1. Concentrates
Concentrates are rich in nutrients (energy and/or protein) and provide far more nutrients than an equivalent weight of roughage. They are low in fibre and usually have higher dry matter content. They include compounded commercial feeds (e.g. dairy meals, cubes and pellets) as well as single ingredients, such as pollard, maize germ meal or cottonseed cake.
1. High-energy concentrates
Concentrates are added to a ration primarily to increase its energy density. They are mostly cereals or cereal by-products, roots and tubers, or liquid feeds like molasses, fats and oils. They also contain other nutrients—proteins, minerals and vitamins—but in small quantities. See Table 5.1 for a list of energy sources for dairy cattle.
Use of whole cereals for feeding dairy cows is not common due to their high cost and competing use as food for humans, thus their by-products are more commonly used.
2. High-protein concentrates
All the energy sources discussed earlier also supply protein but usually not in enough quantity to meet the animal’s requirements. Protein supplements are defined as feedstuffs that contain more than 20% crude protein on a dry matter basis. The main sources are animal, marine, plant, microbial or non-protein nitrogen. The choice depends on availability and cost of the feedstuff (Table 5.2)
3. Non-protein nitrogen
Non-protein nitrogen includes nitrogen compounds that rumen microorganisms use to synthesize protein, which the animal can then use. Examples include ammonia, urea and DAP. In practical feeding, non-protein nitrogen refers to compounds added to feed such as urea. Non-protein nitrogen is used only in ruminant feeds, since simple-stomached animals cannot use ammonia from the urea breakdown.
Of all the non-protein nitrogen sources, urea is the cheapest, thus widely used. Animals fed on poor-quality roughage should not be fed non-protein nitrogen as the energy required to utilize urea may not be available. Under these circumstances, true proteins (e.g. cottonseed cake) should be fed or urea mixed with a good energy source such as molasses.
4. Urea toxicity
Urea can be toxic or lethal depending on the size and timing of the dose. The level of urea the animal can tolerate is affected by its adaptation to urea and the type of diet, among other things. Urea toxicity is treated by administering vinegar (acid) to reduce the rumen pH and prevent further absorption.
Table 5.1. Common energy sources for dairy cattle
| Ingredient | Source | Remarks |
| Maize grain | Whole grain | Rarely used as feed except for high- yielding cows |
| Maize bran | Outer coating of the maize grain | Has moderate energy, CP 11%, CF 10% |
| Full fat maize germ | Embryo, which contains a lot of oil | High-energy content |
| Maize germ meal or cake | Left over after extraction of oil from germ | High-protein content |
| Wheat bran | Coarse outer covering—the husk and some adhering endosperm | Fibre highly digestible, CP 15%, CF 12% |
| Wheat pollard (middlings) | Part of endosperm, germ, bran particles and some flour | Not as palatable as bran due to its tendency to form a pasty mass in the mouth, CP 16%, CF 7.5% |
| Barley | Mostly rejected barley | Low starch content, high fibre. Best fed when steam-rolled to increase digestibility, CP 11% |
| Multiculms (multisprouts) | Sprouts and rootlets obtained from malted barley | Mostly used as protein supplement, CP 27%, CF 16% |
| Wet brewers grain (‘machicha’) | Insoluble residue left after fermentable substrates from barley are removed | High moisture content. Wet grains rapidly become rancid. Use immediately or ensile in absence of air, CP 18%, CF 15% |
| Sorghum | Resembles maize nutritionally | Should be fed to cattle and horses in ground form, CP 12%, CF 3% |
| Rice hull | Low nutritive value, very fibrous | Due to the high fibre, these hulls are of low digestibility and therefore of little value |
| Rice bran | Pericarp, aleurone layer, germ and some endosperm | Very palatable when fresh; CP 12.5%, CF 13%, fat 10–13%. Becomes rancid with storage due to high fat content |
| Rice polishing | Fine powdered material obtained when polishing rice grain after hulls and bran have been removed | CP 12%, CF 4%, fat 11% |
| Ingredient | Source | Remarks |
| Oats | Whole grain | Good cereal for cattle due to high fibre content from the hull, CP 11–14%, CF 12% |
| Cassava root | Whole | Freshly harvested cassava has a high level of prussic acid; boiling or sun drying destroys the poison |
| Cane molasses | By-product from sugar cane milling, dry matter 75%, CP 5.5%, CF 0.3% | Provides energy, improves palatability of poor-quality feedstuffs; levels > 25% can cause diarrhoea and reduced feed efficiency. Molasses is of value in reducing dust in feed, as a pellet binder, or as a liquid protein supplement when mixed with urea |
