Ch 8: Feeding the dairy cow

Feeding the lactating cow

1. Aim of feeding the dairy cow

Maximizing milk yield by meeting the cow’s nutrient requirements is the aim of a feeding program. The nutrient requirements will largely depend on the amount of milk produced, which in turn depends on the stage of lactation—the period from calving. Other factors affecting nutrient requirements are pregnancy and maintenance. The amount required for maintenance is largely affected by the cow’s weight, environmental temperature and activity.
Milk production follows a curve (lactation curve), hence the amount of nutrients required will depend on the point on the curve. During the dry period, the aim should be to feed a diet that provides for the fast-growing foetus, deposition of an energy reserve and regeneration of the mammary gland.

2. Nutrient requirements of a lactating cow

Energy
Quantitatively, energy is the most important nutrient considered during the formulation of dairy cow rations. Energy requirements of a lactating cow depend on

maintenance—keeping the cow alive—which depends on body size (bigger cows require more), activity (walking long distances to graze increases the requirement) and environmental temperature (too cold or too hot increases the requirement)
amount of milk the cow produces
the energy content of milk, indicated by butter fat content—the higher the fat content, the more energy required
reproductive condition—pregnant cows require more energy to cater for the growth of the calf

Protein
Like energy, the protein requirement is dependent on milk yield, maintenance (replaces the amounts lost in urine, faeces and skin), growth and pregnancy. Protein is not stored in the body and any excess is removed.
Protein is an expensive component and overfeeding should be avoided to minimize the cost. In addition, extra energy, which would otherwise be used for milk production, is used to remove the extra protein (nitrogen) from the body in form of urea in the urine.
At the same time, protein deficiency leads to reduced growth and milk yield. See Table

1. for recommended levels of dietary crude protein at different levels of milk yield.

Table 8.1. Recommended levels of dietary crude protein for dairy cows at different levels of milk yield

Milk yield (kg/day)	Crude protein in whole ration (%)
10	13
15	15
20	16
25	17
30	18

Minerals
Dairy cattle require all minerals in their diet for optimal milk production, reproductive performance and health. Although classical mineral deficiency symptoms are rare, in many cases under- and overfeeding of certain minerals does occur.
Even small imbalances or deficiencies can develop into reproductive, health and milk production problems. As herd milk production increases, it will become more critical to balance and fine-tune the dairy cow’s mineral and vitamin feeding program. Generally, the two sources of minerals include natural (organic) feeds (forages and grains) and inorganic mineral supplements to balance the minerals present in the forages and grains.
Vitamins
The dairy cow, like all ruminants, depends on rumen microorganisms to synthesize the water-soluble vitamins and vitamin K. Requirements for vitamins A, D and E must be satisfied from the diet.
Water
Although water is not a nutrient as such, it is essential for life. Water can be obtained from feed, from drinking or from within the body processes. Lactating cows need larger proportions of water relative to body weight than do most livestock species since 87% of milk is water. The amount required depends mainly on milk yield, moisture content of feed, amount of feed consumed and the environmental temperature.
Cows will drink more water if it is available at all times and when warm water is offered on cold days. Dairy cows suffer from a limited intake of water more quickly and severely than from a deficiency of any dietary nutrient. Lack of water has a big effect on feed intake, especially if the feed is low in moisture.

Figure 8.1. Typical lactation pattern of a dairy cow.

