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Average quality roughage contains 0.5-0.57 kg TDN per kg DM and a moderate amount of protein. Examples are grasses that are not too old, young grass hay and sugarcane tops. If supplied as the only feed, a low milk production can be expected. Many types of roughage are of an average quality during the rainy season.
Good quality roughage contains over 0.58 kg TDN per kg DM and has a high protein content sufficient for a production of up to 10 kg of milk per day. Examples are young leafy grass, legumes (Leucaena, Desmodium, Alfalfa, Stylosanthus) and cassava leaves.
Grazing alone involves an average of 8-10 hours a day; (selective) grazing on poor quality roughage may take longer. In hot climates animals prefer to graze during the cooler hours of the night. Ruminating takes up another 8 hours, the cow resting for the remainder of time.
Roughages like grass, legumes and crop residues form the basis for feeding dairy cattle. In exceptional circumstances of year-round availability of young green and tender grass or legumes, cows will be able to produce nearly 10 kg of milk per day without any concentrates. If Feeding the roughage is poor, cows will not produce any milk and if no concentrates are fed they even lose weight. In the tropics, dairy cows generally need concentrates to produce milk. Poor roughage quality is barely enough for maintenance during the dry season and just average during the rainy season, covering the requirements for about 5 kg of milk per day.
Figure 3: Eating and ruminating A: The cow is eating, the grass goes to the first stomach, the rumen B: Ruminating, the grass comes back to the mouth and is chewed C: Ruminating: the grass goes to the second stomach where it is digested
2.1 What do dairy animals need Animals need water and feed to live, grow, work and produce milk and calves. Even at rest an animal needs energy and protein to stay alive, breathe, walk and ruminate. These basic needs for maintaining a stable condition are called ‘maintenance requirements’. If an animal’s maintenance requirements are not covered, it will lose weight, not come in heat and might fall ill. Maintenance requirements depend on body weight: a heavy animal needs more energy and protein for its maintenance than a leaner cow. If the farmer wants animals to grow, work, produce milk or calves, they need additional nutrients. These 14 Dairy cattle husbandry are called its ‘production requirements’. Proportionally more protein is needed for production than for maintenance.
Water Water is essential. Without water animals may die in a couple of days and if they cannot drink enough water, their feed intake will be reduced as well. Dairy cows need permanent access to clean and cool drinking water. If this is not possible they should be offered drinking water ad lib at least twice a day. A 500 kg cow may drink 60 to 100 litres per day, depending on her production, water content of the roughage and climate.
Energy Animals need energy to maintain their bodies, to move, to grow, to produce milk and calves. The needs of animals and the energy value of feedstuffs can be expressed in different ways. In this booklet we use the TDN (total digestible nutrients) system. Kilograms (kg) of TDN can be converted into digestible energy (DE) and metabolisable energy (ME), expressed in megajoules (MJ) or megacalories (Mcal). For conversions see box.
Be aware that energy and protein content of a feedstuff can be expressed in the fresh feed, including water, or on a DM basis. For example, if fresh grass with 20% DM contains 10 % TDN (or 0.1 kg TDN per kg of grass), on a DM basis it contains 10 * 100/20 = 50% TDN or 0.5 kg TDN per kg DM. For the composition of feedstuffs we will use the DM basis.
Main sources of energy in feedstuffs are carbohydrates (starch, sugars, digestible fibres) and fats. Feedstuffs rich in energy are concentrates (cereals, oil seeds and their by-products, molasses) and good roughage. Straws and mature grasses have a low energy and protein content and are slowly digested because they contain much indigestible fibre.
Feeding Proteins Proteins are essential building materials for the animal body and they are a vital component of milk and meat. So animals need protein for maintenance of their bodies, for growing and especially for producing milk and calves. When a cow gives more milk it needs proportionally more protein.
