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P. L. P. Fontes, N. Oosthuizen, D. D. Henry, F. M. Ciriaco, C. D. Sanford, L. B. Canal, V. R. G. Mercadante, S. E. Johnson, A. D. Ealy, N. DiLorenzo, G. C. Lamb, 329 Impact of fetal versus maternal contributions of Bos indicus and Bos taurus genetics on early embryonic development, Journal of Animal Science, Volume 95, Issue suppl_4, August 2017, Page 163, https://doi.org/10.2527/asasann.2017.329
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Abstract
To evaluate maternal and fetal system influence on early embryonic and fetal development in Bos indicus and Bos taurus cattle, a reciprocal embryo transfer approach was used in a completely randomized design with a 2 × 2 × 2 factorial arrangement of treatments in order to generate 55 pregnancies over 2 consecutive years (n = 55). Recipient cows were placed into the University of Florida Feed Efficiency Facility, containing a GrowSafe feed intake monitoring system, and were randomly assigned to 1) a diet to meet daily maintenance requirements (MAINT) or 2) a diet that restricts intake of nutrients to 70% of energy maintenance requirements (RESTR). Angus (AN) and Brangus (BN) embryo donors were superovulated and artificially inseminated with female sexed-sorted semen from the same breed. Embryos were then randomly transferred 7 d after insemination (d 7) to either AN or BN recipients fed the respective diets for 20 d. Recipients remained on the dietary scheme until d 91, at which time cows were commingled and fed a common diet that met their energy and protein requirements to the same feeding regime until calving. Transrectal ultrasonography was performed to assess fetal crown to rump length (CRL) weekly from d 42 to 91. Blood samples were collected weekly from d 28 to 91 to determine plasma concentrations of pregnancy-specific protein B (PSPB). All analyses were performed using the MIXED procedure of SAS. There was an effect of diet (P < 0.001) and day (P < 0.001) on recipient BW, with RESTR recipients having lower BW than MAINT. Similarly, diet altered recipient BCS from d 70 to 91 (diet × day, P = 0.005). Embryos from BN donors transferred to recipients fed the RESTR diet resulted in a greater (embryo breed × diet, P < 0.001) plasma concentrations of PSPB. Although no effects of embryo breed (P > 0.05) or diet (P > 0.05) were observed on fetal morphometries, fetuses from AN recipients had greater CRL on d 91 (breed × day, P = 0.021) when compared with BN recipients (167.7 ± 1.8 vs. 160.7 ± 1.6 mm, respectively). No effect of recipient breed, embryo breed, or diet was detected on gestation length (P > 0.05) or birth weight of the offspring (P > 0.05). In conclusion, Bos indicus genotype was a significant factor altering concentrations of PSPB during early gestation, whereas Bos taurus recipient genotype positively impacted early fetal growth.
