250. Impact of Paternal Overnutrition on Fetal Morphometrics During the First Trimester of Gestation.

Abstract The aim of this study was to evaluate the impact of paternal overnutrition on fetal development during the first trimester of gestation. We hypothesized that paternal overnutrition would negatively affect fetal placental and fetal development. Half-siblings Angus bulls (n = 29) were randomly assigned to one of two dietary treatments for 114 days: Moderate Gain (MG), a diet formulated to promote an average daily gain of 1.2 kg/day, or High Gain (HG), a diet formulated to promote an average daily gain of 1.8 kg/day. Semen was collected and cryopreserved at the end of the feeding period, and pregnancies were generated using the collected semen. Nonlactating beef cows were exposed to an industry-standard ovulation synchronization protocol and were randomly assigned to semen from HG or MG bulls. A total of 17 HG and 21 MG pregnancies were generated. Bull was considered the experimental unit. Transrectal ultrasonography was performed on days 36, 43, 56, 70, and 84 of gestation, and videos were recorded. Videos were retrospectively assessed for fetal and placental measurements, including amniotic vesicle circumference (AVC) and amniotic vesicle area (AVA) on d36 and d43, and crown-rump length (CRL), crown-nose length (CNL), head diameter (HD), abdominal frontal (AF), abdominal transverse (AT), and trunk diameter (TD) on d56, d70, and d84. Fetal sex was determined by day 70 of gestation and included in the statistical analyses. There was no effect of treatment on CRL, CNL, HD, or TD (P ≥ 0.12). A treatment × day interaction (P ≤ 0.02) was observed for both AVC and AVA. There were no differences between treatments on day 36 of gestation; however, HG pregnancies had larger (P ≤ 0.05) AVC (83.00 ± 1.58 mm vs. 77.40 ± 1.45 mm) and AVA (3.32 ± 0.13 mm vs. 2.94 ± 0.12 mm) compared with MG pregnancies. Overall, these results indicate that paternal overnutrition resulted in no detectable changes fetal development in this study. Alternatively, pregnancies generated using semen from HG sires had greater amniotic vesicles compared with MG-sired pregnancies.