Identification of molecular markers of reproductive and productive precocity in Angus breed cattle

Author(s)

Mônica Degraf Cavallin

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD)
• Defense date: 2022-03-31

Examining board members

Renata Marino Romano; Juliana Afonso; Carla Fredrichsen Moya Araujo; Claudio Alvarenga de Oliveira; Paula Bargi de Souza

• Advisor: Marcilio Nichi; Renata Marino Romano

Abstract

The growth and development in beef cattle is related to a sequence of age-dependent phases composed of pre - and postpubertal phases. However, Angus breed animals develop finishing characteristics for slaughter at ages between 11 and 24 months. This variation has a great impact on the production system, and there are still no biomarkers available that include genes related to these traits. Thus, the present study aimed to evaluate characteristics related to the productive and reproductive precocity of Angus cattle slaughtered at different ages. For this, the animals were divided into a hyperprecocious group (slaughtered up to 13 months) and a precocious group (slaughtered over 17 months). We evaluated the productive characteristics of live weight, carcass weight and fat cover, the reproductive characteristics of testis volume, seminal evaluation by conventional and functionality techniques and the hormonal serum levels of testosterone, dihydrotestosterone, thyroxine (T4) and triiodothyronine (T3). Using the RT qPCR assay, we analyzed genes related to spermatogenesis (NDRG2, ADAM11, TRIP13, SPA17, CSNK2A1 and CSNK2A2), steroidogenesis (STAR, HSD3B1) and puberty (AMH) in testis tissue. In muscle tissue, we analyzed genes related to cell proliferation and differentiation (MYOD, MYF5, RB1 and MSTN) and growth (IGFR1 and LEP). Finally, we performed testis and muscle transcriptome sequencing by RNA-seq. No differences were observed in the productive parameters between the groups; however, we observed greater testicular volume and sperm concentration in the animals of the precocious group. No differences were observed in relation to sperm functionality; morphology analysis of the same cells showed a greater number of major defects in the animals of the hyperprecocious group. Regarding hormone dosages, we observed lower levels in the serum concentration of testosterone, dihydrotestosterone and T4 in the precocious group. The expression of TRIP13, ADAM11, STAR and HSD3B1 genes was higher in the precocious group. In contrast, the expression of the MYOD1 and MYF5 genes was higher in the hyperprecocious group. In RNA-Seq, we identified 12 differentially expressed genes (DEGs), 7 downregulated genes and 5 upregulated genes in testis tissue in the hyperprecocious group. In muscle tissue, we identified 50 DEGs, of which 40 genes were downregulated and 10 genes were upregulated in the hyperprecocious group. In the testis tissue, we highlight the increase in the expression of the genes PODNL1, UPK1A and TRIM40and the reduction in the expression of the genes WAP, GSK3B, ZNF, G3N2E2 and F1MUF2 in the hyperprecocious group. In muscle tissue, we highlight the increased expression of the EDN1, MRC1, CDC6 and CCBE1 genes and the reduced expression of the SPATA3, TNP2, FSCB, PRM2, IQCF1 and CDKN1A genes in the hyperprecocious group. The results suggest that variations in slaughter age may be related to the different stages of growth in which the animals are, with the hyperprecocious group in the peripubertal phase and still growing, while the precocious group seems to have reached sexual maturity and adulthood. The genes identified from the RNA-Seq methodology are potential candidates for simultaneous biomarkers related to characteristics of reproductive precocity and early muscle development. (AU)

• FAPESP's process: 17/22240-4 - Identification of molecular markers of reproductive and productive precocity in Angus breed cattle
• Grantee: Mônica Degraf Cavallin
• Support Opportunities: Scholarships in Brazil - Doctorate