The ideal time to take them out for grazing is the early hours of the morning preferably any time after 10.00am. This is because it is better to allow sun to rise so that eggs of worms attached to grasses would have been destroyed before the grasses are consumed by the animals.
If they are not destroyed, the worm load of the ruminants will be increased and this is not good for their health.
The physical nature of the feeds can pose serious limitations to efficient utilization of a feed or a ration comprised of several feed resources. However, the influence of physical attributes of feeds on quality is often ignored.
Some of the physical aspects that can limit the quality and utilization of feeds in dairy production are briefly discussed:
Stage of growth
|Vetch (Vicia villosis) harvesting at the right stage of growth|
|(c) T. P. Lanyasunya, Kenya|
The nutritive quality of forages varies as they grow towards maturity. Consideration of the stage at which both biomass yield and nutrient content are optimal is therefore important. After attainment of maturity, the forages generally depreciate in nutritive value.
This is mostly due to increase fibrous material, particularly lignin. For many forages, the leaves die off systemically after attainment of maturity, and this reduces photosynthetic activities. As a result, there will be reduced accumulation of nutrients: the yield does not increase anymore.
These factors are important to be considered e.g. when harvesting forage for conservation as hay. For instance, when making hay from grass (e.g. Rhodes grass) and legumes (e.g. Lucerne) it is generally advisable to cut at the onset of flowering up to the time of 50% flowering.
For a vegetatively propagated forage such as Napier grass, cutting height is the most important physical consideration for quality. Studies have shown that optimum harvesting height for Napier grass range between 50-60 cm (dry season) and 130-140 (rainy season).
Another disadvantage of a mature stage and dying leaves is that the leaves fall off and are lost from the roughage. The leaves in general contain most easy available feeding value.
|Grass exhibiting difference in quality due to the impact of texture|
|(c) JO Ouda, KARI, Kenya|
The physical/textural changes which occur as forages grow can impact on palatability, intake and animal digestive physiology. For instance, high intake of succulent young forages (e.g. Lucerne, vetch, clover and Comelina spp) may cause bloat.
At young stage the dry matter (DM) content of some forages can be very low (e.g. sweet-potato vines and Napier grass), and this can limit the adequate intake of dry matter to support the desired level of production.
The palatability can be compromised as the forages age because of increase in toughness and crude fibre. This can further complicate issues if some species and classes of livestock e.g. young ones are unable to consume fibrous old and tough forages or parts of.
Ratio of stem and foliage
It is important to have knowledge of the nutritive attributes of the various morphological components of the individual forages. In fodder crops, the leaf is in most cases the most nutritive component, hence the need to consider the utilization of a forage when the biomass yield and leaf:stem ratio are optimal.
Where the cattle are stall fed with chopped roughage, the particle size may play an important role in selection, intake and digestibility. For instance, the chop length of ensiled maize stovers have been shown to influence the selection where leafy parts are consumed more and the overall intake is reduced with increase in chop length.
Also, where different feed resources are to be mixed, the particle size must be considered to enable homogeneity in mixing.
Some ingredients necessary in the diets may not be in appropriate physical/textural form for cattle intake. Generally, cattle do not prefer powdery or finely processed feeds. Also, feed resources like molasses (semi-liquid) need to be mixed appropriately with a carrier feed.
Some feed additives or supplements are better provided in pellet or lick block forms e.g. calf pellets and mineral licks. It prevents selective intake.
Appearance and Colour
Generally, feeds have their own typical appearance, which the farmers are or should be familiar with. The appearance can be an important attraction to both farmers and animals. Deviation from the typical appearance should be taken seriously as this may have implication on quality.
The colour of specific feed resources can be good indicators for the quality of the feed. Thus feed users need to know the typical colour of feeds so that when there is deviation from the norm, precaution can be observed. For most fresh forages, green colour indicates good quality.
For instance, greenness may depict good growing conditions, hence abundance of nutrients. It may also indicate absence of diseases, pests and parasites. Appropriate colour can be used by farmers to judge the stage of harvesting.
