Effects of supplementation with 2-hydroxy-4-(methylthio)-butanoic acid isopropyl ester on splanchnic amino acid metabolism and essential amino acid mobilization in postpartum transition Holstein cows

摘要: Abstract The present study aimed to investigate the effects of 2-hydroxy-4-(methylthio)-butanoic acid isopropyl ester (HMBi) supplementation on splanchnic AA metabolism, essential (EAA) mobilization, and plasma status in postpartum transition dairy cows. EAA mobilization was calculated by difference: excretion milk protein − net portal absorption or release EAA. Eight Holstein cows fitted with permanent indwelling catheters hepatic vein, mesenteric an artery dry period preceding second parturition were used study. Cows randomly allocated 1 4 treatments a 2×2 factorial arrangement factor 1: control (calcium carbonate) versus HMBi [1.5g HMBi/kg matter (DM)] 2: high dietary ethanol (19g/kg DM) propanol (16g/kg DM). Only data are presented. Treatments administered total mixed rations initiated day parturition. sampled 14 d before expected 4, 15, 29 after Supplementation tended increase fat content but not yield, impose slower rate decrease casein increasing days (DIM), prevented Met associated for control, reduced concentration Ser, reduce concentrations Gly His, uptake postpartum. excreted 248±18g more at DIM than released from tissues. deficiency decreased as lactation progressed affected supplementation. It estimated that 4,700±600g extra-splanchnic tissues secreted during first DIM. Extra-splanchnic can be crucial sustain yield is fast-working source improve