Why Cow’s milk is Amrit ?
Cow milk has amino acids which makes its protein easily digestible and is good for kidney. Cow milk is a rich source of Vitamins like B2, B3, Vit A which help increasing immunity. Cow milk help in reducing acidity a common problem today and reduces chances of peptic ulcer. Cow milk help in reducing chances of colon, breast and skin cancer. Cow milk help reducing formation of serum cholesterol. Cow milk is one of the best natural anti-oxidants. Cow milk has Potassium which help in development of healthy mind. Cow milk not only help against diabetes but has good sugar for diabetic patients. Cow milk is an ideal food for people of all age groups. Cow milk is best for infant feeding after mothers milk. Low fat content helps one keep fit and to check obesity. Calcium and Phosphorus in Cow milk help in balanced absorption of nutrients and are good for healthy growth specially for children. COW’S MILK IN INFANT FEEDING There is general agreement that breast milk of the mother is the best food for infant, exclusive breast feed for the first 6 months without any additional feed of water is considered ideal for all newborns. However, changing social and cultural patterns in the last 4 decades have led to change from breast to formula feed specially among urban elites and working mothers. In the west, there is again a reversal of the phenomenon and more and more mothers are now preferring to breast feed their babies. There are some factors which influence a mother to start formula feed e.g. employed mother, fear of failure of nursing limitation of the activities and even loss of breast tone. All the above factors are not genuine reason to start formula feeds. However, in following situations breast milk may not be available or contraindicated or need to be supplemented and there is need to search for an ideal milk formula. Conditions where formula feed may be indicated 1. Death of the mother. 2. Serious illness in the mother e.g. HIV/AIDS, human T-cell lymphographic virus type 1 and type 2 and diseases like cancer, severe post partum psychosis. 3. Maternal ingestion of drugs e.g. anticancer, radioactive drugs in therapeutic doses and drugs of abuse. 4. As a supplement to breast milk, formula milk may be used in very low birth weight preterm babies. Comparison of Cow’s Milk and human milk Average values for the various constituents of human milk and the whole fresh cow’s milk are listed in table 1. Both differ during the various stages of lactation and among individuals. However, the differences in human milk from woman with adequate diets are insignificant. Colostrum The secretion of the breasts during the latter part of pregnancy and for the 2-4 days after delivery is called colostrums. This is deep lemon yellow coloured and about 10-40 ml is being secreted per day. Both cow and human colostrums contains very high protein and minerals but less carbohydrate and fat. In addition, human colostrums is rich in immunologic factors which prevent infection in the newborn babies. Colostrum, therefore, is essential for human nutrition and should not be discarded. Water and Calories The relative amounts of water and solids in human and cow’s milk are about the same. The energy value of each milk vary slightly and is approximately 20 Kcal/ounce or 0.67 Kcal/ml. Protein, Carbohydrate and fat Human milk contains only 1-1.5% protein compared to 3.3% in cow’s milk. The increased protein content of cow’s milk is largely due to 6 fold higher content of casein. On the other hand, human milk kprotein consists of approximately 65% whey proteins largely lactalbumins and 35% casein. Human milk contains 6.5-7% and cow’s milk contains 4.5% lactose. The fat contents of both milk are about 3.5%. In human milk, the fat content varies somewhat with material diet and during a single nursing. It is higher in latter part of the feeding (hind milk). The milks of different breeds of cattle vary in fat content. Most market milk specially in urban areas are now pooled and fat content adjusted to a standard level. The quality of fat varies in both human and cow’s milk. The more absorbable fat (Olein) is twice as much in human milk and volatile fatty acids are less in human milk (1.3%) compared to 9% in cow’s milk. Minerals Cow’s milk contains more minerals except iron copper, than human milk. The total mineral content of cow’s milk is 0.7-0.75% in contrast to human milk (0.15-0.25%). Cow’s milk iron content is low and poor bio-availability for infants. Although, the iron content of human milk is also low, the absorption is better. Although the need for calcium and phosphorus is great during period of rapid growth, adequate balances are maintained on breast milk despite its low content of these minerals. Vitamins Vitamin contents of each ;milk vary with the maternal intake. Cow’s milk is low in Vit. C and D. Cow’s milk contains more Vit. K than human milk. Both types of milk seem to contain adequate amounts of Vit.A and the B Complex to meet the nutritional requirements of young infants. Bacterial Content Human milk is essentially uncontaminated by bacteria and is therefore most suitable. Cow’s milk is regularly contaminated with harmful bacterial and is a very good culture media for various organisms. Therefore, terminal sterilization or boiling the milk before feeding is advisable. Digestibility The stomach empties more rapidly after human milk than after cow’s milk. However, no appreciable difference in gastrointestinal passage time exists between human milk and processed milk formulas during the first 45 days of life. The curd of cow’s milk is reduced in size boiling. The fat of cow’s milk is less readily digested than that of breast milk. Growth and Development Objective nutritional studies of growing infants in terms of rate of growth in weight and length, performance in metabolic studies and body composition show relatively very minor differences between infants fed human milk or these fed cow’s milk. However, in developing countries it has been observed that infants fed on cow’s or other formula milk suffer from more morbidities and mortalities than infants fed on human milk. This is not because of the fault in cow’s milk or formula but the technique and the dilution in which cow’s milk is being fed. Milk used in Formulas - Raw milk - Pasteurized milk - Homogenized milk - Evaporated milk - Prepared powdered milk - Condensed milk Conclusion Human milk is the best option for infant feeding. However, in certain situation other milk may need to be used. Cow’s milk is the best alternative option in such a situation. In developed countries fresh cow’s milk is not used in infants less than 1 year and cow’s milk based formula is used. In India, boiled whole cow’s milk is routinely used without any significant problem. The milk should not be diluted and there is no place of bottle in infant feeding. The milk can be given to the newborn and infants with cup and spoon or directly from cup. In developing countries like ;Inida where protein energy malnutrition is very common in children under the age of 5 years, cow’s milk with its high protein content and biological value and easy availability would be extremely beneficial as nutritional rehabilitation of these children.
