Effects of microbial phytase on the apparent and standardized total tract digestibility of phosphorus in rice coproducts fed to growing pigs

Evaluation of exogenous phytase in high-phytate diets for broiler chickens and pigs

There is a gap in the understanding of the relationship between dietary phytate levels and the relative efficacy of phytase to improve amino acid (AA) digestibility in pigs and chickens. Two experiments were conducted to investigate the effect of exogenous phytase on standardized ileal digestibility (SID) of AA and the apparent ileal digestibility (AID) of P in both standard- (SP) and high-phytate (HP) diets for broilers and swine. There were either 40 cages of Cobb 500 male broilers or 10 crossbred barrows (35 kg) fitted with ileal T-cannulas. Both studies were allotted to five dietary treatments (8 replicates). Treatments consisted of four corn-soybean meal-based diets arranged in a 2 × 2 factorial of standard or high phytate and exogenous phytase at 0 or 1 000 phytase units (FYT)/kg; and one N-free diet. Birds were fed a common starter diet from d 0 to 20 and fed experimental diets from d 20 to 25. Birds were euthanized on d 25 via CO2 asphyxiation, and digesta were collected from the terminal ileum. Pigs were fed for a total of four 7-d periods, where digesta were collected on d 6 and 7 of each period. Diet and digesta samples were analyzed for DM, N, Ti, AA, and P to determine AA and P digestibility. The SID of AA was determined by correcting the AID of AA for the basal endogenous losses estimated using the N-free diet. Main effects of the diet type (standard or HP) and phytase (0 or 1 000 FYT/kg), and the interaction of diet type and phytase were evaluated. For both experiments, the HP diets produced lower SID of AA compared to the SP (P < 0.001). For broilers, there was a phytase effect (P < 0.001) for the SID of all AAs evaluated regardless of the diet type. For pigs, phytase improved (P < 0.05) the SID of Met, Lys, Cys, Glu and Ser and tended to improve (P < 0.10) Arg, Leu, Thr, and Tyr. There were no significant interactions for either experiment. For both experiments, AID of P was lower for the HP diets (P < 0.01), and phytase produced greater AID of P for both diet types (P < 0.01). These data indicate that phytase greatly improves the digestibility of P for broilers and pigs and has the ability to significantly increase the digestibility of amino acids for these animals, regardless of the dietary phytate P.

Chemical composition of banana meal and rice bran from Australia or South-East Asia

OBJECTIVE

A study was conducted to determine the chemical composition of banana meal and rice bran from Australia or South-East Asia and test the hypothesis that there are no differences in rice bran produced in different countries, but there are differences between full-fat and defatted rice bran.

METHODS

Two sources of banana meal and 22 sources of rice bran (full-fat or defatted) from Australia or South-East Asia were used. All samples were analyzed for dry matter, gross energy, nitrogen, amino acids (AA), acid hydrolyzed ether extract (AEE), ash, minerals, total starch, insoluble dietary fiber, and soluble dietary fiber. Banana meal was also analyzed for sugars including glucose, fructose, maltose, sucrose, stachyose, and raffinose.

RESULTS

Chemical analysis demonstrated that banana meal from the Philippines is primarily composed of starch. Full-fat rice bran from Australia had greater (p<0.05) concentrations of AEE, lysine, and glycine than samples from the Philippines and Vietnam. Full-fat rice bran from Australia and Thailand had greater (p<0.05) concentrations of gross energy and most AA than rice bran from Vietnam. Full-fat rice bran from Australia had greater (p<0.05) concentrations of tryptophan and manganese than all other sources, but full-fat rice bran from the Philippines contained less (p<0.05) zinc than all other sources of rice bran. Gross energy, AEE, and copper were greater (p<0.05) in full-fat rice bran compared with defatted rice bran, but defatted rice bran contained more (p<0.05) crude protein, ash, insoluble dietary fiber, total dietary fiber, AA, and some minerals than full-fat rice bran.

CONCLUSION

Banana meal is a high-energy source that can be used as an alternative ingredient in livestock diets. Full-fat rice bran from Australia and Thailand contained more concentrations of AEE and AA than samples from the Philippines or Vietnam. Full-fat rice bran had more gross energy and AEE than defatted rice bran, whereas defatted rice bran contained more crude protein, ash, and total dietary fiber.