Protein needs of animals and content of feedstuffs can be expressed in different ways. Here we use crude protein (CP) in grams per kg DM feed. If a feed contains 18% CP on a fresh base with 90% DM content, then on a DM base it contains 18 * 100/90 = 20% CP or 200 gram CP per kg DM. Important sources of proteins are young grasses, legumes (Alfalfa, Leucaena) and oilseeds and their cakes. Cereals, cassava meal, molasses and mature roughages are low in protein.
Urea is sometimes used as a ‘protein’ source for ruminants. However, this chemical product, which is also used as fertilizer, is poisonous in high quantities. So be careful.
Minerals Animals need small amounts of common salt and minerals, calcium and phosphorus being the most important. If cows are fed a variety of feeds, they often get all the minerals they need. However, in many regions of the world feedstuffs do not contain all the necessary minerals, so it is wise to provide cows with a mineral mix. Buy a good quality mix and give your animals free access to it so they can eat as much as they want. But be cautious and introduce the mix gradually if the animals are not accustomed to minerals, otherwise they may overeat and fall ill. It is best to offer the mineral mix and salt separately.
Other needs Well-balanced dairy cattle rations contain enough vitamins, so it is normally not necessary to pay special attention to vitamins.
As cattle are ruminants, they need a certain amount of fibre (structure) in their ration. But this is seldom a problem in the tropics. On the conDairy cattle husbandry trary, most roughage contains too much fibre, which restricts the amount the animals will eat because it is digested slowly.
Daily requirements of cows Table 2 lists daily requirements of cows according to their weight and production.
Table 2: Daily requirements of cows
2.2 Feedstuffs for ruminants Feedstuffs consist of water and dry matter (DM). Young fresh grass contains about 20 % DM, straws have over 80% and concentrates 90 % DM, the remainder is water. Dry matter contains energy, protein and minerals.
A cow weighing 500 kg and offered good young grass may eat 12 kg of DM or 60 kg of fresh grass per day. That same cow will eat only about 7 kg of dry straw a day. If small amounts of concentrates are offered, the cow will eat these as extra. However, if large amounts of concentrates are given, the animal will eat less roughage.
Roughages The better the roughage, the more the animal will eat, the more energy and protein it can absorb and the less concentrates it will need. As concentrates are generally more expensive than roughage, trying to provide the best roughage is worthwhile. See Chapter 3 for more information about roughages.
Table 3: Composition of some roughages. Large variations occur due to growth stage, fertilization and season.
18 Dairy cattle husbandry Concentrates
Concentrates or supplements are given in addition to roughage. Although more expensive than roughage, they are essential when roughage alone cannot satisfy the animal’s maintenance and production requirements. Concentrates are especially useful in the following situations:
? During early lactation to stimulate the cows to fully express their genetic potential for milk production. They cannot cover their requirements and reach peak yield on roughage alone.
? For all producing cows during the dry season when roughage is of poor quality.
? For calves up to 10 months because their rumen is not yet fully functioning.
As a general rule for lactating cows one kg of balanced concentrates covers the requirements of 2 to 2.5 kg milk. This implies that it is justified to feed concentrates if they cost less per kg than 2 kg milk, which is nearly always the case.
Balanced concentrates can be bought readymade or can be mixed at the farm. Readymade concentrates are best but also the most expensive. They normally consist of different cereals or their by-products, oilseed cakes, salt and other minerals.
Mixing concentrates Some of the following ingredients can be combined to make a balanced concentrate mix on the farm. The composition is given on a DM basis.
The ingredients for concentrates can be divided into energy supplements and protein supplements. The first group (Table 4) contains feedstuffs with a lot of energy but little protein; they should be combined with protein rich supplements.
The protein rich supplements are frequently also rich in energy. They are especially used for mixing with the cheaper energy supplements.
The mix of maize bran and cottonseed cake is commonly used in Africa, the mix of rice bran and coconut cake in Asia. Of course other mixes are also used, such as soybean or groundnut cake as protein source plus wheat or maize bran for energy. For 2 kg milk, 0.66 kg TDN and 156 g CP is required, and this is provided by 1 kg of such a mix.