Table-1: Comparison of Cow’s and Human Milk
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| Mature Human Milk | Cow’s Milk |
| Calories | 747 | 701 |
| Kcal/litre |
|
|
| Protein |
|
|
| gl | 10.6 | 32.46 |
| Casein 3.724.9 |
|
|
| Lactalbumin | 3.6 | 2.4 |
| Carbohydrate |
|
|
| Gl |
|
|
WHY COWS MILK IS AN INDISPENSABLE PART OF BALANCED DIET?
MILK IS THE FIRST FOOD A CHILD TAKES TO SURVIVE. IT IS THE BEST AND MOST COMPLETE OF ALL FOODS.
Milk has always been considered ideal food for infants and children and a good supplementary food for adults. There can not be any substitute for milk. What is a balanced diet? Balanced diet is defined as one which contains a variety of foods in such quantities & proportions that the n maintaining health vitality & general well being & also makes a small provision for extra nutrients to withstand short duration of leanness.
Milk is a fine blend of all the nutrients necessary for growth and development of young once, it’s a good source of protein fats sugar vitamins and minerals.
Cows milk is an integral part of balanced diet due to following reasons:-
1. Availability:
Dietary pattern varies widely in different parts of world depending upon socio economic status, customs, taboos etc. but milk surpasses all these barriers as it is the only food widely available and acceptable.
2. Nutritive value:
Lets compare the nutritive value of cows milk and buffaloes milk. All values are per 100 ml of milk
CALORIES AND PROTEINS:
Cow’s milk provides 67kcl and buffalo milk provides 117kcl of energy per 100 ml. The protein content of cows and buffalo milk is about 3.2gm and 4.25gm per 100ml respectively. The milk proteins mainly consist of casein (about 80%) and whey (about 20%). The proteins of milk are of a high biological value. This low content of protein cows milk from buffalo milk makes it ideal for infants and people with renal disorders. Milk proteins have excellent nutritional quality in terms of their constituent amino acids.
The use of milk proteins as nutritional supplements to enhance dietary protein quality is very feasible as they can provide lysine and tryptophan, the limiting amino acids of wheat and maize proteins.
FAT CONTENT
Cow’s milk contains practically half the fat content of buffalo milk. This reduces the risk of coronary heart diseases. Milk Fat – It’s Good for You! Parodi (1997) succinctly summarized the contribution of cow’s milk fat components as potential anticarcinogenic agents. The best-characterized anticarcinogenic agent presently is conjugated. Iinoleic acid- In mouse models, dietary CLA has been shown to protect against the induction end proliferation of chemically-induced skin, for estomach, colon, prostate and mammary tumors. CLA has drawn a great deal of attention among dairy, medical and nutrition scientists, other components of milk fat also have biological effects with anti-cancer properties. Among these, sphingomeyelin, a component of the milk fat globule membrane, and thus particularly rich in buttermilk, contains the biologically-active components ceramide and sphingosine CLA fed before puberty may impart long-lasting protection against induction and proliferation of tumors.
Research suggests that CLA can decrease the amount of fat in the blood the amount stored in the body.
These effects coculd help in the fight against two other major killers, heart disease and obesity.
CARBOHYDRATES
The main sugar present in milk is lactose. It is less sweet than cane sugar. Lactose favours the absorption of calcium and phosphorous and the synthesis of some B complex vitamins in the small intestine.
VITAMINS
Milk has got valuable amounts of vitamin A, thiamine, riboflavin and nicotinic acid but is a poor source of vitamin C and E. It also contain vitamin 812 which is absent in vegetarian food items. Cows milk has more carotene than buffaloes milk. It is very important for vision. FOLIC ACID PREVENTS ANEAMIA AND NEURAL TUBE DEFECTS IN NEWBORN. A distinct advantage of cows milk over human milk is that it’s a better source of vitamin K which prevents hemorrhagic disease of newborn.
MINERALS
The important minerals of milk are calcium, phosphorous, sodium and potassium. It is a poor source of iron. Less phosphorous content of cows milk allows better absorption of calcium. It is a good source of zinc which is required for synthesis of insulin by the pancreas and for immunity function. While calcium has been the main nutrient of interest in relation to milk and milk products and their effects on bone growth there is also the possibility that other nutrients which are found in milk may be important. Energy and protein modulate bone growth and micro nutrients such as zinc may also have an effect. The form of calcium salt may also be important. It has been prposed that the calcium phosphate in milk may have different mechanistic effects on bone compared to other calcium salts.