Microbial phytase reduces basal endogenous loss of calcium in pigs fed diets containing phytate phosphorus at commercial levels

The objective of this experiment was to test the hypothesis that increasing dietary phytase reduces basal endogenous loss of Ca and increases P balance in pigs. Seventy barrows (initial body weight: 17.66 ± 1.69 kg) were allotted to seven Ca-free diets using a randomized complete block design with two blocks and five pigs per diet in each block. All diets were based on corn, potato protein concentrate, and full-fat rice bran. A positive control (PC) diet was formulated to contain P at the requirement for standardized total tract digestible (STTD) P by 11 to 25 kg pigs. Six negative control (NC) diets were formulated by reducing the provision of digestible P by 0.15% and adding 0, 250, 500, 1,000, 2,000, or 4,000 phytase units/kg diet. Pigs were housed individually in metabolism crates that allowed for total, but separate, collection of urine and feces. Daily feed allowance was 3.0 times the maintenance requirement for metabolizable energy and was divided into two equal meals. Diets were fed for 12 d with the first 5 d considered the adaptation period. Urine collections started on day 6 in the morning and ceased on day 10 in the morning. Fecal markers were also included in the morning meals on day 6 and day 10 and feces were collected according to the marker-to-marker procedure. Results indicated that the apparent total tract digestibility of dry matter was not affected by dietary P or phytase levels. The basal endogenous loss of Ca was not affected by dietary P, but exponentially decreased (P = 0.030) as phytase level increased in the diets. Phosphorus retention (g/d) and standardized total tract digestibility of phosphorus were greater (P < 0.05) in pigs fed the PC diet compared with pigs fed the NC diet with no phytase. The STTD of P exponentially (P < 0.001) increased as phytase level increased in the diets, but because of the lack of Ca, retention of P (% of absorbed) linearly decreased (P = 0.006) as phytase increased. In conclusion, basal endogenous loss of Ca decreased as dietary phytase increased demonstrating that endogenous Ca can be bound to phytate in the intestinal tract of pigs. However, STTD of P increased as phytase level in the diets increased.

Intrinsic phytase in hybrid rye increases the digestibility of phosphorus in corn and soybean meal in diets fed to growing pigs

An experiment was conducted to test the hypothesis that inclusion of hybrid rye in diets containing corn and soybean meal (SBM) without or with microbial phytase improves the apparent total tract digestibility (ATTD) and the standardized total tract digestibility (STTD) of P because of the intrinsic phytase activity in hybrid rye. Forty-eight growing barrows (initial body weight: 39.5 ± 7.7 kg) were allotted to six diets. A basal diet containing corn and SBM; a rye-based diet; and a diet containing corn, SBM, and rye were formulated. Each diet was formulated without and with microbial phytase (500 units/kg of diet) for a total of six diets. Fecal samples were collected for 4 d following a 5-d adaptation period according to the marker-to-marker procedure. Results indicated that no interactions between diets and concentration of phytase were observed for any of the response criteria measured. The ATTD and STTD of P and the ATTD of Ca differed (P < 0.05) among diets, but regardless of diet, the concentration of P in feces was reduced (P < 0.05) by adding microbial phytase to the diets. As a consequence, microbial phytase increased (P < 0.05) ATTD and STTD of P, and the ATTD of Ca was also increased (P < 0.05) by the use of microbial phytase. Measured values for the ATTD and STTD of P in the diets containing corn, SBM, and hybrid rye without or with phytase were greater (P < 0.05) than values that were predicted based on the ATTD and STTD of P for the corn-SBM and the hybrid rye diet. The observation that STTD predicted from the individual ingredients underestimated the STTD of P in the mixed diet indicates that the intrinsic phytase in hybrid rye resulted in increased digestibility of the P in the corn and SBM included in the corn-SBM-hybrid rye diet. In conclusion, microbial phytase increased the ATTD and STTD of P and the ATTD of Ca regardless of feed ingredients used in diets fed to pigs. In addition, the intrinsic phytase from hybrid rye increased the ATTD and STTD of P in corn and SBM.

