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Role of Phosphorus in Rumen Fermentation

Dr. Manish Kumawat1* and Dr. Maina Kumari2

1 PhD Scholar, Department of Animal Nutrition, NDRI, Karnal (Haryana) 2 PhD Scholar, Department of Veterinary and Animal Husbandry Extension Education, IVRI,

Izatnagar, Bareilly (Uttar Pradesh)

Corresponding Author

Manish Kumawat

Email: drmanish.nutrition@gmail.comm

Keywords

Phosphorous, Rumen, Fermentation

How to cite this article:

INTRODUCTION

hosphorus (P) was discovered by

Hennig Brand in 1669 through urine

distillation and it’s Greek meaning is

“bringer of light or light bearer”. P occurs

abundantly in nature (0.08- 0.12 % weight in

earth crust) both as in compound and elemental

form. The compound forms of P are available

as Organic compounds and Inorganic salts. The

inorganic P occurs as phosphate while organic

P occurs in plants as phytic acid, phospholipid,

nucleic acid etc. (Mcdowell and Sharpley,

2003).

P DYNAMICS IN RUMINANT ANIMALS

METABOLISM:

Metabolism of P in ruminants is complicated.

Reason for this complexity is that, a significant

amount of P is incorporated by the rumen

microbial population as a component of their

nucleic acids and phospholipids. Furthermore,

ruminants secrete a large amount of saliva

containing inorganic P into the rumen, more

than 100 litres per day. Therefore, ruminants

require phosphorus both for growth of tissue

and bone as well as for multiplication of

microorganisms within the rumen.

P

ABSTRACT

Phosphorus is one of the most important minerals in animal nutrition. It is the second most

abundant element in an animal body after calcium, with 80% of phosphorus found in the

bones and teeth, and the remainder located in the body fluids and soft tissue. Phosphorus

(P) is an essential element for animals as it takes part in structural functions and in

metabolism. In ruminants, P is also used by ruminal bacteria, which needs for the

fermentation, more than the double of the required P for maintenance. The conclusion is

that the levels of P found in the rumeno-reticulum are generally adequate for optimal

microbial activity even with highly P-deficient diets.

OPEN ACCESS

Kumawat, M. and Kumari, M. 2021. Role of Phosphorous in Rumen Fermentation. Vigyan Varta

2(1): 77-80.

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Ruminants are unique because of this ability to

recycle phosphorus to the early part of the

gastrointestinal tract through both saliva and

blood. Since the pH in the rumen is within the

buffering range of phosphates, they serve as

buffering agents for volatile fatty acids

produced in the rumen, although the phosphate

contribution to ruminal buffering relative to

carbonates appears very low (Counotte et. al.,

1979).

P IN SALIVA:

In ruminants the salivary glands are the major

site for endogenous inorganic phosphorus (Pi)

secretion into the gastrointestinal tract (GIT).

The P concentration in cattle saliva is 370-720

mg/L (Clark et al., 1953). Salivary Pi has 2

major functions:

1. Acts as a buffer in the rumen,

2. Provides adequate P for rumen microbes

(Cohen, 1980).

Salivary secretions of P constitute about 80% of

the endogenous P recycled to the

gastrointestinal tract (the balance is mainly

from bile), depending on dry matter intake

(DMI), usually combined with P intake and the

fibre content of the diet (Care, 1994). The daily

secretion rate between 5 and 10 g Pi in sheep

and between 30 and 60 g Pi in cows. It is

achieved by both the high salivary flow-rate

and the ability of the salivary glands to

concentrate Pi 3-8 folds in comparison with

plasma Pi. Therefore, the salivary glands have

an important role in homeostasis of P.

Block diagram illustrating the difference

between apparent and true digestions of feed

AVAILABILITY

The availability of P may be defined as the

proportion of the dietary P which may be

absorbed by the animal when it is absorbing P

at a maximal rate. Phosphorus availability is

based on the chemical form of P in the feed and

various animal factors such as age, stage of

production, and overall level of nutrition. For

ruminants, the NRC (1996) estimates P

availability to be 68%. Most livestock diets are

derived from plant-based feedstuffs. These

types of feeds contain the organic form of P

known as phytate (Tillman and Brethour,

1958).

Two factors are peculiar to ruminant animals:

1. Ruminal phytase liberates one type of

bound phosphorus-phytin phosphorus.

This complex appears in many plants and

the bound phosphorus has very low

availability for nonruminants.

2. Pancreatic ribonuclease, which is secreted

into the small intestine of ruminant

animals in large amounts, releases the

phosphorus present in nucleic acids

reaching the small intestine for absorption

and recycling to the rumen. In this manner,

phosphorus used by ruminal microbes is

well recovered.

Phosphorus availability for the animal could

theoretically differ from availability in the

rumen. The term, ruminal phosphorus

availability reflects the concentration of

phosphorus in the rumen derived from

solubilized or degraded feed ingredients as well

as from recycling to the rumen of endogenous

phosphorus through saliva and by diffusion

through the ruminal wall.

ABSORPTION:

Inorganic P sources which are water soluble are

available for absorption in ruminant, while the

solubility of P in organic compound depends

upon the ability of the animal to convert organic

into inorganic form or more acceptable organic

form (Underwood and Suttle, 1999). In rumen,

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microbes secrete phytase enzymes which

hydrolysed the phytate P and released inorganic

P. The organic P which is not hydrolysed in

rumen becomes soluble in low pH of

abomasum.

