PERSISTENCE OF THE EFFECTS OF EARLY EXPERIENCE ON CONSUMPTION OF LOW-QUALITY ROUGHAGE BY SHEEP

The aim of this study was to determine the effects of experience early in life with cured weeping lovegrass (Eragrostis curvula) (low-qualit y roughage) or fresh oats (Avena sativa) (high-duality roughage) on vo luntary intake and nitrogen retention when sheep ate a low-quality rou ghage 9 mo after initial exposure. From 1 to 5 mo of age, experienced wethers (EW) grazed cured weeping lovegrass, whereas inexperienced wet hers (IW) grazed fresh oats (initial exposure). Then both EW and IW we re fed sorghum (Sorghum bicolor) hay for 45 d, fresh weeping lovegrass for 105 d, and finally alfalfa hay for 120 d. Nine months after compl etion of the initial exposure EW and IW were offered sorghum hay (low- quality roughage), and, in addition, both groups were offered sorghum with ad libitum access simultaneously to alfalfa hay at six levels of availability. Experienced wethers ingested 15% more (P <.02) sorghum t han IW. When given sorghum simultaneously with alfalfa at different le vels of availability, EW ingested more (P <.10) sorghum than IW when o nly sorghum was freely available. Nitrogen retention was negative in b oth groups, but it was less negative in EW than in IW per unit of meta bolic weight (P < .09) and per wether (P <.04). The results show that early dietary experience can have profound and persistent effects on c onsumption of foods low in nutritional quality, apparently through cha nges in critical physiological mechanisms.