Effect of abomasal butyrate infusion on net nutrient flux across the portal-drained viscera and liver of growing lambs.

Abstract

The purpose of this experiment was to determine if supplying butyrate to the postruminal gastrointestinal tract of growing lambs alters blood flow and nutrient flux across the portal-drained viscera (PDV) and hepatic tissues. Polled Dorset wether lambs ( = 10; initial BW = 55 ± 3.3 kg) had catheters surgically implanted into the portal vein, a branch of the hepatic vein, a mesenteric vein, and the abdominal aorta. A cannula was placed in the abomasum to deliver the treatment. Lambs were fed a pelleted ration once daily consisting of 69.7% dehydrated alfalfa, 30.0% ground corn, and 0.3% salt at 1.3 × NE requirement. The experimental design was a crossover balanced in time, so that each lamb received both treatments. Treatments consisted of either a pulse dose infusion of butyrate (buffered solution) to supply butyrate (10 mg/kg BW) or a buffered saline solution (1 mL/kg BW) once daily at the time of feeding. On d 14 of the treatment period, nutrient fluxes were measured using para-aminohippuric acid as a blood flow marker. Blood samples were collected from the aorta, portal vein, and hepatic vein every hour for 9 h beginning at 30 min prior to treatment/feeding. There was a tendency for a treatment × time interaction ( = 0.05) for portal vein blood flow, indicating that blood flow began to decrease earlier postprandial in lambs receiving butyrate. The butyrate treatment tended to increase the uptake of O ( = 0.07) and increased the uptake of glucose ( = 0.002), glutamate ( = 0.04), and glutamine ( = 0.02) by the PDV. There was a treatment × time interaction ( < 0.01) for flux of acetate, propionate, butyrate, isobutyrate, and valerate across the PDV. The interaction was mainly due to an earlier postprandial peak and associated decrease in the flux rate of the VFA. The alteration in timing of the postprandial peak of VFA flux was also observed in hepatic fluxes of VFA. It appears that supplying butyrate to the postruminal tissues through an abomasal cannula increases glucose, glutamate, and glutamine metabolism by the PDV.