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.
There are two types of feed resources used for Livestock feed.
Roughages are plant material in a fresh dried or ensiled state which are bulky and fibrous in nature and normally contain higher percentage of crude fibre (18%) and low percentage of TDN (less than 60%). There are two types of roughages including green roughages and dry roughages.
Fodders, forages, range grasses, sugar cane tops, and tree leaves are the examples of green roughages. Green roughages are high in moisture content, easily digestible and are commonly used for the feeding of dairy animals. Pasture species which are naturally growing are called forages while those which are cultivated are called fodder.
There are two types of fodders depending upon the amount of protein present. These include leguminous fodder and non-leguminous fodder. Leguminous fodders are higher in nitrogen/protein content because they have the ability to utilize the environmental nitrogen with the help of nitrogen fixing bacteria present in their roots. On the other hand non leguminous fodder have no such ability so they are low in nitrogen content. Important legume fodders are barseem, lucerne, shaftal, soyabean and cowpea. Non leguminous fodders include many cereal fodder crops such as maize, sorghum, millet and oats.
On the basis of growing season green fodders in Pakistan are classified as Rabbi fodders and kharif fodders. Rabbi fodders are grown in November and December and include barseem, oats, barley, mustard/rape seed, lucern and sugar cane etc. Kharif fodders are grown in May-June and include sorghum, millet, mott grass, sadabhar, guar, jantar, sugar beet tops.
Dry roughages include hays, straws, stovers and hulls. Hay is prepared by drying the fodder and then preserving it. In Pakistan farmers mostly prepare hay from lucerne, sorghum, millet, oats and grasses. Hay is used during the scarcity period of fodder.
When the grain portions of the crops are removed, remaining dried plant material are straws and stovers. They consist mostly of stems and leaves. These may also be termed as crop residues. These are low in protein, high in fibre, less digestible, low in minerals and cannot be consumed in large quantities by the animals. Therefore they are classified as poor quality or low quality roughages. The commonly available straws and stovers in different areas of Pakistan are wheat straw, rice straw, barley straw, chickpea straw, moth and moung straw, and soyabean straw, maize stovers and sorghum stovers.
Hulls are the outer hard coverings of grains which are obtained as by product during seed processing. Cottonseed hulls are commonly used for livestock feeding in some parts of country. Seeds broken in processing are mixed in with the hulls to increase their nutritive value. Rice hulls are also abundantly available but they are of extremely poor quality.
Concentrates are high in energy and protein, low in fibre and highly digestible. Being the expensive part of feed these are used mostly in small quantities as supplement. Concentrates are of two types: energy rich concentrates and protein rich concentrates. Protein rich concentrates further differentiated on the basis of their origin as plant origin and animal origin.
Energy Rich Concentrates
Cereal grains (wheat, maize, barley, oats, sorghum, rice), wheat bran, rice polishing, molasses, and sugar beet pulp are characterized as energy rich concentrates. Although cereal grains are mainly used as human food and not included in the feed of dairy animals but their byproducts like rice polishing, maize bran and wheat bran are commonly used as animal feed.
Molasses is by product of sugar industry. It is a thick viscous material which is high insoluble carbohydrates and some minerals. Although molasses is a cheap and energy rich feed but still it is not commonly used by local farmers. Molasses can be included in the diet by mixing it with other concentrates, spraying it on dry roughages or providing it as a free lick or as solidified molasses urea block. The palatability and consumption of poor quality roughages are increased by the use of molasses. Fats and oils contain about 2.25 times as much energy as carbohydrates or proteins. Due to their cost, fats and oils are not routinely used for livestock feeding.
Protein Rich Concentrate
Protein rich concentrates are derived from plants and animals. Protein concentrates of plant origin are mostly by products of the oil extraction industry. Oilcakes are produced when oil from seed is extracted mechanically while oil meals are the byproducts of the solvent extraction process. Compared to oil meals oilcakes are low in protein and high in residual fat. They generally include the fibrous part of seeds. Among the available oilcakes, cottonseed cake and maize oilcake have high protein value for ruminants due to their low ruminal degradability as compared to mustard seed cake which is highly degradable. Generally all animal origin proteins are less degradable in the rumen and therefore are good sources of protein for ruminants. These include blood meal, fish meal, bone meal, meat meal, feather meal. But concentrates of animal origin are normally not recommended in ruminant’s feeding.
Feeding Requirements of Dairy Animals
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.
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.
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).
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 non protein nitrogen (NPN) sources. Urea and ammonium slats are examples of NPN sources.
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 micro mineral and macro mineral. Macro minerals are those which are required in relatively large amounts while micro minerals are those which are required in small amount. Micro minerals are also called trace elements.
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.
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 water.
- For milk production the animal should be given at least 1Kg concentrate mixture per 2 litres milk yield.