In concentrates and processed feeds it is more difficult to judge the quality on the colour. Whole grains on the contrary can be judges well on colour and shine.
Freshness of the feeds can be indicated by e.g. colour, smell and/or presence of mould and temperature. Generally, the cattle intake will be negatively affected as the feed deteriorates in freshness. Consumption of stale feed can harm the cattle due to toxicity.
|Mould infested maize stovers as a result of poor conservation practice.|
|(c) JO Ouda, Kenya|
Presence of visible undesirable objects is also a good pointer to poor quality. The foreign bodies may include soil, pieces of glass, polythene, nails and metals and wood particles or rodent faeces.
Visual inspection of feeds should not be neglected, because this can lead to harmful or at worse fatal consequences for the animals being fed. Be sure that there are no poisonous plants or parts included in the feed and no residues of pesticides or herbicides.
Dairy meal contaminated with foreign objects.
|Dairy meal contaminated with foreign objects.|
|(c) JO Ouda, Kenya|
Cattle, like most animals have natural instinct of preference. It is therefore possible that a good feed may be rejected because animals are not familiar with it and have to get accustomed. On the other hand, rejection of certain feeds can be a good indicator of hidden factors which should be identified and eliminated to improve the intake.
In this regard, it may be dangerous and unethical to provide such a feed in mixtures where the cattle cannot select and are forced to consume it. It is therefore necessary to ascertain the factors causing rejection and the benefits of such a feed before its use.
One of the commonest feature of dairy cattle feeding in Kenya is variability of type and nature of roughage feed. This is due of fodder inadequacy and this has implications on acceptability and also utilization due to its effect on rumen microbe composition. It takes time for the rumen microbe composition to stabilize with change of diet and consequently digestibility and utilization of the feed. br]
Negative symptoms after feeding
Cattle may consume feeds normally, but there can be negative symptoms shown as result of the consumption of certain feeds. These may include diarrhoea, abnormal water intake, bloat, poor appetite, non-typical or unpleasant smells in products (e.g. milk) and excreta and of discomfort. Appropriate action must be to ascertain the quality aspects of the feed concerned when such negative effects are noted.
Read Also: Stocking Management for Ruminant Animals
Formulation of Balanced Dairy Cattle Rations
Inadequate nutrition is a major cause of low live-weight gains, infertility and low milk yields in dairy cattle. About 50-70 % of cost of dairy production is made up of cost of feeds. It is important to use the available feeds in a diet that meets the needs of the cattle in the different stages of production.
|Poorly nourished dairy cow|
|(c) JO Ouda, KARI, Kenya|
Good dairy cattle feeding practices can be implemented with due regard to different nutrient requirements for the various classes of dairy stock in order to avoid either overfeeding or underfeeding of the dairy cattle and hence wastage of scarce feed resources.
Balanced dairy cattle rations can be formulated using various methods, A simple calculation of the main ingredients and estimating the minerals and vitamins content or more accurate calculations using different models for reliable rations.
For smallholder farmers the sophisticated method will not be applicable because of lack of reliable chemical composition of the feed and complicated calculations. If feed specifics are available and precise rations are wanted, the assistance of the local livestock Production Officer could be of help in ration calculation.
Dairy Cattle Feed Requirements
Dairy cattle feed requirements depend very much on their weight and stage of production. Whereas most farmers do not have access to weighing scales that can weigh animals, a system has been developed whereby the weight can be determined by chest measurements using a simple measuring tape (weigh band) available everywhere.
The weigh band is placed around the chest a hand’s breadth behind the front legs and not too tight.
How to estimate the live-weight of dairy cattle
The amount of feed which will provide adequate nutrients to animals will depend on their body size (live-weight). Figure 1 and 2 below give data which can be used by farmers to estimate live-weight of their cattle from girth measurements.
