Contents lists available at ScienceDirect Animal Feed Science and Technology journal homepage: www.elsevier.com/locate/anifeedsci Progressive adaptation of sheep to a microencapsulated blend of essential oils: Ruminal fermentation, methane emission, nutrient digestibility, and microbial protein synthesis Y.A. Soltan a, ⁎ , A.S. Natel b , R.C. Araujo c , A.S. Morsy d , A.L. Abdalla b a Alexandria University, Faculty of Agriculture, Animal and Fish production Department, Alexandria, Egypt b University of São Paulo, Centre for Nuclear Energy in Agriculture, Laboratory of Animal Nutrition, Piracicaba, Brazil c GRASP Ind. & Com. LTDA, Department of Research and Development—Ruminant Division, Curitiba, Brazil d City of Scientific Research and Technological Applications, Arid Lands Cultivation Research Institute, Livestock Research Department, New Borg El- Arab, Alexandria, Egypt ARTICLE INFO Keywords: Phenylpropanes Terpene hydrocarbons Rumen manipulation Purine derivatives Nitrogen retention ABSTRACT The combination of various active components in essential oils (EO) may be highly effective as a natural dietary supplementation option to manipulate ruminal fermentation and decrease me- thane (CH 4 ) emissions. Nine rumen cannulated Santa Inês sheep (55 ± 3.7 kg of body weight) were randomly divided into three groups to receive three experimental treatments: control (basal diet without additives); basal diet with 200 (EO200) mg of EO of a microencapsulated blend of essential oils (MBEO)/kg dietary DM offered; and basal diet with 400 (EO400) mg of EO of MBEO/kg dietary DM offered. The experiment was recorded in a triple 3 × 3 Latin Square design. The number of days necessary to observe the manipulation of rumen fermentation with MBEO was determined with an evaluation of nutrient digestibility, CH 4 emissions, and microbial protein synthesis. Ruminal samples were collected at day zero (the day before starting the dietary treatments), and on days 1, 2, 3, 7, and 15 after MBEO introduction, while the subsequent 7 days were assigned for the nutrient digestibility trial and CH 4 determination. On day 3, propionate concentrations began to increase (P < 0.01) for EO200 and EO400, which resulted in an asso- ciated decrease (P = 0.03) in the acetate: propionate ratio; this effect lasted until day 15. The enhancement (P = 0.003) in the overall mean of total short-chain fatty acids was consistent with the decrease (P = 0.06) in the overall mean of ruminal pH for both MBEO doses, compared to the control. A decline (P < 0.01) in the protozoal count was observed after a week in the EO400 treatment, whereas no differences were observed in the EO200 and control treatments. No sig- nificant differences among the three treatments were detected for ammonia concentration, dry matter intake, or total tract nutrient digestibility. A reduction (P = 0.009) in CH 4 emissions was observed in the EO200 and EO400 [24.5 and 27.6 l/kg digestible organic matter (DOM), re- spectively] treatments, compared to the control (38.2 l/kg DOM). Among the treatments, EO400 resulted in the highest body nitrogen (N) retention (P = 0.03) and microbial protein synthesis (P < 0.01). The results suggest that the addition of MBEO favorably modifies the ruminal https://doi.org/10.1016/j.anifeedsci.2018.01.004 Received 6 May 2017; Received in revised form 16 December 2017; Accepted 2 January 2018 ⁎ Corresponding author. E-mail address: uosra_eng@yahoo.com (Y.A. Soltan). Abbreviations: ADFom, ash-free acid detergent fibre; AOAC, Association of Official Analytical Chemists; aNDFom, ash-free neutral detergent fibre treated with heat- stable amylase expressed exclusively of residual ash; BW, body weight; C2/C3, acetate to propionate ratio; CH 4 , methane; CP, crude protein; DOM, digestible organic matter; EO, essential oils; DM, dry matter; DMI, dry matter intake; lignin(sa), lignin determined by solubilisation of cellulose with sulfuric acid; MBEO, micro- encapsulated blend of essential oils; MN PD , daily duodenal flux of microbial N; N, nitrogen; OM, organic matter; PD a , microbial purines absorbed from the small intestine; PD, urinary purine derivatives; SCFAs, short-chain fatty acids; SE, standard error Animal Feed Science and Technology 237 (2018) 8–18 0377-8401/ © 2018 Elsevier B.V. All rights reserved. T