Relationship between true digestibility of dietary phosphorus and gastrointestinal bacteria of goats

The present research was conducted to evaluate the connection between the true digestibility of Phosphorus (TDP) in diet and bacterial community structure in the gastrointestinal tract (GIT) of goats. Twenty-eight Nubian goats were chosen and metabolic experiment was conducted to analyze TDP of research animals. Eight goats were grouped into the high digestibility of phosphorus (HP) phenotype, and another 8 were grouped into the low digestibility of phosphorus (LP) phenotype. And from the rumen, abomasum, jejunim, cecum and colon content of the goats, bacterial 16S rRNA gene amplicons were sequenced. In the rumen 239 genera belonging to 23 phyla, in abomasum 319 genera belonging to 30 phyla, in jejunum 248 genera belonging to 36 phyla, in colon 248 genera belonging to 25 phyla and in cecum 246 genera belonging to 23 phyla were noticed. In addition, there was a significant correlation between the TDP and the abundance of Ruminococcaceae_UCG-010, Ruminococcus_2, Ruminococcaceae_UCG-014, Selenomonas_1 and Prevotella in the rumen, Lachnospiraceae_ND3007_group, Saccharofermentans, Ruminococcus_1, Ruminococcaceae_UCG-014, Lachnospiraceae_XPB1014_group and Desulfovibrio in the abomasum, Prevotella, Clostridium_sensu_stricto_1, Fibrobacter, Desulfovibrio and Ruminococcus_2 in the jejunum, Ruminococcaceae_UCG-014 in the colon, and Desulfovibrio in the cecum. Present research trial recommended that the community of gastrointestinal microbiota is a factor affecting TDP in goats.

Effect of microbial phytase supplementation on P digestibility in pigs: a meta-analysis

The objectives of this meta-analysis were to determine to which extent phosphorus (P) digestibility and digestible P concentration in pig diets were increased by phytase supplementation and to quantify factors that potentially influence effects of phytase supplementation. A data set with a total of 547 data lines was compiled from 88 experiments published in 74 peer-reviewed papers between 2007 and April 2019. An exponential model was determined as more suitable to describe the response of P digestibility to phytase supplementation than a polynomial model. Phytase supplementation increased P digestibility by 25.6 percentage points (standard error (SE) = 1.54) to a plateau at 64.9% (SE = 1.82). The digestible P concentration was increased by phytase supplementation in the order of 1.01 g/kg (SE = 0.102) to a plateau at 2.62 g/kg (SE = 0.122). Goodness-of-fit criteria were R² = 0.780 and root mean square error = 7.55% for P digestibility, and R² = 0.691 and root mean square error = 0.48 g/kg for digestible P concentration. Consideration of further factors such as mineral P supplementation (yes or no), ad libitum vs. restrictive feeding, mixed diets vs. single feed ingredients, sex and age of pigs did not increase the accuracy of prediction in this data set. Some of these traits exhibited responses, but they likely are artefacts generated through the imbalanced structure of the data set. Effects of dietary total P, phytate (InsP₆), InsP₆-P to total P ratio, and Ca on the effect of supplemented phytase were not quantifiable. The present meta-analysis showed that responses to phytase supplementation can be well predicted although variation in P digestibility and digestible P concentration in the data set was high. Overall, predicted effects of phytase on P digestibility well corresponded to predictions made 25 years ago.

The level of feed intake does not influence digestibility of calcium and phosphorus in diets fed to gestating sows, but gestating sows have reduced digestibility of calcium and phosphorus compared with growing gilts

Level of feed intake did not affect the apparent total tract digestibility (ATTD) of calcium (Ca) and phosphorus (P) in gestating sows. Gestating sows had reduced ATTD of Ca and P compared with growing gilts. Formulating diets for sows using values obtained from growing pigs, therefore, may result in inaccuracies.

Additivity of values for phosphorus digestibility in corn, soybean meal, and canola meal in diets fed to growing pigs

OBJECTIVE

This study was conducted to determine the apparent and standardized total tract digestibility (ATTD and STTD) of phosphorus (P) in corn, soybean meal (SBM), and canola meal (CM), and additivity of values for ATTD and STTD of P in corn, SBM, and CM in diets fed to growing pigs.

METHODS

Thirty-six growing barrows (initial body weight of 21.6±1.7 kg) were placed in metabolism crates and allotted to a completely randomized design with 6 diets and 6 pigs per diet. Six diets were formulated using corn, SBM or CM as the sole source of P, or corn and SBM, or corn and CM, or corn, SBM, and CM as the P source in each diet, respectively. Fecal samples were collected for 5 d following a 7 d adaptation period to the diets.

RESULTS

Values for ATTD and STTD of P in corn, SBM, and CM in growing pigs were 33.12% and 37.76%, 50.19% and 56.62%, 34.93% and 39.45%, respectively. The ATTD and STTD of P in SBM were greater (p<0.05) than those in corn and CM. However, there were no differences in the ATTD or STTD of P between corn and CM. The determined STTD of P in the mixture of corn and SBM, corn and CM, and corn, SBM, and CM is not different from the calculated STTD values.

