The Influence of Monensin on In Vivo Rumen Fermentation Characteristics in Fistulated Steers Fed Corn Stalk Diet
Category: Research Poster
Author(s): Zachary Araujo-Lovato
Presenter(s): Zachary Araujo-Lovato
Mentors(s): Terry Engle, Huey Yi Loh
Sixteen individually fed steers fitted with ruminal cannulae were used in a randomized block design to examine the impact of monensin supplementation on in vivo rumen fermentation characteristics while being fed a low-quality cornstalk based diet (4.2% CP). Prior to beginning the experiment, all steers received the basal diet for 21 d. Steers were then blocked by body weight and randomly assigned to one of two treatments. Treatments consisted of: 1) Control (no added monensin; carrier only) or 2) Monensin (250 mg·steer-1·day-1). Treatments were administered daily, directly into the rumen via the cannula as a single bolus dose at the time of feeding over a 21d period. The carrier for treatments delivered consisted of 250 g of dried distillers grains for both treatments. Rumen contents were sampled two h post-feeding daily and analyzed for short chain fatty acids (SCFA). Animal was considered the experimental unit, and data were analyzed as a randomized complete block design using Proc Mixed procedures in SAS. There were no treatment by time interactions for any of the response variables measured. Therefore, only treatment main effects are reported. In vivo molar proportions of propionic acid and total SCFA (mM) were greater (P < 0.05) in rumen fluid from steers receiving monensin compared to controls. Molar proportions of acetic acid were lesser (P < 0.05) in treated steers than steers not receiving monensin. Molar proportions of isobutyrate and butyrate and pH were similar across treatments. These data indicate that the monensin alters in vivo rumen fermentation characteristics.