Published online by Cambridge University Press: 02 September 2010
Intakes and feeding patterns were studied in two groups of 24 Scottish Blackface ewes, with initial mean body condition scores of 2·15 (thin) and 3·15 (fat). Three treatments, allowing access to a dried-grass pellet diet ad libitum for 6, 12 or 24 h/day, were applied in a Latin-square design, with each sheep receiving each treatment for one 12-day period. Food intakes were measured daily and feeding activity was recorded automatically every minute for one 24-h period during the last 5 days of each 12-day treatment period.
Mean intakes were higher for thin than for fat ewes (1720 v. 1467 g dry matter (DM) per day; P < 0·001). There were no interactions between the effects of body condition and food access time and mean intakes over the last 7 days for the 6-, 12- and 24-h food access treatments were 1429, 1686 and 1805 g DM per day respectively (T < 0·001). Time spent feeding was higher for thin than for fat ewes, over the whole day (231 v. 197 mini day; P < 0·05) and in the first 6 h after the introduction of fresh food (140 v. 120 min; P < 0·05), but there were no differences between thin and fat ewes in the frequency of meals or in the rate of intake during meals. Intakes for the first 6 h were higher with restricted food access (1402, 1109 and 819 g DM per day for 6-, 12- and 24-h access; P < 0·001) but there were no differences in time spent feeding. The number of meals during the first 6 h was higher (10·4 v. 8·3; P < 0·05) and the rate of intake was higher (11·4 v. 7·8 g/min; P < 0·05) for 6-h compared with 24-h food access.
It was concluded that long-term differences in intake due to body condition and short-term changes due to restricting food access time, involve different behavioural responses and this may reflect differences in the mechanisms involved in the regulation of voluntary intake. Keywords: body condition, feeding behaviour, sheep.