Published online by Cambridge University Press: 01 June 2009
Housed dairy heifers (62 cows) were fed concentrates exclusively through variable-time, out-of-parlour dispensers. They were observed to visit the dispensers on average 20·4 times/d but significantly less frequently (13·9 times/d) shortly after calving. The dispensers were occupied for 25·8% of the night (22.00–06.00 h) compared with 30·4% of the day (06.00–22.00 h). This difference was small but significant, whereas the differences between the proportion of night and day spent standing (32·5 v. 66·2%) or eating silage (4·8 v. 24·7%) were noticeably greater. In a herd of ∼ 80 cows in which the daily average number of visits to the dispenser was 20·5/cow there was a significant decrease in the number of visits/d (y) with increasing time after calving (x) where y = 23·4–0·030x (r = 0·88). Some cows repeatedly visited the dispensers more frequently than others (range 13·2–34·9±5·3 visits/d, giving a repeatability of 0·58). Cows in a grazing herd (∼ 60) visited the dispensers on average 14·6 times/d during an average 3·6 visits to a cubicle house to which they had continuous access. The number of visits to the dispensers (y) again decreased with increasing time after calving (x) where y = 22·7–0·072x (r = 0·45). The average time spent in the cubicle house (z) also decreased as the days after calving (x) increased (z = 8·4 – 0073x+0·000203x2, r =–0·66). All cows, however, stayed in the cubicle house during periods of heavy rainfall.