Regulation of Blood Fatty Acids and Glycerol in Lactating Cows

Abstract

Responses of blood plasma glycerol and free fatty acids (FFA) to 2.5 to 5.0 mg L-norepinephrine (NE) in nine lactating (3 to 5 weeks) and nine nonlactating (3 to 5 weeks prepartum) cows were compared at 0, 15, 30, 45, and 60 min after intravenous iniection. Mean control values (μM) for nonlactating and lactating cows were: glycerol, 98 and 118; FFA, 379 and 420. Post NE injection means (μM) for nonlactating and lactating cows were: glycerol, 119 and 120; FFA, 430 and 557. Response to NE was apparently higher (P ∼ .12) for FFA and lower (P < .09) for glycerol in lactating cows than in nonlactating cows. Average hormone-sensitive lipase activities (micromoles fatty acids released per hour per milligram protein) in adipose tissue homogenates from four nonlactating and five lactating cows were 1.6 and 2,6. Lactation increases plasma FFA and glycerol concentrations by inhibiting re-esterification of fatty acids and by increasing the active form of the lipase in adipose tissue. © 1972, American Dairy Science Association. All rights reserved.