The process through which large feed particles are broken down into smaller units that are absorbed and undigested material is excreted out of the body is called digestion. The process of digestion is carried out through digestive system. There are two types of animals on the basis of variations in structure and function of digestive system i.e. ruminants and non ruminants. Ruminants which are also called polygastrics and include cattle, buffalo, sheep and goats while non ruminants which are also called monogastrics and include horses, donkeys, rabbits, dogs and cats. The key difference between digestive systems of ruminants and non ruminants is the structure of stomach. Non ruminants have simple stomach while the stomach of ruminants consists of four compartments i.e. rumen, reticulum, omasum and abomasum.
The digestive system of ruminants consists of following organs:
- Mouth – with teeth, tongue and pharynx
- Esophagus – a muscular tube extending from the back of the mouth to the stomach
- Stomach – consists of rumen, reticulum, omasum and abomasums
- Small intestine – consists of duodenum, jejunum and ileum
- Large intestine – consists of caecum, colon and rectum
As accessory organs or glands, salivary glands, liver, gall bladder and pancreas also take part in the process of digestion. The process of digestion includes prehension, deglutition, grinding or mastication, digestion of feed, absorption of nutrients and excretion of waste products.
First step in digestion is prehension. It is the act of bringing food into mouth. Tongue is main prehensile organ in ruminants which also plays role in the selection of feed with the help of taste buds.
Mastication is the act of chewing feed which involves the physical grinding and tearing of the feed with the help of teeth in addition to the admixture of saliva. Saliva lubricates the feed as well as initiates a limited amount of enzymatic digestion. Feed after mastication is formed into a small compact ball called bolus which is passed into digestive tract.
Deglutition is the act of swallowing in which bolus is lifted by the tongue and moved to the back of the mouth. The bolus passes through the pharynx during which respiration is temporarily inhibited by the reflex closure of larynx and then passes down the esophagus to the stomach through peristaltic movements. Peristaltic movements consist of alternate relaxation and contraction of muscles in the wall of esophagus.
Role of saliva:
Saliva is released by salivary glands. There are three pairs of salivary glands:
● Parotid Glands
● Submaxillary Glands
● Sublingual Glands
Salivary secretions act as an aid in mastication, formation of bolus, and swallowing. It provides a means for recycling the nutrients back to the rumen. It contains considerable amounts of urea, mucin, phosphorus, magnesium and chloride all of which can be used by bacteria and protozoa in the rumen. It, acting as a surfactant, helps to prevent the problem of gas accumulation in the rumen and development of serious bloat. It also solublizes several of the chemicals in the feed and thus helps their detection by the taste buds. It provides moisture to keep the membranes in the mouth moist and thus viable. The most important for the lactiating dairy animal perhaps is the large quantity of sodium and other cations that are secreted in saliva, thus serving as a buffer in the ingesta. The buffering capacity of saliva is critical since over 170 literes of saliva can be secreted by cattle daily into the rumen.
Digestion in Stomach:
From mouth bolus enters stomach through esophagus where active digestion starts. The stomach of ruminants is a complex structure consisting of four morphologically distinct compartments; rumen, reticulum, omasum and abomasum.
Rumen & Reticulum- The rumen and reticulum are collectively called fore stomach as they are closely related in physiological function. The rumen is a large physiological fermentation vat which does not secrete enzymes but causes the mixing and breakdown of feed particles through strong movements or contractions. The feed in rumen move back to the mouth due to these movements which is called regurgitation. The regurgitated matter in the form of bolus is remasticated and again swallowed; this process is called rumination. Due to rumination animal becomes able to take feed at one time and chew it slowly later on while resting.
In rumen the process of digestion occurs in an anaerobic environment with the help of rumen microorganisms. Such type of digestion is termed as fermentative digestion. Carbohydrates in feed are digested by rumen microbes and as a result carbon dioxide and volatile fatty acids are produced. Among several volatile fatty acids (VFAs) the primary VFAs are acetic acid, propionic acid and butyric acid. VFAs are absorbed directly from rumen and supply much of the energy required by the animal. These are also used in the synthesis of milk fat in lactating animals. Protein digested by ruminal microbes is converted into ammonia which is utilized by microorganisms for their growth. These microorganisms are a major source of dietary protein for ruminants as they passes down the abomasums and digested there. These microorganisms have also the ability to utilize non protein nitrogen source like urea because they can convert them into ammonia with the help of urease enzyme. The protein which is degraded by ruminal microbes is called ruminal degradable protein. The protein which is not degraded by ruminants and escape rumen is called ruminal undegradable protein or bypass protein which is digested in abomasum. Vitamin B complex is also synthesized by ruminal microbes.
Sometimes nails, tones, and various foreign objects along with the bolus of food enter rumen. The churning movement of the rumen causes these heavy objects to be driven to the front portion of reticulum. The wall of reticulum is also non secretary like that of rumen as it does not secrete any enzyme. Its functions are to assist the passing of bolus up the esophagus and to regulate passage of the food from rumen to the omasum and from the rumen to the esophagus.
Omasum & Abomasum – From rumen and reticulum bolus enters omasum where absorption of water occurs and the size of feed particles is reduced. From omasum food is passed on to the abomasum which has the similar function as that of the stomach of the non ruminants. It is the only glandular part of the ruminant stomach means it secretes enzymes which play role in the process of digestion. The secretion of abomasums is called gastric juice which contains water, hydrochloric acid, mucus, intrinsic factord, pepsinogen, and rennin. Gastric juice has low pH as 2 or less which is protective for animal as most of the foreign microbes ingested with food cannot survive in such an acidic environment. The low pH is also essential for the functioning of enzymes in abomasum like pepsinogen is an inactivated form of enzyme pepsin which is activated by low pH. Pepsin plays its role in the digestion of protein due to which protein is broken down into simpler compounds mainly peptides which are short chains of amino acids as pepsin cannot cause the complete digestion of protein into amino acids. Rennin is another enzyme which coagulate milk and reduce its rate of passage through gastrointestinal tract which is important in young calves.
