The effect of frozen grass silage on the feed intake and feeding behavior of pregnant ewes.

The aim of the current study was to investigate the effect of frozen grass silage on the feed intake, feed preferences, and feeding behavior of ewes. Two experiments were conducted, each involving 8 pregnant ewes in a Latin square design with 4 treatments: 1) frozen silage; 2) partly frozen silage; 3) frozen, chopped silage; 4) and unfrozen silage (control). In Exp. 2, the ewes in square 1 were fed grass silage with low DM content (LDM) and in square 2 the ewes were fed grass silage with high DM content (HDM). In both experiments, each treatment period lasted for 14 d. A feed preference test was conducted, where the ewes could choose between 2 of the experimental feed treatments for 1 d in a changeover design so that they were exposed to all pairwise combinations of the 4 treatments. On the last day of each experimental period in Exp. 1, the feeding behavior was scored by direct observation for 4 h. In Exp. 1 ( < 0.0001) and in Exp. 2 ( = 0.03), feed intake in the first 4 h after feeding was lowest on the frozen silage treatment and highest on the control treatment. The DMI in the first 4 h after feeding was higher ( = 0.005) in the HDM treatment than in the LDM treatment. The total daily feed intake in Exp. 1 was lowest on the frozen, chopped silage treatment and highest on the unfrozen silage treatment ( = 0.02). In Exp. 2, daily feed intake did not differ ( = 0.32) among treatments. Total daily feed intake was higher ( < 0.0001) in the LDM treatment than in the HDM treatment but there was no difference in the DMI. There was no difference in the preference for the different feed treatments, when considering either the first 4 h ( = 0.12 to = 0.86) or the whole 24-h period ( = 0.25 to = 0.53). Time spent eating normally was longer on the control treatment and shorter on the frozen silage treatments ( < 0.0001) whereas time spent eating by tearing off feed from the frozen block followed the opposite pattern ( < 0.0001). We conclude that intake of frozen silage was lower for the first 4 h but that frozen silage had a very moderate effect on daily feed intake. Partly thawing or chopping improved the feed intake. Treatment had no significant effect on feed preferences. Feeding frozen silage increased time spent tearing off feed from frozen block, but total time eating was moderately increased.