3. Lactation period

The lactation period is divided into four phases based on the cow’s physiological cycle and nutrient requirements. Feeding should be based on these phases.
Phase 1: 1–70 days
The first phase lasts from calving to peak milk production, which occurs at about 70 days. During this phase of lactation, milk production increases rapidly such that the voluntary feed intake cannot meet the energy demand. This results in an energy deficit leading to use of body reserves and to weight loss (negative energy).
The health status and feeding of the cow during this phase are critical to its entire lactation performance. The cow should be fed so as to achieve peak production. If it does not peak, feeding later in the lactation period will not result in any appreciable increase in lactation yield.
In an attempt to maximize milk production while maintaining good health, the tendency is to feed high levels of concentrates in this phase. However, if excessive concentrates are added too rapidly to the rations of non-accustomed cows, they may lead to digestive disturbances (e.g. rumen acidosis, loss of appetite, reduced milk production and low milk fat content). It is therefore recommended that concentrates be limited to 50–60% of diet dry matter, the rest being forage to ensure rumination (proper function of the rumen).
During this phase, buffers can be helpful for cows fed high levels of concentrates.
During this phase, a high-protein diet is important since the body cannot mobilize all the needed protein from itself, and microbial protein, which is synthesized in the rumen by microbes, can only partially meet requirements. A protein content of 18% crude protein is recommended in rations for high-yielding cows.
Animals that are well fed during this phase come on heat and achieve a 365-day calving interval—a calf every year.
Phase 2: 71–150 days
The second phase lasts from peak lactation to mid-lactation. The voluntary dry matter intake is adequate to support milk production and either maintain or slightly increase body weight. The aim should be to maintain peak milk production for as long as possible with milk yield declining at the rate of 8–10% per month.
The forage quality should be high. A 15–18% whole ration crude protein content is recommended. Concentrates high in digestible fibre (e.g. wheat or maize bran rather than starch) can be used as an energy source.
Phase 3: 151–305 days
The third phase lasts from mid- to end-lactation, during which the decline in milk production continues. The voluntary feed intake meets energy requirements for milk production and body weight increase. The increase is because body reserves are being replenished, and towards the end of lactation, it is because of increased growth of the foetus. It is more efficient to replenish body weight during late lactation than during the dry period. Animals can be fed on lower-quality roughage and more limited amounts of concentrate than during the earlier two phases.
Phase 4: Dry period (306–365 days)
This phase lasts from the time cow is dried to the start of the next lactation. The cow continues to gain weight primarily due to the weight of the foetus. Proper feeding of the cow during this stage will help realize the cow’s potential during the next lactation and minimize health problems at calving time (e.g. ketosis, milk fever and dehydration, dystocia).
Drying a cow
To minimize stress on the drying cow, consider the following options.

Reduce feed intake to maintenance level (withdraw concentrates).
If the cow is a low yielder, just stop milking. Pressure builds up in the udder and cuts off milk production.

• If the cow is a high yielder, practise intermittent milking, skipping some milking times (milk only in mornings) so as to reduce milk synthesis caused by pressure building up in the udder.
Temporarily withdraw water or reduce the amount for very high yielders to reduce milk synthesis.

After milking is stopped, treat (infuse) all the quarters with long-acting antibiotics to prevent mastitis from developing.

The aims of drying a cow are to

build up body reserves in time for the next lactation period—if a cow is not dried in time, milk production will be reduced during the next lactation period.
allow the cow to regenerate alveolar tissue (milk-synthesizing tissue) that might have degenerated during the lactation period.
save nutrients for the fast-growing foetus. During the last phase of pregnancy, the calf grows rapidly and the cow’s drying saves nutrients for the calf’s growth.

At the time of drying, the cow should be fed a ration that caters for maintenance and pregnancy, but 2 weeks before calving the cow should be fed on high-level concentrates in preparation for the next lactation. This extra concentrate (steaming) enables the cow to store reserves to be used in early lactation.
To avoid over-conditioning, cows should not be fed large amounts of concentrate. The aim is to achieve a body condition score of 3.5–4.0 (see Table 8.2). If the diet is rich in energy, limit the intake of concentrates. Feeding bulky roughages can help increase rumen size to accommodate more feed at parturition (birth).
Before calving, feed concentrate progressively to adapt the rumen microbial population. This will minimize digestive disturbances in early lactation when the diet changes to high concentrate.
The amount of calcium fed during the dry period should be restricted to minimize incidents of milk fever in early lactation. A ration providing 15 g of calcium per day for the last 10 days of the dry period or an intake of 30–40 g/day over the whole dry period should reduce the number of incidents.
This extra concentrate (steaming) enables the cow to store reserves to be used in early lactation. During this phase the cow may be fed good-quality forage or poor-quality supplemented with concentrate to provide 12% crude protein.
Transitional feeding (3 weeks before and after calving)
During the 3 weeks immediately before and after calving, the cow should be given high-energy, highly palatable and digestible feed (e.g. commercial dairy meal and maize germ) or starchy feeds and molasses (this is also referred to as close-up feeding). This is to prepare the cow to consume large amounts of feed (for high milk production), accustom the rumen bacteria to high concentrate levels and prevent nutritional disorders (e.g. milk fever and ketosis) that are common in early lactation without over-fattening the cow.
This period is important because there is rapid growth of the unborn calf, regeneration of the mammary tissue and colostrum production.