For example: a calf with a chest girth of 61 cm will have a weight of about 31 kg, a cow with a chest girth of 188 cm will weigh about 550 kg.
|Figure 1. Estimation of live-weight of cattle based on chest girth|
|Animal nutrition and feed rations|
|(c) Lanyasunya et al, KARI, Kenya|
|Figure 2: Estimation of live-weight of dairy cattle using chest girth measurements|
Maximum dry matter intake
Animal feedstuff can be divided into two major components namely dry matter and water. The dry matter component consists of organic and inorganic matter. The organic matter consists of carbohydrates (source of energy), lipids and fats (source of energy), protein and vitamins.
The inorganic matter is the source of macro- and micro-minerals. Since all nutrients are contained in the dry matter the animal must consume this portion in adequate amounts to obtain the required nutrients.
With feeds low in energy there is a risk that the intake capacity of the animals is too small to consume enough nutrients to meet the requirements for maintenance and production. Low energy feeds might be feeds with high moisture content (low dry matter) or feeds with high fibre content (low energy) or a combination.
The maximum dry mater intake is about 3 – 3.5% of a cows live weight and can be estimated with the formula kg Dry mater/cow/day = 0.025*live-weight + 0.1*kg milk.
|Table 5: Dairy cattle under stall feeding; feed intake must adequately supply desired nutrients.|
|(c) JO Ouda, KARI, Kenya|
Table 5 shows the maximum dry matter intake by dairy cattle of various live-weights. The intake capacity increases with live-weight and milk production (in the table kg milk standardized at 4% butterfat).
|Cow live-weight (kg)|
Nutrient requirements for maintenance and milk production
The nutrient requirements for maintenance of animals are influenced by their live-weight, activity (e.g. walking long distance) and environmental temperature (too cold or too hot).
Table 6 shows nutrient requirements for maintenance of dairy cattle of various live-weights (NRC, 1988. Dairying in KwaZulu-Natal, 1995 ). Dry matter intake is calculated with Fuentes-Pila (2003) and NRC (2001).
Table 6: Daily nutrient requirements for a dairy cow of a certain live weight and a certain milk production
Nutrient requirements for growth of young stock
The amount of nutrients required by an animal is equal to the nutrients in the tissue gained. Nutrients concentrations in deposited tissue are influenced by the animal rate of weight gain and the stage of growth or live-weight.
The nutrients required for growth by dairy cattle of various live-weights are given in Table 7 (NRC, 2001).
Table 7. Daily nutrient requirements for growth of young stock of dairy cattle
Nutrient requirements for milk production
When feeding a dairy cow the aim should be to maximize milk yield by meeting cow’s feed requirements. Requirements for milk production will depend on the amount of milk produced by the cow, energy content of milk which is indicated by fat content (the higher the fat content the higher the energy required).
Table 8: Nutrient requirements for production of 1 kg of milk of various butter fat contents
|Milk fat (%)||ME Energy
In addition to nutrient requirements for milk production nutrients will also be required to cater for other functions such as reproduction (pregnant cows require more to cater for growth of calf) and growth rate if she is not mature (in case of first calf cows).
Table 1 shows that the energy required for the production of 1 kg of milk can be met by amongst others 1 kg of dry matter of coffee hulls, napier grass early bloom, star grass or straw of rice, barley or wheat.
Mineral, trace-element and vitamin requirements for cattle
When available from feed analyses or from average feed composition, the amount of minerals, trace-elements and vitamins in a ration can also be calculated and compared with the animal requirements (as shown in table 9).
Table 9. Requirements of minerals, trace-elements and main vitamins for different categories of cattle.
|Table 9. Requirements of minerals, trace-elements and main vitamins for different categories of cattle.|
As mentioned before, in generally rations with roughages for cattle will be low in copper, selenium and cobalt.
Proportions of basal diet and supplement in a dairy cow ration
The cheapest feed for milk production is good quality roughage. However, quality of roughage fed to dairy cattle is usually low resulting in sub-optimal levels of production. Further increase in production can therefore be achieved by the use of supplements.
