Dietary Phosphorus Availability Research Articles

Dietary Phytase and Lactic Acid-Treated CerealGrains Differently Affected Calcium and PhosphorusHomeostasis from Intestinal Uptake to SystemicMetabolism in a Pig Model.

High intestinal availability of dietary phosphorus (P) may impair calcium (Ca) homeostasis and bone integrity. In the present study, we investigated the effect of phytase supplementation in comparison to the soaking of cereal grains in 2.5% lactic acid (LA) on intestinal Ca and P absorption; intestinal, renal, and bone gene expression regarding Ca and P homeostasis; bone parameters; and serum levels of regulatory hormones in growing pigs. Thirty-two pigs were randomly assigned to one of four diets in a 2 × 2 factorial design in four replicate batches for 19 days. The diets comprised either untreated or LA-treated wheat and maize without and with phytase supplementation (500 phytase units/kg). Although both treatments improved the P balance, phytase and LA-treated cereals differently modulated gene expression related to intestinal absorption, and renal and bone metabolism of Ca and P, thereby altering homeostatic regulatory mechanisms as indicated by serum Ca, P, vitamin D, and fibroblast growth factor 23 levels. Moreover, phytase increased the gene expression related to reabsorption of Ca in the kidney, whereas LA-treated cereals decreased the expression of genes for osteoclastogenesis in bones, indicating an unbalanced systemic availability of minerals. In conclusion, high intestinal availability of dietary P may impair Ca homeostasis and bone integrity.

Phosphorus availability in the source population influences response to dietary phosphorus quantity in a New Zealand freshwater snail.

We investigated whether previously documented variation among populations in availability of dietary phosphorus (P) is linked to heterogeneity in growth rate of the New Zealand freshwater snail Potamopyrgus antipodarum on a P-limited diet. We chose this system because P. antipodarum inhabits water bodies that vary in P availability and because P. antipodarum growth rate varies considerably in response to low P. We quantified specific growth rate and alkaline phosphatase (AP) expression in a diverse array of juvenile P. antipodarum fed high vs. low-P diets. We found strong associations between P content of epilithon in the source lake and P. antipodarum growth rate on high vs. low-P diets, with snails collected from lakes with relatively low-P epilithon showing the greatest increase in growth rate on the high-P relative to low-P diet. We also found substantial intraspecific variation in growth response to P limitation. Expression of AP also varied among lineages and was negatively associated with C: P of lake epilithon but did not explain the relationship between C: P in the lake of origin and sensitivity to P limitation. Together, our results demonstrate a strong signature of the P environment in the lake of origin on how this snail responds to P limitation as well as preliminary evidence for intraspecific variation of AP expression in animals.

Use of phytases in fish and shrimp feeds: a review

AbstractPhytases have been employed in animal feeds for several years, used primarily for reducing the environmental impact and phosphorus loads of farm effluents. Beneficial effect of dietary phytase has been associated with the limited ability of monogastric animals to utilize dietary plant phytates. To date, numerous studies have shown the positive effect of phytase supplementation on the availability of dietary phosphorus and trace minerals within plant‐based feeds for monogastric farm animals, including farmed fish and shrimp. Individual feed ingredients may also be improved with phytases as an exogenous treatment, also termed pre‐conditioning dephytinization prior to mixing. This review presents data on the potential benefit of phytase application for fish and shrimp species in improving digestibility of phosphorus and other minerals as well as organics nutrient fractions such as protein, amino acids and lipids.

The availability of dietary phosphorus to long yearlings and mature horses

Changes to agri-environmental policy, with an emphasis on encouraging more environmentally friendly farming practices, have been paralleled in the last two decades by a body of research into agri-environment scheme adoption. To date much of this research has considered conservation behaviour as a static issue across whole farms, and viewed participation decisions as solely a present-day issue. Based on an in-depth case study from the Peak District (UK) this paper considers the case of hay meadows—an important cultural, ecological and agricultural feature of the landscape which has been seriously threatened by changing farm practices during the last century, and which now features as a conservation option in the main agri-environment schemes. Drawing on material from semi-structured interviews on 62 farms, and participant observation on 20 farms, the paper discusses how hay meadows represent a unique case for conservation and considers the limitations of existing conceptualisations of scheme adoption for understanding hay meadow conservation. In particular, the paper examines how current conservation decisions are constrained by, and intersect with, past managements that affect the “eligibility” of meadows for scheme adoption. A model is developed which places meadow types of different eligibility against conservation styles to illustrate how different conservation scenarios are created.

How dietary phosphorus availability during development influences condition and life history traits of the cricket, Acheta domesticas.

