Rumen bacteria population in Nellore steers fed with crude glycerin and soybean oil association Laís O. Lima1, Yury T. Granja-Salcedo1, Juliana D. Messana1, Vinícius C. Souza1, Ana L. Dias1, Telma T. Berchielli1 1Department of Animal Science, Universidade Estadual Paulista, Jaboticabal/SP *E-mail: laisolima@hotmail.com, Jaboticabal, São Paulo, Brazil. Via de Acesso Prof. Paulo Donato Castellane , km 5. CEP: 14884-900 - Jaboticabal, SP – Brazil Introduction Results Lipid supplementation could cause negative effects on the dry matter intake (DMI) and diet digestibility when the ether extract (EE) content exceeds 70 g/kg. However, crude glycerin (CG) could partially inhibit ruminal lipolysis and modulate the release of unsaturated fatty acid (UFA) in the rumen, and could thereby reduce the deleterious effects of UFA on DMI and diet digestibility. Thus, the objective of this study was evaluated the intake and digestibility in Nellore steers fed with CG and high soybean oil (SO) content (> 80 g EE/kg DM). Steers fed with oil and glycerin presented similar DM and CP intake than steers fed with a no oil and no glycerin diet (p = 0.216; Fig 2). Diets with oil addition reduced the NDF intake (4.81 vs 4.20 kg of NDF/d;) p = 0.049) but increased the EE intake (0.91 vs 0.35 kg of EE/d; p < 0.001). The highest NFC intake was presented by animals fed with a no oil and no glycerin diet (p <0.05; Fig 2) and the no oil and glycerin diet generated the lowest GE intake (4.09 vs 4.24 Kcal/Kg DM; p < 0.001). There was an interaction effect of SO and CG on DM and NDF digestibility (Fig 2). EE digestibility was lowest for the diet with no oil and no glycerin when compared with diets contained soybean oil (83.23 vs 89.54 %; p = 0.001). Steers fed with diets containing soybean oil showed higher CP digestibility (78.68 vs 74.61%; p <0.001). Material and Methods B A A b c a ab Figure 1. A. Animal and facilities used. B. Total feces collection procedures. Eight Nellore steers (501.3±18 kg BW), castrated were used in a double, simultaneous, Latin square design 4 × 4 with a 2 × 2 factorial arrangement of treatments (with or without SO and with or without CG). The experiment consisted of four consecutive periods of 20 days each (15 d adaptation). The diet was offered as a total mixed ration two times a day at 07:00 h and 17:00 h. Analyses of variance were performed using R Software. Tukey’s post-hoc test was applied when ANOVA indicated a significant difference between means, considering significance when P≤ 0.05. B ab b a Figure 2. Intake (A) and total apparent digestibility (B) of DM and NDF in feedlot Nellore steers fed with diets containing or not soybean oil (SO) with or without Crude Glycerine (CG).. Table 1. Ingredients and bromatological composition of experimental diets. Conclusions Ingredients, % of DM   Diets SO and CG SO and no CG No SO and CG No SO and no CG Tifton 85 hay 300.0 Ground Corn 362.0 485.0 434.0 560.0 Soybean meal 168.0 145.0 156.0 130.0 Urea 10.0 Soybean oil 60.0 - Crude glycerine 100.0 Bromatological composition Dry matter (g/kg) 858.3 896.4 849.5 839.9 Crude protein (g/kg DM) 153.7 152.4 153.5 151.2 Neutral-detergent fiber (g/kg DM) 404.6 430.5 420.1 446.0 Gross energy (MJ/kg DM) 17.3 17.00 17.6 Ether extract (g/kg DM) 86.4 89.2 30.0 33.0 Crude glycerin associated with soybean oil could be used as an energy source in cattle diets without affecting dietary intake and digestibility, even when high lipid content is added to the diet. Acknowledgements The authors would like to thank the São Paulo Research Foundation (FAPESP) for providing financial support through grant # 2014/09033-1, 2015/17966-0 and 2013/23851-6. .