Genetic parameters of in vitro production of Nellore and Senepol embryos

Abstract

This study aimed to estimate genetic parameters for traits of in vitro embryo production (IVEP) of Nellore and Senepol cattle. Data from 1,247 rounds of in vitro fertilization (1,029 Nellore, 218 Senepol) were used, totaling 148,311 oocytes (116,972 Nellore, 31,339 Senepol), 47,301 embryos (38,722 Nellore, 8,579 Senepol), and 6,323 pregnancies (5,534 Nellore, 789 Senepol). The variables percentage of viable oocytes (Pooc), percentage of cleaved embryos (Pcleav), percentage of produced embryos (Pemb), percentage of pregnancy (Ppreg) per round per bull, mean number of viable oocytes per donor (MOD), mean number of embryos produced per donor (MED), and mean number of pregnancies per donor (MPD) were analyzed from data provided by a partner company between the years 2019 and 2022. The SAS program was used to analyze fixed effects and Pearson linear correlation. The components of variance for heritabilities were calculated using the MTDFREML program. MOD, MED, and MPD values of 29.94, 10.01, and 2.53 were obtained for Nellore and 30.12, 8.17, and 2.34 for Senepol, respectively. In general, Nellore provided better embryo production compared to Senepol. Heritability estimates showed low to medium magnitude, with values Nellore and Senepol of 0.16 and 0.04 (Pcleav), 0.14 and 0.08 (Pemb), 0.02 and 0.15 (Ppreg), 0.07 and 0.02 (MED), and 0.05 and 0.00 (MPD), respectively. However, it indicates the presence of genetic variability and the possibility of selection. Therefore, there is genetic variability for IVEP traits in both breeds, indicating that they can be used as selection criteria because they are heritable and that Nellore presents better performance for IVEP traits compared to Senepol.