Proper feeding is very important for the success of dairy farming and represents the highest single variable cost in livestock production. First, a farmer needs to understand the nutritional requirements of his dairy animals in order to provide the right ration.
To maximise milk yields, a cow must be fed on a balanced and adequate ration according to its requirements.
Feeding dairy cows for efficient production involves supplying five classes of nutrients in appropriate amounts. In order of descending priority, the nutrients are used for purposes of life maintenance, growth, reproduction and production.
For instance should a cow on its second month of lactation be indisposed through disease such that its feeding is impaired for a few weeks, the animal first responds by cutting on milk yield.
Afterwards, the cow fails to show heat signs and if it had been served already, conception or pregnancy failure follows before it gradually grows thin and eventually dies.
The five classes of nutrients are:
a) Energy
High producing cows usually cannot consume adequate feed during early lactation to meet their energy requirements. The energy deficiency is made-up by converting body fat to energy.
However, this leads to loss of body weight where the cow could lose as much as 0.7 kilos per day. This loss should be kept to a minimum to avoid metabolic disturbances.
Bearing in mind that early lactation is the period when peak milk yield is attained, the farmer therefore needs to feed a dairy cow adequately during the last trimester of pregnancy.
This activity is commonly known as steaming up. The main sources of energy are provided by carbohydrates and fats. Common sources of carbohydrates include maize, sorghum, oats and grasses such as Kikuyu, Rhodes, star, brachiaria and Napier.
b) Protein
Proteins constitute approximately 3.2 to 3.5 per cent of milk meaning that a cow producing 25 litres of milk per day secretes about 800 to 900 grammes of protein daily.
Unlike energy, proteins cannot be mobilised in significant amounts when the requirement is greater than the demand. Adequate amounts of protein must therefore be supplied daily in order to avoid depression in milk production.
Protein is an expensive nutrient and giving a cow more than it needs is a waste of money as protein is not stored in the body but is broken down by microorganisms in the rumen and excreted as urea. Protein is usually measured using the nitrogen content of the feedstuff, hence the term crude protein (CP).
Much of the protein is usually first digested by rumen microbes before being availed to the animal as microbial protein. Dairy rations are balanced mainly on the basis of CP requirements as it is among the most limiting nutrients.
Depending on milk yield, a lactating dairy cow’s daily ration requires between 14 to 18 per cent CP on dry matter basis. Rich CP sources are legume forages (such as lucerne or desmodium), plant oil seed meals (such as cotton seed cake, sunflower cake or soyabean) and animal origin meals (such as fish meal or blood meal).
Non-protein nitrogen sources, such as urea and poultry waste which contains uric acid, can be used by microorganisms in the rumen to synthesize microbial protein.
However such sources must only be included in small amounts as they can be toxic. Grains and non-legume forages are somewhat deficient in protein and usually require supplementation for dairy rations.
Legume crops like lucerne are best planted alone but others like desmodium may be intercropped with crops like Napier.
c) Minerals
Major minerals not adequately supplied by most feedstuff are calcium, phosphorus, sodium and chlorine. Most rations will therefore require supplementation with these minerals in various forms like sodium chloride salt and limestone.
Other minerals such as copper, manganese and selenium are only required in trace amounts. These trace elements also need to be supplemented to ensure maximum productivity. Young calves, high-producing cows and pregnant animals have higher mineral requirements.
Mineral deficiency results in conditions such as depressed heat signs, poor conception, abortion, low milk production, deformed skeletons in young animals and metabolic diseases like milk fever.
Luckily, mineral premixes containing both major and minor minerals can be bought at agro-vet stores across the country. However it is wise to source the minerals from reputable animal feed firms to avoid sub-standard products.
d) Vitamins
With the exception of vitamins A and D, the other vitamins needed by dairy cows are generally present in proper amounts in common feedstuff or are manufactured in adequate quantities by micro-organisms in the rumen.
Though rare, deficiencies may occur under certain conditions such as prolonged stress periods like during illness as well as feeding animals on poor quality roughage or lots of grain. Vitamin supplements are expensive and hence feeding too much of it may bring economic loss to the farmer.
e) Water
This is a very important component of feeding. It is required to maintain many body functions like blood circulation and to produce milk. Water constitutes about 87 per cent of milk and should be provided at all times without rationing.
High producing cows may drink as much as 200 litres of water daily. Provide water in a well lit area within 15 metres of the feeding trough. The amount of water consumed at free will increases with an increase in diet dry matter content and intake, milk yield, environmental temperature and salt intake.
Groups of feedstuff
Feedstuff can be divided into two groups namely roughages and concentrates. Roughages include bulky feedstuff relatively high in crude fibre content like fresh grasses, hay and silage. Good quality roughage is the basis of a high milk production and should be fed to the cow at the right stage usually around plant flowering.
If possible, a farmer is encouraged to grow them to reduce costs. Kikuyu grass, Rhodes grass and maize are normally more superior nutritionally compared to Napier which as the only feedstuff will support less than 10 kg of milk. Napier is best at no more than a metre tall, wilted, chopped and mixed with good quality legume roughage.
Roughages rich in both energy and crude protein are essential in providing cheap balanced rations.
Concentrates, on the other hand, contain high proportions of nutrients, less crude fibre and cost more than roughages. They are products like cotton seed cake, maize bran, maize germ, fish meal, brewer’s waste and di-calcium phosphate (DCP). These products are usually combined and mixed in varying ratios to formulate rations like dairy meal for supplementation.
A dairy cow of good genetic potential fed only on quality roughage containing both energy and protein sources can produce about 8 litres a day. As a rule of thumb, 1 kilo of dairy meal is provided for every 1.5 litres of milk above the 8 litres.
A balanced ration should contain between 60 to 70 per cent roughage and between 30 to 40 per cent concentrates.