Generally, absorption of ingested P depends

upon its solubility at the point of contact with

the absorbing membranes. It is primarily

absorbed in the small intestine mainly in

duodenum and jejunum, but the relationship

between P intake and P absorption is still

inconclusive whether it is inverse relationship

or curvilinear. Furthermore, only a small

amount of P is absorbed from rumen, omasum

and abomasum which still need to be

researched thoroughly.

P LEVEL IN BLOOD:

Whole blood contains 350-450 mg/L P and

most of which present in the cells. The element

occurs in variety of forms (inorganic and

organic P), mostly organic form is found. The

inorganic form of P ranges from 4 to 8 mg/dL

(about 10% is bound to serum protein and 50-

60 % in ionized form) for dairy cattle with

slightly higher value for young animals. The

intercellular P concentration in cattle is about

78 mg/dL and whole blood contains 6-8 time

more P than plasma as higher concentration of

P is present in erythrocytes (NRC, 2001).

EXCRETION:

The excess of inorganic phosphate formed in

the process of the exchange or liberated during

resorption of bone tissue is excreted from the

body via the kidney. In adult ruminant almost

all P excretion occur through faeces (Betteridge

et al., 1986). Recently, Alvarez-Fuentes et al.,

(2016) reported that on average, lactating dairy

cows excreted 58% of ingested P in faeces and

0.44% in urine, and secreted 40% in milk.

Whereas, at constant P intake, cows with higher

milk production excreted less P than cows with

lower milk production

P IN RUMEN AND RUMEN MICROBES

Rumen microbes have a P requirement

apart from the animal's requirement which

must be met for optimum rumen microbial

activities to occur (Powell et al., 2002).

Rumen microbes obtain P from the P

released during fermentation of feed in the

rumen and from salivary secretions.

The concentration of P in the rumen

contents was reported to be 200-600 mg/L

and in this context Durand and Kawashima

(1980) suggested the maximum P

requirement for ruminal microbes is

satisfied when the diet contains 4 g P/Kg

digestible organic matter. This is

equivalent to <0.30% dietary P.

Rumen microbes concentrate P mainly in

organic form as nucleotides

(Komisarczuk, 1985). Rumen microbes

appear to be an intermediary source of P

for the host animal.

It was observed that rumen microbes had

higher P requirement than host animal,

therefore, care should be taken to meet the

microbe’s P requirement.

If a feed is low in its P content, then

salivary P secretion also get lowered which

ultimately affect the performance of

microorganism in the rumen. However,

maximum microbial degradative and

synthetic activities can be maintained if

ruminal inorganic P levels are at least 75-

100 mg/L (Komisarczuk et al., 1987).

Moreover, when cattle were fed 0.12 %

dietary P, ruminal fluid concentration was

over 200 mg P/L, considerably greater

than the 20 to 80 mg of P/L needed for

maximum cellulose digestion under in

vitro conditions. This concentration of P in

rumen is achieved usually in cattle by

salivary recycling of P and from diets

adequate to meet the animal’s requirement.

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The general conclusion is that the levels of

P found in the rumeno-reticulum are

generally adequate for optimal microbial

activity even with highly P-deficient diets.

REFERENCES:

Alvarez-Fuentes, G., Appuhamy, J.A.D.R.N.

and Kebreab, E. 2016. Prediction of

phosphorus output in manure and milk

by lactating dairy cows. J. Dairy Sci.

99:771–782.

Betteridge, K. and Andrewes, W. 1986. Intake

and excretion of nitrogen, potassium

and phosphorus by grazing steers. J.

Agric. Sci. (Camb.) 106, 393-404.

Care, A. D. 1994. The absorption of phosphate

from the digestive tract of ruminant

animals. Br. vet. J. 150:197-205.

Chicco, C. F., Ammerman, C. B., Moore, J. E.,

Walleghem. P. A., Arrington, L. R. and

Shirley, R. L. 1965. Utilization of

inorganic ortho-, meta- and

pyrophosphates by lambs and by

cellulolytic rumen microorganisms in

vitro. J. Ani. Sci. 24: 355-363.

Clark, R. 1953. A study of the water-soluble

phosphate concentration of the ruminal

contents in normal and phosphorus

de®cient animals. Onderstepoort J.

Vet. Res. 26: 137-140.

Counotte, G.H.M. 1981. Regulation of lactate

metabolism in the rumen. PhD Thesis.

Utrecht University.

Komisarczuk, S., Durand, M., Beaumatinp, H.

and Hannequart, G. 1987. Effects of

phosphorus deficiency on rumen micro

bial activity associated with the solid

and liquid phase of a fermentor

(Rusitec). Reprod. Nutr. Dev. 27: 907-

919.

McDowell, R.W. and Sharpley, A.N. 2003.

Phosphorus solubility and release

kinetics as a function of soil test P

concentration. Geoderma. 112 (1):

143–154.

Powell, J. M., Jackson-Smith, D. B. and Satter,

L. D. 2002. Phosphorus feeding and

manure nutrient recycling on

Wisconsin dairy farms. Nutr. Cycl.

Agroecosyst. 62, 277–286.

NRC. 1996. Nutrient requirements of beef

cattle. 7th ed. Natl. Academy Press,

Washington, DC.

Tillman, A. D. and Brethour, J. R. 1958.

Dicalcium phosphate and phosphoric

acid as phosphorus sources for beef

cattle. J. Anim. Sci., 17: 100–103.

Underwood, E. J. and Suttle, N. F. 1999. The

mineral nutrition of livestock, 3rd

Edition, CABI Publishing,

Wallingford, Oxon, UK.