feeding in the late lactation as well as the dry period
ensuring that cows are in a good body condition at the
time of calving. Depending on the condition scoring
system, cows should have a condition score of at least
3.0 to 3.5 (out of 5.0) at drying up. Their condition
should be maintained during the dry period. Preferably
cows should not calve down at condition scores less
than 2.0 or higher than 3.5 as both these conditions
can have a detrimental effect on milk production in the
following lactation period.
A study conducted at Elsenburg showed that dry cows
receiving a small amount of concentrates instead of a
mineral supplement together with ammonia treated
wheat straw, produced more milk during the following
lactation period. During the first eight weeks of the
lactation period cows supplemented with a mineral
mixture produced on average 33 kg of milk per day
while cows receiving 2 kg per cow per day of a dry cow
concentrate mixture produced on average 38 kg of milk
per day. Because of the long term effect of feeding
dairy cows, an improvement in the body condition of
dairy cows is often only observed in the following lactation period.
In the past, the amounts of concentrates being fed to
cows, were increased daily during the first 14 days after
calving, after which it was increased weekly if milk yield
responded by increasing further. This was done up to a
maximum amount equal to approximately 2% of live
weight, i.e. 8 kg per cow per day for Jersey cows
weighing 400 kg. Presently, the preferred way of feeding concentrates to cows is to provide a fixed amount
of concentrates from directly after calving, i.e. 6 to 12
kg per cow per day. The daily amount of concentrates
being fed depends on the genetic merit of cows in the
herd as well as the quantity and quality of the roughage being fed. Cows receiving low-grade roughages
require more concentrates per day than cows having
access to high quality pasture. The concentrate intake
of cows on a total mixed ration increases as their daily
feed intake increases. Because the energy content of all
roughages does not always sustain high milk yield levels, the energy content of the concentrate should be
high. In early lactation cows should, to a certain extent,
be overfed in order to ensure that their milk yield potential is fully utilised. However, farmers should realise
that overfeeding cows of low genetic merit for milk
production will not transform them into high producing cows. Such cows tend to become fat which is an
indirect way of showing their genetic merit.
2. Mid-lactation
During this phase of the lactation period, feed intake is
usually sufficient for the energy requirements for milk
production. Production is maintained although declines
in weekly milk yields may occur because of differences
in genetic merit for persistency. Observation studies
indicate that both peak milk yield and the persistency
of milk production are important factors affecting lactation milk yield levels. An improvement in the feeding
level from a low level during mid-lactation usually results in only a minor increase in milk yield (Figure 3).
The positive effect of improved feeding on the milk
yield cows is smaller when the feeding improvement
occurs longer after peak milk yield.
Figure 3. The effect of feeding level during the lactation period on milk yield recovery for Holstein cows ( ■ = consistently feeding at a high level from the start of the lactation period, □ = consistently low feeding level from the
start of lactation period, ▲ = higher feeding level after peak production, ∆ = higher feeding level after midlactation)