Food intake, milk production, and digestive efficiency of cows differing in susceptibility to bloat

Voluntary food intakes of 16 high (HS) and 16 low (LS) bloat-susceptible dairy cows were established when they were offered pasture or hay while pregnant but not lactating and when they were offered pasture or 75% pasture 25% hay while lactating. Each experiment consisted of two 21-day periods with eight HS and eight LS cows on each diet in each period, cows changing diets between periods. Digestibility of the diets and complete energy balances were obtained using, respectively, three and one cow of each susceptibility group per diet per period. There were no significant differences between susceptibility groups in voluntary intake when expressed on a liveweight basis, in apparent digestibility of dry matter (DM), organic matter (OM), nitrogen (N), or energy (E), or in partitioning of E and other nutrients. LS cows produced more milk than HS cows but yields of fat, protein, and lactose were similar for both susceptibility groups.