Effect of a Daily Supplementation of Polyethylene Glycol on Intake and Digestion of Tannin-Containing Leaves (<i>Quercus calliprinos</i>, <i>Pistacia lentiscus</i>, and <i>Ceratonia siliqua</i>) by Goats

Abstract

Intake and digestion of leaves of Quercus calliprinos, Pistacia lentiscus, and Ceratonia siliqua, with and without supplementation of various amounts of polyethylene glycol (PEG), were examined. The tannin contents in these species exerted a substantial negative effect on feed intake and digestion. The effects were species specific and related to tannin content. Once-daily Supplementation with PEG efficiently neutralized the negative effects of tannins. The amount of PEG needed to produce a maximal increase in feed intake was lower than the amount required to produce a maximal increase in digestibility. The intake of digestible crude protein and metabolizable energy was raised in PEG-supplemented animals from a submaintenance level to levels considerably exceeding the maintenance requirement of goats. The response was related to the tannin content of the plant. Keywords: Goats; tannins; polyethylene glycol; foliage digestibility