Bristande mjölknedsläppning hos förstakalvare
en enkätstudie
Milk ejection in dairy cows can be inhibited if oxytocin is not released from the pituitary gland. The problem with inhibition of the milk let down is not new, but has recently regained interest. It is observed during different types of emotional stress, for example when cows are moved to an unfamiliar environment, during oestrus, changing from suckling to machine milking or when being milked for the first time.
The aim of the study was to examine the extent of cows with disturbed milk ejection in Sweden. A survey was sent out to 1000 dairy farmers in order to collect data about herd size, housing systems and routines at calving and milking. Farmers that had primiparous cows with disturbed milk ejection also gave information about treatment of the affected animals and if they differed in temperament compared to the other primiparous cows.
The results of the study showed that the occurrence of inhibited milk let down were more frequent in automatic milking systems compared with tie-stalls and loose-housing systems with for example parlour milking. The herd size had no influence on the frequency of animals with inhibited milk release. There was a tendency that cows who were fed during milking had fewer problems with inhibition of milk let down compared to cows that were not being fed during milking.
The results also showed that it did not matter of how the cows were kept during calving but the time cow and calf were kept together were of importance. Cows that were separated from their calf directly after calving had less problem compared to cows that spent one or more days together with their calf. Differences in udder stimulation before milking did not affect the milk ejection, but in this study all cows got some kind of stimulation of the udder before milking.
There was no difference in the occurrence of inhibited milk let down between heifers that were introduced to the cows housing system before calving, compared to those that were moved to the cow stables after calving. The length of the introduction period varied between herds but there were no difference between heifers with long or short introduction period.
About 3 % of the heifers in the study had inhibited milk let down during the first days of lactation, half of them needed treatment with injections of oxytocin in order to be milked. There were no differences in the occurrence of inhibited milk ejection between the two major breeds, Holstein and Swedish Red and White.