Digestion in Small Intestine:
The small intestine is divided into three portions which include duodenum, jejunum and ileum. The first portion of small intestine is duodenum which originates at the pyloric sphincter of the stomach. Both the secretion of liver which is called bile and the secretion of pancreas which is called pancreatic juice are released in this portion. The next portion is jejunum and last is ileum. Throughout the surface of the small intestine there are fingerlike projections which are called villi which play their role in absorption. When feed enters small intestine from abomasums, it is called chyme which is semi digested feed and further digested and absorbed here through the action of various enzymes. These enzymes are secreted by intestinal glands and also supplied by pancreatic juice (secretion of pancreas). Maltase, amyase, lactase and sucrase are the major enzymes involved in the digestion of carbohydrates. Trypsin, chymotrypsin and peptidases take part in the digestion of protein. Functions of digestive enzymes are given in table below:.
|Enzyme||Origin||Place of action||Substrate||Products|
|Intestinal glands||Small intestine|
|Rennin||Gastric mucosa||Abomasum||Milk protein||Coagulates milk protein|
|Lipase||Gastric mucosa||Abomasum||Lipids||Fatty acid, glycerol|
|Trypsin||Pancreas||Small intestine||Protein||Peptides, amino acids|
|Peptidases||Intestinal glands||Small intestine||Peptides||Amino acids|
|Sucrase||Intestinal glands||Small intestine||Sucrose||Glucose, fructose|
|Lactase||Intestinal glands||Small intestine||Lactose||Glucose, galactose|
Role of Accessory Organs in Digestion:
The pancreas, a glandular structure, plays its role in digestion by the secretion of pancreatic juice in small intestine through pancreatic duct. Pancreatic juice primarily consists of a variety of digestive enzymes and sodium bicarbonate. Sodium bicarbonate raises the pH of chyme because small intestinal epithelium is not protected against acidic solution. The higher pH is also better for the action of pancreatic digestive enzymes. There are three major groups of pancreatic enzymes including proteases (proteolytic enzymes), amylases (amylolytic enzymes) and lipases (lipolytic enzymes). Proteolytic enzymes include trypsin and chymotrypsin which are secreted as inactive form, trypsinogen and chymotrypsinogen and activated by enterokinase enzyme. These two enzymes cause the digestion of protein and convert it to the peptides which are further hydrolyzed completely into amino acids for hydrolysis by peptidases secreted from the cells of small intestine. Amylase is secreted in its active form and digests starches to oligosaccharides which are further digested to monosaccharides by the action of maltase and sucrase enzymes secreted by small intestine. Lactase enzyme secreted by small intestine of young animals digests lactose. Lipase hydrolyzes triglycerides into fatty acids and glycerol. This action is mostly effective after the fats have been emulsified by bile.
The liver is the largest gland in the body and the secretion of it is called bile which is stored in gall bladder and released per requirement. Bile causes the emulsification of large globules of fats entering into small intestine due to which pancreatic lipases become able to hydrolyze them. Bile contains calcium and potassium salts of glycocholic and taruocholic acids which are required for maintaining alkaline pH and emulsification of fats. Bile facilitates the solublization and absorption of dietary fats and also aids in excretion of certain waste products such as cholesterol and the by products of hemoglobin breakdown.
Role of Large Intestine in Digestion:
After digestion and absorption in small intestine digesta enters large intestine. Large intestine is a major site for the absorption of water and salts like sodium and chloride and consists of three parts as caecum, colon, and rectum. Some absorption of VFAs occurs in caecum while considerable amounts of water and electrolytes are absorbed in colon. The last part of large intestine is rectum which is a dilatable tube serving as a storage place for feaces until it is excreted out through anus. The feaces consist of the undigested residue of the feed, the remains of the digestive secretions, waste material resulting from wear and tear of the digestive tract, certain excretory products and the bacterial flora.
Feed can be described as the materials which give nourishment to animals. The components of a feed which are capable of being utilized by the animal in life support functions are called nutrients. Nutrients may also be defined as a specific element or compound derived from ingested food and used to support the physiological processes of life. Nutrients are required for normal body functions such as digestion, respiration, blood circulation, locomotion, reproduction etc.
The major nutrients found in dairy animal feed are water, carbohydrates, proteins, minerals or ash and vitamins.
Water is the most abundant, the cheapest but the most important nutrient. Its importance can be estimated from the fact that life cannot exist without it and adult animal’s body contains 70-80% water. Moreover animal product such as milk contains a large amount of water (upto 83 to 87%).
Functions of Water:
- It is an essential part of all body tissues
- It helps in maintenance of body temperature and pH
- It helps in digestion, absorption and excretion
- It helps in respiration by moistening alveoli
- It helps in the transportation of nutrients to different parts of the body
- It acts as solvent for many constituents of body nutrients
- It protects the various vital organs against outer shocks and injuries
- It acts as a cushion for tissue cells and nervous system
- It provides shapes to the body cells
- It maintains proper fluid and ion balance in body
- All the biochemical and physiological reactions take place in water
Sources of Water in Animals:
There are three sources of water:
- Drinking water which is the major portion of water consumed by an animal
- Feed water which reaches the animal body along with feed. For example green fodder contains 75-95% moisture
- Metabolic water which result from the metabolic activities of various nutrients present inside the animal body. For example one gram carbohydrates, one gram fat and one gram protein yield 0.60 ml, 1.70 ml and 0.42 ml metabolic water respectively.
Carbohydrates are compound of carbon, hydrogen and oxygen in which the ratio of hydrogen to oxygen is almost the same as that in water. Carbohydrates may be defined as polyhydroxy aldehyde or ketone or anhydrides of such derivatives. These are synthesized in plant through photosynthesis. Plants tissue may contain carbohydrates up to 50% of its dry weight in forages and about 80% in cereal grains.
Classification of Carbohydrates:
Carbohydrates are divided into three main groups:
Monosaccharides – Monosaccharides are simple sugars which cannot further be hydrolyzed. They are the building block of more complex carbohydrates. They may be subdivided into trioses (having three carbons), tetroses (having four carbons), pentoses (having five carbons), hexoses (having six carbons) and heptoses (having seven carbons). Glucose, fructose, mannose and ribose are the examples of simple sugars.
Disaccharides – Disaccharides are compound sugars which are composed of two monosaccharides. These mononsaccharides are connected through glycosidic linkage. Sucrose, maltose, lactose and cellobiose are the examples disaccharides.
Polysaccharides – Polysaccharides are complex sugars which contain a large number of monosaccharides. These are not sweet in taste that is why also called as non sugars. These are further classified as structural and non structural carbohydrates.
Structural polysaccharides – Most of the cell wall in plant is composed of structural polysaccharides in the form of cellulose and hemicelluloses. These polysaccharides provide structural support for plant tissue. Like starch, cellulose and hemicelluloses are also made of glucose units but are less digestible due to complex linkages among the glucose units. The structural carbohydrate content increases with the maturity of plants.
Non structural polysaccharides – Starch is one of the most important non structural and non fibrous polysaccharide found in plants, particularly in grains ad tubers. Most of the plant glucose is stored in the form of starch. Starch contains amylose and amylopectin in variable concentrations. Starch from different sources varies in its digestibility.