Studies show that milk and products may decrease the risk of osteoporosis through their effects on growth.
WATER
Milk contains about 85% water. It thus supplies both food and fluid.
VARIOUS FORMS IN WHICH MILK CAN BE CONSUMED
Unfermented Products:
Skimmed milk is deficient in fats and fat soluble vitamins but the protein, sugar, minerals and vitamin B factors (except pyrodoxine) are well preserved. If skimmed milk power is supplemented with vitamin A, D and pyri doxine, it is a comparatively cheap food of high nutritive value. It is useful for the treatment of malnutrition, the nephritic syndrome and the cirrhosis of liver. The addition of about 6 tablespoons of skimmed milk power during the preparation of chapattis, custard, curd, etc will supply an additional 35 gms of protein.
Toned milk: This is prepared by mixing equal parts of fresh buffalo milk (rich in fats) and reconstituted skimmed milk power. The fat, protein, carbohydrate, vitamin and mineral contents – and thus the nutritive value – are the same as fresh cow’s milk. It is a useful source of proteins for malnourished children and pregnant women.
Double toned milk contains only 1.5% fat.
Khoa (Mava) is milk in which the water content is reduced to between 20% and 25%. It is prepared by vigorously boiling milk, and stirring it continuously to avoid burning at the bottom or overflowing at the top. When cooled, khoa forms a uniform mass, containing fats, heat-coagulated proteins and lactose. Khoa supplies 82 kcal (344 KJ) per table spoon.
Chhana (cottage cheese) is prepared by adding lemon juice to boiling milk; this precipitates casein, lactalbumin and fat. The liquid part (whey) is strained through a cloth and chhana is collected.
Whey is a byproduct of butter and cheese production and is frequently discarded. However, when dried it can be preserved, and forms a good source of nutrition in poorer countries.
Fermented Products:
Dahi (Curd) The mode of preparation of dahi varies considerably, as does its flavour. The flavour depends upon the type of lactic acid organisms predominant in the starter. It has same calorie value as that of milk from which it has been prepared.
Yoghurt is the name given to milk cuddled by a specific type of lactic acid bacillus called Lactobacillus bulgaricus.
Lassi (Butter milk) When dahi is churned with water and fat is removed, the residual acid buttermilk is called lassi. Dahi and lassi can be prepared from whole or skimmed milk.
Ghee (Clarifled butter: Butter-fat) The composition of cow and buffalo ghee is similar: 99% fat, mostly saturated; about 1114 microgms (3800 iu) vitamin A per 100 gms, varying with the exposure of cattle to the sunshine.
Cheese Cottage cheese is an unfermented milk product, but cheese produced commercially in the west is a fermented product. There are over 400 varieties of cheese.
MYTHS ABOUT MILK:-
IS MILK PROTEIN, CASEIN, DIFFICULT TO DIGEST?
When cow’s milk is heated (as in pasteurization), homogenized or acidified to produce a softer curd, the protein is used by infants as efficiently as is the protein of human milk.
IS MILK FAT DIFFICULT TO DIGEST?
Milk fat is considered to be the most complex of all of the common fats and exhibits unique physical, chemical and biological properties not easily duplicated by other fats. It is though that this arrangement contributes to the ease of digestibility of milk fat compared with other fats.
To summarize cows milk is best source nutrition and every effort must be made to channelise the available milk to vulnerable groups like young infants preschool children, pregnant and lactating women.
BIO-PROTECTIVE ROLE OF COW MILK IN HUMAN HEALTH
Cow milk occupies a special position among foods in being an animal food that has a vegetarian connotation. Milk carries many nutrients that the infant needs for growth and development. For children, adolescent, elderly people pregnant and nursing mothers, milk plays an important role in meeting the requirements of many essential nutrients, and hence milk is considered as a protective food. Milk helps to balance human diet by supplementing good quality protein, calcium and vitamins particularly, vitamin A, riboflavin, niacin and folic acid. In addition milk contains several bio-protective molecule that ensure health security to humans.
Nutritional quality of milk proteins
Milk proteins are rich in essential amino acids. The Protein Efficiency Ratio (3.1), Biological Value (91) and Net Protein Utilization (82) of milk protein are very close to that of egg proteins (3.8, 100 and 94, respectively). Lactalbumin is superior to casein having Biological Value (BV), Net Protein Utilization (NPU) and Protein Efficiency Ratio (PER) 100, 92 and 3.6, respectively. The corresponding value for casein are 77, 76 and 2.5, respectively. Only 14.5g of lactalbumin or 28.5g milk proteins is sufficient to meet the daily requirement of essential amino acids for adult humans.
Supplementary value and digestibility of milk proteins
Because milk proteins contain a surplus of certain essential amino acids (lysine and threonine), they can raise the BV of vegetable proteins. Milk proteins can be added to cereal based products to increase their lysine and threonine content. Whey proteins have even better supplementary value and can raise the BV of soy proteins because of their high concentration of sulphur amino acids. Whey obtained as a by- product in cheese manufacture has thus a great potential for incorporation in cereal based products.
