ABSTRACT
Different doses of propylene glycol were compared for lowering plasma NEFA concentration during restricted feed intake. Eight Holstein heifers, averaging 90 d prior to calving at initiation of the trial, were in a 4 x 4 Latin square design with 12-d periods. Heifers consumed alfalfa silage on an ad libitum basis during d 1 to 7 of each period. During d 8 to 12, heifers were gradually restricted to 50% of ad libitum intake. Heifers received an oral drench of 0, 296, 592, or 887 ml of propylene glycol once daily at 6 h prior to feeding on d 8 to 12. Propylene glycol linearly increased glucose and insulin and decreased BHBA and NEFA in blood. Quadratic effects of propylene glycol on plasma glucose, BHBA, and NEFA also occurred; response per milliliter of propylene glycol was greatest at the lowest dose. The highest dose of propylene glycol returned blood glucose, insulin, and NEFA concentrations to those prior to feed restriction. Ruminal acetate to propionate ratio decreased as propylene glycol dose was increased, indicating ruminal conversion of propylene glycol to propionate. A dose of 296 ml of propylene glycol was almost as effective as a dose of 887 ml in reducing lipid mobilization during restricted feed intake.
Subject(s)
Cattle/blood , Food Deprivation , Propylene Glycols/administration & dosage , 3-Hydroxybutyric Acid , Animals , Blood Glucose/metabolism , Dose-Response Relationship, Drug , Fatty Acids, Nonesterified/blood , Female , Hydroxybutyrates/blood , Insulin/blood , Liver/metabolism , Pregnancy , Propylene Glycol , Propylene Glycols/pharmacology , Triglycerides/metabolismABSTRACT
Plasma glucose concentration during late gestation was thought to be important for the development of fatty liver near parturition. Thirteen multiparous cows were given a 1-L oral drench of propylene glycol once daily beginning 10 +/- 3.6 d prepartum until parturition. Eleven control cows received a 1-L water drench. Plasma glucose increased following propylene glycol administration. Plasma NEFA concentration was 403 and 234 microM, and plasma insulin concentrations were .354 and .679 ng/ml, for control cows and cows treated with propylene glycol measured from 1 to 7 d prepartum. Plasma NEFA tended to be lower in cows treated with propylene glycol from 1 to 21 d postpartum. Prepartum propylene glycol administration reduced hepatic triglyceride accumulation by 32 and 42% at 1 and 21 d postpartum, respectively. Prepartum plasma BHBA was reduced during propylene glycol administration. Prepartum plasma glucose, NEFA, BHBA, and insulin were strongly correlated with liver triglyceride at 1 d postpartum (r = -.49, .45, .36, and -.49, respectively). Pre- and postpartum DMI were not affected by treatment. Milk production and composition measured through 21 d postpartum were not different between groups.
