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

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