The digestibility of milk proteins is rated higher (96%) then that of plant proteins (74-78%). Because of their high BV, the milk proteins are useful in the diet of patients suffering from liver and gall bladder diseases, hyperlipidaemia and diabetes. Patients with impaired kidney functions rely on protein with high BV for relieving strain on the excretory function of the kidney. The milk proteins are also used in slimming diets.
Milk fat and misconceptions about its role in coronary heart diseases (CHD)
Milk fat has often been implicated in CHD because of its cholesterol content and composition of its fatty acids. It is however, not correct to judge the implication of milk fat in development of CHD solely on the basis of its fatty acid composition and cholesterol content. The average cholesterol content in cow and buffalo milk is only 2.8 and 1.9 mg/g fat respectively. Moreover, humans absorb 10-14% of dietary cholesterol, thus Only 20-40 mg cholesterol will be absorbed from 50g of dietary milk fat. On the other hand, the body itself synthesizes cholesterol (1-4g daily) in much higher amounts than what is absorbed from the diet.
The so called "Lipid hypothesis" states that there is a connection between fatty acid composition of the diet and cholesterol content of serum in that the saturated fatty acids (SFA) increase cholesterol and polyunsaturated fatty acids (PUFA) decrease it. Since increased cholesterol levels are believed to play a role in the development of CHD, the demand is often made that the dietary fat having low proportion of PUFA be replaced with oil that are rich in PUFA. The question that naturally arises is should one avoid milk or milk fat because it contains high content of saturated fat. The major saturated fatty acids in milk fat are palmitic acid (24-28%), myristic acid (13-14%) and stearic acid (11-12%), and the major unsaturated fatty acid is oleic acid (23-28%). Milk fat has high proportion of short and medium-chain saturated fatty acids, which do not raise serum cholesterol levels, nor does oleic and stearic acid. Only palmitic and myristic acid has some effect. The idea that excess of SFA and/or cholesterol were associated with the development of CHD arose from epidemiological association between high total and animal fat intake, high serum cholesterol levels and incidences of CHD, in some countries. The conclusion made from such empirical studies have been criticized by many researchers in that the population that consumed fat with higher PUFA/ SFA ratio also consumed less calories from sugars and total fat.
Regarding the role of PUFA in decreasing cholesterol levels and preventing heart diseases, it has not been proven unambiguously. On the other hand, the recommendations advocating for increasing intake of PUFA have been questioned. There is an increasing evidence that excessive intake of PUFA is harmful in that it may lead to (1) formation of gall stones due to increased production of bile acids (2) increased requirements for vitamin E, (3) increased formation of peroxides which may cause alteration in membrane of blood corpuscles, (4) oxidation of PUFA enriched LDL increasing susceptibility to atherosclerosis and (5) higher incidences of colon tumours due to colonisation of the intestine with bile degrading bacteria, since the excessive intake of PUFA increases the excretion of cholesterol in the form of bile acids. It is, therefore, unjustified to raise the hope that cardiac infracts could be prevented by a diet rich in PUFA. An excessive intake of energy, resulting in excess weight is one of the major reasons of altered cholesterol metabolism and atherosclerosis. Indeed, a diet containing optimum amounts of calorie and essential nutrients, wherein the type of fat has no significance, is a real safeguard against high mortality from atherosclerosis.
Nutritional benefits of milk fat
Compared to other fats and oils, milk fat is easily digestible. The digestibility of milk fat is 99%, while that of natural palm oil is 91%. The excellent digestibility of milk fat is due to dispersion of fat globules in the aqueous phase of milk forming an emulsion. They are absorbed directly unlike other dietary fats that have to be emulsified by bile, pancreatic enzymes and intestinal lipases before they can pass through intestinal well. Also, milk fat is rich in short and medium-chain fatty acids, which are more easily absorbed than long chain fatty acids. The ester bonds involving short-chain fatty acids are more easily cleaved by lipases. The easy digestibility of milk fat makes it a valuable dietary constituent in diseases of stomach, intestine, liver, gall bladder, kidney and disorders of fat digestion.
In infant and child nutrition, milk fat is of immense benefit. It helps them in meeting their energy requirements by increasing energy density of the diet. A sufficient fat supply is essential for thriving babies, a rosy and smooth skin and also resistance to bacterial infections.
Milk fat has a low content of essential fatty acids (EFA), linoleic and linolenic acid. The EFA requirement is only 3% of total calories, two-third of which is met from invisible fat present in dietary cereals, pulses and vegetables. Therefore there is no justification to replace milk fat with another fat having a higher linoleic acid content.
Milk is a rich source of vitamins
Milk is a rich source of vitamins not only in terms of their contents but also their better bioavailability. Milk is one of the richest natural sources of riboflavin (vitamin B2). A 250 ml serving of cow milk contains riboflavin equivalent to 50% of the daily requirement of a pre-school child. Although milk contains only small amounts of preformed niacin (Vitamin B3), nevertheless, it is a very good source of this vitamin. Niacin can be synthesized in the body from tryptophan, which is present in milk proteins in good amount (480 mg/L). Sixty mg tryptophan is metabolised in the body to give rise to one mg niacin. Indeed, milk is used as dietary ingredient for patient suffering from pellagra, a niacin deficiency disease. For vegetarian, milk is sole natural source of vitamin B12, as this vitamin is present only in animal foods. Milk is also a good source of folic acid. Vitamin A deficiency is a major cause of widespread blindness among children in India. A 250 ml serving of cow milk contain vitamin A sufficient to meet 75% daily vitamin A requirement of pre-school child.