Functions of Carbohydrates:
- They are the source of energy for animal
- They are building stones for other nutrients
- They are stored in animal body in form of glycogen
- They give the filing effect to stomach
Lipids are organic compounds which are soluble in organic solvents and have important biochemical and physiological functions in body. Nutritionally important lipids are fats and oils. The building blocks of lipids are fatty acids and glycerol. Depending upon the number of fatty acids present in lipids they are classified as monoglycerides, diglycerides, and triglycerides. Fats are solid at room temperature while oils are liquid at room temperature. Waxes are esters of fatty acids with alcohols other than glycerol.
- They supply energy
- They provide heat insulation and protection from minor injury
- They are source of essential fatty acid
- They carry fat soluble vitamins
- They play role in structural functioning
Proteins are complex organic compounds which are made up of amino acids. Like carbohydrates proteins are composed of carbon, hydrogen, oxygen, but in addition nitrogen is also present. Some proteins also contain sulphur, iron and phosphorus. Proteins are found in large amount in muscles, cell membrane, skin, wool/hair, hormones and enzymes. Plants and some bacteria are the original sources of all proteins because they have ability to synthesize their own proteins.
Amino acids present in protein are associated with each other by peptide linkages. The type of amino acids present in protein molecule and their relative proportion and arrangement are unique for each protein. Nutritional value of protein depends primarily on its amino acid composition. From nutritional point of view amino acids are grouped as essential and non essential amino acids.
Essential amino acids are those, which body cannot synthesize and they are required to be supplied in the diets. So they are dietary essential. On the other hand non essential amino acids are those which body can synthesize through transamination. Essential amino acids include threonine, valine, histidine, arginine, lysine, leucine, isoleusine, methionine, phenyalanine, and tryptophan. Non essential amino acids include hydroxyproline, proline, alanine, serine, cystine, gycine, glutamic acid, aspartic acid, tyrosine, and citrulline.
Functions of Proteins:
- They have role in formation of body structure and tissues
- They have regulatory function as osmotic pressure, water balance and pH
- They are necessary for body hormones and enzymes
- They are required for milk synthesis
- They are involved in hereditary transmission
- They play role in antibodies formation to develop immunity in body
Minerals are essential dietary constituents which are required in relatively small quantities. Animal tissue and feed contain about 45 mineral elements in varying quantities. On the basis of requirement minerals are classified as micromineral and macromineral. Macrominerals are those which are required in relatively large amounts while micro minerals are those which are required in small amount. Microminerals are also called trace elements. Calcium, phosphorus, potassium, sodium, chlorine, magnesium and sulphur are the examples of some macrominerals while iron, zinc, manganese, copper, cobalt, iodine, selenium, chromium and molybdenum are the examples of some microminerals. Animal body contains 3-5% minerals on empty body weight basis.
Functions of Minerals:
- They give rigidity and strength to body skeleton
- They are components of certain biomolecules such as proteins, phospholipids, mucopolysaccharides, hormones and vitamins
- They also act as activator of many enzymes
- As soluble salts, they play an important role in osmosis, acid base balance, muscle contraction and nerve transmission
- Mineral status of animal also affects the balance of symbiotic microflora of gastrointestinal tract, modulates immunity and helps the animals against stress.
Vitamins are complex organic compounds that are essential for life and good health. These are classified as fat soluble vitamins and water soluble vitamins. Fat soluble vitamins include A, D, E and K while water soluble vitamins are thiamin (B1), riboflavin (vitamin B2), niacin (vitamin B3), pantothenic acid (vitamin B5), pyridoxamine (vitamin B6), cobalamin (vitamin B12), choline, folic acid and ascorbic acid (vitamin C).
Proximate analysis is a system for estimating the nutritive value of feed or material for feeding purposes. The principle of the analysis is to separate the feed components into groups or fractions in accordance with their feeding value. The various components are moisture, ash, crude protein, crude fiber, and nitrogen free extract.
Moisture and Dry Matter:
Moisture in a feed is estimated by drying a sample in a laboratory oven at 100 oC until it reaches a constant weight. First of all sample is weighed and this weight is called wet weight. Then it is kept in oven and weighed after certain period of time. It is again kept in oven and again weighed after certain period of time. Sample is kept on keeping in oven and weighing until further change in weight of sample stops. The weight at this point is called dry weight. This is the amount of dry mater in sample. Subtract dry weight from wet weight which will give the amount of moisture in sample. The moisture free fraction is called dry matter.
|% Moisture =||Wet weight – Dry Weight||× 100|
|% DM =||Dry Weight||× 100|
Crude protein in feed is estimated by determining the nitrogen content of feed with Kjeldahl Digestion and Distillation Procedure. In this procedure feed is digested with sulphuric acid, which convert all nitrogen present in feed into ammonia except nitrate and nitrite. This ammonia is liberated by adding sodium hydroxide which is distilled off and collected in standard acid. The quantity so collected is determined by filtration or by an automated colorimetric method. It is assumed that the nitrogen is derived from protein containing 16 percent nitrogen and by multiplying nitrogen with 6.25 an approximate value of protein is obtained. This is not true protein as the method also determines nitrogen from sources other than protein such as free amino acids, amines and nucleic acids and the fraction is therefore digested crude protein.
|% CP =||Units of N × 6.25||× 100|
Ether Extract or Fat:
Ether extract refers to the fraction of the fat in the feed which is soluble in ether and is estimated by continuous extraction of a feed sample with diethyl ether for 6-9 hours in a Soxhlet Apparatus. The residue after evaporating of solvent is ether extract. Pigments and fat soluble vitamins, waxes, gums, resins are also included in this fraction. The ether is then evaporated and the extracted material is weighed.
|% EE =||Weight of Ether Extract||× 100|
Carbohydrates of the feed are obtained in two fractions, the crude fibre and the nitrogen free extracts.
In the laboratory crude fiber is measured by subjecting the residual feed from ether extraction to boiling with diluted acid and then with diluted alkali. The residue after filtration is considered the crude fiber.
|%CF =||Weight of fiber residue||× 100|
Nitrogen Free Extract:
This represents the more soluble carbohydrates or non structural such as starches and sugars. The nitrogen free extract is determined mathematically by difference:
% NFE = 100 – (% H2O + % ash +%EE + %CF)
This represents the mineral components of a feed. A dry sample is placed in a crucible and completely combusted in a furnace at 650 oC, the residue is the ash.
|% ash =||Weight of ash||× 100|
Van Soest Method of Feed Analysis
According to the concept of van soest there are two principal parts of dry matter of plant origin which are cell wall and cell contents. This method is highly efficient to take care of the defects in the principle of estimating crude fibre and NFE by proximate analysis. Plant cell contents consist of sugars, starch, soluble carbohydrates, pectin, non protein nitrogen, protein, lipids and water soluble materials including minerals and several vitamins.