Among the factors influencing the quantities of roughage and supplements offered are their quality and level of production of dairy cattle. Table 10 shows simple guidelines on proportions of basal diet and supplements depending on levels of milk production in dairy cattle.
Table 10: Proportion of basal diet and supplements in dairy cattle rations
|Milk yield (kg/day)||Basal diet DM (%)||Supplement DM (%)|
|25 and more||40||60|
Ration formulation guidelines
The feeds in rations fed to dairy cattle either originate from the farm or are purchased. In order to minimize feed wastage and to overcome the problem of low levels of production, feeds need to be efficiently utilized by the animal.
A cow fed on balanced ration will utilize the feed more efficiently and hence it production will be better than a cow fed on imbalanced rations. Feed rations that are offered to dairy cows are considered balanced if they provide adequate nutrients (Carbohydrates, protein and minerals) to meet the animal requirements for maintenance, reproduction, growth and milk production.
For ration calculation the composition of the feed must be available and the requirements of the animal must be known. The composition of the farms own feed will not be available from all separate feeds.
Tables1 and 2 above give an overview of the composition of feedstuffs used in Kenya: the values can be used in ration calculations. In table 6 the mean requirements for dairy cattle are mentioned as a guideline: in different weather conditions and for instance in diseased animals requirements can be slightly different.
Read Also: How to Prevent Flies on a Ruminant Farm
Formulation of rations using a simple procedure
The simple procedure to calculate rations is chosen so that all farmers are able to calculate their own dairy rations. Using average composition data in this simple calculation gives a good idea where the ration needs compensation.
If the following information is provided:
- A cow weighing 450 kg and producing 20 kg/day of milk (4 % butter fat)
- Feeds available:
– Napier grass, young: 7.9 Mj ME and 98 gram CP per kg DM
– dairy meal: 9.1 Mj ME and 156 gram CP per kg DM
– Maclick super:
How much of the Napier, dairy meal and minerals will meet the cows requirements.
From table 5 estimate maximum dry matter intake for a 450 kg cow producing 20 kg of milk (4 % butter fat) = 17 kg. The cow needs 161 Mj ME and 1826 g crude protein (and 75 g Calcium and 59 g Phosphor).
STEP 1a. Calculate whether it is possible to feed the cow with napier grass as the sole feed. Divide the ME requirement of the cow by the ME content of the napier grass: 161 / 7.9 = 20.4 kg DM of napier grass. That is far more than the maximum dry matter intake capacity of the cow. That shows that with napier grass as sole feed the cow cannot eat enough to produce 20 kg of milk.
From table 6 estimate proportions of Napier and dairy meal for a cow producing 20 kg/ day of milk Napier grass = 17*50/100 = 8.5 kg DM and the other half of the ration is Dairy meal = also 8.5 kg DM.
From tables 1 and 2 estimate nutrients supplied by the feedstuffs and from table 6 estimate nutrient requirements by a 450 kg cow producing 20 kg/ day of milk (4 % butter fat)
|Nutrients supplied by feeds and requirements to produce 20 kg/day of milk|
There is a shortage of 16.5 Mj ME and a surplus of protein. According to table 811 does the energy shortage correspond with 3 kg of milk. To close the gap to 20 kg of milk, the cow needs more energy rich feed while the protein content can be lower; for example cassava peels.
By replacing 3 kg of dairy meal by cassava peels, energy and protein get more in balance with the requirements of the cow. Whether the dairy meal will be replaced by an energy rich feed depends on the price of the feed stuffs and the price of the extra milk produced.
Estimate the amount of feed to be fed to the cow per day. The ration contains 8.5 kg of dry matter from Napier grass. Fresh Napier grass has a dry matter content of 20%, or 200 g/kg.
The cow should be fed 8.5*1000/200 = 42.5 kg fresh Napier grass. If 5 % of the grass is wasted (not eaten by the cow) she should be provided with 42.5 *1.05) = 45 kg of fresh Napier grass. Dairy meal with a dry matter content of 90% has to be provided 8.5 *1.10 = 9.3 kg. Calcium and phosphor are sufficient.
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