Abstract #450

# 450
Effects of abomasal infusions of amino acids or glucose on energy and protein metabolism during an induced negative energy balance.
I. Ansia*1, Y. Ohta2, T. Fujieda2, J. K. Drackley1, 1University of Illinois, Urbana, IL, 2Ajinomoto Co. Inc, Tokyo, Japan.

The aim of the study was to assess the effects of 5 supplements during a short-term period of negative energy balance (NEB) induced by feed restriction (FR). Seven multiparous Holstein cows (93 ± 15 DIM) were randomly assigned to 7 treatments in a 7 × 4 incomplete Latin square design with 5-d periods. Daily DMI was restricted to provide 60% of net energy requirements except in one treatment that was fed for ad libitum (AL) DMI. Treatments were 4-h abomasal infusions (0.4 mol/kg BW) initiated at feeding time (0900 h) of: glucose (GLC), monosodium glutamate (MSG), lysine (LYS), glutamine (GLN), valine (VAL), and water (CON and AL) as control. Effects of infusions were compared using the MIXED procedure of SAS. Milk yield was lower (P = 0.05) than AL for all except MSG and GLN, with MSG the only treatment with no decrease (MSG × d; P = 0.39). Milk protein yield during GLN only tended (P = 0.07) to differ from AL. Lactose yield was not lower than AL for VAL, MSG, and GLN. Concentrations of NEFA did not differ from AL for MSG and GLN. Treatments MSG and VAL had no linear increase of BHB across periods. Plasma glucose tended to decrease (P = 0.10) during GLN, but increased continuously after d 2 with MSG. The LYS treatment increased plasma concentrations of Lys (LYS vs.. CON; P < 0.01), Arg (LYS × h; P < 0.01), α-AAA (LYS × h; P < 0.01) and 3-methylhistidine (LYS vs. CON; P < 0.01), suggesting that both catabolic and anabolic processes were induced. Treatment VAL increased concentrations of Val (VAL vs CON; P < 0.01) and resulted in the lowest plasma concentrations of urea N and AA involved in the urea cycle (Arg, Orn, Cit). The MSG treatment increased concentration of Glu (MSG × d; P < 0.06) across periods. Moreover, MSG was the only treatment that did not decrease Orn, Asp, and Trp, induced the biggest increase of Arg (18%), and increased (MSG x d; P = 0.01) linearly (P < 0.01) serum albumin concentration during FR. Enhancing metabolic pathways to support AA deamination processes and the interconnected gluconeogenesis and ureagenesis (treatments MSG, GLN, and VAL) seemed to lessen the negative effects of the NEB period.

Key Words: negative energy balance, amino acid, catabolism