Sows’ preferences for different fresh and dry mixed forages

The aim of this study was to determine sows’ preferences for different forage mixtures used in Canada. Four forage mixtures, composed of different proportions and species of legume [alfalfa (Alf) or clover (Clo)] and grass [tall fescue (F) and/or timothy (T)], were compared when offered either fresh or as hay. The proportions of legume in fresh forages and hays were, respectively: AlfFT=31 and 40%; CloFT=36 and 31%; AlfT=55 and 61%; and CloT=77 and 77%. Over 6 consecutive days, all 6 combinations of two forage mixtures were offered (one combination per day) during 45 min to eight second-parity gestating sows housed in individual pens and fed a concentrate for 100% of their requirements. Fresh and dry forages were tested on different sows. Voluntary intake was measured for each sow and each forage. For each pair proposed, difference in intake between the two forages offered was determined using a Student’s t-test, and the most ingested forage was considered as the preferred one. Preference ratio was calculated by subtracting the amount of the least preferred forage from the most preferred forage and dividing by the sum of the two intakes. Results revealed clear preferences for some mixtures. When served fresh, AlfT and CloT forages were preferred over AlfFT and CloFT (P<0.05) with preference ratios varying from 0.40 to 0.87. When served as hay, AlfT was preferred over AlfFT and CloFT; and CloT was preferred over CloFT (P<0.05) with preference ratios varying from 0.44 to 0.75. Therefore, it seems that forage mixtures with a greater proportion of legume (AlfT and CloT) were preferred over forage mixtures with a higher proportion of grass (AlfFT and CloFT). AlfFT and CloFT contained at least 30% of tall fescue and, therefore, the preference for AlfT and CloT could also be due to the absence of tall fescue. In previous studies, legumes were often preferred over grasses by sows, thus the preferences observed in this study are most likely due to the greater proportion of legume. Our results suggest that forage mixtures with high proportion of legume are preferable to maximise both fresh and dry forage intake in sows.