Phosphorus in Animals

White Phosphorus. No changes in urinary creatinine levels were observed in workers exposed to an unspecified amount of airborne white phosphorus (Hughes et al. 1962). Evidence of severe renal effects have been observed in humans orally exposed to white phosphorus and burned by white phosphorus. In animals, renal effects have been observed following oral and dermal burn exposure. There is no information on the potential of white phosphorus to induce renal effects in humans dermally exposed to white phosphorus or animals exposed by inhalation and dermal routes. 

Information on the toxicity of inhaled white phosphorus in animals is limited to a study that examined some parameters of systemic toxicity following intermediate-duration exposure. Information on death, acute, intermediate, and chronic systemic effects, neurological effects, reproductive effects, and developmental effects has been located. 

The accumulation of soil phosphorus associated with manure application from intensive animal operations ranks amongst the greatest threats to water quality in agricultural regions (Sims et al., 2000). Organic phosphorus can be a large proportion of the total phosphorus in animal manures (Barnett, 1994), and may play a key role in determining the impact of manure application on phosphorus transfer. In particular, there is considerable current interest in the role of manure-derived myo-inositol hexa-kisphosphate in the phosphorus transfer process (see below). 

Phytic acid (inisitol hexakisphosphate) is the main storage form of phosphorus in plants. The phosphorus is not bioavailable to non-ruminants as they lack the enzymes to break it down. Novozyme has developed a commercial enzyme, phytase, that can be added to animal feed to release the phosphorus. No inorganic phosphorus needs to be added. This shift in the source of phosphorous has a large impact on the environmental footprint of pig farming. 

Two types of OPIDN have been described in animals (Abou-Donia and Lapadula 1990). Type I is produced by compounds with a pentavalent phosphorus (like TOCP), and Type II is produced by compounds with a trivalent phosphorus. Characteristics used to differentiate between the types of OPIDN include species selectivity, age sensitivity, length of latent period, and morphology of neuropathologic lesions. Thus, at doses that did not produce death due to acetylcholinesterase inhibition, TOCP (a Type I compound) produced lesions in the spinal cord of rats without producing ataxia. In contrast, triphenyl phosphite (a Type II compound) produced delayed (1 week) ataxia in the rat and a distribution of spinal cord lesions distinct from those produced by TOCP (Abou-Donia and Lapadula 1990). 

It has also been demonstrated in animals that lead blocks the intestinal responses to vitamin D and its metabolites (Smith et al. 1981). Dietary concentrations of lead in combination with a low phosphorus or a low calcium diet administered to rats suppressed plasma levels of the vitamin D metabolite, 1,25-dihydroxycholecaliferol, while dietary intakes rich in calcium and phosphorus protected against this effect (Smith et al. 1981). Thus, animals fed a diet high in calcium or phosphorus appear to be less susceptible to the effects of lead, because of hindered tissue accumulation of lead. 

Susceptibility to lead toxicity is influenced by dietary levels of calcium, iron, phosphorus, vitamins A and D, dietary protein, and alcohol (Calabrese 1978). Low dietary ingestion of calcium or iron increased the predisposition to lead toxicity in animals (Barton et al. 1978a Carpenter 1982 Hashmi et al. 1989a Six and Goyer 1972 Waxman and Rabinowitz 1966). Iron deficiency combined with lead exposure acts synergistically to impair heme synthesis and cell metabolism (Waxman and Rabinowitz 1966). 

The availability of selenium to plants may be lessened by modem agricultural practices, eventually contributing to selenium deficiency in animal consumers. For example, fertilizers containing nitrogen, sulfur, and phosphorus all influence selenium uptake by plants through different... 

Effect of Varying Calcium and Phosphorus Content in Animal or Plant Protein-Based Diets... 

Although much attention has been directed toward the relationship between calcium intake and osteoporosis, little consideration has been given to the possible influence of dietary phosphorus on the development of this disease in either man or animals. In a study designed to determine the optimal concentration of calcium and phosphorus in the diet of adult mice, aging animals were found to undergo a greater loss of bone when the Ca/P ratio was 1 1 than... 