The principal components of cell wall consist of cellulose, hemicelluloses, silica, lignin etc. This part is considered fibre. Fibre is classified as acid detergent fibre (ADF) and neutral detergent fibre. Acid detergent fiber (ADF) consists of cellulose, lignin, lignified nitrogen compounds (heat damaged protein), and insoluble ash. Acid detergent fiber does not represent the total fiber content in feed, as it does not account for hemicellulose. Neutral detergent fiber (NDF) consists of ADF plus hemicellulose, and is often called cell walls. Because NDF represents the total fiber in a feed, it is highly correlated to intake, rumination, and total chewing time.
There are two types of feed resources; conventional feed resources and non conventional feed resources.
Conventional Feed Resources:
Conventional feed resources refer to those which are traditionally used for animal feeding. In Pakistan conventional feed resources include roughages and concentrates. Roughages are further classified as green roughages and dry roughages.
Non conventional feed resources:
Non conventional feed resources are those which are not traditionally used for animal feeding but have the potential to be used as feed. Non conventional feed resources include different agro industrial by products and wastes for example by products of the sugar industry, food and fruit processing industry and cereal industry. Urea and diammonium phosphate and other nonprotein nitrogen sources are also the examples of non conventional feed resources.
Feeding Requirements of Dairy Animals
Different requirements of dairy animals are as follows
Water is the cheapest nutrient. Animal get water from three sources:
- Free Water Intake
- Water contained in feed
- Water produced by body’s metabolism
Metabolic water is an insignificant source compared with the water ingested freely or in feed. The sum of Free water Intake and the water ingested in feed is the total water intake (TWI). Large amount of fresh and clean drinking water should be available to the dairy animals all the times. Three to four units of water is normally required by dairy animal for each unit of dry feed consumed. Requirement of water is governed by different factors like what is the physiological state of the animal, what type of feed consumed, and what are climatic conditions. Water requirement of a dairy animal when not in milk is 26 to 37 liters per day, and this requirement increases at a rate of four litres for each litre of milk produced. Requirement of water can also be determined by this equation:
Water intake (gal/day) = 4.22 + (0.19 x DM intake) + (0.108 x pounds of milk) + (0.374 x ounces of sodium)
+ (0.06 x minimum daily temperature in F)
Dairy animals are very sensitive to the quality of water as availability of inadequate or poor quality water can limit milk production and growth and may cause even health problems.
Dry Matter Intake
Dry matter intake is quantity of dry matter which is consumed by an animal over a period for 24 hours. It is usually measured in %age. DMI is normally calculated as 3-4 % of body weight. An average size cattle DMI is 2.5 – 3% of body weight. A dairy animal may reach maximum daily DMI (4% of Body weight) not later than 10 weeks after calving.
The capacity to do work is called energy. It is the basic requirement of animal and essential to maintain normal body functioning. Energy is quantitatively the major nutrient required by dairy cattle after water.
Carbohydrates, fats and protein are the main sources of energy. Mostly the energy is supplied to the dairy cattle from carbohydrates being the most economical. Protein is also a good source of energy but it is usually 5 to 10 times higher in price as compared to carbohydrates and therefore its use is less as energy source. Fat is very good source of energy and supply 2.25 more energy as compared to carbohydrates and protein. It is mainly included in the rations of young calves but may also be added to the rations of lactating dairy animals.
On the basis of energy losses in body energy can be divided as follows:
Gross energy refers to the total energy in feed, which is determined by complete oxidation (burning) of the feedstuff and measurement of the heat produced. The energy value is expressed in calories. Common feedstuffs are similar in gross energy content, but differ in feeding value because of differences in digestibility.
Digestible energy is gross energy minus fecal (manure) loss. These losses will be greater for high fiber rations than for low fiber rations.
Other losses include those in urine and gas. In the rumen, considerable methane is produced, representing an energy loss because the animal cannot use methane and must eructate (belch) the gas. These losses, added to fecal losses, are considered in calculating the metabolizable energy.
Heat is produced during digestion and metabolism. Other than during cold weather, this heat has no value and represents a loss of energy. The remaining energy is net energy (NE). NE system divides energy into NE for maintenance (NEm), NE for growth (NEg) and NE for lactation (NEl). NEl is energy required for maintenance plus milk production during lactation.
Total digestible nutrients (TDN) is another method of expressing the energy content of feeds or the energy requirements of cattle. TDN is comparable to digestible energy. It has been in use longer than the net energy system and more values are available for feedstuffs.
TDN = Digestible NFE + Digestible crude fiber + Digestible protein + (Digestible ether extract x 2.25)
Carbohydrates are the major source of energy in diets for dairy cattle and usually comprise 60-70% of total diet. The main function of carbohydrates is to provide energy for rumen microbes and the host animal. A secondary, but essential, function of certain types of carbohydrates is to maintain the health of the gastrointestinal tract. There are two major categories of carbohydrate as structural carbohydrates and non structural carbohydrates. Non structural carbohydrates are found inside the cell of plants while structural carbohydrates are found inside the cell wall. Non structural carbohydrates are more soluble than structural carbohydrates.
Non structural carbohydrates include sugars, starches, organic acids, and other reserve carbohydrates such as fructans and are major sources of energy for high producing dairy cattle. Non structural carbohydrates are highly digestible.
Structural carbohydrates include cellulose hemicellulose, and lignin are classified as fiber, giving structure and strength to plant tissues. Simple-stomach animals, cat, dogs and poultry, cannot digest much fiber. Adult ruminants digest fiber because the microbial population in the rumen breaks it down into usable products. Lignin, which is also a component of plants, is not a true carbohydrate. This compound is virtually indigestible. Feed digestibility is lowered when lignin is present in large amounts, such as in mature forages.
Crude fiber, acid detergent fiber, and neutral detergent fiber are the most common measures of fiber used for routine feed analysis, but none of these fractions are chemically uniform. Neutral detergent fiber measures most of
the structural components in plant cells (i.e. cellulose, hemicellulose, and lignin). Acid detergent fiber does not include hemicellulose, and crude fiber does not quantitatively recover hemicellulose and lignin. Neutral detergent fiber is the method that best separates structural from nonstructural carbohydrates in plants, and NDF measures most of the chemical compounds generally considered to comprise fiber. Within a specific feed stuff, concentrations of NDF, ADF, and crude fiber are highly correlated, but for mixed diets that contain different fiber sources, the correlations among the different measures of fiber are lower. Neutral detergent fiber is the best expression of fiber available currently, but recommendations are also given for ADF because of its wide spread use.
Neutral detergent fiber (NDF) consists of ADF plus hemicellulose, and is often called cell walls. Because NDF represents the total fiber in a feed, it is highly correlated to intake, rumination, and total chewing time. Corrected for physical form, NDF provides the best measurement of effective fiber for formulating dairy rations.
