Low-phytate Corn Research Articles

Effect of fermentation on antinutrients, and total and extractable minerals of high and low phytate corn genotypes.

Two corn genotypes, Var-113 (high phytate) and TL-98B-6225-9×TL617 (low phytate) were fermented for 14days. The fermented flour was dried and milled. Phytic acid and polyphenols contents and hydrochloric acid (HCl) extractability of minerals from the fermented flours were determined at intervals of 2days during fermentation period. Phytic acid and polyphenols decreased significantly (P ≤ 0.05) with an increase in fermentation period, with a concomitant increase in HCl extractable minerals. For both genotypes the major and trace minerals content was increased with fermentation period. When the grains flour was fermented for 14days, TL-98B-6225-9×TL617 genotype had higher extractable calcium (94.73%) while Var-113 had higher extractable phosphorus (76.55%), whereas iron recorded high extractability levels (84.93%) in TL-98B-6225-9×TL617 and manganese recorded high extractability levels (81.07%) in Var-113. There was good correlation between phytate and polyphenols levels reduction and the increment in extractable minerals with fermentation period.

Effect of malting and fermentation on antinutrients, and total and extractable minerals of high and low phytate corn genotypes

SummaryTwo corn genotypes, Var‐113 (high phytate) and TL‐98B‐6225‐9 × TL617 (low phytate), were germinated for 6 days. The germinated grains were dried and milled. A mixture of 5% malt and 95% corn flour was fermented for 14 days. Phytic acid and polyphenol contents and hydrochloric acid (HCl) extractability of minerals from the fermented flours were determined at the intervals of 2 days during fermentation. Phytic acid and polyphenol contents decreased significantly (P ≤ 0.05) with an increase in fermentation time, with a concomitant increase in HCl‐extractable minerals. For both genotypes, the major mineral content was increased, while that of trace minerals was increased but at slow rate with fermentation time. When the grains were fermented for 14 days, TL‐98B‐6225‐9 × TL617 genotype had higher extractable calcium and Var‐113 had higher extractable phosphorus, whereas iron and manganese recorded high extractability levels in Var‐113. There was good correlation between phytate and polyphenol level reduction and the increment in extractable minerals with fermentation time.

Effect of germination on antinutritional factors, total, and extractable minerals of high and low phytate corn (Zea mays L.) genotypes

Two corn genotypes, Var-113 (high phytate) and TL-98B-6225-9×TL617 (low phytate) were germinated for 6days. The germinated seeds were dried and milled. Phytic acid, polyphenols, and hydrochloric acid (HCl) extractable minerals were determined at intervals of two days of germination. Phytic acid decreased significantly (P⩽0.05) with a concomitant increase in HCl extractable minerals, while polyphenol contents increased significantly (P⩽0.05) with an increase in germination time. However, the major mineral content was initially decreased and then increased while that of trace minerals was increased with germination time. After 6days of germination, the high phytate sample (Var-113) exhibited higher extractable calcium compared to the other genotype, whereas the low phytate sample (TL-98B-6225-9×TL617) showed higher extractable phosphorus. Iron extractability was higher for the low phytate samples, while that of magnesium was higher for the high phytate sample. High correlation between lower phytate and higher extractable minerals was noted as a function of longer germination time. Nevertheless, no correlation was observed between polyphenol content and mineral extractability level.

Runoff Losses of N and P After Low Phosphorus Swine Slurry Application to No-Tillage Sorghum

Abstract Swine (Sus scrofa) manure can serve as a fertilizer source for crop production, but it typically contains more P relative to N than the crop requires, creating the potential for P losses in runoff. A 3-year study was conducted to compare runoff losses of NO3-N, NH4-N, total N, dissolved P, and total P under natural rainfall conditions from no-tillage sorghum plots [Sorghum bicolor (L.) Moench] receiving inorganic fertilizer, manure from swine fed low-phytate corn (Zea mays L.) diet, or manure from swine fed a traditional corn diet. Runoff (26.5 mm in 1999, 14.2 mm in 2000, and 1.6 mm in 2001), sediment loss (2.9 kg ha−1 in 1999, 0.9 kg ha−1 in 2000, and 0.4 kg ha−1 in 2001), and runoff nutrient losses differed among years but were similar among treatments within a year. Runoff losses of NO3-N (5.3 g ha−1 in 1999, 1.0 g ha−1 in 2000, and 2.6 g ha−1 in 2001), NH4-N (2.9 g ha−1 in 1999, 0.6 g ha−1 in 2000, and 5.6 g ha−1 in 2001), total N (89.7 g ha−1 in 1999, 8.4 g ha−1 in 2000, and 100.2 g ha−1 in 2001), dissolved P (1.5 g ha−1 in 1999, 0.5 g ha−1 in 2000, and 3.1 g ha−1 in 2001), and total P (3.8 g ha−1 in 1999, 0.9 g ha−1 in 2000, and 3.5 g ha−1 in 2001) from these plots represented less than 1% of that applied each year. Although use of low-phytate corn reduces manure P content, it did not decrease runoff P under these no-tillage conditions.