Meat and such high protein plant foods as soy are excellent sources of phosphorus as well as protein. The phosphorus in meat is readily absorbed from the gastrointestinal tract however, much of the phosphorus in plant products is in a bound form which may inhibit the absorption of calcium as well as phosphorus. This study was designed to determine the effect of different levels of calcium and phosphorus with plant protein or animal protein on bone breaking strength and calcium and phosphorus utilization of weanling mice. 

Table VI shows the effect of 0.75% dietary zinc on the phosphorus balance in young rats. A decrease in the apparent retention of phosphorus was noted in the zinc-fed rats as early as the end of the first week. Possibly a more significant observation was the apparent movement of phosphorus excretion from the urine, the normal pathway for phosphorus excretion, to the feces in rats fed the high zinc diet. Such a shifting of the phosphorus excretion to the fecal pathway in animals fed a high zinc diet should result in an increase...

Table VII shows the calcium balance of zinc-fed and non-zinc-fed rats supplemented with 0.8% calcium and/or phosphorus. Marked increases in fecal calcium and corresponding decreases in apparent calcium retentions in the zinc-fed rats could be reversed with calcium supplementation. Phosphorus supplements appeared to be associated with increases in calcium retention in the absence of zinc, but decreases in calcium retention in the presence of zinc without calcium supplementation. Decreases in fecal calcium were noted in animals fed calcium supplements in the presence of phosphorus or zinc. High levels of zinc were associated with increases in fecal calcium excretion in the absence of extra calcium or in the presence of extra phosphorus. Calcium supplementation was generally associated with a decrease in the urinary excretion of calcium, while zinc and phosphorus supplements were generally associated with an increase in urinary calcium excretion.

The data presented in this paper indicate that excess levels (0.75%) of dietary zinc result in decreases in the bioavailability of calcium and phosphorus in rats and interfere with normal bone mineralization. High dietary levels of calcium or zinc appeared to cause a shift in the excretion of phosphorus from the urine to the feces, while the presence of extra phosphorus tended to keep the pathway of phosphorus excretion via the urine. The presence of large amounts of phosphorus in the Intestinal tract due to high intakes of zinc would increase the possibility of the formation of insoluble phosphate salts with various cations, including calcium, which may be present. A shift in phosphorus excretion from the feces to the urine, however, could result in an environmental condition within the system which would tend to increase the bioavailability of cations to the animal. The adverse effect of zinc toxicity on calcium and phosphorus status of young rats could be alleviated with calcium and/or phosphorus supplements. 

Potassium, along with nitrogen and phosphorus, is an essential element needed for plant growth. In plants, it occurs mostly as K+ ion in cell juice. It is found in fruit or seed. Deficiency can cause curling leaves, yellow or brown coloration of leaves, weak stalk and diminished root growth. Potassium deficiency has been associated with several common animal ailments. Potassium is in extracellular fluid in animals at lower concentrations than sodium. 

Since plants and animals are able to concentrate phosphorus in their tissues, and since these tissues contain their own reducing agents, E. B. R. Prideaux does not consider it surprising that physicians and pharmacists of the seventeenth and eighteenth centuries first prepared this element from substances of vegetable and animal origm (36). 

Physiological Effects.—Phosphorus introduced into the etomaeh of animals acts as a cans tic poison. According to ORfila, the corrosion depends on the formation of phosphorous add, by the oxidation of phosphorus in the pulmonary canal, and the action of this acid upon the tissue with which it comes in contact. It is very rarely used in medicine, though it has been strongly recommended in oases attended with... 

In animals and in many bacteria, PEP is formed by decarboxylation of oxaloacetate. In this reaction, which is catalyzed by PEP carboxykinase (PEPCK), a molecule of GTP, ATP, or inosine triphosphate captures and phosphorylates the enolate anion generated by the decarboxylation (Eq. 13-46).252 The stereochemistry is such that C02 departs from the si face of the forming enol.253 The phospho group is transferred from GTP with inversion at the phosphorus atom 254 The enzyme requires a divalent metal ion, preferably Mn2+. 

PHOSPHORUS (In Biological Systems). Phosphorus is required by every living plant and animal cell. Deficiencies of available phosphorus in soils are a major cause of limited crop production, Phosphorus deficiency is probably the most critical mineral deficiency in grazing livestock. Phosphorus, as orthophosphate or as the phosphoric acid ester of organic compounds, has many functions in the animal body. As such, phosphorus is an essential dietary nutrient. 

---