Effect of Adding Extra Virgin Olive Oil to Hair Sheep Lambs’ Diets on Productive Performance, Ruminal Fermentation Kinetics and Rumen Ciliate Protozoa

SIMPLE SUMMARY: The use of added lipids in the diets of ruminants has been found to have beneficial effects. In this study, the effects of different doses of extra virgin olive oil on the productive traits and ruminal fermentation parameters in lambs were evaluated. The relationship between nutrient intake and digestibility was optimal with 2% oil inclusion. The concentration of propionic acid increased with 2 and 4% DM of olive oil, while butyric acid decreased. The intake of olive oil did not affect the population of protozoa or animal performance. The inclusion of olive oil in low concentrations (2% of DM) positively influences feed intake and nutrient digestibility in hair sheep lambs. ABSTRACT: This study determined productive performance, ruminal fermentation kinetics and rumen ciliate protozoa in hair sheep lambs fed different levels of olive oil. Twenty-four growing lambs were used, with an initial live weight of 10.5 ± 2.9 kg, and randomly assigned into four treatments (six animals per treatment) containing increasing levels of extra virgin olive oil (0, 2, 4 and 6% of dry matter). Animals were fed for 80 days, and sampling was carried out weekly. Intake of dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF) and metabolizable energy (ME) differed between treatments (p < 0.05), with a linear and cubic tendency to decrease when oil concentrations were increased. Digestibility coefficients of OM, CP and NDF were not affected; however, the relationship between total intake and nutrient digestibility (DM, OM, NDF, ADF) increased with 2% DM olive oil. Compared with all treatments, the concentration of propionic acid increased by 16% with 4% olive oil. The intake of olive oil did not affect the protozoa population and live weight gain. Overall, the inclusion of olive oil in low concentrations (2% of DM) positively influences feed intake and nutrient digestibility in hair sheep lambs.