The effects of conditioning to suckling, milking and of calf presence on the release of oxytocin in dairy cows.
The aim of the study was to record the oxytocin (OT) release during milking (M) without or with calf presence, suckling (S) and finally calf removal just before the next milking in cows during postpartum or early lactation periods. Furthermore, the release of OT was examined during S and M in unknown surroundings (parlour). A total of 20 Brown Swiss cows kept under loose housing environment were used in our experiment. In both periods, the cows were milked twice daily at 07.00 and 18.00h and suckled three times daily at 09.00, 14.00 and 20.00h in the stall (tie housing). In the postpartum period, 13 cows were suckled and milked in the presence of their calves in the stall for the first 5 days of postpartum. Five from seven primiparous cows were additionally suckled by their own calves in the parlour on day 5 at 20.00h. On day 6, calves were separated and moved from mothers to the calf barn 10min before morning M. After evening milking cows were relocated to the herd within the same stable and milked in the parlour for a period of 4 weeks without contact to their calf. For control, additional seven primiparous cows without calf presence (not suckled) were also milked in the tie housing. In the early lactation period, suckled cows were moved back to the tie housing 2 days before the start of two consecutive days of S by their own calves and milking. Afterwards, 10min before M calves were separated again. Before S, two consecutive M were considered as controls. Results: The S stimulus during postpartum resulted in a higher OT release as compared with M in the calf presence and M after calf separation but not during M of not suckled cows. S in parlour reduced OT release. However, when not suckled primiparous cows were first milked in parlour, OT release was more reduced and in some cows total inhibition was observed. In early lactation during the first S, release of OT was lower than during control M, but increased gradually with repeated S and reached a maximum already on the second day. After two S, during evening M, the M related OT release was reduced as compared with controls. Calf removal 10min before M reduced OT release as compared with control M or M in calf presence. In conclusion, the calf presence and its removal can negatively influence OT secretion during M. Conditioning to machine milking caused a short-term reduction of OT release during first suckling, which normalised within 1 day.
Tancin
V
V
Institute of Physiology, Technical University Munich-Weihenstephan, FML, Weihenstephaner Berg 5, D-85350, Freising-Weihenstephan, Germany
Kraetzl
W -D.
W
Schams
D
D
Bruckmaier
R M.
RM