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The objective of this study was to determine how the use of different sires affects embryonic development and fetal growth. Crossbred ewes (n = 15) were synchronized and randomly allocated to be naturally mated with one of two rams (Suffolk vs. Hampshire). Natural mating occurred over a 24 h period, after which the rams were removed and the ewes from each treatment were combined. Transabdominal ultrasonography (at 3.5 MHz) was conducted twice weekly during weeks 3 to 6 of gestation. Pregnancy diagnosis, fetal count, and ultrasonic images were recorded for embryonic measurements. Out of the group of 15, eleven ewes were confirmed pregnant. The mixed procedure in SAS was used for statistical analysis. Sire did not have an effect on embryonic vesicle length (EVL), crown rump length (CRL), trunk diameter (TTD), and placentome blood area (PBVA; P ≥ 0.634). Sire tended to effect both embryonic vesicle depth (EVD) and placentome area (PA; P = 0.085), where ewes mated with the Suffolk ram tended to have a greater embryonic vesicle depth and placentome area compared to those mated with the Hampshire ram.
Zinke, Maya, "Effects of Sire Breed on Embryonic Development and Fetal Growth" (2021). Agriculture. 4.