Ruminants phosphorus

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. 

Phosphorus deficiencies are not common in humans and most other species, but they have been observed in ruminants, Symptoms of the deficiency are loss of appetite and a depraved appetite (termed pica )... 

Experimentation has indicated that, under normal dietary conditions and caldum intake, food phytate is of no nutritional concern in humans. The microbial population of the ruminant also elaborates a phytase enzyme that makes phytate phosphorus readily available in this class of animals. Phytates may be of nutritional consequence for another reason—dietary caldum can be bound in an unavailable, insoluble complex, thereby decreasing the absorption of this element... 

In most species the level of pancreatic ribonuclease is quite low. Its function presumably is the digestion of exogenous RNA in the diet. In ruminants there is very much more of the enzyme, and Barnard (12) has concluded that the primary purpose of pancreatic ribonuclease is digestion of the RNA of the bacteria in the rumen rather than of the dietary RNA. The reutilization of the nitrogen and phosphorus of this... 

Some potassium is secreted into the rumens of ruminants, but it is absorbed very quickly. In contrast to potassium, sodium and phosphorus are secreted into the rumen in very great amounts (Anke etal. 2001). 

Soil pH is one of the most important factors that affect the availability of Mo to plants. There are interactions between Mo and a number of nutrients, such as sulfur, nitrogen, phosphorus, and copper, that can affect its plant availability. Although large concentrations of Mo show no effects on crop yields of grains and forage crops, feeds containing Mo in excess of 10mgkg- when fed to ruminants, can produce severe Mo toxicity (Mo-induced copper deficiency). 

In the case of ruminants, the tables now include the digestible amino acids in the intestine, calculated according to the method published by Rulquin et a/. (1993 and 2001). In addition to updating the in sacco degradability values for nitrogen in the rumen and the intestine, we have indicated the kinetic parameters of in sacco degradation of dry matter and starch in the rumen. We have also included, when the data were available, the levels of absorbed phosphorus for ruminants. 

The tables present three types of nutritive values for phosphorus apparent faecal phosphorus digestibility for the pigs (with, in some cases, different values depending on the denatured or non-denatured state of the endogenous phytase), phosphorus availability for chickens and absorbed phosphorus for ruminants. 

Absorbed phosphorus (g/kg) Ruminal degradation Effective degradability a(%) b(%) c (%/h)... 

The following tables present for 12 mineral and trace elements the relative biological values (RBV) of the principal mineral sources (data compiled by EMFEMA). For each mineral, the first source indicated is the one used as a reference, except in the case of phosphorus where the references are different for ruminants and monogastrics. 

Essential nutrient elements snch as Cu, Fe and Mn can be successfully incorporated into slowly soluble phosphate glass pellets, and fed to ruminant animals (Section 12.9). The glass pellet stays lodged in the rumen for several months where it supplies the nutrient elements [12]. Phospholipids are incorporated in some formnlations to improve animal metabolism. Phosphorus compounds are sometimes added to commercial prodncts for anti-microbial action or to increase their stability. Grains and seeds generally contain more P than hays and grasses, but in the former case much is present as phytic acid salts which are not easily nutritionally available. In some cases appropriate enzymes can be added to rectify this. 

Phosphorus has more known fimctions than any other mineral element in the animal body. The close association of phosphorus with calcium in bone has already been mentioned. In addition, phosphorus occms in phosphoproteins, nucleic acids and phosphohpids.The element plays a vital role in energy metabolism in the formation of sugar-phosphates and adenosine di- and triphosphates (see Chapter 9). The importance of vitamin D in calcimn and phosphorus metabolism has already been discussed in Chapter 5. The phosphorus content of the animal body is considerably less than that of calcimn content. Whereas 99 per cent of the calcium found in the body occurs in the bones and teeth, the proportion of the phosphorus in these structures is about 80-85 per cent of the total the remainder is in the soft tissues and fluids, where it serves the essential fimctions mentioned above. The control of phosphorus metabolism is different from that of calcium. If it is in an available form, phosphorus is absorbed well even when there is an excess over requirement. The excess is excreted via the kidney or the gut (via sahva). In monogastric animals, the kidney is the primary route of excretion. Plasma phosphorus diffuses into saliva and in ruminants the large amount of chewing during rumination results in saliva being the major input of phosphorus into the rumen rather than the food. 

