Eating barley too frequently or in excess decreases lambs' preference for barley but sodium bicarbonate and lasalocid attenuate the response.

We conducted experiments to determine whether preference for barley was affected when lambs ate various amounts of barley and whether lambs ate more barley when it contained lasalocid and sodium bicarbonate (NaHCO3), both of which attenuate acidosis. In Exp. 1, lambs were assigned to two treatments (six lambs/treatment). For 2 d, lambs in two treatments were offered either 400 or 1,200 g of rolled barley from 0600 to 0700 as a preload meal. A preference ratio [PR = barley ingested/(total amount of alfalfa + barley ingested)] was calculated based on lambs' intake when offered a choice of 200 g each of rolled barley and alfalfa pellets hourly from 0700 to 1100. After the preload meal, lambs in Treatment 1 (400 g preload) showed equal preference for barley (.52) and alfalfa (.48) for 4 h on d 1 (P > .05); their preference for barley was less after the meal of barley on d 1 (.52) than on d 2 (.72), but their preference for barley declined between h 3 (.81) and 4 (.55) of d 2 (P = .11). Lambs in Treatment 2 (1,200 g preload) showed a low preference for barley on d 1 (.29) and 2 (.19) (P < .001). In Exp. 2, lambs were assigned to four treatments (six lambs/treatment): 1) rolled barley + NaHCO3 (2%) + lasalocid (33 ppm); 2) rolled barley + NaHCO3 (2%); 3) rolled barley + lasalocid (33 ppm); or 4) rolled barley. Intake of barley by lambs offered NaHCO3 + lasalocid (Treatment 1) was greater (P = .07) than that by lambs offered NaHCO3 (Treatment 2), whereas intake by lambs offered lasalocid (Treatment 3) was similar (P > .05) to that by controls. We conclude that eating barley too frequently or in excess caused a decrease in lambs' preference for barley and that NaHCO3 and lasalocid attenuated the aversion.