Enhanced mitochondrial complex gene function and reduced liver size may mediate improved feed efficiency of beef cattle during compensatory growth.
Growing ruminants under extended dietary restriction exhibit compensatory growth upon ad libitum feeding, which is associated with increased feed efficiency, lower basal energy requirements, and changes in circulating concentrations of metabolic hormones. To identify mechanisms contributing to these physiological changes, 8-month-old steers were fed either ad libitum (control; n = 6) or 60-70% of intake of control animals (feed-restricted; n = 6) for a period of 12 weeks. All steers were fed ad libitum for the remaining 8 weeks of experimentation (realimentation). Liver was biopsied at days -14, +1, and +14 relative to realimentation for gene expression analysis by microarray hybridization. During early realimentation, feed-restricted steers exhibited greater rates of gain and feed efficiency than controls and an increase in expression of genes functioning in cellular metabolism, cholesterol biosynthesis, oxidative phosphorylation, glycolysis, and gluconeogenesis. Gene expression changes during feed restriction were similar to those reported in mice, indicating similar effects of caloric restriction across species. Based on expression of genes involved in cell division and growth and upregulation of genes encoding mitochondrial complex proteins in early realimentation, it was concluded that reduced hepatic size and increased mitochondrial function may contribute to improved feed efficiency observed during compensatory growth.
Beltsville Agricultural Research Center, ARS, USDA, MD 20705, USA. erin.connor@ars.usda.gov
Erin E
EE
Connor
Stanislaw
S
Kahl
Theodore H
TH
Elsasser
Joel S
JS
Parker
Robert W
RW
Li
Curtis P
CP
Van Tassell
Ransom L
RL
Baldwin
Scott M
SM
Barao
D000818:Animals; D002417:Cattle / Q000235:genetics* / Q000254:growth & development*; D045222:Electron Transport Chain Complex Proteins / Q000235:genetics* / Q000378:metabolism; D005247:Feeding Behavior; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D008099:Liver / Q000378:metabolism / Q000473:pathology*; D008460:Meat; D020411:Oligonucleotide Array Sequence Analysis; D009929:Organ Size; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction
D045222:Electron Transport Chain Complex Proteins; D012333:RNA, Messenger