4. Milk from pasture and fodder

Dairy cattle can be fed on forage or on pasture with no supplementation and milk production will depend on the quality and quantity of the pasture. However, it is difficult to realize the full genetic potential of a cow fed in this manner.
On Napier grass only, the expected milk production is 7 kg/day; it is 9–12 kg/day when the cow is fed on a Napier–legume (desmodium) mixture. On grass alone (e.g. Rhodes grass or Nandi setaria), an average milk yield of 5–7 kg/day has been obtained and 7–10 kg/day on a grass–legume mixture. Oats harvested at milk stage and fed to a dairy animal can enable it to produce up to 12 kg/day.

5. Challenge feeding

Lactating cows may be challenged with increasing amounts of concentrate until there is no corresponding increase in milk production. This method of feeding is recommended only if the extra milk produced offsets the added cost of the concentrate.
Challenge feeding should take place in the early lactation, when there is a risk of underfeeding. Feed each cow the maximum amount of concentrates that it can consume, without reducing its roughage intake. Continue this until the cow reaches peak milk production, 4 to 10 weeks after calving. By using this strategy, each cow is given the possibility to show its production potential.

Use of body conditioning to assess feeding

Body conditioning can assess the appropriateness of a feeding regime for lactating dairy cows. Dairy cattle deposit their energy reserves around the pelvic area and by scoring the amount of deposit using a standard score, their condition can be assessed. Condition scores are normally on a scale of 1–5 with 1 being too thin and 5 too fat. Animals prior to calving should be in good condition (3.75–4). Table 8.2 shows body-conditioning scores and indications.
Overweight cows (over-conditioned) have been shown to be more susceptible to metabolic problems (ketosis) and to both infectious (mastitis) and non-infectious (retained placenta and lameness) health problems. They are also more likely to have difficulties at calving. Under-conditioning can lower milk production as there are insufficient energy and protein reserves for mobilization in early lactation.
Important areas assessed when scoring are short ribs, thurl, tail head, hook and pin bones (Figure 8.2). An ideal cow has a body condition score of about 3.5, but the system is designed to have cows at certain stages of lactation at certain body conditions.
After calving, cows should lose less than one point before they begin to gain weight; those losing more than one point are more vulnerable to reproductive problems.
Table 8.2. Body-conditioning scores and indications

Score	Indications
1	Skin and bones
2–2.4	Severe negative energy balance in cow in early lactation; risk of production loss
2.5–2.9	High producer in early lactation
3.0–3.4	Milking cow in good nutrient balance
3.5–3.9	Late lactation and dry cow in good condition
4	Over-conditioned; potential calving problems if dry
5	Severely over-conditioned; risk of fat cow syndrome

Source: Heinrichs AJ, Ishler VA and Adams RS. 1989. Feeding and managing dry cows. Pennsylvania State University, USA.

Figure 8.2. Areas assessed in scoring body condition.

From peak milk production to dry-off, cows should gain back the body condition that was lost before they reached the peak. Ideally, the body condition score of a cow should be taken whenever it is handled. At the very minimum, scores should be taken at freshening, breeding and dry-off. If evaluation indicates over- or under-conditioning, the feeding strategy for an individual cow or group has to be evaluated. Feed rations may have to be recalculated and corrected to satisfy the cow’s demand.