Effect of Low-Phytate Corn and Phytase on Nutrient Excretion and Performance of Feedlot Cattle

ABSTRACT Two trials were conducted to determine the effect of microbial phytase (PHY) addition and low phytic acid (LPA) corn, on the nutrient digestibility and performance of growing beef steers. Four crossbred steers (initial BW = 345 ± 25 kg; Exp. 1) were used in a 4 × 4 Latin square design digestibility trial and were provided ad libitum access to 1 of 4 diets: 1) a normal corn and 15% corn silage diet (control diet), 2) diet 1 + PHY (control + PHY diet; 600 FTU/kg, where a FTU is the quantity of enzyme that liberates 1 µmol inorganic P/min from 0.005 mol/L sodium phytate at pH 5.5 and 37°C), 3) diet 1 with LPA corn replacing normal corn (LPA diet), and 4) diet 3 + PHY (LPA + PHY diet; 600 FTU/kg). Dietary P content was 0.38 to 0.40%, with no supplemental P added. Forty-eight crossbred steers (initial BW = 273 ± 6.9 kg; Exp. 2) were individually fed 4 diets: 1) a control diet; 2) a control + PHY diet; 3) diet 1 limit fed to 85% of ad libitum intake (limit-fed diet); and 4) the limit-fed diet + PHY. In Exp. 1, P digestibility, retention, and excretion were not affected (P > 0.05) by corn type or PHY. There was a trend (P

Crop Nitrogen and Phosphorus Utilization following Application of Slurry from Swine Fed Traditional or Low Phytate Corn Diets

Field application of swine (Sus scrofa) slurry provides essential nutrients for crop production. The N to P ratio for slurry is lower than needed by most crops resulting in P accumulation when applied at N rates required for crop growth. Low phytate corn (Zea mays L.) (LPC) contains similar amounts of total P but less phytate P than traditional corn (TC) resulting in improved P bioavailability and reduced P excretion by monogastric animals. While manure from swine‐fed LPC diets has a higher N to P ratio than that from TC diets, field studies comparing crop utilization of nutrients from LPC manure have not been conducted. A field study was conducted to compare N and P utilization by no‐tillage rainfed sorghum [Sorghum bicolor (L.) Moench.] receiving three annual surface applications of nutrients (inorganic fertilizer, LPC slurry, and TC slurry) and by irrigated corn receiving one incorporated application of nutrients. Sorghum grain and total dry matter N utilization exhibited a year by treatment interaction but total dry matter N utilization was similar for both manure types in all years (61.2 ± 2.6% for TC and 53.8 ± 2.6% for LPC). Grain P utilization was similar for inorganic fertilizer and manure but differed among years (44.4 ± 7.0% in 1999, 25.1 ± 1.4% in 2000, and 57.0 ± 2.2% in 2001). Corn grain N and P utilization did not differ among nutrient sources in the year of application (50.7 ± 2.4% for N and 40.4 ± 3.0 for P) and increased little in the year following application (62.2 ± 3.0% for N and 50.2 ± 4.5% for P). Crop N and P utilization from LPC manure and TC manure was similar and nutrient guidelines developed for TC swine slurry should also apply for LPC slurry.

