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

Abstract

BACKGROUND: 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 3 2 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 ± 1.3 kg) for each treatment were used in the digestibility trial and kept individually in metabolic cages. RESULTS: 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. CONCLUSION: 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