In vitro rumen fermentation and in vivo bloat dynamics of steers grazing winter wheat to corn oil supplementation

Abstract The influence of corn oil on in vitro ruminal gas production, bloat potential and weight gain of steers was investigated. Overall objectives were to: (1) quantify in vitro , the effect of sources of rumen fluid, levels of corn oil supplementation on rate of gas production, foam height and foam strength and (2) quantify the influence of corn oil on in vivo rumen fluid bio-film production, bloat potential and weight gain of steers grazing wheat pasture. In Experiment 1, in vitro gas production was measured from 0 to 6 h rumen incubation periods. In vitro rumen foam production and foam strength were measured. In Experiment 2, rumen cannulated steers ( n  = 18; 330 ± 22 kg) were randomly allocated to one of three treatments (0, 7.5 and 15.0 g corn oil of kg dry matter intake (DMI) steer −1 per day). Samples of rumen contents were taken at day −30, 0, 20 and 30 for analysis of rumen microbial protein fractions, rumen microbial DNA concentration and ethanol precipitable polysaccharide slime (referred to as bio-film). Bloat was visually scored (from 0 to 3) 5 days a week. In Experiment 1, mineral oil was used as a non-nutritive surfactant to serve as a non-nutritive negative control. In vitro rate of gas production was greater (P