Nutritional diseases

Milk fever

Milk fever is a common metabolic disorder in dairy cattle. It generally affects older, high- producing cows. It may also be referred to as parturient paresis or hypocalcaemia.
At the beginning of lactation, high-yielding cows experience a sudden rise in demand for calcium to replace the large amount lost through milk. This may result in a great decrease in blood calcium if the cow is not able to replenish the calcium fast enough, causing a disease called milk fever.
Most milk fever cases occur within 48 to 72 hours of calving when demand for calcium for milk production exceeds the body’s ability to mobilize calcium reserves. Fever is a misnomer as body temperature is usually below normal. Low blood calcium interferes with muscle function throughout the body causing general weakness, loss of appetite and eventually heart failure.
Signs
At first, the cow experiences muscle tremors, lack of appetite and unsteadiness. Eventually, the cow is unable to rise, body temperature falls, and constipation occurs. Cows go down to a sitting position often with a kink in the neck. Death may occur if the cow is not treated promptly.
Causes
The onset of milk production drains the animal’s blood calcium levels. If the cow is unable to replace this calcium quickly, due to loss of its ability to mobilize reserves of calcium in bone and absorb calcium from the gastrointestinal tract, milk fever occurs.
Older cows are more susceptible as they produce more milk and are unable to replenish calcium quickly enough.
Prevention
Managing the diet can be a valuable aid in preventing milk fever. The key to prevention is managing a dry (close-up) cow nearing parturition, which should be kept on a low calcium diet. Such a diet stimulates the calcium regulatory system to keep the blood levels normal by mobilizing the body stores from the bone. Lucerne, a feed high in calcium and potassium, should thus not be a major ingredient in close-up dry cow diets to avoid too high calcium levels before calving.
When the demand for calcium increases at calving, calcium can be mobilized much more rapidly thus preventing milk fever. In early lactation, high-yielding cows should receive as much calcium as possible. High-risk cows can be injected with vitamin D3 2–8 days before calving.
Diets providing less than 15 g of calcium per day per cow and fed for at least 10 days before calving will reduce the incidence of milk fever.

Ketosis

Ketosis is a disorder that occurs when energy intake fails to meet the high glucose requirement necessary for maintenance and for producing milk lactose. Ketosis affects high-producing cows during the first 6–8 weeks of lactation when cows are in negative energy balance. The excessive ketone bodies in the bloodstream come from the breakdown of fat when the animal is forced to draw on its bodily reserves for energy.
Predisposing factors
Cows of any age may be affected but the disease appears more common in later lactations, peaking at about the fourth lactation. Over-conditioning at calving has been associated with increased incidence of ketosis.
Clinical signs
Many cases of ketosis are subclinical. The cow’s performance and health are compromised but there are no obvious clinical signs. Some of the signs include lack of appetite (refusal to eat even concentrates) and a sudden drop in milk output.
The urine, breath and milk carry a sweet smell of acetone. Cows have raised blood ketone levels and may excrete ketones in urine and milk. Body condition is gradually lost over several days or even weeks.
Prevention
Ketosis causes financial loss through lost production and treatment. It may be prevented by management strategies that maintain a good appetite and supply adequate feed to meet this appetite during the late dry period and immediately after calving.
These strategies include

feeding transition rations to close-up cows
ensuring cows are in body condition of 4.0 or less before calving
ensuring that any health problems that might cause reduced feed intake are treated as early as possible

Acidosis

Acidosis is a syndrome related to a fermentative disorder of the rumen resulting in overproduction of acid, which lowers rumen pH below pH 5.5. The problem is related to feeding management, where the ration has high levels of digestible carbohydrates and low effective fibre.
Causes
Acidosis may be caused by

diets high in readily fermentable carbohydrates and low in roughage
fast switch from high forage to high concentrate
excessive particle size reduction by feeding finely chopped forage

Signs
Watery milk: Acetate, one of the end products of fibre digestion, is a precursor of milk fat synthesis. A diet that is low in fibre will lead to low levels of acetate in milk and thus low levels of milk fat. As a result, the milk appears watery.