The fineness at which forages are chopped during harvesting can alter the effectiveness of fiber for maintaining chewing activity. Hay crop silages should be chopped at a minimum of 3/8 inch theoretical length of cut (TLC) to provide 15 to 20 percent (weight basis) of the particles greater than two inches long. Chopping at 1/4 inch TLC provides only about 10 percent of the forage particles greater than two inches long. Corn silage should be chopped at 1/4 to 3/8 inch TLC. Rations based on 1/4 inch TLC silage should include 5 pounds of long stem hay to provide adequate “effective” fiber. Hay crop silage chopped at 3/16 inch TLC with less than 7 percent coarse particles should be fed with 8 to 10 pounds of long hay. Holstein cows need to chew about 11 to 12 hours per day or 12 to 14 minutes per pound of DM eaten to keep milk fat above 3.5 percent.
High fiber by-product feeds supply some “effective” NDF and can be used to partially replace NDF coming from forages in the ration. Whole cottonseed possesses the best forage NDF replacement value of commonly available by-product feeds fed in milking cow rations.
Starch, sugar, and pectin make up the highly digestible carbohydrate fraction in feeds termed non-fiber carbohydrates (NFC). Subtracting percent (DM basis) NDF, CP, ether extract or fat and ash from 100 provides an estimate of NFC percent in feeds.
(NFC% = 100 – [%NDF + %CP + %fat + %ash])
The term nonstructural carbohydrate is often used interchangeably with NFC but is analytically determined and may be slightly different from NFC.
Carbohydrate status of dairy rations has traditionally been evaluated with regard to measures of structural carbohydrates—ADF or NDF. However, optimum microbial growth in the rumen requires adequate amounts of NFC along with degradable intake protein (DIP) in the ration. Insufficient amounts of NFC in rations depress microbial growth and digestion of feed in the rumen, while excess NFC in rations causes acidosis and/or low milk fat tests.
Protein is required in animal rations to provide the supply of amino acids needed for tissue repair and synthesis, hormone synthesis, milk synthesis and many other physiological functions. Amino acids are supplied by the digestion of microbial protein, and by feed protein that escapes microbial breakdown in the rumen.
Protein requirements are expressed as crude protein (CP), either in amounts or as a percentage of the dietary DM. Crude protein is determined by multiplying the nitrogen content in a feed by the factor 6.25 (feed protein averages 16 percent nitrogen). Feedstuffs that contain nitrogen in a form other than proteins or peptides are called nonprotein nitrogen (NPN) sources. Urea and ammonium slats are examples of NPN sources. They have crude protein value, but they do not supply any amino acids directly. Nitrogen of NPN sources is utilized by ruminal microorganisms. They convert it into amino acid and use them for their growth. These microbes then pass into small intestine where they are digested and amino acids are released for absorption and utilization, the same way as amino acids released from the digestion of true proteins in feeds.
All feed protein sources are not degraded in the rumen to the same extent. Three protein terms describe the fate of dietary protein in the rumen:
- Degradable intake protein (DIP) is the portion of feed protein broken down to ammonia or amino acids by the rumen microbes.
- Soluble intake protein (SIP) is the portion of DIP that is rapidly degraded in the rumen. Generally, SIP is about half of the DIP.
- Undegradable intake protein (UIP) is the portion of feed protein that is not degraded by the rumen microbes and remains intact as it passes through the rumen. Other terms for UIP include by-pass protein and escape protein.
Values for UIP, SIP and DIP can be expressed as either a percent of the dietary DM (for example, a feed may contain 17 percent CP and 6.8 percent UIP in the DM) or as a percent of the CP (for example, 40 percent UIP calculated by 6.8/17). The sum of DIP and UIP, expressed as percent of CP, must equal 100. Diets for high producing dairy cows should contain 19 percent CP with 38 percent of the CP as UIP, 62 percent as DIP and 30 percent as SIP; or 19 percent CP with 7.2 percent UIP, 11.8 percent DIP and 5.7 percent SIP in the dietary DM.
The optimal diet fed to dairy cattle will meet the nitrogen requirement of rumen micro-organisms for maximum synthesis of micro-organism protein and allow for maximum escape or bypass of high quality feed protein for digestion in the small intestine. Protein synthesis by rumen microbes will depend on feed intake, organic matter digestibility, feed type, protein level, and feeding system. Since 4.5 pounds of microbial protein synthesis per day is near the maximum, the remainder of the protein must be derived from UIP sources. Young, fast-growing heifers and high-producing cows may require additional UIP sources beyond their normal diet to meet their amino acid requirements. Excess protein, above requirements, is used as a source of energy.
Urea is a good example of NPN. Its use in dairy cattle feeding is limited by its lack of palatability and the animal’s ability to utilize it for protein synthesis. Its utilization is affected by the way it is fed, the availability of a source of the carbon compounds needed for protein synthesis and the level of protein of the total ration. Starches are a very effective source of carbon compounds for ruminants amino acid synthesis. Cellulose is less effective as it is degraded too slowly and simple sugars degraded too rapidly to be mass effective. NPN is not very effective utilized by high producing cows being fed relatively high levels of total ration protein (14-15% of the DM). It can however be more effectively utilized by lower producing cows being fed lower levels of total ration protein (up to 12 to 13% of the DM).
Minerals are essential dietary constituents and required in relatively small quantities. On the basis of requirement minerals are classified as micromineral and macromineral. Macrominerals are those which are required in relatively large amounts while micro minerals are those which are required in small amount. Microminerals are also called trace elements.
Sodium is an extracellular and potassium an intracellular cation, while chloride is associated with sodium as an extracellular anion. These minerals help in acid base balance along with bicarbonate ions, electrolyte balance, fluid balance and regulation of osmotic tension. Sodium and sodium chloride are usually provided in the form of common salt. However potassium chloride may also be used as a source of chloride, excessive levels of chloride without sodium or potassium can contribute to acidosis in dairy animals. The deficiency of sodium causes poor growth, poor feed utilization, dehydration and decreased cardiac output. The first sign of sodium deficiency is craving for salt manifested by licking of wood, skin, soil etc.
Milk contains about 0.15% potassium. Heat stress increases the need for potassium because of its greater loss in sweat. Potassium deficiency does not normally occur since roughages supply sufficient potassium to meet the dairy animals requirements. The signs of severe potassium deficiency in lactating animal include a marked decrease in feed intake, loss in weight, decreased milk yield, pica, loss of hair glossiness, decreased pliability of the hide, lower plasma and milk potassium and higher haematocrit (PCV), potassium (3% or above) in every lush forages growing on high potassium soils in cool weather may cause both grass tetany and milk fever of lactating animals.
