|dc.description.abstract||The suckling behaviour of 66 Hereford and Simmentaler cows was studied.
The average frequency of suckling in 24 hours was four times, and the average
duration of each suckling bout was 10 minutes. Suckling events were not
evenly distributed throughout the 24 hour period. Regardless of suckling
frequency or days post partum, the most favoured suckling period was between
04:00 and 06:00, i.e. dawn. The lowest incidence of suckling was recorded in
the period from midnight to dawn. The longest interval between two suckling
bouts over the 24 hours always occurred before the dawn and became longer as
the calf grew older (p<0,01).
Once the mating season commenced, the onset of oestrus was positively
correlated (p<0,01) to the length of the longest inter-suckling period.
Suckling behaviour was not affected by the milk yields of the cows studied .
In a follow up investigation, 88 cows were separated from their calves
for 12 hours out of 24, for the fortnight prior to the start of the breeding
season. Fifty-six percent of the 44 cows which were separated from their
calves from 18:00 to 06:00 (dayfeeders) exhibited oestrus within 28 days of
the breeding season, compared to 22% of the group separated from 06:00 to
It was concluded that not only the suppression of suckling may be
involved in the onset of ovarian activity . The specific time period during
the 24 hours when suckling is prohibited may also play a role.||en