Evaluation of NutriDense low-phytate corn and added fat in growing and finishing swine diets1,2

Two experiments were conducted to evaluate the effects of NutriDense low-phytate corn in conjunction with increasing added dietary fat on growing and finishing pig performance. Diets in both experiments were corn-soybean meal-based, with yellow dent or NutriDense low-phytate corn and 0, 3, or 6% added choice white grease arranged in a 2 x 3 factorial design. There were 25 to 28 pigs per pen and 7 pens (replications) per treatment in both experiments. In Exp. 1, a total of 1,162 gilts with an initial BW of 44.6 kg were used in a 28-d growth study. A constant true ileal digestible (TID) Lys:ME ratio of 2.80 g/Mcal and available P:ME ratio of 0.90 g/Mcal were maintained in all treatment diets. Overall (d 0 to 28), there were no corn source x added fat interactions (P >/= 0.79). Regardless of corn source, ADG and G:F increased (linear, P = 0.03) with increasing added fat. There were no differences (P >/= 0.34) in pig growth performance between those fed NutriDense low-phytate or yellow dent corn. In Exp. 2, a total of 1,128 gilts with an initial BW of 81.6 kg were used in a 28-d growth study. A constant TID Lys:ME ratio of 2.15 g/Mcal of ME and available P:ME ratio of 0.75 g/Mcal were maintained in all treatment diets. Overall (d 0 to 28), there was a tendency (P = 0.07) for a corn source x added fat interaction for G:F, which can be explained by the improved G:F in pigs fed yellow dent corn only when 6% fat was added to the diet, whereas G:F was improved at both 3 and 6% added fat in pigs fed NutriDense low-phytate corn. There were no differences (P >/= 0.18) in growth performance between pigs fed NutriDense low-phytate or yellow dent corn. These results indicate that increasing added fat improved growth performance regardless of the corn source. In addition, growth performance was similar for pigs fed NutriDense low-phytate or yellow dent corn.

Effects of Various Phytase Concentrations in Diets with Low-phytate Corn on Broiler Chick Performance and Nutrient Use

Research indicates a reduction in phosphorus content of broiler excreta with the supplementation of phytase to corn-soybean meal based diets or with the use of Low Phytate Corn (LPC). This study examined how broiler chicks are impacted by phytase supplementation to a LPC [0.136% Phytate Phosphorus (PP) by analysis] based diet. Different dietary inclusion levels from a 2,500 or a 5,000 FYT/g of Peniophora lycii phytase product were used as experimental treatments. Following a six day pretest, 576 broiler chicks were randomly assigned to one of 12 dietary treatments, using eight diet replicates and six birds per cage. Live performance, tibia ash, mineral digestibility and apparent metabolizable energy were determined. The percent of phosphorus that may have been spared due to each phytase treatment was calculated using response curves created with increasing levels of monocalcium phosphate. Results demonstrated that phytase supplementation to a LPC based diet had a positive impact on broiler chick growth. However, this impact is expressed to a lesser extent than would be expected for normal corn. In addition, phytase efficacy did not vary based on the concentration of phytase product, likely due to adequate mix uniformity.

Influence of nutridense low phytate corn and added fat on growing-finishing pig growth performance (2006)

Influence of nutridense low phytate corn and added fat on growing-finishing pig growth performance (2006)

