Effects of cyclic monensin feeding on in vitro true digestibility of low quality forage fed cattle
Abstract: Monensin, a carboxylic polyether ionophore antibiotic, is a feed additive commonly provided to ruminant animals to improve feed efficiency. Unfortunately the beneficial effects of monensin diminish over time. In this study, digestibility will be evaluated, through in vitro true digestibility (IVTD), with the use of a new feeding strategy designed to prolong the beneficial effects of monensin. Twelve cannulated steers fed a low-quality forage (LQF; 4.9% CP) diet will be randomly assigned to one of three treatments: 1) Control (CON; 0 mg?hd-1?d-1 monensin), 2) Monensin (MON; 200 mg?hd-1?d-1 monensin) or 3) Cyclic (CYC; 200 mg?hd-1?d-1 monensin for 14 d and 0 mg?hd-1?d-1 monensin for subsequent 14 d). Dried distillers grains (1kg?hd-1?d-1) will be fed for monensin inclusion. The project will consist of four 28 d periods. On d 10 and 12 of each period, rumen fluid will be removed from each animal, filtered through four layers of cheesecloth and transported to the laboratory. In the laboratory, rumen fluid will be combined within treatment and processed according to ANKOM (2005) utilizing a DaisyII Incubator. It is anticipated that IVTD for the CON group will remain constant for the duration of the trial while IVTD for the MON group will be improved in the first period, but slowly become similar to the CON group as the trial progresses. The CYC group, due to being fed cyclically is expected to maintain its improved IVTD throughout the duration of the trial.
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