EFFECT OF METHOD OF DELIVERY OF PROPYLENE-GLYCOL ON PLASMA METABOLITES OF FEED-RESTRICTED CATTLE

Methods of administering propylene glycol to reduce plasma nonesterifi ed fatty acids (NEFA) during feed restriction of cattle were evaluated . Treatments were 1) no propylene glycol supplementation, 2) propylene glycol provided as an oral drench once per day, 3) propylene glycol m ixed with concentrate and fed separately from forage, or 4) propylene glycol blended as part of the total mixed ration (TMR). Prior to or du ring feed restriction at 50% of ad libitum intake, propylene glycol wa s provided once daily at 2.5 ml/kg of body weight(0.75). Prior to feed restriction, administration of propylene glycol as an oral drench or mixed with concentrate was more effective in increasing serum insulin than was feeding propylene glycol as part of the TMR. During feed rest riction, administration of propylene glycol as an oral drench or mixed with concentrate resulted in higher serum insulin and lower plasma NE FA concentrations than did feeding propylene glycol as part of the TMR . Propylene glycol decreased the molar percentage of ruminal acetate a nd the ratio of acetate to propionate. Propylene glycol administered a s an oral drench or mixed with concentrate and fed separately from for age appeared to be more effective than feeding propylene glycol as par t of the TMR for influencing plasma NEFA in cattle during feed restric tion.