Comparison of yellow dent and NutriDense corn hybrids in swine diets1,2

Two experiments were conducted to verify the feeding value of NutriDense (ND) and Nutri-Dense Low-Phytate (NDLP) corn (Exseed Genetics LLC, BASF Plant Science, Research Triangle Park, NC) relative to that of yellow dent (YD) corn in swine diets. NutriDense corn is a high-protein, high-oil variety, and NDLP is a high-protein, high-oil, low-phytate variety. In Exp. 1, 315 nursery pigs that initially weighed 15.2 kg were used in a 21-d growth assay. Dietary treatments were arranged in a 3 x 3 factorial; main effects were corn source (YD, ND, and NDLP) and added fat (0, 3, or 6%, as-fed basis). Diets were formulated to contain 3.83 g of lysine/Mcal using calculated nutrient values. There were no corn source x fat interactions observed. Pigs fed YD, ND, and NDLP had ADG of 750, 734, and 738 g/d and G:F of 0.64, 0.66, and 0.65, respectively. No differences (P > 0.10) in ADG were observed among the three corn sources; however, pigs fed diets containing either ND or NDLP corn had decreased ADFI (P < 0.02) and improved G:F (P < 0.05) compared with pigs fed diets containing YD corn. Increasing dietary fat increased ADG (727, 746, and 748 g/d; linear, P < 0.04) and G:F (0.62, 0.66, and 0.68; linear, P < 0.01) and decreased ADFI (linear, P < 0.01). Using the NRC (1998) value for ME in YD corn, we calculated the energy value for ND and NDLP based on G:F differences compared with pigs fed YD corn. These data indicated the ME values for ND and NDLP corn are 4.5 and 2.5% greater (3,575 and 3,505 Kcal/kg), respectively, than for YD corn (3,420 Kcal/kg). In Exp. 2, 1,144 gilts (initial BW = 50.1 kg) were used in a commercial research facility to evaluate the effects of corn source (ND and YD) and added fat (0, 3, or 6%, as-fed basis) in a 2 x 3 factorial on pig performance and carcass traits. There was a corn source x fat interaction for ADFI and G:F. Increasing added fat resulted in greater changes in ADFI and G:F in pigs fed YD corn diets compared with those fed ND corn. Feeding ND corn increased ADG (main effect, P < 0.04), and greater percentages of added fat increased ADG (main effect; linear, P < 0.01). Results of Exp. 2 suggest that ND corn has 5.3% more ME than YD corn. The additional energy provided by ND corn improves G:F in both nursery and grow-finish pigs, and ND corn offers a means of formulating diets more concentrated in energy than YD corn.

Calcium, phosphorus, and amino acid digestibility in low-phytate corn, normal corn, and soybean meal by growing pigs1,2

Nine growing barrows were equipped with a T-cannula in the distal ileum and used to determine apparent ileal (AID) and apparent total-tract digestibility (ATTD) coefficients of Ca and P in low-phytate corn, normal corn, soybean meal, and in diets where soybean meal was mixed with low-phytate corn or normal corn. The AID and the standardized ileal digestibility coefficients (SID) of CP and AA also were determined. The animals (initial BW = 29.3 +/- 1 kg) were allotted to a 9 x 9 Latin square with nine diets and nine periods. Three diets contained low-phytate corn, normal corn, and soybean meal as their sole source of CP, AA, Ca, and P, respectively. Three additional diets were identical to these diets except that limestone and monosodium phosphate were added. Two diets contained low-phytate corn or normal corn and soybean meal, limestone, and monosodium phosphate, and the final diet was a N-free diet. The AID and ATTD of Ca were higher (P < 0.05) for low-phytate corn than for normal corn (70.0 and 69.1% vs. 47.4 and 49.6%, respectively). The AID and ATTD for Ca in soybean meal (50.9 and 46.7%, respectively) did not differ from values for normal corn but were lower (P < 0.05) than for low-phytate corn. The AID and ATTD for P from low-phytate corn (56.5 and 54.5%, respectively) were greater (P < 0.05) than from normal corn (28.3 and 28.8%, respectively), whereas soybean meal had intermediate AID and ATTD for P (37.2 and 38.0%, respectively). The AID and ATTD of P increased (P < 0.05) when monosodium phosphate was added to normal corn (44.9 and 49.8%, respectively) and soybean meal (49.6 and 46.2%, respectively), but adding monosodium phosphate to low-phytate corn, did not alter either AID (49.7%) or ATTD (50.7%) of P. No differences between AID and ATTD for Ca or P within the same diet were observed. The AID of Arg, Asp, Gly, Ile, Lys, Phe, Thr, and Val were greater (P < 0.05) in low-phytate corn than in normal corn. The AID of all AA in soybean meal were greater (P < 0.05) than in both types of corn, with the exception of Ala, Cys, Leu, and Met. The SID of Lys, Phe, and Thr were higher (P < 0.05) in low-phytate corn than in normal corn. Because low-phytate corn has a higher digestibility of Ca and P, less inorganic Ca and P need to be supplemented to diets containing low-phytate corn than to those containing normal corn, and P excretion may be decreased when low-phytate corn is used in the diet.

