Effects of Dietary Intake on Amino Acid Composition of Histotroph (Uterine Luminal fluid) in Nonpregnant Cows: Implications for Pregnancy

Abstract When the developing embryo enters the uterus, before the placenta develops, the embryo receives nourishment from endometrially derived histotroph produced by the uterine glands that remain functional throughout gestation. Throughout pregnancy, this histotroph remains necessary for proper embryonic development. Maternal nutrition may affect histotroph composition resulting in altered embryo development. The objectives were to determine the effects of dietary intake on histotroph amino acid (AA) concentrations. Eighteen multiparous nonpregnant cows (initial BW = 597 kg) were housed at the North Dakota State University Animal Nutrition and Physiology Center (n = 6 cows/pen). Cows were individually fed a TMR once daily via a Calan feeding system and had ad libitum access to fresh water. Cows were randomly assigned to 1 of 2 treatments (n = 9/treatment): dietary intake designed to maintain body weight (CON) or dietary intake designed to lose body weight at a moderate rate (-0.7 kg/d; NEG), for 63 days. Slaughter group 1 contained 4 CON and 5 NEG cows, and group 2 contained 5 CON and 4 NEG cows. Cows were estrus-synchronized with the Co-Synch + CIDR protocol to ensure a common day of the estrous cycle at the time of slaughter (3 d after completion of the Co-Synch + CIDR protocol). When total uterine histotroph AA was calculated (luteal + non-luteal horns) and analyzed by treatment with group in the model, the differences were: CON > NEG for 1) Trp as % of essential AA, and 2) Ser as % of total AA (P = 0.04 and 0.05, respectively). Tendencies for total tract histotroph were observed for Phe and Trp as a % of total AA (P = 0.07 and 0.06, respectively) for CON > NEG. Luteal histotroph Ser as a % of total AA was greater (P = 0.05) for CON vs. NEG. When evaluating non-luteal histotroph, CON had greater (P < 0.05) Cys as a % of total AA compared with NEG cows. Non-luteal histotroph Arg concentration tended (P = 0.10) to be greater for NEG vs. CON. These results demonstrate that feed intake affects cow AA supply in the uterine histotroph, and these AA (Trp, Ser, Phe, Cys and Arg) may function in critical nutrient pathways, reproductive tract vascularization, and antioxidant production, which are necessary for optimal fetal development.