Phosphorus

Standardized total tract digestibility of phosphorus in three different sources of field peas (Pisum sativum L.) with different particle sizes fed to weanling pigs

Field peas have been produced mainly for human consumption, but lastly, the industry has been included in diets fed to livestock due to its content of starch and protein. In diets for swine, only peas that are harvested at maturity are used. Almost 80% of P in non-oilseed legumes is bound to phytate, and pigs do not synthesize an adequate amount of endogenous phytate to liberate the P bound to phytate. Therefore, the digestibility of P in field peas is relatively low. Values for apparent total tract digestibility (ATTD) and standardized total tract digestibility (STTD) of P in field peas have been reported, but there are no comparative values for the ATTD and STTD of P among different varieties of field peas at different particle sizes. Therefore, the objective of this experiment was to test the hypothesis that there are no differences in the ATTD and the STTD of P among different sources of field peas fed to young pigs and the second hypothesis was that there is a linear increase in the ATTD and STTD of P as the particle size of field peas increases.

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Apparent ileal digestibility of amino acids by pigs is not affected by increasing dietary calcium from deficient to excess concentrations, but phosphorus digestibility is reduced

Lee, Su A, H. H. Stein. 2022. Apparent ileal digestibility of amino acids by pigs is not affected by increasing dietary calcium from deficient to excess concentrations, but phosphorus digestibility is reduced. Animal Feed Science and Technology 292 (2022) 115436. Link to full text.
 

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Vitamin D and vitamin D metabolites impact on calcium and phosphorus balance in gestating sows

Lee, S. A, and H. H. Stein. 2022. Vitamin D and vitamin D metabolites impact on calcium and phosphorus balance in gestating sows. Proc. 21th Annual Midwest Swine Nutrition Conf. Danville, IN, Sep. 8, 2022. Pages 39-43. Link to full text.

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Effect of microbial phytase on digestibility of phosphorus in seven sources of sunflower meal fed to growing pigs

The majority of P in oilseed co-products is bound to phytate; however, pigs do not synthesize adequate amount of endogenous phytate to liberate the P bound to phytate and the digestibility of P in sunflower meal, therefore is low. Values for ATTD and STTD of P in sunflower meal (SFM) without and with phytase have been reported, but there are no comparative values for the ATTD and STTD of P in sunflower co-products produced in different parts of the world. Therefore, the objective of this experiment was to determine the ATTD and the STTD of P in different sources of sunflower co-products, and to test the hypothesis that regardless of source, microbial phytase increases the digestibility of P in sunflower co-products fed to young pigs.

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Calcium and phosphorus in late-gestation

Lee, S. A., and H. H. Stein. 2022. Calcium and phosphorus in late-gestation. National Hog Farmer, On-line edition, July 14, 2022. Link to full text. 

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Apparent ileal digestibility of amino acids is not likely affected by increasing calcium from deficient to over sufficient concentration in diets fed to pigs

There are several factors related to dietary Ca that may influence digestibility of amino acids (AA). By chelating to dietary phytate, dietary Ca can form non-digestible Ca-phytate complexes, and this may result in reductions of P and AA digestibility. However, adding Ca to diets may increase activation of proteases as co-factors, which could result in increased AA digestibility. In contrast, pH in the digesta may be increased by adding Ca to diets, which likely will have a negative effect on activation of protein digesting enzymes. However, to our knowledge, no data demonstrating effects of increasing dietary Ca on digestibility of AA in pigs have been reported. Therefore, the objective of this experiment was to test the hypothesis that the concentration of Ca in diets affects apparent ileal digestibility (AID) of AA by pigs.

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Effects of dietary levels of calcium, phosphorus, and 1-alphahydroxycholecalciferol on digestibility, retention of calcium and phosphorus, and concentration of metabolizable energy in diets fed to sows in late-gestation

Lee, Su A., and Hans H. Stein. 2022. Effects of dietary levels of calcium, phosphorus, and 1-alphahydroxycholecalciferol on digestibility, retention of calcium and phosphorus, and concentration of  metabolizable energy in diets fed to sows in late-gestation. Can. J. Anim. Sci. 102: 184–188 (2022) dx.doi.org/10.1139/cjas-2021-0018. Link to full text.