Diarrhoea—Accumulation of acid causes an influx of water from the tissues into the gut resulting in diarrhoea. Faeces are foamy with gas bubbles and have mucin or fibrin casts.
Sore hooves (laminitis)—Endotoxins resulting from high acid production in the rumen also affect blood capillaries in the hoof, causing hooves to constrict, resulting in laminitis.
Ulcers, liver abscesses—High levels of acid in the rumen also cause ulcers, allowing bacteria to infiltrate the blood and causing liver abscesses, which are seen at post-mortem.
Prevention—Good management practices are needed to prevent predisposing situations from occurring. The root problem must be found and corrected.
Buffers can also be used to prevent a drop in rumen pH when high-concentrate diets are fed. Ensuring the presence of effective fibre in the diet promotes production of saliva, which is a buffer.

Bloat

Bloat is the abnormal accumulation of gas in the rumen. There are three categories:

frothy bloat that occurs when diets lead to formation of a stable froth or foam in the rumen
free gas bloat caused by diets that lead to excessive gas production
free gas bloat caused by failure to belch rumen gases, leading to accumulation of gas (e.g. oesophageal obstruction)

Bloat occurs when gases cannot escape but continue to build up causing severe distension of the abdomen, compression of the heart and lungs, and eventually death.
Predisposing factors
Bloat is a risk when animals are grazing young lush pasture, particularly if the pasture has a high legume content (e.g. clover or lucerne). Ruminant animals produce large volumes of gas during the normal process of digestion, which either is belched or passes through the gastrointestinal tract. If anything interferes with the gas escape from the rumen, bloat occurs.
Natural foaming agents in legumes and some rapidly growing grasses cause a stable foam to form in the rumen. Gas is trapped in small bubbles in this foam and the animal cannot belch it up. Pressure builds up in the rumen causing obvious swelling on the left side of the body.
Signs

The animal stops grazing and is reluctant to walk.
The left side of the abdomen is distended.
The animal strains to urinate and defecate.
Rapid breathing—the mouth may be open with the tongue protruding.
The animal staggers.

Prevention
Pasture management: Legumes should be introduced into the diet gradually over several days. Avoid cows gorging on new pastures by feeding them on other feeds before letting them out to graze. Silage, hay or mature pasture can be used to reduce the cow’s appetite.
Initially, cows should be allowed access to the pasture only for short periods (an hour or so) and monitored closely during grazing and immediately after removal. Cutting and wilting the pasture for 2–3 hours before feeding reduces the risk of bloat.
Preventive medication: Drench with detergents and anti-foaming agents before letting animals graze.
Treatment
Insert a stomach tube through the oesophagus to release the gas. In an emergency on the farm, puncture the rumen on the left side of the animal with a sharp knife. Puncturing the rumen with the standard trocar and cannula is the quickest way to release the gas that cannot be expelled with a stomach tube.

Ration formulation

To formulate rations, knowledge of nutrients, feedstuffs (ingredients) and the animal to be fed is required. The ration formulated must be nutritionally adequate and be consumed in sufficient amounts to provide for the level of production desired at a reasonable cost.

Balanced rations

A ration is balanced when all the nutrients an animal requires are present in the feed the animal consumes during a 24-hour period. When an animal consumes nutrients in excess or in insufficient amounts, the ration is imbalanced.
Some imbalances have drastic consequences and if not corrected may lead to the death of the animal (e.g. milk fever due to calcium imbalance in dairy cows). However, most imbalances are difficult to identify as they result in some degree of loss of production, which causes animals not to realize their genetic potential.

Formulation

Ration formulation is the recipe, that is, the list and amounts of feed ingredients to be included in a ration. Before formulating a ration, the following information is needed.
Nutrients required
Obtain information on nutrients from feed requirement tables developed by various bodies.
Feedstuffs (ingredients)
Prepare an inventory of all available feedstuffs. For home-made rations, use materials available at home as much as possible; commercial feeds may use a wider range.
The nutrient composition of each feedstuff should be known. Analysis of the ingredients is most desirable but if not possible, obtain estimates from textbooks. Book values, however, can at times be misleading, especially for by-products. Also consider the palatability of the ingredient and any limitations such as toxicity.
Always consider the cost of the ingredients. Least-cost formulations should be made to obtain the cheapest ration.
Type of ration
Ration type may be complete (total mixed ration), concentrate mix or a nutrient supplement of protein, vitamin or mineral.
Expected feed consumption
Rations should be formulated to ensure that the animal consumes the desired amount of nutrients in a day. For example, if a heifer requires 500 g of crude protein per day and consumes 5 kg of feed, the crude protein content should be 10%. If it consumes 4 kg per day the crude protein content should be 12.5%.
Calculations
The simplest formulation is when two ingredients are being mixed to balance one nutrient. Using a Pearson’s square method allows blending of two feedstuffs or two mixtures. Figure 8.3 illustrates how to make a ration with 18% crude protein using cottonseed cake (40% crude protein) and maize (10% crude protein).

