284 Supranutritional Mineral Supplementation During Pregnancy Alters Placental Blood Flow and Calf Mineral Concentrations

Abstract

Abstract Fetal development is dependent on maternal nutrient status, and the maternal-fetal connection is mediated by the placenta. There are well-established nutrient requirements for gestating cattle aimed at promoting the health of dam and fetus; however, there is limited information on the impact of supranutritional nutrient availability on placental function and calf development. This study evaluated the effect of supranutritional mineral administration during gestation on uterine artery blood flow and calf mineral status. Angus and SimAngus cows (n = 52) were bred via artificial insemination. At d 60 of gestation, cows were assigned to treatment groups; an injectable group (INJ, n = 26) receiving a single subcutaneous mineral injection and access to free-choice trace minerals and a control group (CON; n = 26) having access to free-choice trace minerals. Liver mineral content was analyzed in a subset of cows (CON n = 10; INJ n = 6) at d 60 and 209 ± 1 of gestation. At d 139.5 ± 0.5 and 209 ±1 of gestation, uterine artery measurements were collected using Color Doppler ultrasonography. Placental cotyledons, liver tissue, and blood samples were collected from a subset of animals at calving (n = 11; CON, n = 5; INJ, n = 6). Analysis revealed a TRT*day interaction at d 139.5 ± 0.5 for circulating Co concentrations which were greater (P = 0.05) and Se tended to be greater in INJ cows (P = 0.09) compared with CON cows. Circulating Zn concentrations tended to be decreased at d 209 ± 1 (P = 0.06) in INJ cows compared with the CON cows. Circulating Cu tended to be increased (P = 0.09) and Mn was decreased (P = 0.04) in INJ cows throughout the study. Hepatic Fe concentrations were decreased in INJ cows (P = 0.01) at d 209 ± 1. At d 139.5 ± 0.5, non-gravid uterine artery area, diameter, and circumference were increased in the INJ cows (P < 0.006 ). Additionally, pulsatility index of the gravid uterine artery tended to be increased (P = 0.09) in the INJ cows. Blood and liver samples were collected from calves (CON n = 24; INJ n = 26) at 4 to 8 d post-calving to assess mineral concentrations. INJ calves had greater liver Se (P = 0.001), decreased Fe (P = 0.04), and tended to have increased Zn (P = 0.09) and Mn (P = 0.08) concentrations compared with CON calves. Finally, INJ calves tended to have greater serum Se concentrations (P = 0.09) compared with CON calves. Trace minerals have roles in immune function and impact overall calf health. These results indicate that supranutritional trace mineral administration during early gestation alters placental blood flow and improves calf mineral availability. This supplementation protocol may provide the opportunity to improve the health of future calf crops.