Relationship between the expected progeny difference for growth and protein turnover and energetic metabolism in Nellore cattle

• Grant number: 16/19628-8
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: February 01, 2017
• End date: March 31, 2017
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Nutrition and Feeding
• Agreement: Coordination of Improvement of Higher Education Personnel (CAPES)
• Principal Investigator: Saulo da Luz e Silva
• Grantee: Rafael Aparecido Gomes
• Host Institution: Faculdade de Zootecnia e Engenharia de Alimentos (FZEA). Universidade de São Paulo (USP). Pirassununga , SP, Brazil

Abstract

This study aims to evaluate the relationship between the expected progeny difference (EPD) for growth, accessed by the average daily gain from weaning to yearling (ADG345), and the expression of genes related to protein turnover and mitochondrial metabolism in Nellore cattle. One hundred and thirty Nellore young bulls will be selected aiming to use animals contrasting with respect to EPD values for ADG345. The animals will be individually fed for 100 days, and every 28 days the bulls will be weighed and evaluated by ultrasound and infrared thermography images. Average daily feed intake and average daily gain will be used to calculate feed efficiency. Ribeye area and backfat thickness will be determined through ultrasound images, and heat production through infrared thermography images. In the day before the slaughter, blood samples will be taken to determine creatinine, 3-methyl histidine and IGF-1 plasma levels. Two samples of the Longissimus muscle and a sample of liver will be taken immediately after slaughter and stored at -80°C. One muscle sample will be used to determine the type of muscle fibers, while another muscle sample and the liver sample will be used to evaluate the expression of genes related to protein turnover (IGF1R, IGFBP3, IGFBP5, GSK3ß, TRIM63, FBXO32 , MSTN, SMAD2 and SMAD3) and mitochondrial metabolism (CYC1, CYB5B, ATP5A1, UCP2, UCP3, SOD1, GPX1) by quantitative reverse transcription PCR. One second liver sample will be collected and immediately processed for mitochondrial respiration and proton-leak kinetic analysis, using a Clark type oxygen electrode. The data obtained will be evaluated using univariate and multivariate approaches, aiming to find possible links between the EPD and the characteristics evaluated. Exploratory data analysis will be performed using simple correlations. The means will be compared using the Tukey test. All statistical procedures will be performed using the SAS MIXED procedure, adopting ± = 0.05. (AU)