Nutrition has important effects on the environment as a consequence of the processes of digestion (methane and phosphorus) or a combination of digestion and metabolism (nitrogen). Methane is produced by the fermentation of foods in the gut by microbes, particularly in ruminants, and the decomposition of carbon compoimds in faeces stored as manure. Undigested phosphorus compoimds are excreted in the faeces. Undigested and waste products of the metabohsm of nitrogen compounds are excreted in the faeces and urine and the decomposition of these produces nitrous oxide (N2O). Ammonia in animal wastes is responsible for soil acidification and nutrient enrichment. 

The mineral requirements presented in Appendix 2 are based partly on factorial calculations and partly on feeding trials. For all species, the elements that are most likely to be deficient are calcium and phosphorus. Consequently, these have been subject to most investigation. In the case of ruminants, estimates of calcium and phosphorus requirements have changed markedly over the past 50 years as new information on endogenous losses and availability has become available. For example, the UK Agricultural Research Council in 1965 stated the phosphorus requirement of a 400 kg steer gaining 0.75 kg/day to be 26 g/day however, in 1980 this was revised to 18 g/day, and in 1991 it was revised again to 20 g/day. 

Many nutrient deficiencies influence fertility indirectly, through their effects on the general metabolism of the animal. For example, phosphorus deficiency in grazing ruminants, which has often been associated with poor fertihty, appears to affect reproduction because it restricts many metabolic processes, hence food intake and the general plane of nutrition. However, there is also some evidence that phosphorus deficiency has a direct effect on reproduction through suppressing oestrous cycles. 

The calcium content is low. The phosphorus content is moderate but has a reduced availability to non-ruminants, much of it being in the form of phytate phosphorus. 

Phytase is in this category of enzyme. It releases the orthophosphate groups from phytic acid, which is only partially broken down by non-ruminants and is the major form of phosphorus in cereal grains and oilseeds (see p. 115).This results in a greater availability of phosphorus to the animal, and the amount of inorganic phosphorus added to the diet can be reduced, with beneficial effects on the environment through reduced phosphorus excretion. 

Agboola, H.A., Cahill, V.R., Ockerman, H.W., Parrett, N.A., Plumpton, R.F. and Conrad, H.R. (1988) Cholesterol, hemoglobin, and mineral composition from non-ruminating Holstein bull calves as affected by a milk replacer diet in high phosphorus and alpha-tocopherol supplement. J. Dairy Sci. 71, 2264-2270. 

Presscakes for cattle feed. The high protein and fiber content (33% and 25%, respectively) should make the presscake useable for ruminant feed. Tomato seed meal contains about 10% moisture, 47% protein, 32% crude fiber and 15% other carbohydrates with an ash content of 5% which is rich in magnesium, calcium, potassium, and also contains sodium, phosphorus and iron. 

It is noteworthy that there is much evidence indicating that calcium-phosphorus ratios of 1 1 to 2 1 for nonruminants (hogs and horses) and 1 1 to 7 1 for ruminants are satisfactory but that ratios below 1 1 are often disastrous. 

Clark, J.H., K.C. Olson, T.B. Schmidt, M.L. Linville, D.O. Alkire, D.L. Meyer, G.K. Rentfrow, C.C. Carr, and E.P. Berg, 2007. Effects of dry matter intake restriction on diet digestion, energy partitioning, phosphorus retention, and ruminal fermentation by beef steers. J. Anim. Sei. 85, 3383-3390. 

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