Confirmation of Phosphorus Availability in Low-Phytate and High-Protein Corn to Growing-Finishing Large White Toms

A 115-d (16.5-wk) experiment was conducted to validate the estimated availability of P in a high nutrient-dense (amino acids and calories), low-phytic acid (NDLP) corn variety as compared with conventional yellow dent (YD) corn when fed to commercial toms. The NDLP corn contained 0.32% P and 90% of this was nonphytate P (NPP) compared with YD corn, which had 0.25% P and 32% of the total P was NPP. Toms consuming NDLP corn were fed diets formulated to have the same dietary NPP level as the control diet with reduced levels of total P. Phosphorus was successfully formulated at 90% availability for NDLP corn with no compromise to growth performance or bone integrity measurements compared with the control diet with YD corn. Ulna breaking strength was the most sensitive measurement of dietary P adequacy under the conditions of the experiment. Excretion of P from toms was decreased by 30% when NDLP corn was fed in place of YD corn during the finishing phase, and litter P was decreased by 19% by replacement of YD corn with NDLP corn.

Changes in Soil Attributes Following Low Phosphorus Swine Slurry Application to No-Tillage Sorghum

Swine (Sus scrofa) slurry can serve as an excellent fertilizer source. Application at rates to meet crop N requirements can result in excess soil P due to low manure N/P ratios. Low phytate corn (LPC) (Zea mays L.) stores a greater proportion of P as phosphate than does traditional corn (TC) increasing bioavailability of P in pig feed grain. Improved utilization of feed P reduces P concentration in manure and soil P accumulation. However, the potential effects of LPC manure on other soil properties are not known. Changes in soil attributes over 3 yr were compared for soils receiving LPC manure, TC manure, inorganic fertilizer, and no nutrients in no-tillage sorghum [Sorghum bicolor (L.) Moench] on a Sharpsburg clay loam (fine, smectitic, mesic Typic Argiudolls). Soil physical properties exhibited values that should not inhibit crop growth. Several soil chemical properties differed by year and treatment. Particulate organic matter (POM), NO 3 -N, pH, and extractable P increased with manure additions. Extractable P content was greater with addition of TC than LPC manure. Soil chemical properties exhibited values acceptable for crop production, but increasing extractable P increases the potential for environmental contamination. Biological soil properties varied in their response to treatments. Microbial biomass C decreased in the control and increased in manure treatments. The Soil Management Assessment Framework (SMAF) was used to conduct a dynamic soil quality assessment. The SMAF index values were similar across years in the control and inorganic fertilizer treatments and increased in both manure treatments. Manure additions improved soil properties affecting crop production, with P accumulation and the potential for environmental contamination being lower with LPC manure. LPC manure applied at rates to meet crop N requirements will have slower soil P accumulation rates and a lower potential for P contamination of the environment.

Phosphorus fractionation in manure from swine fed traditional and low-phytate corn diets.

Traditional corn (Zea mays L.) (TC), the primary grain used in swine (Sus scrofa) diets, stores a majority of its P as phytate, which is largely unavailable for digestion by nonruminant animals. Low-phytate corn (LPC) contains similar amounts of total P but a smaller percentage of P as phytate. When fed to swine, LPC increases P utilization and reduces P content of manure. While differences in P content between manure from animals fed TC and LPC diets have been documented, solubility and lability of manure P have not been compared. Manure P was characterized in manure from swine fed either LPC or TC diets in 2000 and 2001. Total P was lower (20 vs. 34 g kg(-1)) and N to P ratio was higher (4.5 vs. 3.3) in LPC manure than in TC manure. Manures were sequentially extracted with deionized water, 0.5 M NaHCO3, 0.1 M NaOH, and 1.0 M HCl. Extracts were analyzed for inorganic and total P. Most P (approximately 80%) in the extracts was in the inorganic form. Concentration of P in the water-extractable fraction was lower for LPC manure (10.2 g kg(-1) in 2000 and 9.7 g kg(-1) in 2001) than for TC manure (13.6 g kg(-1) in 2000 and 17.0 g kg(-1) in 2001). Percentage of total P in each extract was in the order of: H2O (60%), HCl (22%), NaHCO3 (12%), NaOH (8%), and residue (<1%). Total P and distribution of P in extracts indicates swine are able to utilize more P contained in LPC feed but the composition of P excreted in LPC manure is similar to TC manure. Solubility, crop availability, and lability of P in LPC manure should be similar to that of TC manure.