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Effects of 25-hydroxycholecalciferol (25-OH-D3)and 1-alpha-hydroxycholecalciferol (1-α-OH-D3) on serum bone biomarkers and calcium and phosphorus balance and concentrations on energy in diets without or with microbial phytase fed to sows in late gestation

Absorption of Ca and P by active transport in the small intestine is regulated by calcitriol, which is the active form of vitamin D (1,25-dihydroxycholecalciferol) and the hormones calcitonin and PTH. One-alpha-hydroxycholecalciferol (1-α-OH-D3) and 25-hydroxycholecalciferol (25-OH-D3) are vitamin D metabolites that may be added to diets for pigs. Because 1-α-OH-D3 is already hydroxylated at the 1-position, only the first hydroxylation in the liver at the 25-position is needed to convert the metabolite to calcitriol. Likewise, because the 25-OH-D3 is already hydroxylated at the 25-position, only the second hydroxylation in the kidney at the 1-position is needed if this metabolite is used. It is possible that supplementation of diets with 25-OH-D3 or 1-α-OH-D3 increases absorption and retention of Ca and P by increasing the conversion efficiency to calcitriol compared with the conversion of cholecalciferol to calcitriol. It is possible that the effects on Ca and P balance differ between 25-OH-D3 and 1-α-OH-D, but research to test this hypothesis has not been reported.

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Reduced dietary Ca and P did not affect gastric pH or fecal score, but reduced growth performance and bone ash, whereas increased microbial phytase increased plasma inositol, and feed efficiency of weanling pigs

Lagos, L. V., and H. H. Stein. 2021. Reduced dietary Ca and P did not affect gastric pH or fecal score, but reduced growth performance and bone ash, whereas increased microbial phytase increased plasma inositol, and feed efficiency of weanling pigs. National Hog Farmer, On-line edition, September, 2021. Link to full text.

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Calcium and phosphorus in late gestation.

Lee, Su A, and H. H. Stein. 2022. Calcium and phosphorus in late gestation. National Hog Farmer, On-line edition, January, 2022. Link to full text.

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Increased microbial phytase increased phytate destruction, plasma inositol, and feed efficiency of weanling pigs, but reduced dietary calcium and phosphorus did not affect gastric pH or fecal score and reduced growth performance and bone ash

Lagos, L. Vanessa, Mike R. Bedford, and Hans H. Stein. 2021. Increased microbial phytase increased phytate destruction, plasma inositol, and feed efficiency of weanling pigs, but reduced dietary calcium and phosphorus did not affect gastric pH or fecal score and reduced growth performance and bone ash. J. Anim. Sci. 99: 12, 1-13. doi.org/10.1093/jas/skab333.

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Effects of increasing phytase dose on total tract digestibility of minerals and energy in pigs

In most plant feed ingredients, the majority of P is bound to phytate, which reduces digestibility of P in pigs, and therefore, the concentration of digestible P in these ingredients is relatively low. Phytate is negatively charged in the intestinal tract and can bind both endogenous and dietary nutrients, which results in precipitation of non-digestible nutrient-phytate complexes. Therefore, it is possible that the use of exogenous phytase can also increase the digestibility of other nutrients than P. As an example, addition of exogenous phytase to diets also releases Ca from phytate, and thus, increases the digestibility of Ca. However, it has not been conclusively demonstrated that phytase also increases the digestibility of energy-generating nutrients and other minerals in diets fed to pigs and inconsistent results among experiments have been reported. Therefore, the objective of this experiment was to test the hypothesis that increasing phytase dose increases the apparent total tract digestibility (ATTD) of minerals and gross energy (GE) in corn and soybean meal-based diets fed to growing pigs.

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Comparative digestibility and retention of calcium and phosphorus in normal- and high-phytate diets fed to gestating sows and growing pigs

Lee, S. A., M. R. Bedford, H. H. Stein. 2021. Comparative digestibility and retention of calcium and phosphorus in normal- and high-phytate diets fed to gestating sows and growing pigs. Animal Feed Science and Technology 280 (2021) 115084. doi.org/10.1016/j.anifeedsci.2021.115084. Link to full text.

