Effect of the administration of quebracho extract on rumen fermentation and diet digestibility in sheep

Abstract

This work was carried out with the aim of studying the effect of the administration of commercial quebracho extract (76% condensed tannins, CT) to sheep, for 70 days. Ten ruminally cannulated ewes were distributed into two experimental groups (control and quebracho). Zero (placebo) or 0.75 g of quebracho tannins extract per kg of live weight and day were intra-ruminally administered to the animals. The nylon bag technique was used to examine alfalfa hay in situ dry matter (DM), nitrogen (N) and neutral-detergent fiber (NDF) disappearances. In vivo digestibility, pH and ammonia-N and volatile fatty acid (VFA) concentrations were also measured. The daily ruminal administration of quebracho extract did not affect rumen fermentation parameters such as pH and ammonia-N and VFA concentrations, but reduced significantly the alfalfa hay DM potentially degradable fraction and the fractional rate of N degradation. Only on day 8 of the experiment were the DM and NDF disappearance values, after 24 h of in situ incubation, significantly lower in the animals treated with quebracho. No differences were observed on any other day of the experiment. Furthermore, the quebracho CT extract significantly decreased the in vivo digestibility of the following diet components: DM, crude protein and NDF.