In Vitro Production of β;-Hydroxybutyrate from 1,3-Butanediof by Bovine Liver, Rumen Mucosa, and Kidney

A model ketosis can be produced in dairy cows by restricting feed intake plus feeding 1,3-butanediol. Increases in D-β;-hydroxybutyrate in blood result from metabolism of the 1,3-butanediol, but the site of metabolism has not been established. In vitro production of D-β;-hydroxybutyrate from butyrate and from isomers of 1,3-butanediol was measured in bovine liver, rumen papillae, and kidney cortex, all obtained at slaughter from nonlactating, nonpregnant Holstein cows. Production of D-β;-hydroxybutyrate from butyrate by the tissues was greatest for liver and rumen and much less for kidney. Only liver, however, produced appreciable amounts of D-β;-hydroxybutyrate from R-, S-, or RS-1,3-butanediol, and rates were maximal at substrate concentrations of 5 mM. Production of D-β;-hydroxybutyrate from R-1,3-butanediol by liver was greater than from S-1,3-butanediol. In vitro rates of production of D-β;-hydroxybutyrate were consistent with liver being the primary tissue involved in the metabolism of 1,3-butanediol, and capacity of the liver probably is sufficient to account for metabolism of 1,3-butanediol when 1 kg is fed daily to dairy cows.