Many types and combinations of feeds for dairy cattle will
result in good health and high milk production. No particular feed is essential.
Rather it is the proper balance of nutrients (protein, energy, minerals and
vitamins ) offered in a palatable form that distinguishes a good ration from a
poor one.
In order to formulate a ration for the dairy cow, we need
to know the amounts of each nutrient needed to meet the requirements for
maintenance of her body and for milk production. Furthermore , lactating
"heifers" need additional nutrients for continued growth and pregnant
cows need extra nutrients for the growth of the fetus, especially during the
last two months of gestation.
The following table is taken from the 1989 National
Research Council update on the requirements of dairy cattle and serves as a
guide for establishing the needs of your cows.
| Cow
mass (Kg) |
Fat
% |
Weight
gain (kg/day) |
Lactating Cow Diets Milk yield kg/day |
|||||
| 400 | 5.0 | 0.220 | 7 | 13 | 20 | 26 | 33 | |
| 500 | 4.5 | 0.275 | 8 | 17 | 25 | 33 | 41 | |
| 600 | 4.0 | 0.330 | 10 | 20 | 30 | 40 | 50 | |
| 700 | 3.5 | 0.385 | 12 | 24 | 36 | 48 | 60 | |
| 800 | 3.5 | 0.440 | 13 | 27 | 40 | 53 | 67 | |
| Energy | ||||||||
| mj/kg | 9.45 | 10.05 | 10.45 | 11.25 | 11.25 | |||
| TDN g/kg | 630 | 670 | 710 | 750 | 750 | |||
| Protein | ||||||||
| Crude
g/kg |
120 | 150 | 160 | 170 | 180 | |||
| by-pass
protein |
44 | 52 | 57 | 59 | 62 | |||
| Fibre | ||||||||
| crude% | 17 | 17 | 17 | 15 | 15 | |||
| ADF% | 21 | 21 | 21 | 19 | 19 | |||
| NDF% | 28 | 28 | 28 | 25 | 25 | |||
| Minerals
g/kg |
||||||||
| Calcium | 4.3 | 5.1 | 5.8 | 6.4 | 6.6 | |||
| Phosphorus | 2.8 | 3.3 | 3.7 | 4.1 | 4.1 | |||
The figures preceding this indicate the nutrients that are
required for a given milk production. However they should be read in conjunction
with the dry matter intake of the particular group of animals. It stands to
reason that the intake will affect the nutrient density of the feed for a
particular group of animals.
The following table was compiled using the data from a cow
weighing 600kg and producing 4% butter fat (FCM).
Dry matter intake requirements to fulfill the
nutrient allowances for maintenance, milk production and normal live weight gain
during mid- and late lactation.
| Mass (kg) | 400 | 500 | 600 | 700 | 800 |
| FCM (4%)
kg |
----------------------------------- % live mass ------------------------------------------ | ||||
| 10 | 2.7 | 2.4 | 2.2 | 2.0 | 1.9 |
| 15 | 3.2 | 2.8 | 2.6 | 2.3 | 2.2 |
| 20 | 3.6 | 3.2 | 2.9 | 2.6 | 2.4 |
| 25 | 4.0 | 3.5 | 3.2 | 2.9 | 2.7 |
| 30 | 4.4 | 3.9 | 3.5 | 3.2 | 2.9 |
| 35 | 5.0 | 4.2 | 3.7 | 3.4 | 3.1 |
| 40 | 5.5 | 4.6 | 4.0 | 3.6 | 3.3 |
| 45 | - | 5.0 | 4.3 | 3.8 | 3.5 |
| 50 | - | 5.4 | 4.7 | 4.1 | 3.7 |
| 55 | - | - | 5.0 | 4.4 | 4.0 |
| 60 | - | - | 5.4 | 4.8 | 4.3 |
These figures are given as guidance. The intakes in
practice can differ somewhat from the above and should be observed by the
stockman. The actual figures can then be utilised to maximise the profitability
of the herd.
Various factors influence the intake of feed. Among them
is total moisture content, fibre content (bulk) and the overall palatability of
the feed. It has been observed that dry matter intakes of silage fed alone will
level out at 2.5% and yet that those same cows will consume 3% of body weight
when fed good quality lucerne. The exact reasons for this phenomenon have yet to
be fully explained. We know that by adding protein to silage we are able to
increase the intake. It is also assumed that physical restraints such as rumen
capacity limit intakes. This has led to on going research to use a fill unit
(FU) system. The system proposes that a particular forage has a specific forage
fill value (SFFU) measured as (FU)/kg of dry matter. Different forages are
indexed to a standard or reference, forage. The FU of a forage is analogous to
its protein and energy concentration. The system assumes that the cow consumes a
fixed amount of FU rather than a fixed amount of dry matter. Whether this system
will see the light of day remains a question at this stage.
