A quality mixed ration is a reliable and safe ration, enabling every animal in the herd to fulfil its genetic potential.
In this section, we give you 10 nutritional criteria as a simple guide to feeding your herd
1. Evaluate the fibre content of your ration!
As a first step, look at the structure of the ration in a handful of mixed feed :
The mixture should be loose, airy and not compacted: watch out for wet silages and bulky feeds. The total DM(1) content of the finished ration ideally should be 40% to 45%. There should be a minimum of 10% of the DM present as 3 – 4 cms long scratchy fibre. At that level, your ration should naturally stimulate the rumen.
Maize diet structure should be protected. Monitor mixing time and loading order.
Depending on the type of mixer wagon, a few minutes are enough to obtain a well-structured, homogenous mixture.
If you are incorporating long fibre such as straw, it should be chopped, and should be clean and neat for optimum rumen performance (a shear effect on the fibre, rather than fraying).
Secondly, observe your herd's cudding behaviour :
Good structure can also be monitored by simply counting the number of chewing movements :
The ideal is 60 chewing movements between swallows.
(1) Dry Matter (2) pH is the acidity level
2. Evaluating your herd's feed intake levels
To exploit your herd's full genetic potential, each cow should be using its maximum intake capacity. But how can you assess the quantity of mixed ration that your herd will eat?
For a herd composed say of 30% or more heifers, and with all stages of lactation present, the minimum intake is defined based on average live weight and standard milk yield:
Intake in Kg of DM = 2% of average adult weight + 25% of standard milk yield standard
3. To what extent should farm-grown bulk feeds be used?
A quality mixed ration is also an economical ration. Ideally the ruminant should eat and make use of maximum high quality forage, with a minimum of bought-in concentrates. That balance will depend upon the relative feed cost, and the level of output wanted from the stock.
To obtain the ideal value for a ration that is efficient in both technical and economic terms for a 30 litre per cow milking group, you should aim to achieve a balance of: 80% DM roughages and 20% DM concentrates
4. Fibre for a safer ration
The fibre content of a ration is usually measured as NDF, which relates closely to total feed intake. The level for higher yielding cows is:
Target NDF level is 32-38% of the diet, with 75% coming from forage
5. Adapt the energy balance to the herd's production level
The energy balance is defined by the amount of metabolisable energy (ME) in megajoules (MJ) consumed over 24 hours (by the herd on average.) It is calculated as follows:
Energy balance: energy density of diet (in MJ of ME) x the DM intake (in kg)
6. Balance the ration's energy with protein
The overall crude protein of the whole ration will vary with the herd yield expectations. The rumen is a ruminants own protein factory – but it needs a balanced supply of nutrients.
Ideal value: 16.0% CP per kg DM in modest yielding diets, to 18% CP per kg DM – and more of the quality proteins - for higher yielding cow diets
7. Soluble protein to feed the rumen bacteria
Rumen soluble proteins provide the nitrogen to feed the rumen bacteria. All proteins are degraded in the rumen: some like the protein in spring grass are very soluble and quickly degraded. Others like soya, and especially the cooked and “protected” proteins are less soluble in the rumen, and are digested more in the true intestine. The available rumen bug nitrogen must be balanced with rumen bug energy to get the best performance from all ruminants.
That is what the complex “Feed into Milk” calculations do for us, in mimicking the way that the rumen will break down any nitrogen and energy source in order to optimise the amount of the free true protein that the cow will make for herself.
A shortage of soluble protein causes a drop in intake and yield. An excess will cause scouring, loss of body weight, and infertility – but that excess protein may also be caused by a lack of bug energy with which to use that soluble protein.
In some diets, adding small quantities of urea (50 – 100 gms per cow) may be recommended, but only in a well mixed diet, and in well managed herds, as there are risks. To prevent excess, urea levels in the milk should be measured.
8. Yes to milk yield - but not to the detriment of milk quality!
An increase in milk yield is not always matched by an improvement in protein and butterfat. Extra milk flow is often synonymous with a dilution of these levels, ie lower percentages. Correct balancing of the rumen bug protein and energy, together with undegradable protein is the determining factor for milk solids and volume output - and thus income.
There should be 9.5 - 11 gms of ERDP per unit of ME, and 4 – 4.5 gms of DUP - bypass protein - per unit of ME
(ERDP = effective rumen degradable protein)
(DUP = digestible but rumen undegradable protein)
9. Don't forget free sugars!
Like soluble protein, quickly soluble energy such as free sugars is also essential for the rumen flora. They also affect the palatability of the feed. The sugar level should be similar to those in pasture.
10. Don't forget minerals!
To compensate for the mineral deficits of the diet, mineral supplementation (in whatever form, powder, granules or pellets) should be continuous, based on:
Phosphate: 0.36 to 0.40% of DM intake
Calcium: 0.70 to 0.75% of DM intake