The relationship between mitochondrial function and residual feed intake in Angus steers

Area of Science:

• Animal Science
• Metabolic Physiology
• Mitochondrial Biology

Background:

• Residual feed intake (RFI) is a key indicator of feed efficiency in livestock.
• Understanding the physiological basis of RFI variation is crucial for improving animal production.
• Mitochondrial function plays a critical role in energy metabolism and efficiency.

Purpose of the Study:

• To investigate the relationship between mitochondrial respiration and hydrogen peroxide production in Angus steers with varying RFI.
• To determine if differences in mitochondrial function explain variations in feed efficiency.
• To correlate mitochondrial activity with plasma glucose and insulin concentrations.

Main Methods:

• Feed intake was measured using the GrowSafe system to calculate RFI in 40 Angus steers.
• Steers were categorized into low and high RFI groups.
• Mitochondrial oxygen consumption, hydrogen peroxide production, plasma glucose, and insulin were measured from tissue and blood samples.

Main Results:

• Low RFI steers showed significantly higher rates of mitochondrial respiration (state 2 and 3) and hydrogen peroxide production compared to high RFI steers.
• No significant differences were observed in overall mitochondrial function (acceptor control, ADP:O ratios) or electron leak between groups.
• High RFI steers had higher plasma glucose concentrations, presumed to be due to greater feed intake.

Conclusions:

• The rate of mitochondrial respiration, not overall mitochondrial function, differs between low and high RFI steers.
• Increased mitochondrial respiration in low RFI steers may contribute to their improved feed efficiency.
• Differences in feed intake, rather than intrinsic mitochondrial defects, likely explain plasma glucose variations.