Milk is a richest natural source of calcium
Recent research has shown that poor nutritional status with respect to calcium is related to diseases like osteoporosis, hypertension and colon cancer. The hypertensive patients have shown significant reduction in blood pressure in response to increased calcium intake. The effect of calcium on blood pressure is mediated by (1) increase in urinary excretion of sodium, (2)) preventing the rise in vitamin D hormone which increases blood vessel resistance (3) relaxing smooth muscle cells which lines the blood vessels (4) suppressing the renin-angiotensin system and (5) increasing production of endothelial relaxing factors.
Introduction of increased dietary calcium through dairy products has been shown to reduce incidences in colon cancer and hyper-proliferation in the colonic mucosa in rodents. Calcium produces these effects by neutralizing deconjugated bile acids and free acids, thereby removing their mitogenic/ toxic influence.
Milk and dairy products are the most important source of calcium in readily available form. A 250 ml serving of cow milk contains calcium equivalent to 60% of ICMR’s Recommended Dietary Allowance (RDA) for adults. Incorporation of milk in the diet also improves the bioavailability of calcium from vegetable foods. The factors that contribute to better availability of calcium from milk include lactose, protein and phosphorus.
A part of calcium in milk is associated with phosphorylated casein. The casein phosphopeptides, released in the gastrointestinal tract during digestion, form soluble complex with calcium phosphate salts and improves the diffusion of calcium across the intestine. Milk is rich in phosphorus that reduces urinary calcium excretion, and counter balances, at least in part, the calciuric effect of dietary proteins. Milk and most dairy products, except some processed cheese, have a near 1:1 calcium to phosphorus ratio considered to be ideal for retention of calcium in the body.
Therapeutic properties and extra-nutritional role of milk constituents
Milk proteins have high buffering power; therefore it is useful in the treatment of inflammation of mucous lining of stomach and of stomach ulcers, preventing hyperacidity. Milk and milk products are used as a source of proteins in hyperuricaemia and goat disease. In contrast to other foods, these do not contain purines, which are precursors in the synthesis of uric acid that causes gout when deposited in the joints or may lead to formation of urinary calculi.
Short and medium-chain fatty acids with 4-12 carbon atoms, which occur in a relatively high concentration in milk fat are reported to have antibacterial and fungicidal activity against gram negative bacteria and certain moulds. Milk fat has a protective effect against human tooth decay. This effect has been ascribed in part to adsorption of milk fat onto the enamel surface and in part to antimicrobial effect of milk fatty acids.
Protective effect of milk fat against some types of cancer (colon, breast and skin) has recently been reported. Fat in general is regarded as increasing cancer risk, although not for all types of cancer. However, a specific fatty acid (a cis-trans isomer of linoleic acid) has been identified in milk fat, which appears to be an inhibitor of cancerous growth.
Immunological aspects of proteins
The substances in milk which have an antimicrobial effect are immunoglobulins, lactoferrin, lysozyme, lactoperoxidase and vitamin B12-binding protein. The immunoglobulins, mainly 1gA are not broken down by the digestive enzymes. Thus, they not only act against the microorganisms in the intestine but also prevent the absorption of foreign proteins.
Lactoferrin is an iron binding glycoprotein that occurs in cow milk at a level of 0.2 mg/ml. Mother's milk contains large amounts of lactoferrin (0.1-0.2g/100 ml). Lactoferrin plays an important role in the resistance against intestinal infection, particularly Escherichia coli. Lactoferrin has both bacteriostatic and bactericidal properties. The bacteriostatic effect is of lactoferrin is due to its iron binding ability making iron unavailable for iron requiring bacteria. Mother's milk also contains a large amount of an unsaturated vitamin B12-binding protein, which competes with bacteria that have a vitamin B12.
A number of enzymes are also involved in the milk immune system. These are lactoperoxidase, xanthin oxidase and lysozyme. Lysozyme has a direct effect by breaking down the cell wall of gram-positive bacteria. The lactoperoxidase-thiocyanate-H2O2 system is an antibacterial system. Lactoperoxidase and thiocyanate are found in milk and other tissue secretions, and H2O2 is produced by lactic acid bacteria or by the action of xanthin oxidase. Thiocyanate is oxidized by H2O2 and lactoperoxidase to an intermediate product that destroys the microorganisms.
Functional peptides
Many milk-derived peptides possess functional properties. Several peptides with opium like (sleep inducing) activity have been extracted from the degradation products of milk proteins. These include ß-casomorphins (from ß-casein), exorphin (from µS1 casin), ß-lactostensin (from lactoglobulin) and serorphin (from serum albumin). These opium-like peptides have been shown to prolong gastrointestinal transit time exerting anti-diarrhoeal effect. They also stimulate secretion of insulin and somatostatin.
Glycomacro peptide (GMP) derived from K-casein induces production of cholecystokinin, a hormone associated with satiety. GMP and other fractions of K-casein digest inhibit the adhesion of oral actinomycetes and streptococci to erythrocytes, and binding of cholera toxins to its receptor.