It is required for growth of hair, hooves and horn. Milk contains 0.03% sulphur, much of which is in the form of amino acids, methionine and cystine.
The adult animal body contains about 0.044% of magnesium and is closely related to calcium and phosphorus. About 70% of magnesium is present in bones, while the rest is in soft tissues and body fluids. Milk contains about 0.15% magnesium. Magnesium requirement increase with the level of milk production. Magnesium toxicity is not known to be a problem in dairy animals. Oil cakes and leguminous fodders are rich sources of magnesium. Tolerance level of magnesium in diary animals is 0.50 %.
It is the major element present in animal body from 1 to 1.6%. More than 90% of body calcium is present in bones and teeth while the rest is found in soft tissues and body fluids. Whole milk contains about 0.12% calcium. Calcium serves a number of physiological functions in the body such as coagulation of blood, acid base balance, excitability of nerves, muscle tone, and activates enzymes like lipases, peptidases. Deficiency of Ca causes rickets in young animals and osteomalacia in adults. In addition slow growth, poor bone development, reduced milk yield and increase incidence of milk fever are also caused by calcium deficiency.
It is the major intracellular anion found in animal body. Whole milk contains 0.09%. About 80% of the total body phosphorus is present in bones, 10% in combination with proteins, fats and carbohydrates. Deoxyribonucleic acid and ribonucleic acid which are required for gene expression and protein synthesis, contain phosphorus. As a component of phospholipid phosphorus forms the cell membrane structure and helps in absorption and transportation of lipid. Its deficiency leads to rickets, poor growth, arched back, muscular weakness and poor reproductive performance. Excessive phosphorus intakes may cause bone resorption, elevated plasma phosphorus levels and urinary calculi. High calcium, iron and aluminium in feeds predispose the animals to phosphorus deficiency.
Probably cobalt as such has no physiological function in animal body but as a component of vitamin B12 it plays an important role. It is utilized by the rumen microbes for the synthesis of vitamin B12. Deficiency of cobalt causes anorexia, anemia, progressive emaciation, rough hair coat, restlessness and decreased milk production.
Copper helps in utilization of iron, hemoglobin synthesis, maturation of RBCs, pigmentation of hair, myoglobin synthesis and bone formation. It is also a component of superoxide dismutase involved in antioxidation process. Thus protecting cells form any damage. A deficiency of copper results in anemia and depigmentation of hair. Black hair turns grey and red becoming yellow. Swelling of long bones, stiff joints, delayed oestrus and reproductive failure take place due to Copper deficiency.
Iodine is deficient in many hilly subhilly areas of Pakistan. The iodine uptake is also reduced by plants in summer months under tropical conditions and supplemental iodine above the requirement is beneficial to improve milk production in buffaloes. Goiter (an enlargement of thyroid glands) occurs in newborn calves if their mothers are fed iodine deficient ration. The necks of calves are also swollen. They are weak at birth or they are born dead. Calves may be born blind and hairless. Fertility is reduced in both sexes.
Iron is essential because it is a constituent of hemoglobin, the oxygen carrier in the blood. It plays a key role in oxygen transportation and oxidative process. Deficiency symptoms are anemia, loss of appetite, depressed body weight gain and painful respiration even on slight exercise. The higher concentration of iron in feeds and fodders in tropical countries may hamper availability of phosphorus, Zinc , and copper.
It is involved in several enzymatic systems required for metabolism of amino acids and nucleic acids, oxidative phosphorylation, synthesis of fatty acids, cholesterol and mucopolysaccharides. Manganese deficiency in calves leads to weak and twisted legs and enlarged joints.
Molybdenum is an indispensable component of enzyme xanthine oxidase which is found in milk distributed widely in animal tissue. Yet a deficiency of molybdenum has not been observed in cattle. Molybdenum is known largely for its toxic effects. It toxicosis is a practical problem in grazing cattle in many areas of the world. There is a antagonistic relationship between molybdenum and copper. Elevated dietary molybdenum increases both the animals requirements of copper and the amount of copper that causes toxicosis. Increased dietary copper can reduce the toxic effects of molybdenum. If the level of copper in the body is low, a lesser amount of molybdenum is toxic. High levels of both molybdenum and sulphur interfere with Cu absorption.
As a component of enzyme glutathione peroxidase selenium serves as an antioxidant. Like molybdenum, selenium was known for its toxic effects, before it was discovered to be an essential nutrient for ruminants. It is needed in trace amounts to prevent retarded growth, reproductive problem, retained placenta, while muscle disease and some mastitis problems. Selenium is closely associated with vitamin E. both selenium and vitamin E protect cells form the detrimental effects of peroxidation but each takes a different approach. Deficient or toxic selenium areas are widely scattered throughout the world.
Zink is associated with many enzymes as an essential component or activator and is responsible for metabolism of carbohydrates, lipids, proteins and nucleic acids. As a component of alcohol dehydrogenase, it helps in conversion of retinol to retinal and vice versa. Zink is adversely affected when excess quantities of calcium are present. Moderate excesses of zink are not toxic to dairy animals. Galvanized pipes and galvnanized buckets which are commonly used to provide water to dairy animals contribute zink along the way. Anorexia depressed growth feed intake and feed utilization, reduced testicular growth and development, loss of hair, scaly skin, unhealthy appearance and stiffness of joints are the signs of zinc deficiency.
Factor Affecting Mineral Requirement
The requirements of minerals are governed by many factors including:
- Dietary concentration of the relevant mineral
- Its chemical form and solubility
- Its status in animal body
- Breed, age, physiological state of the animal
- Relative concentration of other interacting minerals
- Loss of body fluid due to trauma
- Infection and disease
Vitamins are complex organic compounds that are required in traces by various farm animals for maintenance, normal growth, production, reproduction and health. Vitamins are classified as fat soluble vitamins and water soluble vitamins. Fat soluble vitamins include A, D, E and K while water soluble vitamins are vitamins B, (B1, B2, B6, B12), choline, pantothenic acid, folic acid and vitamin C.
Vitamin A is the most important of all vitamins. It is not found in plants and strictly a product of animal metabolism. Its precursor is carotene which is present in plants. Animal body has the ability to transform carotene into vitamin A. Vitamin A is required for the normal functioning of the osteoclasts and osteoblasts in the epithelial cartilages. It is important for the vision of animal.
Vitamin D is significant for regulating calcium and phosphorus metabolism. It promotes intestinal absorption. Sources of vitamin D are fish oils, eggs, milk and liver. Vitamin D can be formed in body by exposure to sun.
Vitamin E is an antioxidant associated with selenium. It stimulates the immune system and reduces the incidence of oxidized flavor when consumed at high levels. It may aid in protection against white muscle disease caused by a deficiency of selenium. It is also involved in formation of biological membranes.
