Relationships between residual feed intake and hepatic mitochondrial function in growing beef cattle

Area of Science:

• Animal Science
• Nutritional Physiology
• Mitochondrial Biology

Background:

• Residual feed intake (RFI) is a measure of feed efficiency in beef cattle, independent of production traits.
• Hepatic mitochondrial function plays a crucial role in energy metabolism and can influence feed efficiency.
• Understanding the link between mitochondrial function and RFI can lead to strategies for improving beef cattle production.

Purpose of the Study:

• To investigate the relationship between hepatic mitochondrial function and residual feed intake (RFI) in growing beef cattle.
• To compare mitochondrial respiration rates and efficiency between cattle with low and high RFI.

Main Methods:

• Residual feed intake (RFI) was measured in two trials involving Angus heifers and Santa Gertrudis steers fed different diets.
• Cattle were selected for low and high RFI based on deviations from the mean RFI.
• Hepatic mitochondrial function was assessed by measuring state 3 respiration, acceptor control ratios, and proton-leak kinetics.

Main Results:

• Cattle with low RFI consumed less dry matter and had improved gain-to-feed ratios compared to high RFI cattle.
• Low RFI cattle exhibited greater acceptor control ratios, indicating tighter coupling of respiration to ATP synthesis.
• A trend for greater state 3 respiration and respiratory control ratio was observed in low RFI cattle in one trial.

Conclusions:

• Hepatic mitochondrial function, specifically ADP control of oxidative phosphorylation, differs between low and high RFI beef cattle.
• Enhanced mitochondrial efficiency in low RFI cattle may contribute to their improved feed conversion.
• These findings provide insights into the physiological basis of feed efficiency in beef cattle.