CONCLUSION

Values for STTD of P in corn, SBM, and CM are additive in their mixture fed to growing pigs.

Effects of extrusion and microbial phytase on the apparent and standardized total tract digestibility of phosphorus in hemp hulls fed to growing pigs

An experiment was carried out to determine the apparent total tract digestibility (ATTD) and the standardized total tract digestibility (STTD) of P and the effects of extrusion and microbial phytase on ATTD and STTD of P in hemp hulls (HH). Thirty-six pigs (30.3 ± 2.7 kg) were randomly allotted to 1 of 6 experimental diets in a complete randomized design with 6 replicates per diet. A corn-soybean meal (SBM)-based basal diet was formulated. Two additional diets were formulated by replacing 40% of corn and SBM (on a 100% of total diet basis) with HH or extruded HH (EHH). The test ingredients, corn, and SBM were the only sources of P in the diets. Three additional diets were also prepared by supplementing 500 unit/kg of microbial phytase to the initial 3 diets (the corn-SBM basal diet and diets containing test ingredients). Pigs were fed experimental diets at 3 times the maintenance energy requirement (197 kcal ME/kg BW0.60). Results indicated that fecal P concentration and daily P output were reduced (P < 0.05) from pigs fed diets with dietary phytase compared with pigs fed diets without dietary phytase. The ATTD and STTD of P in experimental diets were not different. However, the ATTD and STTD of P in experimental diets supplemented with dietary phytase were increased (P < 0.05) compared with the diets without phytase. The ATTD and STTD of P in HH were 18.8% and 22.0%, respectively, whereas respective values for EHH were 22.5% and 26.3%. Extrusion had no effects on ATTD and STTD of P in HH. However, the ATTD and STTD of P in HH and EHH increased (P < 0.05) when dietary phytase was added to the diets. The concentration of Ca in feces and daily Ca output were reduced (P < 0.05) as a result of phytase supplementation. Addition of dietary phytase increased (P < 0.05) the ATTD of Ca in all experimental diets. In conclusion, the ATTD and STTD of P in HH fed to growing pigs were 18.8% and 22.0%, respectively. Respective values for EHH were 22.5% and 26.3%. Extrusion did not affect the ATTD and STTD of P in HH. However, the addition of microbial phytase to experimental diets increased the ATTD and STTD of P in diets and test ingredients and decreased fecal P output from pigs fed experimental diets. There was no interaction between extrusion and dietary phytase supplementation.

Methodological aspects of determining phosphorus digestibility in swine: A review

The role of phosphorus (P) in swine nutrition has been taken on new significance in recent years. Methods to determine the available phosphorus (AP) content of swine feeds include relative bioavailability (RBV), apparent total tract digestibility (ATTD), standardized total tract digestibility (STTD), and true total tract digestibility (TTTD). The RBV of P is determined by measuring bone ash or bone P, whereas the ATTD of P is determined by calculating the difference between P intake and P excretion in feces. Recent research has shown that the use of ATTD of P underestimates the AP due to the existence of endogenous P in feces and digesta. The STTD can be calculated from ATTD by taking basal endogenous phosphorus losses (EPL) into consideration. The basal EPL in pigs can be measured by feeding a P-free diet. Values for STTD of P are believed to be additive in mixed diets but not for ATTD of P. The regression method is a common approach to determine total EPL and TTTD of P, which measures the linear relationship between fecal P excretion and the dietary intake of total P. In addition, in vitro methods such as the bionic enzymatic method are being increasingly utilized because they can be done quickly and simply. Several dietary factors such as P and Ca concentrations, phytate, Ca to P ratio and vitamin D may affect AP. This review summarizes the evolution of methods to measure AP and factors that can affect AP, which may provide information to formulate swine diet more accurately. Moreover, the knowledge about AP may help to reduce the P waste in swine production and thus decrease its impact on the environment.

