Effects of early experience on voluntary intake of low-quality roughage by sheep

Abstract

This study determined 1) how experience early in life with cured weeping lovegrass (Eragrostis curvula) (low-quality roughage) or fresh oats (Avena sativa) (high-quality roughage) affected consumption of low- or high-quality roughage by lambs later in life and 2) whether this early dietary experience affected passage of undigested residues through the digestive tract and digestion of low-quality roughage. From 1 to 5 mo of age, experienced lambs (EL) were grazing cured weeping lovegrass, whereas inexperienced lambs (IL) were grazing fresh oats. Immediately after exposure, in Trial 1 lambs were fed sorghum (Sorghum bicolor) hay (low-quality roughage) supplemented with a protein concentrate. In Trial 2 lambs were offered sorghum only. Finally, in Trial 3 lambs were offered a choice between sorghum and alfalfa hay. When the sorghum was supplemented with protein there was no difference (P > .05) between treatments in intake of sorghum, but when the supplement was withheld in Trial 2, EL ingested 20% more (P < .01) sorghum than IL. When given a choice between sorghum and alfalfa, EL ingested 2.5 times more (P < .01) sorghum than IL. The apparent digestibility of sorghum was 4.5% higher (P < .01) in EL than in IL, whereas passage of undigested matter through the digestive tract was similar (P > .05). The results show that early dietary experience can have a significant effect on consumption of low-quality roughage and diet selection in free-choice situations.