Phosphorus is extremely limited in the environment, often being 10–20 times lower in plants than what invertebrate herbivores require. This mismatch between resource availability and resource need can profoundly influence herbivore life history traits and fitness. This study investigated how dietary phosphorus availability influenced invertebrate growth, development time, consumption, condition, and lifespan using juvenile European house crickets, Acheta domesticus L. (Orthoptera: Gryllidae). Crickets reared on high phosphorus diets ate more food, gained more weight, were in better condition at maturity, and contained more phosphorus, nitrogen, and carbon in their bodies at death than crickets reared on low phosphorus diets. There was also a trend for crickets reared on high phosphorus diets to become larger adults (interaction with weight prior to the start of the experiment). These findings can be added to the small but growing number of studies that reveal the importance of phosphorus to insect life history traits. Future research should explore the importance of dietary phosphorus availability relative to protein, lipid, and carbohydrate availability.

Dietary phosphorus availability influences female cricket lifetime reproductive effort

1. Recent ecological stoichiometric findings indicate that the relationships among key macronutrient elements [e.g. carbon (C), nitrogen (N), and phosphorus (P) of organisms and their resources] may underlie variation in life‐history traits. The amount of phosphorus in an individual's body is often correlated with its rate of growth, and low‐phosphorus diets are known to reduce growth in a number of insect and crustacean herbivores.2. These findings suggest that the stoichiometric imbalance between organismal biomass requirements and the relative scarcity of nutrients in nature may also underlie variation in lifetime reproductive success.3. This study investigated how dietary phosphorus availability during adulthood influenced lifetime reproductive effort, compensatory feeding, lifespan, condition, and stoichiometry of adult European House Cricket, Acheta domesticus.4. Female crickets fed high amounts of phosphorus during adulthood laid significantly more eggs compared to those fed low amounts of phosphorus. Phosphorus availability did not directly influence lifespan, condition, or body stoichiometry, and crickets did not compensate for low phosphorus diets by eating more food.5. A stoichiometric perspective may help understand the causes of variation in invertebrate fitness.

Phosphorus availability influences cricket mate attraction displays

Adopting a stoichiometric perspective (e.g. the balance of carbon, nitrogen and phosphorus in organisms and their resources) has enhanced our understanding of ecological phenomena at a variety of hierarchical levels of organization. Unfortunately, little is presently known about how stoichiometry directly influences animal behaviour. Here we use a stoichiometric perspective to investigate how phosphorus availability in the environment influences mate attraction behaviour in insects. Using adult male European house crickets (Acheta domesticus), we manipulated the availability of dietary phosphorus and we quantified how survival, propensity to signal acoustically or not (‘signallers’ versus nonsignalling ‘silent’ males) and lifetime mate attraction signalling were affected. Dietary phosphorus availability did not influence the proportion of signallers versus silent males. However, signallers fed a diet rich in phosphorus had significantly higher signalling efforts than those that consumed a phosphorus-poor diet. Interestingly, signallers also lived longer than silent males, but neither signaller nor silent male survival was influenced by diet. Our findings suggest that the availability of dietary phosphorus has the potential to impact mating system evolution.

Role of Dietary Phosphorus and Degree of Uremia in the Development of Renal Bone Disease in Rats

The remnant kidney rat model has been extensively used for the evaluation of bone changes due to uremia. The present study aimed to assess the effect of the dietary phosphorus availability and of the severity of renal failure on bone histomorphometric changes and various biochemical markers over time in this model. Chronic renal failure (CRF) was induced in male Wistar rats by 5/6th nephrectomy. Half of the number of animals received a standard rat diet (STD) (0.67% P, containing low bioavailable phosphorus of plant origin); the other animals were fed a high phosphorus diet (HPD) (0.93% P, containing inorganic phosphorus with high bioavailability). Every two weeks, blood and urine samples were collected. At sacrifice after 6 or 12 weeks, bone samples were taken for the measurement of histological and histodynamic parameters. Serum creatinine measurements indicated the development of mild to moderate renal failure in both diet groups. Phosphaturia was unexpectedly low in all animals that received the STD, indicating relative phosphorus depletion despite the normal dietary phosphorus content. In the HPD CRF group, a decrease in calcemia and a rise in phosphatemia were seen after 12 weeks of CRF, which were more pronounced in animals with higher serum creatinine. Serum iPTH levels were distinctly increased in CRF rats fed a HPD, especially those with more pronounced renal failure. Serum osteocalcin and to a lesser extend tartrate-resistant acid phosphatase and urinary pyridinoline and deoxypyridinoline crosslinks were higher in the CRF animals compared to the shams, particularly in the animals of the HPD group with more pronounced CRF. In both diet groups, the CRF animals had significantly higher amounts of osteoid compared to shams. Only the animals that received a HPD developed distinct histological signs of secondary hyperparathyroidism (sHPTH), that is, an increased bone formation rate, mineral apposition rate, osteoblast perimeter, and eroded perimeter. Again, this effect was most prominent in rats with more severe CRF. In conclusion, data of the present study indicate that in experimental studies using the remnant kidney rat model, both the dietary phosphorus bioavailability and the degree of renal failure in the development of hyperparathyroidism should be considered.