Standardized total tract digestibility of phosphorus in flaxseed meal fed to growing and finishing pigs without or with phytase supplementation

Two experiments were conducted to determine the apparent total tract digestibility (ATTD) and standardized total tract digestibility (STTD) of P in flaxseed meal (FM) and the effect of dietary microbial phytase on the digestibility of P in FM fed to growing and finishing pigs. In Exp. 1, eighteen growing barrows (26.6 ± 1.8 kg BW) were allotted to 1 of 3 experimental diets consisting of a diet containing 32% FM that was fed with or without phytase at 500 phytase units (FTU/kg and a P-free diet in a completely randomized design to give 6 replicates per diet. The experimental period lasted 12 d including first 7 d for adaptation and 5 d for total collection of feces. Pigs were fed their assigned diets at 4% of BW at the beginning of the experiment. The daily feed allowance was offered in 2 equal portions at 0800 and 1600 h. All experimental diets were provided in mash form. Results indicated that pigs fed the diets containing FM with dietary phytase had less ( < 0.05) fecal P concentration and daily P output than those fed the diets without phytase supplementation. Also, phytase supplementation increased ( < 0.05) the ATTD of P of the diets containing FM from 37.3% to 51.8% and STTD of P of the diets containing FM from 43.2% to 57.7%. The basal endogenous P losses (EPL) was calculated at 140 ± 11 mg/kg of DMI in growing pigs fed the P-free diet. In Exp. 2, eighteen finishing pigs (78.7 ± 2.4 kg BW) were randomly allotted to 1 of 3 dietary treatments. The experimental diets and procedures were similar to those described in Exp. 1. Similar to Exp. 1, pigs fed FM diets with phytase supplementation had less ( < 0.05) P concentration in feces than those fed diets without phytase supplementation. Also, daily P output was reduced ( = 0.08) when pigs were fed the FM diets with phytase compared to those fed the FM diets without phytase. The ATTD of P in FM diets was increased ( < 0.01) from 31.4% to 45.8%, whereas the STTD of P in FM diets was increased ( < 0.01) from 37.8% to 52.3% as a result of phytase supplementation. The basal EPL was calculated at 164 ± 19 mg/kg of DMI in finishing pigs fed the P-free diet. In conclusion, the ATTD and STTD of P in FM fed to growing pigs were 37.3% and 43.2%, respectively, whereas respective values for finishing pigs were 31.4%, and 37.8%, respectively. Also, dietary phytase supplementation improved both ATTD and STTD of P in FM for both stages of pigs by an average of 33%.

Effects of full fat or defatted rice bran on growth performance and blood characteristics of weanling pigs

The objective of this experiment was to determine the effect of increased concentrations of full fat rice bran (FFRB) or defatted rice bran (DFRB) in diets without or with supplementation of an exogenous xylanase on growth performance and blood characteristics in weanling pigs. A total of 532 pigs (9.3 ± 0.5 kg initial BW) were allotted to 14 diets in 4 blocks and 8 replicate pens per diet in a randomized complete block design. There were 4 or 5 pigs per pen. A basal diet containing corn, soybean meal, and whey powder and 6 diets containing corn, soybean meal, whey powder, and 10, 20, or 30% FFRB or 10, 20, or 30% DFRB were used. Seven additional diets that were similar to the initial 7 diets with the exception that they also contained 16,000 units/kg of microbial xylanase were also formulated. On the last day of the 23-d experiment, 2 blood samples were collected from 1 pig in each pen. Tumor necrosis factor-α (TNF-α), IgA, and peptide YY (PYY) were measured in plasma samples and blood urea nitrogen (BUN), total protein, and albumin were measured in serum samples. Initial and final BW were not affected by the inclusion level of FFRB or DFRB or by the addition of xylanase. The ADFI linearly decreased ( < 0.05) as inclusion of FFRB increased in diets and there was a tendency ( = 0.08) for reduced ADFI as DFRB was increased in the diets. Pigs fed diets containing DFRB had greater ADFI ( < 0.05) than pigs fed diets containing FFRB. The ADG increased and then decreased (quadratic, < 0.05) with increasing level of FFRB or DFRB in the diets. The G:F linearly and quadratically increased ( < 0.05) as the inclusion of FFRB increased, and the G:F was greater ( < 0.05) in pigs fed diets containing FFRB than in pigs fed diets containing DFRB. The concentration of BUN linearly decreased ( < 0.05) when pigs were fed diets containing increasing levels of FFRB or DFRB. There was a tendency for the concentrations of TNF-α and PYY to linearly decrease ( = 0.09 and = 0.075, respectively) as the inclusion of FFRB increased in the diet. In conclusion, ADG of weanling pigs was not affected by at least 20% FFRB or DFRB and inclusion of 30% DFRB had no effect on the G:F whereas 30% FFRB increased the G:F. However, microbial xylanase did not influence growth performance under the conditions of this experiment and there was minimal influence of rice coproducts or xylanase on blood characteristics.

