Fecha/hora: 11/06/2024 19:17:32

Biblioteca(s): 	INIA Las Brujas.	
Fecha corriente: 	07/11/2018	
Fecha de la última actualización: 	07/11/2018	
Autoria: 	CASAL, A.; GARCÍA-ROCHE, M.; NAVAJAS, E.; CASSINA, A.; CARRIQUIRY, M.	
Afiliación: 	ALBERTO CASAL, Universidad de la República (UdelaR)/ Facultad de Agronomía; MERCEDES GARCÍA ROCHE, Universidad de la República (UdelaR)/ Facultad de Agronomía; Center for Free Radical and Biomedical Research (CEINBIO), Universidad de la República (UdelaR)/ Facultad de Medicina.; ELLY ANA NAVAJAS VALENTINI, INIA (Instituto Nacional de Investigación Agropecuaria), Uruguay; ADRIANA CASSINA, Center for Free Radical and Biomedical Research (CEINBIO), Universidad de la República (UdelaR)/ Facultad de Medicina.; MARIANA CARRIQUIRY, Universidad de la República (UdelaR)/ Facultad de Agronomía.	
Título: 	Hepatic mitochondrial function in Hereford steers with divergent residual feed intake phenotypes.	
Complemento del título: 	Article.	
Año de publicación: 	2018	
Fuente/Imprenta: 	Journal of Animal Science, 29 September 2018, volume 96, Issue 10, pages 4431-4443.	
ISSN: 	1525-3163	
DOI: 	10.1093/jas/sky285	
Idioma: 	Inglés	
Notas: 	Article history: Received: 01 March 2018 // Accepted: 11 July 2018 // Published: 19 July 2018.	
Contenido: 	ABSTRACT.
Variations in phenotypic expression of feed efficiency could be associated with differences or inefficiencies in mitochondria function due to its impact on energy expenditure. The aim of this study was to determine hepatic mitochondrial density and function in terms of respiration, gene and protein expression, and enzyme activity of mitochondrial respiratory complex proteins, in steers of divergent residual feed intake (RFI) phenotypes. Hereford steers (n = 111 and n = 122 for year 1 and 2, respectively) were evaluated in postweaning 70 d standard test for RFI. Forty-six steers exhibiting the greatest (n = 9 and 16 for year 1 and 2; high-RFI) and the lowest (n = 9 and 12 for year 1 and 2; low-RFI) RFI values were selected for this study. After the test, steers were managed together until slaughter under grazing conditions until they reached the slaughter body weight. At slaughter, hepatic samples (biopsies) were obtained. Tissue respiration was evaluated using high-resolution respirometry methods. Data were analyzed using a mixed model that included RFI group as fixed effect and slaughter date and year as a random effect using PROC MIXED of SAS. RFI and dry matter intake were different (P < 0.001) between low and high-RFI groups of year 1 and year 2. Basal respiration and maximum respiratory rate were greater (P ? 0.04) for low than high-RFI steers when complex II substrates (succinate) were supplied. However, when Complex I substrates (glutamate/malate) were used maximum respiratory capacity tended to be greater (P < 0.09) for low vs. high-RFI steers. Low-RFI steers presented greater mitochondria density markers (greater (P < 0.05) citrate synthase (CS) activity and tended (P ? 0.08) to have greater CS mRNA and mtDNA:nDNA ratio) than high-RFI steers. Hepatic expression SDHA, UQCRC1, and CYC1 mRNA was greater (P ? 0.02) and expression of NDUFA4, NDUFA13, SDHD, UQCRH, and ATP5E mRNA tended (P ? 0.10) to be greater in low than high-RFI steers. Hepatic SDHA protein expression tended (P < 0.08) to be greater while succinate dehydrogenase activity was greater (P = 0.04) and NADH dehydrogenase activity was greater (P = 0.03) for low than high-RFI steers. High-efficiency steers (low-RFI) probably had greater efficiency in hepatic nutrient metabolism, which was strongly associated with greater hepatic mitochondrial density and functioning, mainly of mitochondrial complex II.
© The Author(s) 2018. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. 
For permissions, please e-mail: journals.permissions@oup.com.	
Palabras-Clave: 	BEEF CATTLE; FEED EFFICIENCY; LIVER; MITOCHONDRIA; OXYGEN CONSUMPTION.	
Categoría del tema: 	L02 Alimentación animal	
Registro original: 	INIA Las Brujas (LB)	
Ejemplares: 	LB - (101726-1) - PXI - AP - DD - PP/JR.ANIMAL SCIENCE/2018 -  -  - DIS