Angiotensin-converting enzyme (ACE) located in different tissue, splits two amino acids from C-terminal end of angiotensinogen I converting it into angiotensinogen II, which is a highly hypertensive octa-peptide. Peptides with anti-hypertensive activity that act through inhibition of ACE have been identified in the sequence of bovine and human ß-and µS1 casein. Recently µ-lactalbumin and ß-lactglobulin fragments that inhibit ACE have also been characterized.
Several immune-stimulatory peptides have been identified from both bovine and human casein and whey proteins. These peptides have been shown to stimulate the phagocytic activities of murine and human macrophages and enhance resistance against certain bacteria. Certain peptides from casein stimulate the production of immunoglobulins.
Casecidin, a chymosin digest of casein in vitro, inhibits Sarcina, Bacillus subtitis, Diplococcus pneumoniae and Streptococcus pyrogenes. Similarly, fragments of human ß-casein have a protective effect against Klebsiella pneumoniae. Iracidin, an µS1 -casein fragment has both therapeutic and prophylatic effect. Lactoferricin, an acid-pepsin digestion product of lactoferrin, has stronger bactericidal activity compared to the native molecule.
Milk has cholesterol lowering factors
Several studies have shown that milk reduces serum cholesterol levels of the consumers. Experiments with volunteers have shown that cholesterol levels do not rise when as much as 2 litres of milk is consumed daily. On the contrary, the cholesterol level is reduced. Both decreased formation and increased breakdown of cholesterol are responsible for the cholesterol lowering effect of milk. Orotic acid and another nucleotide associated with proteose-peptone fraction of milk proteins and calcium are suggested to have cholesterol reducing properties. Milk slows down the biochemical processes leading to atherogenesis in rabbits fed on atherogenic diet. It has been suggested that the regular intake of milk keeps blood vessels healthy.
Therapeutic role of milk sugar
Lactose, the principal milk sugar, is slowly metabolised and therefore, a considerable portion of it passes into the large intestine where it promotes the growth of lactic acid producing bacteria. Lactic acid creates a desirable condition that inhibits the growth of proteolytic and putrefying bacteria in the intestine and replaces them gradually with acidophilic bacteria.
Several investigations have shown that lactose promotes the utilization of calcium, magnesium and phosphorus. The acidic condition created by fermentation of lactose by intestinal bacteria may increase the solubilization and absorption of calcium. Part of the effect may also be due to the ability of lactose to form soluble complex with calcium. Since lactose is slowly absorbed, it has slight laxative effect. It is due to lowering of the pH that increases the peristalsis of the intestine. The blood glucose does not rise rapidly on lactose diet. Milk consumption, therefore, enables the diabetic person to obtain the biologically highly valuable milk proteins without running the risk of rise in blood glucose levels.
Milk production and per capita availability
India is the largest producer of milk in the world. Milk production in the country was 22.5 million tons in 1970-71, and is now projected to reach 88.5 million tons in 2001-02. Despite increase in population, per capita availability of milk in the country has increased from 114 g per day in 1970-71 to 231 g per day. Milk production enhancement programmes like Operation Flood, artificial insemination, cross breeding, better animal health care and improved feeding practices has led to white revolution in the country. ICMR recommends inclusion of 150 g milk in a balanced Indian diet. The per capita availability of milk is above ICMR recommendations in most of the states, except in north-eastern states, Orrisa and Bihar, and marginally low in Andhra Pradesh.
PUBLIC HEALTH AND COW MILK
Introduction
Milk is one food for which there seems to be no adequate substitute. Man uses milk of many animals as his food. The cow is the most important of all these animals as supplier of food. However, buffalo and goat milk are also used by some communities.
Nutritive Value
Milk is a complex mixture of lipids, carbohydrates, proteins and many other organic compounds and inorganic salts dissolved or dispersed in water. The most variable component of milk is fat followed by protein. The composition of milk varies with the species, bread, diet, lactational period and interval between milkings.
Milk has a very good quality protein and the biological value is over 90. Though milk contains only 3 – 4% protein, due to the rich quality of protein and the amount that can be ingested and the presence of other nutrients, makes it indispensable. Lysine is one of the essential amino acid which is abundant in milk protein. Cheese, Khoa and dehydrated milk powders are concentrated forms hence contain high amount of nutrients per unit.
The fat of milk is easily digestible. It contains linoleic acid (2.1%), linolenic acid (0.5%) and arachidonic acid (0.14%). Diary foods are a major source of calcium because of significant amount of minerals present. The calcium : phosphorous ratio (1.2:1) in milk is regarded as most favourable for bone development. In addition dairy products contain other nutrients such as vitamin D and lactose which favour calcium absorption.
Importance of milk in the diet is evident from the above discussion. Adequate amount of milk should be included in the diet specially for infants, young children and women.
National Family Health Survey – 2 (NFHS-2) has shown that about 45% of married women had either occasionally or never had milk or curd in their diet.
There is also wide variation among states. Women in Haryana and Punjab consume milk or curd at least once a week, whereas women in Manipur and Arunachal Pradesh consume milk or curd regularly.