Figure 8.3. Calculating feedstuff proportions.

Steps

Subtract the lesser value from the larger diagonally. (Hence from the figure: 40 minus 18 = 22 and 18 minus 10 = 8.)
One ingredient must have a higher nutrient content than the desired and the other must have a lower value.
No ration can be formulated with a higher nutrient content than the highest of the ingredients or vice versa. (You cannot make a ration of 15% crude protein if both ingredients are higher than 15% or lower than 15%.)
Therefore: If 8 parts of cottonseed cake are mixed with 22 parts of maize, the mixture will have 18% crude protein.

If expressed as percentage (100 kg feed) then 8/30 x 100 = 26.7% cottonseed cake 22/30 x 100 = 73.3% maize
Confirm crude protein content
The cottonseed cake content in the ration is 26.7%, crude protein 40%; therefore it contributes 26.7 x 40/100 = 10.7. The maize contributes 73.3% of the mixture, crude protein 10%; therefore it contributes 73.3 x 10/100 = 7.3.

Feed budgeting, planning and costs

Feeding high-yielding dairy cows is a challenge to both farmers and nutritionists. Profit margins in the dairy enterprise vary and are dependent on milk prices and feed cost. Feed represents the largest input cost to produce milk (estimated to be 35–50% depending on the production system).
The cheapest way to produce milk is by using farm-grown forages. However, forages are bulky and low in nutrient content and cannot support optimal milk production.Feed costs for a dairy herd can be budgeted to determine ingredients to be purchased or grown on farm. Following is an example of how to budget for feed requirements:
Consider the size of the cow, for example 450 kg. The dry matter requirement is estimated at 3% of the body weight (3/100 x 450 = 13.5 kg).
Dry matter requirement per year is 13.5 x 365 = 4928 kg.
To obtain 4928 kg dry matter from fresh young Napier grass (contains 15 kg dry matter per 100 kg fresh Napier grass) will require 32,850 kg of fresh material. This amount of Napier grass can be harvested from about 0.65 ha of land (Napier yield is estimated at 8000 kg dry matter/ha per year under smallholder farmer conditions).
Assume a farmer has 0.4 ha under Napier grass, dry matter production per year = 3200 kg giving a deficit of 1728 kg dry matter.
If the deficit is to be covered using a commercial concentrate, the farmer will have to buy 1919 kg of concentrate (concentrate 90 kg dry matter per 100 kg fresh weight).
If the cost of concentrate is KES 21 (USD 0.25) per kg, the farmer will spend approximately KES 40,800 (USD 480) per year on it.

Costs of acquisition (consider dry matter and cost of nutrients)

When purchasing feeds off farm, the cost comparison between feedstuffs should be based on nutrients purchased rather than weight of the feedstuff. Thus the nutrient and dry matter contents of the material to be purchased should be known (Table 8.3).

Feedstuff	Cost per kg (KES)	DM per kg feed (g)	CP content (DM basis)	CP per kg DM (g)	Cost per kg DM (KES)	Cost per kg CP (KES)
Rhodes hay	6	850	7	59.5	7.0	101
Napier grass	2	150	8	12.0	13.0	166
Lucerne hay	10	850	18	153.0	11.7	65
Commercial dairy concentrate	18	900	16	144.0	20.0	125

Table 8.3. Costs of various feedstuffs
KES – Kenya shilling, DM – dry matter, CP – crude protein Kenya shilling valued at Ksh 85 to USD 1
According to Table 8.3, Napier grass may appear cheap when being purchased but the nutrient cost is high. The cheapest source of protein is lucerne but it is low in energy.