2.3 Body Scores Body scores can be given to assess the condition of dairy cows. The thinner the animal, the lower its body score (see Figure 4).
20 Dairy cattle husbandry Figure 4: Body scoring of dairy cows from the appearance of the tail head: 1= poor, 2=moderate, 3=good, 4=fat
Details of the body scores:
1= Muscles, tail head and lower back vertebrae are shrunken and hollow. No fatty layers can be felt. Skin is supple and freely moveable.
2= All bones can easily be felt. Muscles sunken around tail head.
Some fatty layers.
3= All bones can be felt but are well covered with fat.
4= Folds and patches of soft fat under the skin. Hipbones can be felt by firm pressure. Side bones of vertebrae cannot be felt.
At the time of calving, cows should have a body score of 3 to 3.5. A lower score means a lower milk production. Cows with a higher body score are more prone to milk fever and often have difficulties at calving. They reach lower peak yields because their appetite is reduced.
Placenta retention occurs more often in fat cows.
When the body score falls below 2, cows may not come in heat and they have less chance of getting pregnant. Their milk production is reduced as well. A body score of 2 or lower is a clear sign to the farmer that something is wrong with the cow’s feeding or health.
Sometimes body scores 0 (very poor) and 5 (very fat) are used but they have little practical relevance.
2.4 Practical feeding Roughage is the basic cattle feed; it is generally cheaper than concentrates and it assures proper rumen functioning. Good roughages include young grass, maize silage of the entire plant, leafy hay and tender legumes without too much stems. Straw is low-quality roughage;
treatment with urea will do little good. In many cases supplying concentrates to lactating cows is necessary to increase milk production.
Cows should be able to eat as much roughage as possible, so it should be provided at least twice daily, but preferably 4 times. Cows are selective feeders; they like to eat only the best part of the roughage. So if possible offer them plenty, enabling them to select the best parts.
Leftovers can be used as bedding or in compost making; they should amount to10% at least, and 20 to 30% in the case of poor roughage.
The feed intake of cows just after calving is low, which implies that they will lose weight. Milk production increases, peaking at about 50 days after calving. (See figure 5.) Cows losing weight are less likely to get pregnant again. So give the best roughage to the high-yielding cows during the first 100 days of lactation.
Figure 5: Lactation curve, DM intake and body weight fluctuations
22 Dairy cattle husbandry Roughage DM intake of about 2-2.5 % of body weight can only be achieved if animals have access to a permanent supply of quality feed.
Provide 1 kg of balanced concentrates for each 2 to 2.5 kg of milk produced. Stimulate peak yield by giving more concentrates than the cow would need for her actual production during the first 60 days of lactation. During the first week after calving concentrates fed should be increased by not more than 0.5 kg per day.
Amount and quality of concentrates fed per day depend on roughage quality and milk yield (see table 6). Concentrate supplement is justified if its price per kg is lower than the price of two kg milk.
Table 6: Kg of concentrates per day in relation to production and roughage quality
Dairy cows should not be too skinny or too fat. A cow that is too skinny (body score 2) shows she does not get enough feed or that she is ill, so her production will drop. A cow that is too fat (body score 3.5) has been given too much (expensive) feed and this often happens at the end of the lactation or during the dry period. Fat cows may present difficulties at calving and are much more susceptible to digestive problems. Start giving some concentrates (1-2 kg per day) to high potential cows during the last 1-2 months of pregnancy but avoid letting them get too fat.
At the end of lactation, cows should be in good condition, not too thin but certainly not too fat. A body score of 3 to 3.5 is correct. This average condition and body score should be maintained during the dry period. Feed about 1-2 kg concentrates daily, as if they were producing about 5 kg milk a day.
Feeding Producing cows should be offered cool drinking water ad lib at least twice a day. Animals should have free access to salt and a mineral mix. Cows will consume about 50 grams of salt and minerals per day, young stock about half that.
Straw is better as bedding than as feed.
Many farms combine dairy production with the cultivation of crops.