All India Institute of Hygiene and Public Health conducted a nutrition survey in six states of India under the National Pilot Programme on Control of Micronutrient Malnutrition, Ministry of Health and Family Welfare, Govt. of India. This survey was conducted in one district of each of six states, namely Assam, Bihar (Jharkhand), Orissa, West Bengal, Tripura and Gujarat.
The study indicated that consumption rates of milk and milk products were much less than the recommended dietary allowances (150 mg/acu/day) as recommended by ICMR.
Consumption rates of milk and milk products in different surveyed states were found to be as follows :
Recommended Dietary Allowances – 150 mg
It is observed that consumption of milk and milk products is most inadequate.
Because of its high nutritive value, milk should be consumed specially by young children, pregnant and lactating mothers, old age people etc. If there is intolerance for ordinary milk, milk products may be consumed. It contributes to the total nutritive value of the diet.
Therefore, necessary steps need to be taken to encourage more intake of milk by making the dairy system strong (health and well looked after animals, proper processing etc.), ensure better availability and access, reduce cost so that it is affordable and lastly motivate people by making them aware. Milk can help in improving the overall nutritional status of the vulnerable population in a significant manner.
COW'S MILK A NOVEL SOURCE OF MICROBIAL WEALTH
The microbial world is a microcosm whose activities are of central importance to the biosphere. Microbial products contribute to environment, plant, public, and soil health. There is a striking diversity of microorganisms in their ecological and physiological specialisations. They have evolved to cope with and flourish in almost every niche, no matter how inhospitable. Microorganisms also form a range of associations with other microbes and with other plants and animals. They can be pathogens, parasites, symbionts, commensales and saprophytes, and thus, their ecological influence infiltrates into all trophic levels of life and gamut of possible ecosystems. Microbes have proved an exceptionally rich source of new products, and there is every indication that they will continue to be so in the future. Therefore, exploration of biodiversity for novel microbes which are ecologically significant or are of economic value is of importance. This has prompted microbiologists to continue to search for novel useful microbes from sources that remain uncharacterised.
India is one of the few countries in world, which has contributed richly to the International livestock gene pool and improvement of animal population in world. Cattle and buffalo contribute nearly 15% of the gross national income. The country possesses 23% of world bovine population. According to Hindu mythology as well as the Indian traditional medical practices (both the classical systems like Ayurveda and Siddha and the oral practices of the rural villagers) cow's milk has rejuvenatory health protecting and health promotery properties and hence has been said as the best one among vitalisers [Caraka-Samhita, Editor-translator P. Sharma, Chaukhambha Orientalia, Varanasi, India, volume 1, p. 213 (1981)]. Milk may be defined as the normal secretion of the mammary gland of the mammals. Milk as it is secreted by the gland of the mammals is free of microorganisms. However, microorganisms associated with the teat move up the teat canal and into the interior of the udder [J.C. Olsen and G. Mocquot. Milk and milk products. In: International commission on microbiological specifications for foods. Microbial ecology of foods. Food commodities. Vol. 2. New York: Academic Press (1980) pp. 470-486]. This causes even aseptically drawn milk to contain microorganisms, mostly bacteria. Bacteria in aseptically drawn milk are usually limited in number and include mostly micrococci, lactococci, staphylococci, streptococci, and bacillus [F.L. Bryan, Journal of Food Protection, Volume 46, pp. 637-649 (1983); R.A. Ledford. Raw milk and fluid milk products. In: Applied dairy microbiology. Eds. E.H. Marth and J.L. Steele, New York: Marcel Dekker, Inc. (1998) pp. 55-64].
It has been known for the past more than four decades that many of the bacteria that occur commonly in milk find it a relatively unfavourable medium and it would thus appear that milk has pronounced selective properties [T. Gibson and Y.A. Abd-El-Malek, Canadian Journal of Microbiology, Volume 3, pp. 203-213, (1957)]. Thus the bacterial flora that have invaded in the teat and/or udder must have the persistence ability for survival and multiplication, under these suboptimal conditions. Therefore, work on the milk described pertains to bacterial flora persisting in the teat and/or udder, which have gained entrance into the aseptically drawn milk, in our attempt to search for novel microbes, from an ecological niche that remain uncharacterised.
Improving soil fertility is one of the most common tactics to increase agricultural and forest production. We have isolated plant beneficial bacteria from cow milk. Inoculation of seeds or soil with beneficial microorganisms for crop improvement has been practised for a number of years. A variety of mechanisms have been identified as being responsible for such plant growth promoting activity. For example, certain microorganisms indirectly promote plant growth by inhibiting the growth of deleterious microorganisms; or directly enhance plant growth by producing growth hormones; and/or by assisting in the uptake of nutrients by the crops, e.g., phosphorus (P) [C.S. Nautiyal et al., FEMS Microbiology Letters, Volume 182, pp. 291-296 (2000)]. However, a major factor in the unsuccessful commercialisation of bioinoculants has been the inconsistency of field test results as their establishment and performance are severely effected by environmental factors especially under stress conditions encountered in soil e.g., salt, pH, and temperature. Therefore, it would be desirable to provide stress tolerant bacterial strains as bioinoculants [C.S. Nautiyal, Biocontrol of plant diseases for agricultural sustainability. In: Biocontrol potential and its exploitation in sustainable agriculture. Volume 1, Eds. R.K. Upaahyay, K.G. Mukerji, and B.P. Chamola, Kluwer Academic/Plenum Publishers, New York (2000) pp. 9-23]. Plant growth promoting microorganisms include but are not limited to Rhizobium, Pseudomonas, Azospirillum, and Bacillus etc.
