Dairy cows, particularly in alpine regions (Switzerland, Austria &etc) are often seen (and heard) wearing bells. See photo:
Although it’s traditional to fit such cows with bells, a question can, and indeed has, been asked : ‘Do Bells Affect Behaviour and Heart Rate Variability in Grazing Dairy Cows?’ Answers are provided in a 2015 PLoS ONE paper by Julia Johns, Antonia Patt, and Edna Hillmann of the Institute of Agricultural Sciences, Animal Behaviour, Health and Welfare Unit, Einheit für Ethologie und Tierwohl (ETH), Zürich, Switzerland, who performed a set of experiments :
“For 3 days each, cows were equipped with no bell (control), with a bell with inactivated clapper (silent bell) or with a functional bell (functional bell). The bells weighed 5.5 kg and had frequencies between 532 Hz and 2.8 kHz and amplitudes between 90 and 113 dB at a distance of 20 cm. Data were collected on either the first and third or on all 3 days of each treatment. Whereas duration of rumination was reduced with a functional bell and a silent bell compared with no bell, feeding duration was reduced with a silent bell and was intermediate with a functional bell. Head movements were reduced when wearing a silent bell compared with no bell and tended to be reduced when wearing a functional compared to no bell. With a functional bell, lying duration was reduced by almost 4 hours on the third day of treatment compared with the first day with a functional bell and compared with no bell or a silent bell.“
The results of the experiments are summed up :
“Wearing a bell for 3 days interfered with feeding, ruminating and lying behaviours as well as head movements of cows compared with not wearing a bell, but it did not affect heart rate variability. Cows did not habituate to the bells over the 3 days of observation. The observed behavioural changes might challenge welfare if they lasted for an extended time period, but long-term observations are necessary to quantify the effects of bells on welfare.”
Bonus: The investigators provide a sound file [.wav format] of some cowbells in action.
Notes: The participants’ names were: Atela, Awina, Biber, Darling, Ela, Flecki, Iso, Marella, Padeira, Pamanda, Paranda, Perla, Pirella, Piwa, Taula, Vara, Vexana, Wia and Zulli.
The 2009 Ig Nobel Veterinary Medicine Prize was awarded to Catherine Douglas and Peter Rowlinson of Newcastle University, Newcastle-Upon-Tyne, UK, for showing that cows who have names give more milk than cows that are nameless.