Expected progeny difference (EPD) for precocity of Nelore bulls and their relationship between adipogenesis, fibrogenesis, lipogenesis and lipid metabolismo

Author(s)

Taiane da Silva Martins

• Document type: Doctoral Thesis
• Press: Pirassununga.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD)
• Defense date: 2021-05-24

Examining board members

Angélica Simone Cravo Pereira; Júlio César de Carvalho Balieiro; Luis Artur Loyola Chardulo; Mario Luiz Chizzotti; Juliano Coelho da Silveira

• Advisor: Angélica Simone Cravo Pereira

Abstract

This study aimed to evaluate the expression of genes related to lipid metabolism, as well as to identify, through the proteomics tool, differences in the protein profile of Longissimus thoracis (LT) and backfat thickness (BFT) proteins of Nelore progenies, offspring of bulls with contrasting factors of expected progeny difference (EPD) for precocity and growth. For this, the present study was divided into 3 manuscripts. In summary, 105 male bulls were used, with a mean age of 20 ± 2 months and 400 ± 24 kg, from the same herd, with the genetic information of precocity and growth. The animals remained confined for 100 days, and the carcass ultrasound was performed every 28 days. Blood samples were collected to determine the metabolic and hormonal profile. The animals were slaughtered after 100 days and during slaughter, muscle LT and BFT were collected between the 12th and 13th ribs, in addition to visceral fat (GV). All of these were immediately frozen in liquid nitrogen and kept in a freezer 80oC until the analysis of gene expression by real-time PCR (RT-qPCR) and analysis and SDS-PAGE, followed by the identification of proteins by coupled mass spectrometry liquid chromatography (LC-MS / MS). During boning, the intramuscular fat (MAR) in the LT muscle was evaluated. Steaks for total lipids, fatty acid profile, and collagen solubility were also collected. The animals were selected according to a EPD from their parent bulls. Were selected 6 parents with EPD contrasting simultaneously for precocity and growth, so that each experimental group had 3 parents bulls. Then, were formed, 2 contrasting groups called high EPD (H_EPD; N = 16) and low EPD (L_EPD; N = 16), using 32 progenies. The animals in the H_EPD group had higher BFT (P = 0.006); lower LDL (P = 0.014); higher IGF-1 (P = 0.064); greater collagen solubility (P = 0.098); lower expression of the LPL gene, in LT (P = 0.045). This group also showed greater expression of the genes involved in lipogenesis evaluated in BFT: ACACA (P = 0.060), LPL (P = 0.085), ACOX1 (P = 0.100), LEP (P = 0.030), SDC (P = 0.009), and GAPDH (P = 0.081), than the animals in the L_EPD group. One electrophoretic band was detected as differently abundant in the LT muscle (band 16) and three electrophoretic bands were detected as differently abundant in the BFT (bands 24, 30, 32). The KEGG pathways of pyruvate metabolism, glycolysis/gluconeogenesis, carbon metabolism, amino acid biosynthesis, among others, were enriched for the differentially abundant proteins identified in the LT and BFT. The genetic selection for precocity and growth affects the muscle proteome and consequently the lipid and protein metabolism of non-castrated cattle. The IGF-1 hormone, the LPL gene, and the PKLR, PKM, ALDOA, DLD, GPI, VIM, ACTC1, OXCT1, GAPDH, LDHA, LDHB, MDH1, MDH2, IDH1, PGK1, SUCLG2, and ACY1 proteins can be considered future biomarkers candidates for BFT. (AU)

• FAPESP's process: 17/02349-1 - Expected progeny difference (EPD) for precocity of Nellore bulls and their relationship between adipogenesis, fibrogenesis, lipogenesis and lipid metabolism
• Grantee: Taiane da Silva Martins
• Support Opportunities: Scholarships in Brazil - Doctorate