monocalcium phosphate (MCP), but tricalcium phosphate (TCP), monosodium phosphate (MSP), and magnesium phosphate (MgP) may be used as well. Because feed phosphates are mostly produced from rock phosphate, feed phosphates have impurities that contain minerals other than P. Concentrations of P in feed phosphates range from 14.8% (MgP) to 25.7% (MSP). The standardized total tract digestibility (STTD) of P in pigs ranges from 71% (TCP) to 95% (MSP). The STTD of Ca and the standardized ileal digestibility (SID) of P and Ca in feed phosphates fed to pigs and poultry have been determined only in a few experiments. Available data indicate that the STTD of Ca and SID of P in MCP are greater than in DCP in both poultry and pigs, but the SID of Ca is similar between DCP and MCP fed to broilers. Information on mineral concentrations and digestibility values in feed phosphates is needed in diet formulation for pigs and poultry, but if diets are formulated to contain equal concentrations of digestible P and Ca, it is unlikely that animal performance will be impacted by the source of feed phosphates used in the diet.