In the meantime parameters have ben set with regard to
fibre. This by means of crude fibre initially and now by Neutral Detergent Fibre
and Acid Detergent Fibre. Crude fibre represents the fibre fraction that is
resistant to degradation in acid and alkali solutions . Acid detergent fibre
consists of cellulose, lignin, acid detergent-insoluble nitrogen and acid
detergent insoluble ash. Neutral detergent fibre consists of hemicellulose,
cellulose, lignin, acid detergent-insoluble N and acid insoluble ash. There is
however, no one method of determining fibre quality and energy values for all
feeds. We therefore have to work on the correlations derived from the analysis'
to determine the relative requirements in a ration (see first table).
When formulating complete mixes for dairy cows taking the
results of analysis' into consideration the chances are that the milk production
of your cows will be fairly constant. Problems arise when you are milking off
pasture or veld. The weather is likely to play a large role in the daily
production of milk. Is there a practical method of altering concentrate feeding
to the changing scenario of grazing? In the second edition of Dairy Cattle:
Principles, Practices, Problems, Profits, printed in 1978 I came across what
appears to be a practical way of dealing with this problem. Those of you who
have ready access to computerised printouts on milk production may care to
ignore the following. All "stockmen" please take note.
The amount of concentrates fed depends on the quality and
quantity of the forage available. Those of you who monitor pasture quality on a
daily basis and have a feel for the changes taking place should find the
following information interesting. Concentrate feeding increases rapidly with
fat production. The following table can be used effectively to alter the feeding
regime as conditions change.
| Forage quality | |||
| Fair | Good | Excellent | |
| Milk fat Kg/month | --------------------------- Concentrates * Kg/day -------------------------- | ||
| Below 14 | 2.5 | 1.0 | 0.0 |
| 14 - 19 | 5.0 | 4.0 | 3.0 |
| 20 - 25 | 8.0 | 7.0 | 6.0 |
| 26 - 30 | 11.0 | 10.0 | 8.5 |
| 31 - 36 | 14.0 | 12.5 | 11.0 |
| 37 plus | ** | ** | ** |
* Add 1kg per day for normal growth of 1st calvers
** All that the cow can consume safely.
A cow producing 22 litres of milk per day (x 30days) of 4% BF = 26.4 kg BF/month. On Ryegrass pastures or silage she would receive 8.5 kg of concentrates per day. On good lucerne hay only 10kg and "Berg wind affected Kikuyu" 11kg. One may also be obliged to alter the protein content of the concentrate to accommodate really rapid and disastrous changes to the roughage component. However, as a rule of thumb it may be a great help for the stockman. The logical method of dividing cows into groups using this method is by butterfat production per cow per month and not volume of milk.
Makes you think? ....Can I rely on the lab for
accurate butterfat analysis?....Will I now not under feed my cows when milk
production drops and % BF increases?.......?......Perhaps there is a method of
combining protein and butterfat readings to allow me to ascertain what changes I
should bring to the concentrates protein level?
The following table gives an idea of the protein levels that may be required with
various roughage types.
| Type of roughage | Crude protein of roughage (dm) | Crude protein in concentrate |
| Lugume / ryegrass
Spring kikuyu |
160g/kg or higher | 120g/kg |
| Legume/grass mixture
Legume/ maize silage Late summer kikuyu |
120 - 160g/kg | 140 -180g/kg |
| Maize silage or other non legumes | 60 -100g/kg | 190 -250g/kg |
The vast majority of farmers in my experience rely on feel
when it comes to feeding their dairy herd. Advice is asked for but only the
broad outlines are used. The simple reason for this is that no consultant is in
a position to offer advice on a daily basis. Consultants can only work from
average figures. You seldom if ever have the average cow. Therefore all of our
actions need to be based on experience. The greatest "experience" is
economic viability. We all have to survive and the advice offered can only be
based on economic reality coupled to common sense. It does not help to listen to
the bank manager who says that you must cut back on concentrates and ignore the
result that must come in terms of poor reproduction / production after the cow
has used her body reserves. Consult your feed supplier's representatives. They
move amongst your colleagues and are generally well informed. It is in their
interests to bring the latest techniques in milk production to your notice;
notwithstanding their inherent ability to lift the price of feed as you start
getting a better price for milk!
The restrictions placed on the dairy industry in recent years by price restraints has made everyone here a survivor! This has occurred because you became more efficient and selected the right cow for your circumstances. I would plead with you today not to forget the lessons of the past. Do not become less efficient, remember that the cycle will continue and price restraints will return! Produce the very best roughage you are able at the lowest cost per unit of energy. Store that roughage in a way that will enable your enterprise to survive / thrive when the next drought comes, as it surely will.