Evaluation of low-phytate corn and barley on broiler chick performance

Grains produced by low-phytate barley and corn isolines homozygous for each species' respective low phytic acid 1-1 allele were compared to grain produced by near-isogenic normal or wild-type barley and corn in broiler chick feeds. Cobb × Cobb (384) chicks were used in a 10-d study. A randomized complete block design with a factorial arrangement of 2 × 2 × 3 was used with 4 replicates (8 chicks / replicate) per treatment. Twelve isocaloric and isonitrogenous treatment diets were formulated to contain 2 types of grain (barley and corn), 2 levels of grain (40% and 60%), and 3 sources of available P (wild-type grain, wild-type P-supplemented grain, and low-phytate grain). Growth parameters, bone parameters, total bone mineral, and apparent digestibilities were measured. The mean growth and bone responses were 1) higher for barley diets compared to corn diets, 2) higher for 60% grain inclusion compared to 40%, 3) higher for low-phytate compared to wild-type grains, and 4) not different for low-phytate compared to P-supplemented wild-type grain diets. Chicks fed low-phytate-based diets excreted 33 and 43% less P than chicks fed wild-type and P-supplemented wild-type diets, respectively. Correlations between percentage bone ash, total bone ash, and bone strength indicated a strong relationship and appear to support the use of bone strength analysis as a simpler method than ash content determination as an indication of P status. Feeding low-phytate grains will reduce the need for supplemental P in chick diets.

EXTRACTABLE PHOSPHORUS FOLLOWING SOIL AMENDMENT WITH MANURE FROM SWINE FED LOW-PHYTATE CORN

Manure application rate recommendations have been based almost exclusively on nitrogen (N) management considerations, which can result in over-application of phosphorus (P) and its accumulation in soil. Low-phytate (LP) corn (Zea mays L.) was introduced into swine (Sus scrofa domesticus) feed to reduce the amount of P in manure. Unlike ruminants, swine cannot utilize phytate, the major form of P in normal hybrid corn. The objectives of this study were to determine extractable P following swine manure application from different manure sources and compare the relative P availability of LP-manure to standard (S) manure. A laboratory incubation study was conducted using a Waukegan silt loam, a Verndale sandy loam soil, and five levels of total P (Pt) from three P sources (KH 2 PO 4 , S-manure, LP-manure). Extractable P from manures of swine fed low-phytate corn and standard corn diets were compared with a soluble P (KH 2 PO 4 ) source. Slope ratio procedure was used to determine a phosphorus availability index (PAI). The effect of the P application rate on extractable Bray-1 P was linear (r 2 >0.97). Small but significant P mineralization was observed for the Verndale sandy loam soil. Mineralization of organic P was detected only at the highest LP-manure application rate for the Waukegan silt loam soil. Relative to KH 2 PO 4 , the LP-manure and S-manure had PAI of 0.55 and 0.61, respectively. Swine manure P availability was about 60% that of the KH 2 PO 4 source for both manure sources. The total P concentration for the LP-manure was 42% lower than that for the S-manure. The important factor in the difference between manure sources is the 42% lower total P content for the LP-manure, not a difference in availability. Further evaluation of available P from LP-manure is needed under field conditions.

Biotechnology: a solution for improving nutrient bioavailability.

Biotechnology strategies are now available to improve the amount and availability of nutrients in plant crops. Those strategies include simple plant selection for varieties with high nutrient density in the seeds, cross-breeding for incorporating a desired trait within a plant, and genetic engineering to manipulate the nutrient content of the plant. In plant cross-breeding, all genes of the parent plants are combined and the progeny have both desirable and undesirable traits. To eliminate undesirable traits, plant breeders "back-cross" the new plant varieties with other plants over several generations. This technique, called hybridization, has been used to create varieties of low-phytate corn, barley, and rice. Using the techniques of genetic engineering, the gene(s) encoding for a desired trait(s) in a plant are introduced in a precise and controlled manner within a relatively short period of time. Golden rice, containing carotenoids, and rice with higher amounts of iron, are two examples of genetically engineered plants for improved nutrition. Genetic engineering has tremendous potential for revolutionizing nutrition. However, public concerns regarding safety, appearance, and ethics must be overcome before these products can be effectively introduced into the food supply.

