1. Early lactation
The total milk yield of dairy cows over the lactation period is mainly determined by their daily milk yield at the
start, peak and end of the lactation milk yield. The milk
yield trend after peak to the end of the lactation is referred to as the persistency of milk production. Naturally, the total milk yield per lactation period is higher at
higher daily milk yields at the start, peak and end of
the lactation period and a higher persistency. Trials
have indicated that total milk yield per lactation in-
creases by 180-200 kg for each one kg increase in peak
milk yield. This implies that correct feeding should be
applied during the early lactation period.
During this stage high quality roughage and a high
energy content concentrate should be provided. Different studies have shown that a decrease in milk production during the early part of the lactation period, as a
result of underfeeding or malnutrition, reduces the total milk yield per lactation by four times (Table 2).
Table 2. Reduction in milk yield as a result of poor feeding during the early lactation as demonstrated in four
trials
Trial
A
B
C
D
Reduction in early lactation (kg)
Reduction over the
lactation period (kg)
136
45
180
190
590
181
862
680
It is well accepted that during early lactation, the
feed intake of high producing dairy cows is not
sufficient to satisfy their nutritional requirements
because of the rapid increase in milk yield. This is
Lactation
effect
4.3
4.0
4.8
3.6
demonstrated in Figure 2 showing the effect of
energy demand and feed energy intake on the
body reserves of dairy cows.
Figure 2. The effect of milk energy demand (□) and intake of fVVBV