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Expression of genes involved in fatty acid profile and proteolysis post mortem from Nelore and Rubia Gallega x Nelore cattle

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Author(s):
Adrielle Matias Ferrinho
Total Authors: 1
Document type: Doctoral Thesis
Press: Pirassununga.
Institution: Universidade de São Paulo (USP). Faculdade de Zootecnica e Engenharia de Alimentos (FZE/BT)
Defense date:
Examining board members:
Angélica Simone Cravo Pereira; Minos Esperândio Carvalho; Aline Silva Mello Cesar; Cesar Augusto Pospissil Garbossa
Advisor: Angélica Simone Cravo Pereira
Abstract

The objective of this study was to evaluate the fatty acid profile and meat tenderness of Nelore and Rubia Gallega x Nelore cattle, and to understand the differences in meat quality through the evaluation of blood biochemical and metabolic parameters, expression of genes involved in lipid metabolism and post mortem proteolysis, and evaluation of the abundance of proteins involved in proteolytic process and muscle growth. Sixteen Nelore (N) and 16 crossbred Rubia Gallega x Nelore (RGN), noncastrated males, with an average age of 11 months and 280 kg ± 15 kg of initial live weight were used. The animals were kept under the same management conditions and received the same diet ad libitum. After 120 days of feedlot finishing, the animals were harvested. During harvest, blood samples were collected for analysis of biochemical and metabolic parameters and longissimus muscle samples for RNA extraction and protein abundance (zero day). The longissimus muscle samples used in the shear force (SF), color, cooking loss (CL), protein degradation, fatty acid profile and total lipids analysis were collected during deboning. Samples from SF, color, CL, and protein degradation were aged for zero, 7, 14 and 21 days. Relative mRNA expression was evaluated for the following genes: C/EBP&alpha;, ZFP423, FABP4, ACC, LPL, ACOX, LEP, SCD, TGF&beta;, MSTN, CAPN1, CAPN2, and CAST. Protein abundance was performed for the proteins: troponin, calpain, HSP 27, HSP 70 and myostatin. The design was completely randomized, considering each animal an experimental unit. For analysis evaluated over the aging time, the data were analyzed in subdivided plots, considering a 2x4 factorial arrangement. The model included the fixed effects: genetic groups (N and RGN), the maturation times (zero, 7, 14 and 21 days) and their interactions. Significance was declared when P <= 0.05. RGN cattle had more tender meat, lower CL and lower total lipids content (P <= 0.05) when compared to N. Beef from N Cattle presented higher concentrations of hypercholesterolemic fatty acids, 14: 0 and 16: 0 and higher enzyme activity &Delta;9 desaturase (P <= 0.05). On the other hand, RGN group had better health index (P <= 0.05) in meat, besides lower serum total cholesterol, HDL and LDL in animals when compared to N group (P <= 0.05). Regarding hormones, growth hormone (GH) and leptin concentrations were not influenced by genetic groups (P > 0.05), unlike IGF-1 and insulin, which presented higher and lower RGN concentrations, respectively, (P <= 0.05). In addition, TGF&beta;, MSTN, C/EBP&alpha;, LPL, and ACOX genes were more expressed in RGN animals, indicating differences in muscle fiber formation and lipid metabolism between genetic groups. No There were no differences in gene expression of CAPN1, CAPN2 and CAST between the genetic groups studied (P > 0.05), although different SF values. On the other hand, RGN cattle showed greater degradation of troponin-T (P = 0.0244). However, there was no difference between the genetic groups for &mu;-calpain autolysis (P = 0.9854), except for aging time (P <0.0001). There was interaction for degradation of HSP 27 (P = 0.0006), indicating that the degradation of this protein is greater and faster in RGN cattle than N. HSP 70 abundance was altered by aging time (P < 0.0001). Myostatin protein abundance was not influenced by genetic group (P = 0.3489). In general, Rubia Gallega x Nelore cattle provide more tender beef and more desirable to human health when compared to Nelore breed. These differences can be explained by the hormonal results of IGF-1 and insulin, besides TGF&beta;, MSTN, LPL, ACOX genes and troponin-T degradation and abundance of HSPs. (AU)

FAPESP's process: 18/01457-8 - Expression of genes involved in fatty acid profile and post mortem proteolysis of Nellore and Galician Blond x Nellore cattle
Grantee:Adrielle Matias Ferrinho
Support Opportunities: Scholarships in Brazil - Doctorate