Dietary supplementation of sunflower oil and quebracho tannins in sheep feeding: in vivo nutrient digestibility, nitrogen utilization and in vitro ruminal degradation kinetics.

Abstract

The effect of the inclusion of sunflower oil (SF) and quebracho tannin (QT) in a sheep diet was evaluated. Nutrient digestibility and nitrogen (N) utilization, as well as in vitro ruminal degradation kinetics, were evaluated at three levels [0, 20 and 40 g kg-1 of diet dry matter] of SF and QT in a 32 arrangement. The treatments were 0 (control); 20 and 40 g of QT and/or SF kg-1 of the diet. Four intact male sheep (45 ± 1.3kg) for each treatment were used in the digestibility trial and kept individually in metabolic cages. Nutrient digestibility and N balance were not affected by SF. However, QT at 40 g kg-1 of dry matter decreased (P <0.05) nutrient digestibility and also increased the proportion of absorbed N. Both SF and QT reduced (P <0.05) the slowly degraded fraction and rate for organic matter and N. Even though the QT had a negative (P <0.05) effect on nutrient digestibility, this effect was mild (P >0.05) when SF was included in the QT-added diets. Moreover, an interaction (P <0.05) of SF × QT was observed on the synchronization index as an indicator of the efficiency of rumen microbial protein synthesis. Supplementation of either SF or QT to sheep diets reduced ruminal organic matter and N degradability, reflecting the compensatory digestion in the post-ruminal track for organic matter feed utilization. © 2019 Society of Chemical Industry.