This is a draft schedule. Presentation dates, times and locations may be subject to change.

643
Effects of Feeding Functional Oils or Monensin on Rumen Morphometrics of Nellore Cattle.

Sunday, July 9, 2017
Exhibit Hall (Baltimore Convention Center)
Ana Laura J Lelis, São Paulo State University (UNESP), Dracena campus, Dracena, Brazil
Alan CB Melo, São Paulo State University (UNESP), Dracena campus, Dracena, Brazil
Murillo CS Pereira, São Paulo State University (UNESP), Botucatu campus, Botucatu, Brazil
Daniela D Estevam, São Paulo State University (UNESP), Botucatu campus, Botucatu, Brazil
Ariany F Toledo, São Paulo State University (UNESP), Dracena campus, Dracena, Brazil
Mylena M Ferreira, São Paulo State University (UNESP), Dracena campus, Dracena, Brazil
Andre LN Rigueiro, São Paulo State University (UNESP), Botucatu campus, Botucatu, Brazil
Mariana M Squizatti, São Paulo State University (UNESP), Dracena campus, Dracena, Brazil
Alice HPM Assumpção, São Paulo State University (UNESP), Dracena campus, Dracena, Brazil
This study, conducted at the São Paulo State University feedlot, Dracena campus, Brazil, was designed to test the effects of adding functional oils (Essential) or monensin on rumen morphometrics and rumenitis incidence of Nellore cattle fed high-concentrate diets. Eighty-eight 22-mo-old Nellore yearling bulls (377.9 ± 32.0 kg) were assigned to 24 pens (4 animals/pen) and used in a completely randomized block design with a 2×2 factorial arrangement of treatments, replicated 6 times. Factors were inclusion (DM basis) or not of functional oils or monensin, at a dose of 500 ppm or 27 ppm, respectively. Animals were adapted for 16-d to the high-concentrate diets fed. The finishing diet contained 68.5% cracked corn grain, 14.0% sugarcane bagasse, 14.1% cottonseed meal, 2.1% supplement, 0.8% urea, and 0.5% limestone (DM basis). Cattle were fed ad libitum three times daily for 105-d, and DMI was recorded daily. At harvest, rumenitis incidence was determined on the entire washed rumen, using a scale of 0 (no lesions noted) to 10 (severe ulcerative rumenitis). Likewise, a 1-cm2 fragment of each rumen was collect from the cranial sac. The number of papillae per cm2 of rumen wall (NOP) was determined, as well as the mean papillae area (MPA). The rumen wall absorptive surface area (ASA) in cm2 was calculated as follows: 1+(NOP*MPA)-(NOP*0.002). No significant (P > 0.10) functional oils or monensin main effects were observed for rumenitis (with functional oils = 1.41, without functional oils = 1.77; with monensin = 1.73, without monensin = 1.45). Also, no significant (P > 0.10) functional oils main effect was observed for MPA in cm2 (with functional oils = 0.54, without functional oils = 0.55) and ASA in cm2 (with functional oils = 33.60, without functional oils = 34.70). However, the addition of monensin led to larger (P < 0.10) MPA in cm2 (with monensin = 0.60, without monensin = 0.48) and ASA in cm2 (with monensin = 37.23, without monensin = 31.06). A significant (P = 0.03) interaction between functional oils and monensin was observed for NOP in cm2 (control = 61.48ab, monensin = 67.61a, functional oils = 69.17a, monensin + functional oils = 58.18b), where the feeding of both additives reduced NOP when compared to the feeding of only monensin or functional oils. Thus, based on these results, the feeding of monensin promoted greater development of rumen epithelium, which could indicate greater short-chain fatty acids absorption.