ABSTRACT The objective of this study was to evaluate the effects of an essential oil blend (EO), based on cinnamaldehyde and diallyl disulfide, associated or not with antibiotics on intake and nutrient digestibility, ingestive behavior, rumen fermentation, ruminal microbial synthesis, and blood metabolites of feedlot cattle fed a no-forage diet. The study was carried out as a Latin Square with five treatments consisting of a blend of essential oil (EO), monensin (MON) and virginiamycin (VM), both separately and combined as follows: CON (monensin at 30 mg kg–1 DM), VM (virginiamycin at 25 mg kg–1 DM and monensin at 30 mg kg–1 DM), MEO25 (monensin at 30 mg kg–1 DM and EO at 25 mg kg–1 DM), MEO35 (monensin at 30 mg kg–1 DM and EO at 35 mg kg–1 DM) and EO35 (blend of EO at 35 mg kg–1 DM). There were no effects from additives and their combinations on the intake and apparent digestibility of nutrients or ingestive behavior. Furthermore, treatments did not modify the ruminal pH, nor the concentration of short-chain fatty acids and ammonia, nor the microbial protein synthesis. Blood glucose concentration was higher 4 h after morning feeding for all treatments. There was a significant contrast between the VM and EO for the blood concentration of D-Lactate and L-Lactate. There was no difference between the additives in the concentration of cortisol metabolites in the feces. The blend of essential oil studied, containing cinnamaldehyde and diallyl disulfide, associated or not with antibiotics, does not change the nutritional parameters nor the metabolism of feedlot cattle fed a no-forage diet. EO, , (EO) disulfide behavior fermentation synthesis noforage forage diet MON (MON VM, (VM) follows 3 kg1 kg 1 kg– DM, 2 MEO MEO2 MEO3 EO3 DM. . Furthermore pH shortchain short chain ammonia DLactate D Lactate LLactate. LLactate L Lactate. L-Lactate feces studied (EO (VM

ABSTRACT This study was carried out to evaluate the effects of corn dried distillers’ grains (DDG) levels in non-forage diets by in vitro, in situ (0 to 50%), and in vivo (0 to 40%) trials on kinetic parameters of gas production (GP) on rumen-degradable protein (RDP) and rumen-undegradable protein (RUP) as well as on nitrogen (N) metabolism in Nellore cattle. For in vitro and in situ studies, three rumen cannulated Nellore males with body weight of 340.48 ± 22.22 kg were used. For the in vivo study, five non-castrated male Nellore cattle with an initial body weight of 355.20 ± 35.28 kg and 24 ± 3 months old were used to evaluate the effect of increasing DDG levels in non-forage diets on N metabolism by a 5 × 5 Latin square design. Experimental diets were based on ground corn, cottonseed cake, urea, mineral supplement, and increasing levels of DDG replacing ground corn. The DDG levels caused a linear decrease in GP and in vitro dry matter digestibility. The DDG presented a lower dry matter digestibility (DMD) and RDP and higher RUP than corn grain and cottonseed cake, making DDG diets present lower DMD and RDP than control. The DDG levels linearly increased the intake of crude protein, neutral detergent fiber, and ether extract, whereas non-fiber carbohydrates intake decreased and tended to decrease the DMD and organic matter digestibility. The DDG levels caused a linear increase in N intake and in total, fecal, and urinary N excretion, which was the major N excretion route, causing a quadratic drop in retained N and caused a quadratic effect on alanine aminotransferase. In contrast, triglycerides were cubically affected, and total blood protein increased. Thus, DDG levels negatively affect in vitro and in situ digestibility, increasing N intake but increasing urinary N excretion. distillers (DDG nonforage non forage 0 ( 50%, 50 50% , 50%) 40% 40 (GP rumendegradable degradable (RDP rumenundegradable undegradable (RUP (N studies 34048 340 48 340.4 2222 22 22.2 noncastrated castrated 35520 355 20 355.2 3528 35 28 35.2 2 design cake urea supplement (DMD control fiber extract nonfiber fecal route aminotransferase contrast affected Thus 4 3404 34 340. 222 22. 3552 355. 352 35.