17.0 SUPPLEMENTARY FEEDING
A practical Feeding Guide For Dairy Smallholders in Pacific Island Countries,
highlighting the use of various by-products and locally available foodstuffs for dairy cattle.
Based on observations made, and field work done in Samoa.
17.1 General principles
Livestock husbandry and management is the process of keeping and caring for animals. Good
husbandry practices are necessary to maintain stock in good health and condition for breeding,
working and consumption or sale. There are three main principles to livestock husbandry and management:
- reproduction and breeding
- livestock management: health, housing, herding, animal product collection, recording.
The major factor affecting the profitability of a dairy cattle farm is timely provision of feed to meet livestock nutritional requirements. This output must be adequate in both nutritional and economic terms. Considerable work has been undertaken to obtain precise estimates of nutritional requirements for all categories of cattle and for the calculation of optimal rations. However, in order for the dairy farmer to undertake the feeding of dairy herd effectively and with confidence. it is necessary to first understand some of the principles of feeding.
This is the most important of the three factors mentioned above. Poor nutrition of animals results when.
- insufficient quantity of feed is supplied to them,
- foodstuffs used are of poor quality. either of low protein content, or low digestibility or lacking
adequate balance among nutrients required by particular categories of animals at a certain time.
- Unbalanced rations are fed which lead to wastage of part of feed inputs and poor performance.
This happens because unbalanced rations do not meet the overall nutritional requirement of the animal
Performance levels displayed by animals kept on good diets, compared to those of animals which are underfed or given diets of poor quality. are distinctly better, well fed animals will
- look better and show relaxed behaviour: appealing coat colours. well fleshed bodies.,
alert and active
- produce more milk
- grow faster
- work longer and better
- show greater resistance to infectious and enjoy better health
- when lactating will produce morn milk for their offspring
- fetch better prices when sold
Livestock must be maintained productive and in healthy condition by good feeding; but farmers cannot afford to waste feed by overfeeding Each category of animals require (different quantities and quality of feed at specific periods. therefore the farmer needs to have
- a clear understanding of feed quality
- good knowledge of livestock feed requirement
- the means to control feed intake by livestock
Extension workers should have a good knowledge of the differences among foodstuffs and among categories of livestock so that he can assist the farmers. Improved animal nutrition and feeding strategies for livestock in the Pacific would do more to increase production of livestock than any other factor. Improved feeding together with improved herd management and disease control programs would increase benefits from investments in genetic improvement, disease control programme and up-grading infrastructure and facilities.
17.2 How do cows use feed through their digestive system ?
For the purposes of feeding and management farm animals can be divided into two main categories according to the type of digestive system that they have. The two types are known as RUMINANTS or POLYGASTRICS (these animals store large quantities of feed in their rumen, and can later on bring it back for re-chewing; when this happens the animal starts to rummage eaten forage ) and NON RUMINANTS or MONOGASTRICS ( for example pigs and young suckling calf). A simplified diagram of the stomach cow is shown in figure 18. There is a very important difference between these two types of digestive systems in practice and is related to the type of feed that animals can eat and digest. The ruminant's stomach or abomasum, small intestines and colon or large intestines are all sections of the digestive system that are similar to those found in non-ruminants. The most significant distinctive feature of the digestive system of ruminants, when compared to monogastrics, is the presence of three additional compartments situated between the oesophagus and the abomasum; these compartments are especially adapted for the break down of bulky and fibrous plant material to compounds that can be digested by these animals.
Their names are: Rumen, Reticulum, Omasum
Figure 18. The digestive tract of a cow
The rumen and reticulum, are large sacks that contain a mixture of solid contents eaten by the animal and fluids containing millions of micro-organisms. Under these conditions micro-organisms assisted by enzyme actions can attack, break down and digest plant material that is rich in fibre; this allows micro-organisms to reproduce themselves and at the same time they transform plant material into a fine mass. The walls of the rumen and reticulum are very active;
they are constantly moving, chumming and mixing the feed that is being fermented by micro-organisms, and thus helping the animal to digest its feed.
After grazing and eating other foodstuffs is finished, animals will rest and ruminate or chew their cud while lying down. Rumination is the action occurring when the animal brings feed back, mainly the larger sized pieces, from the rumen to its mouth in order to re-chew it. The chewing action mixes cud with saliva which facilitates further breakdown feed material. Large amounts of saliva are produced from the glands in the mouth ( up to 100 litres per day in a high-yielding cow ) containing water, enzymes and salts. The former play a key role in buffering acids formed in the rumen during digestion and this therefore keep microbes working at their full capacity. Gases such as carbon dioxide and methane are produced during fermentation and these, in the healthy animal, are removed by belching or during rumination. Bloat is a serious problem and it occurs when an animal is unable to remove gases by normal belching.
A regular supply of fibrous feed keeps the rumen functioning well; rumination proceeds normally and it prevents bloat from occurring. Rumination is a very important activity in the digestive process; it improves the efficiency and rate of digestion. The micro-organisms of the rumen and reticulum are vital to the digestive process; by retaining a relatively stable population of micro-organisms ( sufficient production of saliva ), in active condition ( regular supply of good quality feed ) allows a very active digestion activity of feed to take place ( mainly fibrous plant materials ) and a high biomass production of microbial protein. The type of feed eaten by the animal is an important factor in determining its rate of breakdown -digestion and this in turn determines the amount of energy made available to the animal for maintenance, growth, work and reproduction. For example concentrate foodstuffs: such as cereals and crop roots, and molasses are broken down rapidly, whereas bulky forage , namely feeds which are rich in fibre, are degraded much more slowly.
Grass and other feed that are eaten by the animal are then retained in the rumen and reticulum
long enough to them to be broken down to small particles that can then pass into the Omasum.
About 50 - 70% of the feed eaten is actually absorbed by the animal direct from the rumen into
the blood, to provide the animal energy requirement, or passed out of the animal as gas by belching. The remaining 30 - 50% passes on to the Omasum and later to the small intestines where digestion activity becomes similar to that occurring in non ruminants. Microbial proteins
produced in the reticulo-rumen are also digested and absorbed and therefore they contribute a substantial portion to meet the animal's protein requirements.
In conclusion this difference in the digestive system of ruminants, compared to that of non
ruminants (including man ), allows ruminants to utilise quite different types of feed to that eaten by non ruminants. Ruminants are only able to take advantage of bulky, fibre-rich forages due to their special digestive system. The simultaneous effects of rumination and microbial fermentation, which take place in their reticulo-rumen through the action of the hosted micro-organisms, enables these forages to be degraded into tine particles, for the chemical material to be broken down to simpler forms and for the nutritive elements to be extracted and absorbed by the animal. These nutritive elements are placed at the disposal of the animal through end products from this resonation process; these end products are made up of volatile fatty acids (VFA) and microbial mailer, which is itself digested later on by enzymes in the abomasum - the true stomach - and the large intestine.