Plasma phosphorus content and dietary phosphorus availability in adult sheep

This study was aimed at discriminating different quality phosphorus sources using plasma phosphorus kinetics in sheep. Four adult castrated Vendean sheep received successively two preliminary usual then low phosphorus diets (three weeks on 2.5 g P·kg -1 DM and three weeks on 1.5 g P·kg -1 DM), and then one of four compared diets (2.5 g P·kg -1 DM) in a Youden square design. The four compared diets included either dicalcium phosphate, calcium aluminium phosphate, stan- dard rapeseed meal or formaldehyde-treated rapeseed meal as the main phosphorus source. Inorganic plasma phosphorus was determined in samples taken from the jugular vein from the last week of the first preliminary phase to the last week of the test phase. The first preliminary diet stabilised the plasma phosphorus content (51.2 mg·L -1 , no day effect; no animal effect). The low phosphorus diet induced an initial rapid decrease in plasma phosphorus. After four days, plasma phosphorus in- creased probably resulting from an adjustment in phosphorus homeostasis. During the test phase, dicalcium phosphate and both rapeseed meals were more efficient than calcium aluminium phos- phate in restoring the initial plasma phosphorus levels. Both, rapeseed meal diets induced the highest plasma phosphorus concentration. The physiological significance of these results is discussed. availability / phosphorus / plasma / sheep

Potential for dietary phytase to improve the nutritive value of canola protein concentrate and decrease phosphorus output in rainbow trout ( Oncorhynchus mykiss) held in 11°C fresh water

This study assessed the potential for using dietary phytase to improve the nutritive value of canola protein concentrate (CPC) for rainbow trout, and to concomitantly minimize phosphorus discharge into the environment. Eight diets were prepared. LT-anchovy meal (AM) provided 89% of the protein in the basal diet, whereas in the remaining diets, 59% of the protein originated from CPC by replacement of AM protein. Four CPC diets were supplemented with phytase (Natuphos®) at levels of either 0, 500, 1500 or 4500 phytase units (FTU)/kg diet together with 4505 mg/kg phosphorus. Two CPC diets contained 1500 FTU/kg and either 0 or 2253 mg/kg of supplemental phosphorus. The seventh CPC diet contained no phytase or supplemental phosphorus. A commercial trout feed served as an industry control. All diets were fed to triplicate groups of rainbow trout (initial weight, 17.9 g) to satiation daily for 84 days. Mean water temperature was 11.0°C. The level of phytic acid degradation and the apparent availability of dietary phosphorus were ascertained for all groups. Fish fed the CPC diets, regardless of their phytase and phosphorus levels, exhibited growth rates, feed efficiencies and protein utilization comparable to those of control fish. There was, however, a clear positive dose-response of phytase on dietary phytate digestibility and phosphorus availability was improved significantly by the highest level of phytase. We conclude that dietary phytase has potential to improve the nutritive quality of CPC for rainbow trout and the availability of phytate phosphorus.

Effects on dietary phosphorus of treating cottonseed meal with crystalline ferrous sulphate for the prevention of brown yolk discolouration.

1. Two experiments were carried out to examine whether the adverse effects on laying hen performance of treating cottonseed meal (CSM) with crystalline ferrous sulphate heptahydrate (FSH) to prevent brown yolk discolouration, was a consequence of iron reducing the availability of dietary phosphorus. Two batches of CSM, with different free gossypol and cyclopropenoid fatty acid contents, were treated with FSH at a 4:1 weight ratio of iron to free gossypol, and incorporated into diets at 300 g/kg with or without supplementation with sodium dihydrogen phosphate (SHP), and fed to hens. 2. FSH treatment of CSM reduced food intake and egg production. Although performance was improved by supplementing the FSH-treated CSM diets with SHP, it was still poorer than that achieved by hens fed a non-CSM control diet. 3. Brown yolk discolouration was prevented by treatment of CSM with FSH. Additional phosphorus did not produce any significant effects on brown colour development in yolks, indicating that the bioavailable gossypol content of the diets had not been altered; however, chemical analyses showed an apparent increase in the free gossypol content of the diets with the inclusion of SHP, suggesting that the assay gives misleading results.

The availability to Tilapia nilotica of phosphorus in white fish meal.

The availability for Tilapia nilotica of phosphorus contained in white fish meal was determined by feeding fish meal diets containing different levels of phosphorus. The availability of dietary phosphorus was evaluated by the growth rate of fish, chemical analysee of the whole bodies and bones, gross appearance of the bones and apparent absorption of didtary phosphorws from the digestive tract. The results demonstrated that the availability for Tilapia of the phosphorus contained in the fis meal was around 65%, comparable to those in rainbow trout and chum salmon. thus the supplementation of the diets containing this fish meal with primary sodium phosphate resulted in no acceleration of the growth response of Tilapia. The requiement of phosphours for the maximum growth and the normal growth response of tilapia. The requirement of phosphorus for the maximum growth and the normal bone mineralization is postulated to be less than 0.9% in diet.