Music has a wide range of purposes covering everything from entertainment to medicine to religious praises. Just like humans, cows have good days and bad days. They may wake up in a good mood or they may have a rough start to the day. Loud noise cause stress and makes cows to hold back some milk during milking. Enrichment of milking environment through music has been proposed to help animals to cope with divergent stressors. Studies conducted in Japan found that cows were 23% more likely to (and quicker to) enter an automatic milking stall when music was played just prior to and during milking.
A report from a study by the University of Leicester found that slow music can mitigate stress in cows and increase the amount of milk they produce by 3 percent. A farmer in Turkey reported that playing classical music for his cows increased milk production by 5%. His study was small, but he claims that regardless of feed or other intervening conditions, the cows produced more milk when listening to classical music.
Music can have a positive effect on milk let down, but it must be consistent and calming. Stress can inhibit the release of oxytocin, a hormone key to the milk-releasing process. Classical and country music have been reported to have more positive effects on behaviour than rock music increasing stress. Playing music might be a practical tool to reduce necessary efforts of driving cows to milking Thus, an optimization of musical enrichment of the milking environment of dairy animals is critically needed to maintain an optimal balance of the animal comfort, behavioural needs, and reducing residual milk.