Vitamin K functions as a stimulant to blood coagulation. Either vitamin K1 (phylloquinone) or vitamin K2 (menaquinone) meets the needs of dairy animals. Green, leafy materials of any kind, both fresh and dry, are good sources of vitamin K1. Normally, vitamin K2 is synthesized in large amounts in the rumen; therefore, dietary supplementation is not recommended. When animal consumes mouldy sweet clover hay which is high in dicumarol, blood coagulation may be impaired followed by general haemorrhage. This syndrome commonly called sweet-clover disease or sweet-clover poisoning responds to treatment with vitamin K.
The B-complex group of vitamins includes thiamin (B1), riboflavin (B2), vitamin B6 (pyridoxine), biotin, choline, folic acid, niacin (nicotinic acid, nicotinamide), pantothenic acid (vitamin B5), vitamin B12 (cobalamin, cyanocobalamin). Recent evidence suggests a need for supplemental niacin under certain conditions, and possibly supplemental choline and thiamin in the case of mature dairy animals, for which microbial synthesis and quantities in feeds may be inadequate, especially during diseased conditions or periods of stress. Dairy animals of all ages have a physiological need for most of the B vitamins, especially biotin, choline, niacin, pantothenic acid, riboflavin, thiamin, vitamin B6, and vitamin B12. In young calves, deficiency signs have been noticed when there is inadequate intake of these vitamins, but even without a functioning rumen, their needs for these B vitamins appear to be met when they are fed whole milk. However, when young calves are fed milk replacers, it is advisable to ascertain the adequacy of vitamin intakes until their rumens are functional.
Thiamin (Vitamin B1):
A deficiency of thiamin in the calf may cause polioencephalomalacia, characterized by lack of muscular coordination, convulsions, progressive blindness, listlessness and sudden death, usually preceded by diarrhoea and dehydration. This condition is mainly found in dairy animals fed high concentrate rations, and it has been linked to increased microbial thiaminase activity and the production of thiamin analogue in the rumen.
Riboflavin (Vitamin B2):
Since the rumen bacteria synthesize riboflavin in adequate amounts, it is, therefore, not a dietary essential in ruminants. Also, it is present in many feedstuffs. In the calf, its deficiency is characterized by hyperemia (presence of blood in the mucosa of the mouth), lesions in the corners of the mouth and along the edges of the lips, loss of hair, especially on the belly, and excess salivation. Riboflavin plays role in the intermediary metabolism and assimilation of nutrients. It helps form flavoprotein enzymes and coenzymes, which act in metabolic release of feed energy in the body.
Vitamin B6 (Pyridoxine, Pyridoxamine, Pyridoxal):
Vitamin B6 is considered important in several enzyme systems concerned with metabolism of proteins. Tryptophan will not be completely metabolized in the absence of this vitamin. Its deficiency has been produced in calves fed a synthetic diet. The deficiency has been characterized by loss of appetite, cessation of growth, and epileptic seizures in some, but not all. Calves respond to vitamin B6 therapy if it is initiated in the early stage of the disease.
Biotin is also a part of many enzyme systems in intermediary metabolism. In ruminants, microbial synthesis inrumen takes care of dietary needs. However, in calves, its deficiency has been characterized by paralysis of the hind quarters. Signs of deficiency did not develop when synthetic milk was supplemented with 9 micrograms/kg of feed.
Niacin (Nicotinic Acid, Nicotinamide):
Niacin forms a part of two important co-enzymes (NAD and NADH). These enzymes are involved in a series of reactions in the metabolism of all nutrients, in which biological oxidation-reductions take place. Niacin is required by the young preruminant calf. In addition, rumen microbes may not synthesize adequate amounts of niacin to meet needs of high producing animals in early lactation. The major reason for improvement in milk production that occurs with added niacin may be related to the role of niacin in carbohydrate and lipid metabolism and resultant decrease in ketosis. Niacin may also influence rumen fermentation, as evidenced by greater microbial protein synthesis and increased levels of rumen propionate with niacin supplementation. When dairy animals are fed heated soybean meal, rumen response to niacin is greater than when they are fed unheated soybean meal.
Folic Acid (Folacin):
Folic acid plays an important role in intermediary metabolism. Due to its synthesis in the rumen, it is not a dietary essential.
Pantothenic Acid (Vitamin B5):
Pantothenic acid forms part of co-enzyme A, which is essential for the nutrients to enter the tricarboxylic acid cycle in metabolism. Its deficiency in calves is characterized by a scaly dermatitis around the eyes and muzzle, loss of appetite, diarrhea, weakness, inability to stand, and convulsions. Its deficiency is unlikely to occur in animals with normally functioning rumens (microbial synthesis).
Vitamin B12 (Cobalamin):
Vitamin B12 deficiency has been produced in preruminant calves by feeding them a diet having no animal protein. Signs of deficiency included poor appetite and growth, muscular weakness, and poor general condition.
Vitamin C (Ascorbic):
A deficiency of vitamin C can reduce the ability of neutrophils to migrate to the site of inflammation allowing for increased oxidative damage to the neutrophils and reduced production of major anti microbial agent hypochlorous acid. Ascorbic acid may also modulate the immune system via its role in regulation of hormones associated with stress. There is a close synergism between ascorbic acid and vitamin E is enhancing neutrophil function and minimizing free radical damage. Vitamin C can quench free radicals and there by protect the structural integrity of the cell of immune system.
Vitamin c is synthesized in the rumen of buffalos and cattle. It is in generally assumed that endogenously produced ascorbic acid is sufficient to meet the metabolic demands of ruminants. Under specific environmental and physiological conditions, the amount of ascorbic acid produced by the animal may be insufficient to meet its requirement.
Dairy Cow Nutrition
Dairy cow nutrition varies with phases of lactation and gestation. Lactation period of dairy cow is divided into five phases:
Phase 1. This is phase of early lactation consists of early 70 days postpartum. This is the period during which milk production increases rapidly, peaking at 6 to 8 weeks after calving. During this phase nutrient requirements are not fulfilled because feed intake does not keep pace with nutrient needs for milk production, especially for energy, and body tissue will be mobilized to meet energy requirements for milk production. Ration adjustment is an important management practice during early lactation. Fiber level in the total ration should not be less than 18 percent ADF, 28 percent NDF. Forage should provide at least 21 percentage units of NDF or about 75 percent of the total NDF in the ration. Physical form of the fiber is also important. Normal rumination and digestion will be maintained if greater than 20 percent of the forage is 2 inches in length or longer. Chopping (less than 3/8 inch theoretical length of chop—TLC), grinding, and/or pelleting all reduce physical form of fiber and its effectiveness to stimulate rumination. Protein is a critical nutrient during early lactation. Rations may need to contain 19 percent or more crude protein to meet requirements during this period.
