The effects of maternal nutrition during the first 50 d of gestation on the location and abundance of hexose and cationic amino acid transporters in beef heifer uteroplacental tissues

Authors: Crouse, Matthew; MCLEAN, KYLE - University Of Tennessee; DWAMENA, JOSEPHINE - North Dakota State University; NEVILLE, TAMMI - North Dakota State University; MENEZES, ANA CLARA - North Dakota State University; WARD, ALISON - North Dakota State University; REYNOLDS, LAWRENCE - North Dakota State University; DAHLEN, CARL - North Dakota State University; NEVILLE, BRYAN - North Dakota State University; BOROWICZ, PAWEL - North Dakota State University; CATON, JOEL - North Dakota State University

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/25/2020
Publication Date: 1/4/2021
Citation: Crouse, M.S., McLean, K.J., Dwamena, J., Neville, T.L., Menezes, A.C.B., Ward, A.K., Reynolds, L.P., Dahlen, C.R., Neville, B.W., Borowicz, P.P., Caton, J.S. 2021. The effects of maternal nutrition during the first 50 d of gestation on the location and abundance of hexose and cationic amino acid transporters in beef heifer uteroplacental tissues. Journal of Animal Science. 99(1):1-12. https://doi.org/10.1093/jas/skaa386.
DOI: https://doi.org/10.1093/jas/skaa386

Interpretive Summary: Beef heifers that are bred conceive 90% of the time; however, only 50% of those bred heifers maintain a pregnancy. Therefore, most heifers must be re-bred multiple times to maintain a pregnancy which results in decreased efficiency of livestock production. Although data evaluating how to maintain pregnancies in cattle would have a large impact on beef production, there is little data available to determine how changes in maternal nutrition affect embryonic development and maintenance of pregnancy. In this collaborative manuscript, we found that maternal nutrition does not affect nutrient transporters in the uterus in early pregnancy and that changes in nutrients available to the embryo are possibly due to changes in embryonic metabolism. This work addresses questions from scientists whether maternal nutrition in early gestation changes how embryos receive nutrients, and provides further information on the complex relationship between nutrient supply and demand in heifers and their embryos. Providing increased understanding on the relationship between maternal and fetal nutrition and identification of strategies to increase early embryonic survival will improve the efficiency of beef cattle production.

Technical Abstract: We hypothesized that maternal nutrition during the first 50 d of gestation would influence the abundance of hexose transporters, SLC2A1, SLC2A3, and SLC2A5, and cationic amino acid transporters, SLC7A1 and SLC7A2, in heifer utero-placental tissues. Angus-cross heifers (n = 43) were estrus synchronized, bred via artificial insemination, and assigned at breeding to one of two dietary intake groups (CON = 100% of requirements to achieve 0.45 kg/d of BW gain or RES = 60% of CON intake) and ovariohysterectomized on d 16, 34, or 50 of gestation (n = 6 to 9/d) in a completely randomized design with a 2 × 3 factorial arrangement of treatments. Uterine cross-sections were collected from the horn ipsilateral to the corpus luteum, fixed in 10% Neutral Buffered Formalin, sectioned at 5 µm, and stained via immunofluorescence for transporters. For each image, areas of fetal membrane (FM; chorioallantois), luminal epithelium (ENDO), superficial glands (SG), deep glands (DG), and myometrium (MYO) were analyzed separately for relative intensity of fluorescence as an indicator of transporter abundance. Analysis of FM was only conducted for d 34 and 50. No transporters in target areas were influenced by a day × treatment interaction (P = 0.06). In ENDO, all transporters were differentially abundant from d 16 to 50 of gestation (P = 0.04), and SLC7A2 was greater (P = 0.05) for RES vs. CON. In SG, SLC7A1 and SLC7A2 were greater (P = 0.04) at d 34 vs. d 16. In DG, SLC2A3 and SLC7A1 were greater (P = 0.05) for CON vs. RES heifers; furthermore, SLC7A1 was greater (P < 0.01) at d 50 vs. d 16 and 34 of gestation. In MYO, SLC7A1 was greater (P < 0.01) for CON vs. RES and was greater (P = 0.02) at d 34 and 50 vs. d 16. There were no differences in FM (P = 0.06). Analysis of all uterine tissues at d 16 determined that SLC2A1, SLC2A3, and SLC7A2 were all differentially abundant across uterine tissue type (P < 0.01), and SLC7A1 was greater (P = 0.02) for CON vs. RES. Analysis of all utero-placental tissues at d 34 and 50 demonstrated that all transporters differed (P < 0.01) across utero-placental tissues, and SLC7A1 was greater (P < 0.01) for CON vs. RES. These data are interpreted to imply that transporters are differentially affected by day of gestation, and that hexose and cationic amino acid transporters are differentially abundant across utero-placental tissue types, and that SLC7A1 is responsive to maternal nutritional treatment.