Balanced Concentrate Mixture (Cattle Feed or Wanda)
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).
Forage which has been grown while still green and nutritious can be conserved through a natural ‘pickling’ process. Lactic acid is produced when the sugars in the forage plants are fermented by bacteria in a sealed container (‘silo’) with no air. Forage conserved this way is known as ‘ensiled forage’ or ‘silage’ and will keep for up to three years without deteriorating. Silage is very palatable to livestock and can be fed at any time.
- Stabile composition of the feed (silage) for a longer period (up to 5 years);
- Reduction of nutrient loses which in standard hay production may amount to 30% of the drymatter (in silage is usually below 10%).
- More economical use of plants with high yield of green mass.
- Better use of the land with 2-3 crops annually.
- Requires 10 times less storage space compared to ha.
- Maize silage has 30-50% higher nutritive value compared to maize grain and maize
- 2 kg of silage (70% moisture) has the equal nutritive value of 1 kg of hay.
Steps in the Preparation of Good Silage
To get a good silage one should take care at every stage of ensiling.
Selection of Fodder
There should be adequate amount of fermentable carbohydrates and more than 65% moisture in fodder selected for silage making. Commonly used fodder for silage making are maize, sorghum, millet, oat, and sorghum sudan grass. Leguminous fodder crops can also be used for silage making but they contain fewer amounts of carbohydrates hence molasses or mineral have to be sprinkled over them at the time of silage making. Most of the time maize is used for silage making as maize silage is considered the best silage throughout the world.
Harvesting and Chopping of Fodder
Crop should be harvested at the stage when there are maximum nutrients present in crop and 65-70% moisture content. In case of maize moisture reaches this level when:
- Color of Lower leaves of plant starts changing to light green
- Husk’s color is from green to light green
- Kernel has visible dent
- There is 40-50% moisture in grain
- Kernel Milk line is 50%
Grab test is used to measure the moisture concentration in fodder. To check the moisture, take a hand full of fodder and press it in hand for few seconds. On opening of hand, there will be a ball of fodder.
- If this ball suddenly opens, it means moisture connect is too low.
- If this ball remains it shape, it means moisture content is too high.
- If this ball opens slowly, it means moisture content in fodder is suitable to be ensiled.
Filling of Silo
After chopping and adding additives silo is filled. Inside silo chopped fodder should be compressed with tractor or some other means so that it is packed tightly and there is no air left. If air left anaerobic condition will not be created. In case of baled silage, silage baler makes bale in well compacted form.
Sealing of Silo
The air tight sealing is necessary to avoid the entrance of air in the silo. So after filling of silo, cover it with polythene sheet and put tires or sand filled bags over it or cover it with mud (Lepai). It is better to cut tires in small circular pieces for maximum usage. In case of baled silage baler automatically wrap the bale with wrapper.
Removal of Silage
After a period of 40-45 days the silage is ready for feeding to the livestock. After the removal of silage the open end of the silo should be covered in such a manner that contact with the air is minimum.
Quality of Silage
Good silage should have a milk, pleasant aroma, an acid taste and a slightly greenish color. It should be free from sliminess and mold and have sufficient acid to prevent further action of microorganisms.
Efficient and accurate estrus detection is the most important factor limiting reproduction in most dairy animals/herds. Efficiency defines the proportion of dairy animals seen in estrus of all animals eligible for showing estrus. Accuracy gives the percentages that were correctly identified as being in estrus. In a well-managed herd, the maximal estrus detection rate was found to be 60% of ovulations when dairy animals were observed two or three times daily. With continuous observations, the detection rate may increase to 95% in the second and later postpartum ovulations. Failure to observe animals in estrus delays first service, lengthens oestrus intervals, and is one of the primary factors lengthening projected average minimum calving to conception interval by increasing the number of days open. It contributes more to lengthy calving intervals than conception failure. In addition, inaccurate estrus detection lowers conception rate. Many animals are inseminated when not in estrus.
Efficient reproductive management depends on the ability to detect estrus. There should be a systematic program for estrus detection. Criteria of such a program:
- Frequency of observation (three times a day minimum)
- Time allotted for observations (10 minutes per time for a herd of 50 animals)
- Assignment of employees to estrus detection (no other duties at estrus detection times).
Primary Signs of Estrus
Stand to be mounted, bellowing, restlessness, swollen and reddish vulva, mucous discharge.
Secondary Signs of Estrus
Increased urination, low feed intake, rough hair on back and tail, isolation from other animals, low milk production
Collection of semen from male, processed, evaluated in lab and then transferred to female reproductive tract by artificial means for the purpose of conception is called artificial insemination. It is most widely accepted technique worldwide for the genetic improvement in animals.
- It increases the efficiency of bull usage.
- It increases the potential for genetic selection
- It decreases the inbreeding
- It is cost effective.