Individual variation in eating speed of dry sows

We investigated the variation in eating speed by individual pregnant sows and the influence of feeding dry compared to wet feed. A total of 39 Norwegian Landrace × Yorkshire dry sows, 13 primiparous and 26 multiparous, were included in the experiment. In experimental period 1, each sow was offered 2.2 kg of a standard concentrate feed without added water. In experimental period 2, the sows were offered the same weight of concentrate feed but after mixing with water at a ratio of 1:4, based on weight. The sows were kept in groups of 4 or 5 in pens with individual feeding stalls. The weighed allocations of feed were poured into the troughs before the sows were given access to the food. On d 1, the sows were allowed to eat for 15 min, on d 2 for 10 min, on d 3 for 5 min, on d 4 for 2 min 30 s, and on d 5 for 1 min 15 s. At the designated time, feed troughs were covered, blocking sow access, and residual feed was carefully removed and weighed. Mean consumption rate of dry feed was 183.2 g/min for the first 5 min and 169.7 g/min for the first 10 min. For wet feed, the mean consumption rate was 1,859.8 g/min for the first 5 min and 1,060.7 g/min for the first 10 min. After 5 min, the sows had consumed 41.6% of the dry feed (range 19.5 to 79.1%, CV = 31.0%) and 84.5% of the wet feed (range 54.3 to 99.1%, CV = 14.9%). After 10 min, the sows had consumed 77.1% of the dry feed (range 33.9 to 100.0%, CV = 24.9%) and 5 of the 39 sows had completely ingested their allotted feed. When feed was wet, sows finished 96.4% of the ration (range 72.7 to 99.1%, CV = 6.4%) after 10 min. The speed of eating dry feed was positively correlated with sow weight, both at 5 (R = 0.72, P < 0.001) and 10 min (R = 0.75, P < 0.001), but for wet feed, the correlation was weak at 5 min (R = 0.36, P < 0.05) and there was no correlation at 10 min (R = 0.20, P > 0.10). We conclude that dry feed resulted in larger individual variation in feed consumption rate than wet feed. Furthermore, whereas feed consumption rate was correlated with liveweight of the sow when eating dry feed, the relationship was not significant when sows ate wet feed.