Effects of a delay in feed delivery on behaviour, milk yield and heamatological parameters of dairy cows.

This study aimed to evaluate the effects of a delay (at 09:30 instead of 07:30 h) in Total Mixed Ration (TMR) delivery on the behaviour, milk yield, and haematological parameters in dairy cows. Twelve healthy Italian Holstein cows, divided into two homogeneous groups of six each, were involved. The TMR delay was applied either for one (on Tuesday; single delay, SD) or for three consecutive days (Tuesday to Thursday; repeated delay, RD) to one group at a time while the other acted as control. A week of pause was interposed between treatments and the order of the treatment was randomised. Behaviour was observed by instantaneous scan sampling every 2 min during seven half-hour periods on Tuesday and Thursday and blood samples were taken at 14:30 h on these days. Milk yield was recorded daily. Data were analysed by a mixed models for repeated measurements. The delay caused a marked increase in activities towards the feeding rack prior to feeding on day 1 when delay was applied both as SD (P<0.01) and RD (P<0.05). On the third day of delay, pre- and post-meal agonistic behaviour increased in delayed cows (P<0.01). Milk yield and blood parameters were not affected by the delay. Results suggest that a two hours delay in feeding can affect behaviour in cows, increasing behavioural patterns, which may be a sign of mild frustration.