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Ca and P digestibility values aren’t accurate for formulating sow diets

Lee, Su A and H. H. Stein. 2021. Ca and P digestibility values aren’t accurate for formulating sow diets. Pork Magazine, On-line edition, Sep. 9, 2021. Link to full text.

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Analyzed values for P and phytate in feed ingredients

Phytic acid is the main storage of P in plants, and most P in plant feed ingredients is bound in the phytate complex. Because pigs do not secrete phytase, an enzyme to hydrolyze inositol bonds in phytate, the utilization of P by pigs is very low. Addition of supplemental phytase to diets thus results in release of P and increases P utilization by pigs. However, all enzymes have a special recognition mechanism called specificity that works only with molecules that fit to active sites of the enzyme. Therefore, it is important to know how much of P is phytate-bound and how much of the P in a given diet is not phytate-bound.

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Quantities of ash, Ca, and P in metacarpals, metatarsals, and tibia are better correlated with total body bone ash in growing pigs than ash, Ca, and P in other bones

Lee, Su A, L. Vanessa Lagos, Mike R. Bedford, and Hans H. Stein. 2021. Quantities of ash, Ca, and P in metacarpals, metatarsals, and tibia are better correlated with total body bone ash in growing pigs than ash, Ca, and P in other bones. Journal of Animal Science, 2021, Vol. 99, No. 6, 1–6. doi:10.1093/jas/skab149.

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Formulation of diets for pigs based on a ratio between digestible calcium and digestible phosphorus results in reduced excretion of calcium in urine without affecting retention of calcium and phosphorus compared with formulation based on values for total

Lagos, L. Vanessa, Su A Lee, Mike R. Bedford, and Hans H. Stein. 2021. Formulation of diets for pigs based on a ratio between digestible calcium and digestible phosphorus results in reduced excretion of calcium in urine without affecting retention of calcium and phosphorus compared with formulation based on values for total calcium. Journal of Animal Science, 2021, Vol. 99, No. 5, 1–7. doi:10.1093/jas/skab138.

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Formulating diets based on digestible calcium instead of total calcium does not affect growth performance or carcass characteristics, but microbial phytase ameliorates bone resorption caused by low calcium in diets fed to pigs from 11 to 130 kg

Lagos, L. Vanessa, Su A Lee, Mike R. Bedford, and Hans H. Stein. 2021. Formulating diets based on digestible calcium instead of total calcium does not affect growth performance or carcass characteristics, but microbial phytase ameliorates bone resorption caused by low calcium in diets fed to pigs from 11 to 130 kg. Journal of Animal Science, 2021, Vol. 99, No. 3, 1–11. doi:10.1093/jas/skab057.

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Digestibility of P and concentrations of digestible and metabolizable energy in high-oil corn fed to growing pigs

Conventional breeding of corn has generated a new variety (i.e., high-oil corn; Byron Seeds LLC, Rockville, IN), which is believed to contain more oil and phosphorus than conventional corn. Because of the increased oil, it is possible that high-oil corn contains more digestible energy (DE) and metabolizable energy (ME) than conventional hybrids, but this hypothesis has not been experimentally verified. Inclusion of microbial phytase in diets for pigs usually improves digestibility of P because phytase hydrolyzes the ester bond that binds P to the phytate molecule in corn. However, there are at this point no data for effects of adding phytase to diets containing high-oil corn and no data to demonstrate the nutritional value of high-oil corn. Therefore, an experiment was conducted to test the hypothesis that the standardized total tract digestibility (STTD) of P, as well as concentrations of DE and ME in high-oil corn are greater than in conventional corn. The second hypothesis was that inclusion of microbial phytase to diets improves the STTD of P in corn sources.

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Effects of a novel E. coli phytase expressed in Pseudomonas fluorescens on growth, bone mineralization, and nutrient digestibility in pigs fed corn–soybean meal diets

Ren, Ping, Laia Blavi, Caroline González-Vega, Yanhong Liu, Deana Hancock, Mercedes Vazquez-Añón, Ferdinando N. Almeida, and Hans H. Stein. 2020. Effects of a novel E. coli phytase expressed in Pseudomonas fluorescens on growth, bone mineralization, and nutrient digestibility in pigs fed corn–soybean meal diets. Transl. Anim. Sci.

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