| Fats and oils | Waste fat from eateries | Used to increase the energy density and to reduce dust. High levels of fat in diets lead to rancidity; > 8% fat in ration can cause rumen disturbances |
CP – crude protein, CF – crude fibre
Table 5.2. Common protein sources
| Source | Comments |
| Soybean/ soybean meal | Very palatable and highly digestible. The whole seed has 40% CP and 15–21% oil, which is extracted to make the meal. Extracted meal contains 47% CP. Raw beans have less nutritive value than heated beans or soybean meal, due to toxic substances. The toxins are especially harmful to young animals (calves) |
| Cottonseed/ cottonseed cake | Whole cottonseed has been used with good results for early lactating cows for its energy (fat), protein and highly digestible fibre. CP of whole seed 23%, of cake 35%. Cattle digest it well |
| Sunflower cake | In cows has performance similar to soybean and cottonseed cake. CP 26% |
| Peanut (groundnut) meal | Remains after extraction of oil from groundnuts. CP 45%; aflatoxin contamination may be a problem |
| Corn gluten feed | Mixture of maize bran and gluten. By-product during wet milling of maize. CP 21–23% |
| Corn gluten meal | Dried residue from the maize after removal of the larger part of starch and germ and separation with bran in wet milling. CP 40–60% |
| Coconut (copra) meal | Residue after extraction and drying of coconut meat. CP 20–26%. Has high fat content and may become rancid if stored long |
| Dried brewers yeast | By-product from brewing. Rich in CP (42%) |
| Meat meal, meat and bone meal | Made from carcass trimmings, condemned carcasses, inedible offal and bones. High fat content increases energy. Ash content is high: up to 28–36%, 7–10% of this being calcium and about 4–5% phosphorus |
| Blood meal | Produced from dried (either spray or cooker dried) ground blood. It has a high by-pass rate, thus is good for cows. CP 85% |
| Dry poultry waste | Excreta collected from caged birds, CP 25–28% (dry basis) of which 30% is true protein |
| Poultry litter | Mostly from broiler operations. Can be fed as is or ensiled with other products |
| Fish meal | Clean, dried, ground tissue of undecomposed whole fish or fish cuttings with or without extraction of part of the fat. Locally ‘omena’ is used as fish meal, CP 55%. High levels of fish meal or fish meal with high oil content may give an undesirable flavour to meat or milk. There is no special advantage in feeding fish meal to dairy cattle unless it is for by- pass protein. This protein, however, is expensive. |
CP – crude protein
It is recommended that not more than 1% of the total nitrogen in concentrates be supplied by urea or any other non-protein nitrogen compound. In total mixed rations, urea should be restricted to not more than 0.5% of the diet (dry matter basis). More than this may make the feed unpalatable and reduce feed intake.
2. Minerals
Minerals make up a small portion of the diet but have a major functional contribution. Often their content in the basal diet is inadequate for high-producing dairy cows and supplementation is required. As roughages and concentrates cannot supply all the required minerals, supplementation with a mineral source is recommended.
The level of mineral supplementation depends on the mineral content of the basal diet. The mineral level in plant material in turn depends on the mineral content of the soil. As much as possible, the basal diet should meet the mineral requirements. Individual requirements for minerals depend on age and level of production.
Depending on the amount required, minerals are classified as macrominerals (g/day) or microminerals (mg/day or ppm). Table 5.3 shows some of the most commonly used sources for the macrominerals.
Table 5.3. Typical levels of minerals in commonly used supplements
| Supplement | Dry matter (%) | ||||
| Calcium | Magnesium | Phosphorus | Potassium | Sodium | |
| Sodium chloride | — | — | — | — | 39.34 |
| Limestone | 34.00 | 2.06 | 0.02 | 0.12 | 0.06 |
| Magnesium oxide | 3.07 | 56.20 | — | — | — |
| Di-calcium phosphate | 22.00 | 0.60 | 19.30 | 0.10 | 0.10 |
Microminerals are commonly added to the ration as pre-mixes obtained from commercial pre-mix manufacturers or through commercial mineral supplements. The mineral mixes are specific for age and level of production.
1. Mineral feeding methods
Force-feeding
Force-feeding is recommended for feeding minerals to dairy cows as it eliminates palatability problems, daily and cow-to-cow variation in intake, and over-consumption of minerals. The best method of force-feeding is in a total mixed ration. Another commonly used method is to use a grain carrier. This method is suitable where the requirements can be predicted fairly accurately.