NUTRIENTS IN RUNOFF FOLLOWING THE APPLICATION OF SWINE MANURE TO INTERRILL AREAS

The P content of swine manure can be reduced through the addition of feed supplements or the use of selected corn hybrids. This study was conducted to compare interrill runoff losses of P and N from three soils following the application of swine manure obtained from selected diets. The soils used in this investigation included a Hersh sandy loam, Pierre silty clay, and Sharpsburg silt loam. Simulated rainfall was applied during both initial and wet runs to a soil pan on which swine manure produced from low phytate corn (LPC), phytase added to the diet (PHY), or a traditional corn diet (TCD) was added. Additional experimental treatments included inorganic fertilizer and an untreated check. For the initial rainfall simulation run, concentrations of dissolved P, bioavailable P, and Total P were greater for the fertilizer treatment than any of the manure treatments. Use of manure from a LPC diet generally did not result in a reduction in N and P concentrations in runoff when compared with the TCD. Concentrations and total amounts of nutrients transported in runoff were affected by soil type. Changing the TCD to LPC and PHY diets to reduce the P content of manure did not significantly affect the total amounts of DP, BAP, or Total P transported in runoff, when simulated rainfall was applied soon after manure application.

Comparison of yellow dent and nutridense corn hybrids for nursery pig diets

A total of 315 nursery pigs (initially 33.5 lb) were used in a 21-d growth assay to compare relative energy values of ‘Nutridense’ and ‘Nutridense Low Phytate’ corn compared to Yellow Dent corn. Dietary treatments consisted of a 3 × 3 factorial with three sources of corn with 0, 3, or 6% added fat. Increasing the energy density of the diet with added fat or higher energy corn varieties (Nutridense or Nutridense-LP corn) linearly improved feed efficiency. The linear improvement in feed efficiency allowed us to calculate the energy content of the Nutridense corn varieties relative to Yellow Dent corn. We determined that the ME values published by the University of Illinois indicating that Nutridense and Nutridense Low Phytate corn contain approximately 6.5 and 4% more energy, respectively, than normal Yellow Dent corn are appropriate for diet formulation.

Effects of low phytic acid corn on phosphorus utilization, performance, and bone mineralization in broiler chicks

In vivo and in vitro experiments were conducted to determine whether P in a low-phytate corn (LPC) containing the lpa 1-1 allele is more available than P in a near-isogenic wild-type corn hybrid (NC). The LPC was analyzed to contain 0.18% nonphytate P and 0.26% total P (TP), whereas NC contained 0.05% nonphytate P and 0.25% TP. For these studies, nonphytate P was considered to be available P (AP). In the in vivo study, 150 1-d-old male chicks were randomly assigned to five treatments (six pens of five chicks each) for 21 d. The dietary treatments included: A) a diet containing 60% NC, 0.2% AP, and 0.8% Ca; B) a diet containing 60% LPC, 0.28% AP, and 0.8% Ca; C) an NC diet similar to Diet A, but with KH2PO4 added to increase the AP to 0.28% to match the AP in Diet B; D) an LPC diet containing 0.45% AP and 1% Ca; and E) an NC diet supplemented with KH2PO4 to provide 0.45% AP and 1% Ca. Diets A, B, and C were semipurified diets, with corn being the sole source of phytate. The only differences between Diets A and B were the source of corn and the amount of AP present in the diets. The levels of AP in these diets were deficient in order to measure the animal response to the different levels of AP. Diets D and E were typical corn-soybean meal diets, and were formulated to contain an optimal level of AP. Performance and bone ash were similar (P > 0.05) in chicks fed Diets B and C and in chicks fed Diets D and E. Chicks fed LPC diets (B and D) retained more P (P < 0.05) than chicks fed NC diets (C and E). Chicks fed Diet B had significantly higher (P < 0.05) Ca retention compared with chicks fed Diet A. An in vitro digestion procedure that simulated the physiological conditions of the gastrointestinal tract of broilers was used to determine P release from LPC and NC. Results showed that 65% (1,420 mg/kg) of the TP in LPC was released, compared with 23% (543 mg/kg) from NC. Results of these experiments indicate that the P in LPC is more available than the P in NC, and reducing the phytate content did not compromise the nutritional value of LPC. The increased P retention in chicks fed LPC suggests that substituting LPC for NC leads to a reduction in manure P. Also, the in vitro procedure accurately predicted differences in in vivo P availability between the two corns.