Influence of method of conservation of lucerne on factors associated with voluntary intake in sheep

Abstract

This experiment measured the voluntary intake and rate of eating of sheep fed lucerne (Medicago sativa) that had been conserved as sun-dried material or as silage at 3 different DM contents (29.2, 33.1, and 51.2%). Changes in rumen osmolality and palatability due to diet were measured. Palatability was assessed by introducing feed directly into the rumen and measuring the subsequent oral intake. Eight sheep with rumen fistulae were used in two 4 x 4 latin squares, which allowed for adjustment for carryover effects. There was no significant (P<0.05) difference between voluntary intakes of lucerne conserved as sundried material and as silages of various DM contents (mean intake 1189 g DM/day). The lack of difference in intake was attributed to the high quality of fermentation of the silages. Rate of eating was also generally similar for all diets. Evidence from measurements of palatability and rumen osmolality support these observations. Palatability appeared not to influence the voluntary intake of any of the diets, because the sheep reduced their daily oral intake by an amount similar to that introduced into the rumen. Under normal feeding conditions, rumen osmolality was also similar for all feeds and was relatively consistent for the 9 h immediately after the start of feeding. While rumen osmolality per se may affect voluntary intake, the lack of response reported here for changes in osmolality due to diet support the lack of response reported for feed consumption.