While work on microbiology of the milk so far has been on psychrotrophic bacteria because of their importance in milk and dairy products [M.A. Cousin. Journal of food protection. Volume 45, pp. 172-207 (1982); R.A. Ledford. Raw milk and fluid milk products. In: Applied dairy microbiology. Eds. E.H. Marth and J.L. Steele, New York: Marcel Dekker, Inc. (1998) pp. 55-64], no bacterial strain has been previously found from cow which has the ability to control phytopathogenic fungi, promote plant growth, tolerance for abiotic stresses, solubilise phosphate under abiotic stress conditions. Accordingly, there has been no clear indication heretofore that any bacteria isolated from cow might act as a biocontrol agent, and certainly no showing of direct, bacterial-mediated stimulation of plant growth per se. Nevertheless, a bacterial strain capable of promoting plant growth, tolerance for abiotic stresses, solubilise phosphate under abiotic stress conditions, if one were isolated, could find immediate application, e.g., in soils affected by phytopathogens, poor nutrient availability like phosphorus, and environment stresses etc., did not result in a desired improvement in crop development, additionally, no procedure for the selection of such bacterial strain has been reported. We have found by direct comparison on a variety of plant types that the unique combination of selected bacterial strains is effective in the enhancement of plant growth and health.
Our work relates to method for screening useful bacteria from the milk of human, Sahiwal cow, Holestien cow and buffalo and application thereof for promoting plant growth. Six hundred bacterial strains were screened for their ability to inhibit growth of plant pathogenic fungi Colletotrichum falcatum, Sclerotium rolfsii, Alternaria solani, Penicillium sp., Pythium aphanidermatum, Phytopthora palmivora, Curvularia lunata, Sclerotinia sclerotiorum, and Aspergillus niger under in vitro conditions as follows: Four single bacterial colonies on NA plates were streaked around the edge of a 90-mm diameter petri plate and the plates were incubated it at 28oC for two days. An agar plug inoculum of the fungi to be tested (5-mm square) was then transferred to the centre of the plate individually from a source plate of the fungi. After incubation for 5 to 7 days inhibition zones were readily observed in the case of bacterial strains having the biocontrol activity as the fungal growth around the streak was inhibited. While in case of bacterial strains not having biocontrol activity, fungal growth around the streak was not inhibited and the fungi grew towards the edge of the plate. We have discovered that % of bacterial strains showing biocontrol activity against phytopathogenic fungi was maximum in Sahiwal cow, followed by human, Holestien cow and buffalo (Table 1). From this parameter milk of Sahiwal cow was superior to human, Holestien cow and buffalo. The 3 strains Bacillus lentimorbus NBRI0725, Bacillus subtilis NBRI1205, and Bacillus lentimorbus NBRI3009 isolated from Sahiwal cow milk have the ability to control phytopathogenic fungi and promote plant growth under field conditions, tolerance for abiotic stresses, and solubilise phosphate under abiotic stress conditions.
India has the largest area under sugarcane among cane growing countries of the world. Its sugar industry ranks as the second major agro-industry in the country. Press mud is a "waste" product obtained during sugar manufacture. Many of these sugar mills uses yeast to ferment molasses for producing ethyl alcohol. Spent wash, a distillery effluent of the fermentation process along with press mud are considered as pollutants and therefore can not be disposed off into the environment. We have invented a process of manufacturing plant growth enhancer which utilises press mud and/or spent wash as a raw material. Fermentation of press mud and/or spent wash, using bacteria isolated from Sahiwal cow milk results into an value addition product, useful for enhancing growth of plants. Our plant growth promoting microbes propagates well in the fermented press mud. The following procedures were performed to utilise sugar factory sulphitation press mud and distillery spent wash as carrier for preparing at commercial scale, after its fermentation using consortium of of our novel microbes. About 300 tons of fresh sulphinated press mud, obtained while clarifying sugarcane juice with lime and sulphur dioxide, is laid out on cemented floor with width of 2.5 meter, 1.5 meter tall, and length of 150 meter windrows. The press mud was churned and homogenised, either manually or by the help of an aero tiller before adding 150 kg consortium i.e., 500 gm of the consortium/ton press mud, and mixing again. Within 2-3 days, temperature of the windrow goes up to 70-75oC. Thereafter, the windrows are churned twice a day and spent wash is sprayed on daily basis to maintain 55-65% moisture, for up to 40 days. After about 40 sprays the spraying of spent wash is stopped and windrows regularly turned for 3-5 days to reduce the moisture of the fermented product to about 30%. Usually after 45 days, the temperature of the windrow goes down to 40-45oC. The product at this stage is totally fermented and ready for its application. The procedures for fermenting sugar factory carbonation press mud as carrier for preparing at commercial scale, using consortium is same as described for sulphinated press mud, except water was used instead of spent wash, to maintain the moisture during fermentation
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