Milk yield affects time budget of dairy cows in tie-stalls.

Effective selection in breeding programs and improved management has increased the milk production per cow. However, the effects of the increased yield on behavior have not yet been clarified. We investigated the effect of milk yield on the time budget of 29 Finnish Ayrshire cows in the same stage of lactation kept in tie-stalls. The time spent lying, eating, ruminating, lying inactive without ruminating, and lying with the neck muscles relaxed, as well as the milk yield of primiparous and multiparous cows were recorded for 2d. The effects of milk yield and parity on behavior were analyzed with mixed models. The mean milk yield was 38.3 kg (SD 7.8) per day. Higher-yielding cows spent more time ruminating while standing and less time lying than lower-yielding cows. The latency to lie inactive without ruminating after lying down decreased as milk yield increased and it was shorter in primiparous compared with multiparous cows. Multiparous cows ruminated more while lying than primiparous cows. High milk yield cows spent a shorter time lying and they fell asleep (lay with neck relaxed) sooner. The degree of daily milk yield was associated with modifications in behavior and cows with high milk production had less lying time even with free access to lie down in the tie-stall.