15 Search for Non-Genomic Markers as Puberty Predictors inBos Indicus Cattle

Brahman cattle are used for crossbreeding due to their maternal ability, heat, and parasite tolerance. Brahman displays delayed attainment of puberty compared with taurine breeds. The objective was to identify molecular markers in the blood of prepubertal heifers and bulls that predict early puberty attainment. We hypothesize that Brahmans that attains puberty have a blood metabolite signature that differs from animals that remain prepubertal. Plasma was collected 90 (-90d) and 30 (-30d) days prior to the beginning of the breeding season from 156 yearling Brahman heifers and 28 bulls. Animals were classified as pubertal (pub) or prepubertal (prepub) based on reproductive variables such as the reproductive tract score and pregnancy to insemination for heifers and scrotal circumference and semen quality for bulls. Plasma from 48 pub and 48 prepub heifers and 9 pub and 7 prepub bulls were submitted for quantitative mass spectrometry metabolomics analysis. There was a clear clustering of animals according to puberty status (orthogonal projections of latent structures discriminant analysis). Concentrations of the top three metabolites explaining clustering were analyzed by t-tests. As heifers approached maturity, there was a 3.03-, 11.76- and 2.08-fold change (P < 0.0001) in the concentrations of PC ae C42:3, ProBetaine, and PC ae C42:2 measured at -30 vs. -90 days. Similarly, for bulls, concentrations of HipAcid, C4 and SM (OH) C24:1 were 1.52-, 1.53-, and 1.45-fold greater (P < 0.0001), respectively. Comparing pub vs. prebub heifers on -90 d, there was a 1.26- (P < 0.001), 0.62- (P < 0.01) and 1.11-fold change (P < 0.05) for hArg, Putrescine and AABA concentrations, respectively. Regarding bulls on -90 d, there was a 1.57- (P < 0.01), 1.32- (P < 0.03) and 1.15-fold change (P < 0.03) for FA(18:1), FA(18:2) and DG(16:1_18:2) concentrations, respectively. In conclusion, we discovered potential markers for the prediction of puberty attainment based on plasma metabolomic signatures in Brahman.