Nutrition Page 2

Nutrition

British Dried Grass and Dried Lucerne for dairy cows, beef and sheep

Fresh grass and lucerne are natural feeds for dairy cows and all other ruminants. They are the crops these animals have evolved to eat; the forages their digestive systems utilise most effectively. It follows, therefore, that high temperature dried grass and lucerne are also natural feeds for ruminants, having simply had most of the water removed.

Natural supply of quality protein

The protein in any dairy cow diet must be balanced between the amount supplied to the rumen micro-organisms (Effective Rumen Degradable Protein, or ERDP) and the amount available directly for chemical digestion further down the digestive tract (Digestible Undegradable Protein, or DUP), As most forages supply ample ERDP, it is often the DUP or ‘by-pass’ protein that needs to be topped up via the concentrate. This is particularly true with higher levels of performance.

Although grass and lucerne entering the dryer are, like grazed forage, high in ERDP and relatively low in DUP, the product that leaves the dryer has changed. The short period of intense heat needed to reduce the water content protects some of the protein from breakdown in the rumen and so increases the level of DUP.

Protein values at 8% outflow rate

Source: Energy & Protein Requirements of Ruminants, AFRC

It can be seen that whilst high temperature drying improves the protein profile, silage fermentation actually decreases the DUP available. This clearly makes Dried Grass and Dried Lucerne ideal balancers for use in silage based diets.

Quality energy

The newly adopted Metabolisable Protein system takes the concept of a two-stage digestive system further by accepting that energy also needs to be supplied in two forms. Metabolisable Energy (ME) has therefore been split to show the amount available for use in the rumen – the Fermentable Metabolisable Energy (FME).

As grass and lucerne are natural feeds for ruminants it is not surprising that they are good sources of FME and so help to ensure maximum production from the rumen micro-organisms.

Whilst the fermentation process during silage making uses most of the FME available to feed the organisms that produce the acid needed to preserve the crop, the high temperature drying process preserves this naturally occurring FME in Dried Grass and Dried Lucerne.

Energy values in dry matter

Source: Energy & Protein Requirements of Ruminants, AFRC

The Metabolisable Protein rationing system demonstrates the value of high temperature Dried Grass and Dried Lucerne as balancers for farm forages rather than replacement feeds.

Vital role of fibre

The need to ensure maximum milk protein percentage within a limited quota has lead to many dairy farmers feeding high levels of starch. This can lead to an imbalance of Volatile Fatty Acids (VFAs) in the rumen which all too often results in acidosis and an increase in foot problems. One accepted way around this problem is to increase the amount of fibre included in the diet to act as a buffer.

Dried Grass and Dried Lucerne have a relatively high fibre level which, unlike straw, is highly digestible and has a beneficial effect in helping to balance rumen VFA production and to buffer high starch feeds.

The value of Dried Grass and Dried Lucerne as suppliers of fibre

Along with the need for digestible fibre (NCD) to feed the rumen micro-organisms, high starch diets need a minimum level of ‘structural fibre’ or cell walls. The best measure of this is the level of NDF in the ration and a target of around 35% for dairy cows in early lactation is often suggested.

Dried Grass and Dried Lucerne, with their relatively high levels of NDF, can play an important role in achieving this balance by allowing the use of high starch diets with less risk of acidosis.

Beta-carotene and fertility

Beta-carotene is not only a vital precursor of Vitamin A, but is also required in its own right as a valuable anti-oxidant. It seems to be particularly important in fertility, where a deficiency can lead to silent oestrus, reduced progesterone secretion, delayed ovulation, poor conception rate, increased follicular and luteal cysts and reduced calf vitality.

Effect of Beta-carotene

Source: Proceedings SFT, 1990

Dried Grass and Dried Lucerne are excellent sources of Beta-carotene which is particularly low in many other concentrates used for ruminants. The need for extra Beta-carotene is even greater when maize silage and other maize products are included in the diet.

Example diets

British Dried Grass and Dried Lucerne are natural, high value, proven feeds suitable for all classes of ruminant. Their ability to balance modern diets and contribute significantly to rumen function and health of high performance animals can make them the final, vital piece of the jigsaw when designing a balanced diet.