Ruminal Characteristics and Feedlot Bloat Incidence in Cattle as Influenced by Vegetable Oil, Mineral Oil, and Animal Fat

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Abstract
Results of a series of experiments on feedlot bloat have confirmed a previous report that the addition of an 8% level of crude degummed soybean oil to a mixed ration that was conducive to feedlot bloat increased its bloat-producing capability. On the other hand, when the same amount of oil was administered to cattle as a drench prior to each feeding, it did not significantly alter bloat incidence. Addition of animal fat to the ration had no effect on bloat incidence, but either 4 or 8% levels of mineral oil reduced bloat by 40%. Out of 10 different ruminal characteristics studied only stable ingesta-volume-increase (IVI) was significantly affected by mixing oils or fat into the feed. It was reduced by feeding mineral oil and increased by animal fat. Blood fat was higher when steers were fed soybean oil or animal fat in their feed. IVI was lower when a soybean oil drench was given to steers. Soybean oil given as a drench to steers increased the molar percentage of propionate in ruminal fluid and increased blood serum cholesterol. In vitro results suggested that soybean oil and animal fat were metabolized by ruminal microorganisms. There was some indication that even mineral oil was metabolized to a small extent by rumen bacteria.