219 - Evaluation of Dietary Arginine Supplementation to Increase Placental Nutrient Transporters of Aged Mares

Wednesday, June 29, 2022

9:35 AM – 9:50 AM CT

Location: Oklahoma City Convention Center, 201

Presenting Author(s)

Rafael E. Martinez, n/a

Graduate Student
Department of Animal Science, Texas A&M University and Texas A&M AgriLife Research
College Station, TX

Author(s)

JL

Jessica L. Leatherwood, Ph.D.

Assistant Professor
Department of Animal Science, Texas A&M University and Texas A&M AgriLife Research
College Station, Texas
AB

Amanda N. Bradbery, Ph.D.

Assistant Professor
Department of Animal and Range Sciences, Montana State University
Bozeman, MT
Brittany L. Silvers

Department of Animal Science, Texas A&M University and Texas A&M AgriLife Research
College Station, TX
CH

Carolyn J. Hammer

Department of Animal Sciences, North Dakota State University
Fargo, ND
DK

Dale Kelley

College of Veterinary Medicine, Oklahoma State University
Stillwater, OK
FB

Fuller W. Bazer

Professor
Department of Animal Science, Texas A&M University and Texas A&M AgriLife Research
College Station, TX
Guoyao Wu

Texas A&M University
College Station, Texas

Abstract: Nine pregnant mares (18.2 ± 0.7 y; 493.82 ± 13 kg BW) were used to test the hypothesis that dietary supplementation of arginine would enhance placental vascularity and nutrient transport throughout gestation in aged mares. Mares were balanced by age, BW, and stallion pairing, and randomly assigned to one of two dietary treatments consisting of supplemental L-arginine (50 mg/kg BW; n=5) or L-alanine (100 mg/kg BW; n=4; isonitrogenous control). Mares were individually fed concentrate top-dressed with the respective amino acid treatment plus ad libitum access to Coastal bermudagrass hay. Treatments began on d 14 of gestation and were terminated at parturition. Mare BW, BCS, and rump fat were determined every 28 d and concentrate adjusted accordingly. Parturition was attended with foaling variables and placental measures recorded. Placental tissue from the pregnant horn underwent histological analyses to assess cell-specific localization of vascular endothelial growth factor (VEGF) and cationic amino acid transporter 1 (CAT1) proteins. Semiquantitative analyses were performed using 10 non-overlapping images per sample fixed in a 10X field (Fiji ImageJ v1.2). Data were analyzed using SAS PROC MIXED procedure. BW increased (P < 0.01) in all mares with advancing gestation. BW, BCS, and gestation length of mares were not influenced (P > 0.05) by supplemental arginine. Compared with arginine-supplemented mares, control mares had a thicker rump fat layer (P < 0.01) at parturition. Body length, height, and BW of foals at birth, as well as placental weight, volume, and positive staining for VEGF and CAT1 at parturition were not affected (P > 0.05) by maternal arginine supplementation. These results indicate dietary arginine supplementation (50 mg/kg BW) is safe for gestating mares and promotes mobilization of white adipose tissue. A larger number of mares is required to determine effects of supplemental arginine on embryonic/fetal survival and growth in mares.