TECHNICAL ARTICLES Dairy

Feeding The Guernsey Cow

The Guernsey cow is probably her own worst enemy, producing large volumes of high quality milk, as is seen below:

TABLE

While she is restricted by a limited intake capacity relative to the above. Intake is critical, and is low early in lactation, as can be seen.

TABLE

Dry matter intake must be carefully managed. It must be remembered that a cow’s milk production peaks at 6-10 weeks post calving, maximum intake is normally achieved later, and cows will lose weight – this must be restricted.

The figure below (produced for Friesland cattle) illustrates this.

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Intake is determined by a number of things, but we really only have any influence over conditions in the rumen, which is actually a large fermentation vat, filled with microorganisms, which are very sensitive to change, especially changes in pH (acidity). Adapted organisms can live in a wide range of rumen pH5,5 – pH6,8; optimum lies between 6,0 and 6,3.

Remember:

Microorganisms, which digest starch, thrive at pH 5,5 – 6,0.

Microorganisms, which digest fibre, thrive at pH 6 – 6,8.

We have to find the balance. Dry cows are normally fed high roughage diets (fibre) and have rumen pH levels 6,5 – 6,8 (7); while fresh cows often drop to 5,3 – 5,8 as starch (grain) is introduced. Starch, and other “new” nutrients, must be introduced gradually. Otherwise even healthy cows will become acidotic and go off feed, causing even bigger energy shortages. Cows lose condition as tissue breaks down to try to meet energy requirements early in lactation, the liver is often not able to cope with the increased fat supply, and ketones (“fat bodies”) enter the blood, leading to, in severe cases, ketosis downer cows, fatty livers and sometimes death.

Adaptation must start at least 3 weeks prior to calving, by feeding a diet that is as similar to the diet fed after calving as possible. We unfortunately do not have the scope here to discuss diets, but contact me (082 800 8473) in this regard.

Cost pressure has led to levels of concentrates being cut early in lactation. This can endanger the cow and can limit profits. Maintenance for a given cow does not change, production is duly achieved when maintenance requirement has been met.

The strategy must be to maximise intake by adapting cows timeously – use the best quality roughages and balance the diet. Late dry cows and early calvers are difficult to group and fit in from a management perspective – it means two separate groups, but well worth it when they are treated differently.

GRAPH

Date published: 2004-05-10

Author:
C. Harrington

Publication:
N/A