Effects of microbial xylanase on digestibility of dry matter, organic matter, neutral detergent fiber, and energy and the concentrations of digestible and metabolizable energy in rice coproducts fed to weanling pigs

The objective of this experiment was to test the hypothesis that the apparent total tract digestibility (ATTD) of DM, OM, fiber, and GE by weanling pigs and the concentration of DE and ME in full-fat rice bran (FFRB), defatted rice bran (DFRB), brown rice, and broken rice is improved if microbial xylanase is added to the diet. Eighty pigs (13.6 ± 0.8 kg initial BW) were allotted to 10 diets with 8 replicate pigs per diet in a randomized complete block design with 2 blocks of 40 pigs. A basal diet based on corn and soybean meal and 4 diets containing corn, soybean meal, and each of the 4 rice coproducts were formulated. The rice coproducts and corn and soybean meal were the only sources of energy in the diets. Five additional diets that were similar to the initial 5 diets with the exception that they also contained 16,000 units of xylanase (Econase XT-25; AB Vista, Marlborough, UK) were also formulated. All diets also contained 1,500 units of microbial phytase (Quantum Blue 5G; AB Vista). The DE and ME and the ATTD of DM, OM, fiber, and GE in diets and ingredients were calculated using the direct method and the difference method, respectively. Results indicated that the concentrations of DE and ME (DM basis) in FFRB and DFRB increased ( < 0.05) if xylanase was used. Broken rice had a greater ( < 0.05) concentration of DE and ME than FFRB and DFRB if no xylanase was added to the diets, but if xylanase was used, no differences in ME among FFRB, brown rice, and broken rice were observed. The ATTD of DM was greater ( < 0.05) in ingredients with xylanase than in ingredients without xylanase and there was a tendency ( = 0.067) for the ATTD of OM to be greater if xylanase was used. The ATTD of NDF in FFRB was greater ( < 0.05) when xylanase was added than if no xylanase was used, whereas the ATTD of NDF in DFRB was not affected by the addition of xylanase. In conclusion, if no xylanase was used, broken rice and brown rice have greater concentrations of DE and ME than FFRB and DFRB, and these values were not increased by microbial xylanase. However, xylanase increased the concentration of DE and ME (DM basis) in FFRB and DFRB.

Nutritional value of high fiber co-products from the copra, palm kernel, and rice industries in diets fed to pigs

High fiber co-products from the copra and palm kernel industries are by-products of the production of coconut oil and palm kernel oil. The co-products include copra meal, copra expellers, palm kernel meal, and palm kernel expellers. All 4 ingredients are very high in fiber and the energy value is relatively low when fed to pigs. The protein concentration is between 14 and 22 % and the protein has a low biological value and a very high Arg:Lys ratio. Digestibility of most amino acids is less than in soybean meal but close to that in corn. However, the digestibility of Lys is sometimes low due to Maillard reactions that are initiated due to overheating during drying. Copra and palm kernel ingredients contain 0.5 to 0.6 % P. Most of the P in palm kernel meal and palm kernel expellers is bound to phytate, but in copra products less than one third of the P is bound to phytate. The digestibility of P is, therefore, greater in copra meal and copra expellers than in palm kernel ingredients. Inclusion of copra meal should be less than 15 % in diets fed to weanling pigs and less than 25 % in diets for growing-finishing pigs. Palm kernel meal may be included by 15 % in diets for weanling pigs and 25 % in diets for growing and finishing pigs.

Rice bran contains the pericarp and aleurone layers of brown rice that is removed before polished rice is produced. Rice bran contains approximately 25 % neutral detergent fiber and 25 to 30 % starch. Rice bran has a greater concentration of P than most other plant ingredients, but 75 to 90 % of the P is bound in phytate. Inclusion of microbial phytase in the diets is, therefore, necessary if rice bran is used. Rice bran may contain 15 to 24 % fat, but it may also have been defatted in which case the fat concentration is less than 5 %. Concentrations of digestible energy (DE) and metabolizable energy (ME) are slightly less in full fat rice bran than in corn, but defatted rice bran contains less than 75 % of the DE and ME in corn. The concentration of crude protein is 15 to 18 % in rice bran and the protein has a high biological value and most amino acids are well digested by pigs. Inclusion of rice bran in diets fed to pigs has yielded variable results and based on current research it is recommended that inclusion levels are less than 25 to 30 % in diets for growing-finishing pigs, and less than 20 % in diets for weanling pigs. However, there is a need for additional research to determine the inclusion rates that may be used for both full fat and defatted rice bran.