The effects of noise on cattle performance.

The effects of noise on cattle performance. Husbandry procedures cause the loudest sounds, especially if the metallic equipment is involved or if the work is performed in a hurried manner. The sources of noise can be technical devices, routine works (opening and closing doors, changing pens, washers, push carts, workers’ speech, feed dispensing), basal sound levels caused by mechanical ventilation and animals activities (climbing and chewing on fences). Aircraft overflights are also major sources of noise and can affect feed intake, growth, or production rates in cattle and other domestic animals. The severity of response to disturbance may, however, vary with species, group size, social groups, sex, age, vegetation cover, season, and distance from the aircraft. The exposure of farm animals to noise has been identified as a potential stressor not only in housing but also during the transport and at the abattoir. Animals are often exposed to acute noise levels before slaughter in lairages where noise is caused by ventilation fans and operational equipment. In some parts of the world, grazing cows are often equipped with a bell for several months, to ensure that farmers can locate their animals on the wide pastures. In this case, animals tend to decrease head movements to avoid generation of the sound. As a result, the feeding and ruminating durations are decreased because both behaviors include head movements.