Key performance
indicators for dairy
farmers
Dr Carel Muller
Research Associate, Faculty of Animal Sciences, University of Stellenbosch
M
ilk prices for dairy farmers are
affected by supply and demand.
Farmers have, for except, the
volume and quality of milk being
produced, generally little effect on milk prices.
The profitability of a dairy herd is affected
mostly by the milk yield income (+90% of farm
income) and the production cost of milk. The
feeding cost of all the animals in a dairy herd
constitutes the largest part of the production
cost. By feeding more concentrates to cows,
milk yield increases although feed cost also
increases. This increase in milk yield may
result in a lower income because of the law
of diminishing returns. The profitability of a
dairy herd can also be improved by reducing
the production cost of milk. This can be
done in several ways. This requires applying
specific management actions as suggested by
key performance indicators. Some of these
indicators are discussed in this paper.
Number of cows in milk
The number of cows in milk determines the
total milk yield of a dairy herd. A dairy herd
consists of first lactation cows and older cows.
The milk yield of cows increases from first
to fifth lactation, therefore most cows in the
herd should be older cows (in second plus
lactation). The genetic merit of first lactation
cows affects the herd’s future genetic merit.
At least 82% of all the cows in the herd should
be in milk. This percentage increases when
cows are longer (more days) in milk, i.e. when
herd average days-in-milk (DIM) increases.
The growth of a dairy herd can be observed
by comparing the current number of cows
AgriKultuur |AgriCulture
in milk to the number the previous year(s). A
trendline can be fitted using records of at least
three (or more) previous years. A dairy herd
should increase in numbers from year to year.
When this is not the case, two major problems
may be the cause, i.e. the culling rate among
cows is high or the survival rate of heifers
from birth to first calving is low.
From a dairy herd of 100 cows, at least
85% should calve down every year when
reproduction management is good. The bull:
heifer ratio is usually 50:50 unless sexed
semen is being used. Based on this ratio, 42
heifers are available for rearing to replace
cows. If 85% of heifers survive to first calving,
it means that 36 first lactation cows should
enter the dairy herd. At a culling rate of
25% among cows, there are 11 surplus first
lactation cows; however, when the culling rate
is higher, the number of surplus cows is less.
At a lower heifer survival rate to first calving,
fewer heifers are available to rear to first
lactation.
The survival rate of heifers from birth to first
calving is determined by the comparing the
number of heifers born in a specific year to
the number of these heifers calving down for
the first time. When 100 heifers are born in a
specific year and 80 heifers eventually calve
down for the first time, the heifer survival
rate to first calving is 80%. It is also important
to know at which age heifers are lost from
the herd as this affects the mortality cost of
heifers. A higher age at culling increases the
mortality cost of heifers, mostly due to feeding
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