Free choice
The free choice method is not as accurate as force-feeding but is very practical. The mineral supplement, which is usually in powder or block form, is purchased and placed in a mineral box. Construct a mineral box and place it in the housing unit or at a strategic place in the grazing area. The box should be raised from the ground and covered with a roof to protect the mineral from the rains. Animals consume the mineral ad libitum (as much and as often as desired).
Topdressing
The topdressing method is often used for stall-fed cows where individual feeding is practised. The mineral mixture in powder form is sprinkled on the chopped material and the animal consumes it as it feeds. The problem is the minerals may separate and settle at the bottom of the trough.
3. Vitamins
Most of the vitamins required by a dairy cow are present in the diet in sufficient amounts. Water-soluble vitamins are synthesized by rumen bacteria. Animals consuming aged grasses or improperly cured hay may require vitamin A supplementation.
4. Feed additives
Feed additives are non-nutritive in nature but are used to improve performance through improved feed use or by benefiting in some manner the health or metabolism of the animal. Several additives have been used for dairy cows. Feed additives are, however, neither a requirement nor a guarantee of high productivity or profitability.
An additive should be used only if income is increased over the cost of the additive. If the cost of additive equals the increase in product, there is no financial benefit in using it. The withdrawal period or product discard period should also be considered.
Factors that should be considered to determine whether to use a feed additive include anticipated response, economic return and available information. Response refers to the expected change in performance the user could expect or anticipate when a feed additive is included. Returns reflect the profitability of using a selected additive. One guideline is that an additive should return two shillings or more for each shilling invested to cover non-responsive cows and field conditions that could minimize the anticipated response.
Some of the changes brought about by different additives include
- higher milk yield (peak milk and/or milk persistency)
- increase in milk components (protein and/or fat)
- higher dry matter intake
- stimulated rumen microbial synthesis of protein and/or energy production
- increased digestion of nutrients within the digestive tract
•stabilized rumen environment and pH
- improved growth (gain and/or feed efficiency)
- reduced heat stress effects
- improved health, such as reduced ketosis, reduced acidosis or improved immune response
Bloat control products
Bloat control products are added to feed to prevent bloat, especially when animals are grazing on young grasses or legumes. Examples are Bloat Guard® (poloxalene) and Rumensin®.
Buffers
Buffers are added to dairy cattle rations to mitigate against drastic pH changes in the rumen. High concentrate rations or sudden change from high roughage to high concentrate will result in excessive production of acid in the rumen. The resultant low pH of the rumen changes the microbial populations, favouring acid-producing bacteria. This leads to rumen upsets and reduced fibre digestion, which can be mitigated by buffers through stabilizing the rumen pH. Examples are sodium bicarbonate (baking soda), sodium sesquicarbonate and magnesium oxide.
Probiotics (microbial enhancers)
Probiotics are substances that contain desirable gastrointestinal microbial cultures and/or ingredients that enhance the growth of desirable gastrointestinal microbes, for example, Yea-Sac®, effective microorganisms and Diamond V-XP®.
Ionophores
Ionophores are feed additives that change the metabolism within the rumen by altering the rumen microflora to favour propionic acid production. They are effective in altering the composition of rumen microflora by favouring some types resulting in increased propionic acid production and decreasing production of acetic acid, methane and carbon dioxide. This improves efficiency of feed utilization by reducing gases thus lowering pollution by dairy cattle. Examples are Bovatec® (lasolacid) and Rumensin® (monensin).
Complete meals vs concentrate mix
Total mixed ration exemplifies a complete meal. It is defined as a mixture of all diet ingredients formulated to a specific nutrient requirement, mixed thoroughly and fed ad libitum to the cow.
Concentrate mix is formulated to supplement a basal diet and thus it is not a balanced feed (see Table 5.4). Animals supplemented include those grazing or fed on a basal diet of roughage.
Table 5.4. Kenya Bureau of Standards specifications for dairy cattle concentrates
| Nutrient | Percentage | ||
| Dairy calves | Heifers | Mature cows | |
| Moisture (max) | 12 | 12 | 12 |
| Crude protein (min) | 18 | 14–16 | 14–16 |
| Non-protein N (max) | 0 | 2 | 2 |
| Crude fibre (max) | 8 | 12 | 12 |
| Crude fat (max) | 3.0–8 | 3–6 | 3–6 |
| Calcium (min) | 0.7 | 0.7 | 0.7 |
| Phosphorus (min) | 0.5 | 0.5 | 0.5 |
| Common salt | 0.5–0.6 | 0.5–0.6 | 0.5–0.6 |