Nutrients requirements must be met to avoid the problems like ketosis or low peak production. Loss of 1 litre milk in peak production leads to loss of 100 litres milk for lactation.
Phase 2. This phase is from 70 to 140 days postpartum during which animal reaches peak DM intake. During this phase animal is at its peak production and this production should be maintained as long as possible. Animal should be provided high quality forage along with concentrate.
Phase 3. This period is of mid to late lactation i.e. 140 to 305 days postpartum. During this phase milk production is declining and the cow is pregnant. Animal require nutrients for milk production and replace body weight lost during early lactation. Lactating cows require less feed to replace a pound of body tissue than dry cows. Young cows should receive additional nutrients for growth (2-year-old, 20 percent more; 3-year-old, 10 percent more than maintenance).
Phase 4. Phase 4 is dry period that covers 60 to 14 days before parturition. This is a critical phase of the lactation cycle. A good, sound nutritional management during this phase may lead to high milk yield during the following lactation and minimize metabolic problems at or immediately after parturition as animal is preparing for next lactation during this phase.
Dry cow requirements include body maintenance, fetal growth, and replacing any additional body weight not replaced during phase 3. Nutrients requirements during this phase are lowest. Animal should be provided 1.8-2.1% DM of body weight. A minimum of 12 percent CP in the DM is recommended. Concentrate requirements druing this phase are less. Give 1 Kg Concentrate per day to maintain ruminal movements and microflora. A high forage (85%) content is thought to be beneficial to maintain maximum rumen volume and motility. Due to higher chewing activity more saliva is produced, which will buffer the rumen and help maintain a higher rumen pH which will allow rumen wall lesions to recover from high gain rations during lactation.
Calcium and phosphorus requirements should be met, but large excesses must be avoided. Dry cow rations above 0.6 percent calcium and 0.4 percent phosphorus (DM basis) have substantially increased milk fever problems. Adequate amounts of vitamin A, D, and E in rations to improve calf survival and lower retained placenta and milk fever problems should be proved. Trace minerals, including selenium for most producers, should be adequately supplemented in dry cow diets.
Phase 5. This period is called transition period or close up period which includes last two weeks of parturition. Nutritional requirements for fetal growth are higher during this phase. Good nutritional planning is required during this phase to get high milk production after parturition. DMI intake decreases and energy requirement increases to meet fetal growth so high energy diets should be provided. Mineral and vitamin supplementation is also required. Ingredients like concentrate to be used during lactation should be started in small amounts during this phase as it reduces the nutritional stress after parturition. CP % should be exceeded upto 15%. Feeding some of additional protein in the form of undegradable protein may be beneficial in supplying amino acids for fetal growth. Fat content in the ration should be limited as high fat feeding will depress DM intake. In case of problem of edema salt should be removed from the ration.
It is the feed or feed mixture which contains all the essential nutrients in right quality and quantity as needed by the animals for maintenance, growth, work and production.
In order to meet the nutritive requirements, the amount of feed offered to an animal in twenty four hours is called ration. It can be classified as follows.
The amount of balanced ration which is required to fulfill the maintenance need of a particular animal is called maintenance ration, maintenance requirement or maintenance allowance. This helps to keep the body weight of such an animal unaltered, since it is either, growing, not yielding milk, nor working. The maintenance ration has the following functions to be performed in the body.
- To supply heat for the proper maintenance of body temperature
- To supply energy for proper functioning of heart brain, lungs and other vital organs of the body
- To repair the daily wear and tear of body tissue
- To compensate the loss of minerals from the body
- To provide essential nutrients, particularly vitamins for maintenance of life and well being
The amount of feed mixture which is given to a growing, working or producing animal over and above its maintenance need is known as production ration. This need is mostly met by feeding concentrate mixture to animals.
That feed or feed mixture containing all the essential components of a balanced ration which has the ability to fulfill all the needs of a particular animal when given according to its body weight is called an ideal ration. It should possess the following characteristics:
- It should contain all the essential nutrients like protein, fats, carbohydrates, minerals and vitamins in the right proportion as needed by the body
- It should be well balanced and economical
- It should contain enough amount of crude fibre in order to stimulate the wall of gastrointestinal tract for maximum secretion and excretion of digestive juices
- It should be nontoxic
- It should be easily available locally
- It should be easily digestible and palatable to animals
General Principles in Feeding
- The ration of the animal should be well balanced and feeding trough/table should never be emptied.
- The feed material should contain greens roughages and concentrates so that the animal may get all the essential nutrients
- Avoid sudden change in diet because it upsets the whole GIT resulting in indigestion and reduction in milk yield
- The feed requirement of animal is calculated on dry matter basis. On average dairy animals consume 3 to 4 Kg dry matter per 100Kg body weight
- Of the total dry matter requirement of the animal, two thirds should be met by roughages
- To avoid mineral deficiency in the body, the animal should be offered to 70 to 100 g mineral mixture daily. A piece of common salt should also be placed in manger.
- The animal should be fed according to their body need. Feeding less or more are both detrimental to animal health or production
- Feeding troughs should be cleaned regularly
- The animals should get ad labium clean fresh supply of drinking waster
- For milk production the animal should be given at least 1Kg concentrate mixture per 2 litres milk yield
Cattle Feed or Wanda (Balanced Concentrate Mixture)
A balanced mixture is usually prepared in such a manner that 3.5 to 4 Kg of it may support 10 litres of milk production. Normally in dairy animals this mixture is fed at rate of ½ of the milk yield (one Kg of concentrate mixture for every two litres of milk).
Balanced concentrate mixture feeding is essential for dairy animals because a single concentrate like maize, barley or oat and oilseed cake alone cannot meet the requirements properly. If a single concentrate, such as maize, sorghum, or barley is considered for feeding of 400 kg lactating buffalo yielding 10 litres milk, about 7 Kg grain will be needed to provide the protein requirement. Inferior quality hay or straw roughage is not only costly but also harmful. Similarly when high protein oilcake like groundnut and till cakes are sued as single concentrate, the excess of protein is wasted and the ratio between protein and carbohydrate is also disturbed which affects milk production.
The ingredients in wanda should be used according to following ratio:
|Cotton seed Cake||20-25|
|Rape seed cake||10-13|
|Cotton seed meal||15-20|
|Maize glutan 20%||20-30|
|Maize glutan 30%||20-25|
|Maize glutan 60%||5-10|
Different formulations for wanda for milking animals are given below:
|Cotton seed cake||10|
|Rape seed cake||12|
|Cotton seed cake||15|
|Maize Glutan 30%||20|
|Rape seed cake||15|
|Cotton seed cake||15|