Maximum production vs maximum profit

As already mentioned, feed costs and farm gate price of milk determine the profitability of a dairy enterprise. An enterprise may opt to produce the maximum amount of milk irrespective of the profit margin. This is termed maximum production. If the milk price is high, this method may coincide with maximum profit.On the other hand, an enterprise using home-grown forage may or may not produce the maximum amount of milk but makes a profit. This happens when the cost of concentrate is too high. Farm gate price of milk also depends on location, with peri-urban farmers getting better prices.
A true maximum profit ration program includes a least-cost function, incorporates milk price information, and uses maximum profit (income over feed cost) as one of the constraints or specifications on which to formulate. To maximize profit the computer selects feeds and a milk production level to obtain a maximum profit; but for least-cost or balanced rations the computer selects only feeds to meet the nutrient requirements specified for a given level of milk production.

Feeding systems

Total mixed rations

Total mixed ration is a blend of all of the constituents of a ration fed to a confined animal, mixed to prevent separation to a specific nutrient concentration and fed at free will to the cow. In the total mixed ration feeding system, the concentrates and roughage are mixed either by hand, in small-scale operations, or in a mixer wagon. Where a mixer wagon is used, the mix is often dispensed to the cow directly from the wagon.
Before a total mixed ration is formulated, the following information is needed:
Feedstuffs (ingredients)

available feedstuffs
moisture and nutrient content of feedstuffs
cost
attributes of feed (e.g. maximum allowed in feed mix, presence of undesirable substances)
degree of processing required before mixing Cow to be fed:
body weight (to allow estimation of maintenance requirements and voluntary dry matter intake)
expected milk yield

Total mixed ration feeding
A total mixed ration can be fed to cows using either the same ration to the whole herd (no grouping) or different rations to different groups. In a non-grouping system one mix is usually formulated to suit the high-yielding cows, the risk being overweight cows.
Grouping the cows improves the precision of the feeding. The cows can be grouped according to many criteria: yield, stage of lactation, first-calf heifers etc. The main drawback of grouping is the time spent moving the cows from one group to another as production changes. These group changes can result in reduced milk yield due to social adjustment. In addition, several mixes have to be prepared and dispensed to suit each group.
The total mixed ration feeding regime has several advantages over feeding ingredients separately:

It is possible to use a wide range of feedstuffs.
Total mixed ration allows greater accuracy in ration formulation.
Cows are able to consume large amounts of feed, especially in early lactation when high intake is helpful.
Total mixed ration allows energy and protein to be used more efficiently by microorganisms in the rumen. This also results in good rumen health with few metabolic disturbances.
By mixing roughage and concentrates and feeding the mix at free will, the total nutrient intake for a group of cows can be regulated by the degree of concentration of nutrient in the feed.
Total mixed ration allows use of ingredients that singly are not very palatable. The main disadvantage of total mixed ration is the high initial investment in equipment.

Partly mixed rations

The partly mixed ration regime combines total mixed ration and individual feeding of concentrates. Roughage is mixed with some of the concentrates manually or with a mixer. The concentrate level in the mix is adjusted to fit the lower-yielding cows.
The high-yielding cows are fed extra concentrates in the parlour. The PMR system makes possible combining the advantages of a group total mixed ration with individual feeding.

Guidelines for concentrate feeding

Locally available concentrates for feeding dairy cows are of several types. The most common is the commercial dairy concentrate (referred to locally as Dairy Meal®). Concentrates can also be home made using locally available ingredients with the help of a nutritionist.
For home-made concentrates, the general rule is energy sources should form 70%, protein sources 29% and minerals/vitamins 1%.

In this video Jos teaches us how to make our own dairy meal concentrates.
The maximum amount of milk that can be produced without concentrate supplementation will depend on the quality of the pasture or forage, which has been reported to vary from 7 to 20 kg milk per day.
Guidelines on the amount of concentrate that should be fed to a cow have been suggested. The only accurate one is as calculated by a nutritionist and based on the cow’s nutrient requirements. Examples in Box 8.1 show some of these guidelines.