Submitted to: Conference on Rumen Function
Publication Type: Abstract Only
Publication Acceptance Date: November 6, 1997
Publication Date: N/A
An in vitro ruminal fermentation study was used to investigate the influence of feeding sub-therapeutic levels of chlortetracycline (CTC) at two levels of dietary protein (PRO) on ruminal fermentation characteristics. Rumen fluid was obtained at slaughter from steers fed one of four treatments (- or + CTC and 10% or 13% PRO) and used to initiate continuous culture artificial rumens. CTC and 13% PRO resulted in lower (P < .001) ammonia. However, CTC and 10% PRO had in similar (P > .05) concentrations of ammonia. CTC with 13% PRO resulted in higher (P < .001) pH and acetate, as well as, lower (P < .001) acetate, iso-butyrate, iso-valerate, n-valerate, and total VFA. Fermentors receiving 10% PRO and CTC had similar (P >.05) pH, and total VFA. When CTC was added to fermentors receiving 10% PRO, acetate, iso-butyrate, iso-valerate and the acetate to propionate ratio were lower (P < .001). Propionate was higher (P < .001) when CTC was fed with 10% PRO, but was similar (P > .05) when fed at 13% PRO. Acetate to propionate ratio was decreased (P < .001) by addition of CTC at both PRO levels, with the 10% PRO being lower (P <.001) than 13% PRO. Under these circumstances, CTC maintained similar ammonia concentrations at both 10% and 13% PRO, indicating a sparing of dietary protein.