Relationship between Liver Mitochondrial Respiration and Proton Leak in Low and High RFI Steers from Two Lineages of RFI Angus Bulls.

G Acetoze,J J Ramsey,H A Rossow,K L Weber

doi:10.1155/2015/194014

G Acetoze, J J Ramsey + Show 2 more

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https://doi.org/10.1155/2015/194014

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Abstract

The objective of this research is to evaluate liver mitochondrial oxygen consumption and proton leak kinetics in progeny from two lineages of Angus bulls with high and low residual feed intake (RFI). Two Angus bulls were selected based on results from a genetic test for RFI and were used as sires. Eight offspring at 10-11 months of age from each sire were housed in individual pens for 70–105 days following a diet adaptation period of 14 days. Progeny of the low RFI sire had 0.57 kg/d (P = 0.05) lower average RFI than progeny of the high RFI sire. There was no difference in dry matter intake between low and high RFI steers, but low RFI steers gained more body weight (P = 0.02) and tended to have higher average daily gains (P = 0.07). State 3 and State 4 respiration, RCR, and proton leak did not differ between high and low RFI steers (P = 0.96, P = 0.81, P = 0.93, and P = 0.88, resp.). Therefore, the increase in bodyweight gain which distinguished the low RFI steers from the high RFI steers may be associated with other metabolic mechanisms that are not associated with liver mitochondrial respiration and proton leak kinetics.

Highlights

Residual feed intake (RFI) is defined as the difference between actual dry matter intake and dry matter intake regressed on average daily gain and midtest metabolic body weight [1]
A link between RFI and mitochondrial oxygen consumption or proton leak has not been shown and currently gene chips do not include any sequences for mitochondrial DNA that could be used for selection purposes
The objective of this research is to evaluate liver mitochondrial respiration from progeny of two Angus bulls with high and low RFI to examine the association between RFI, liver mitochondrial respiration rates, and liver mitochondrial proton leak kinetics

Summary

Introduction

Residual feed intake (RFI) is defined as the difference between actual dry matter intake and dry matter intake regressed on average daily gain and midtest metabolic body weight [1]. Only 3 research publications have explored the relationship between production, feed efficiency (RFI), and mitochondrial respiration in cattle. Brown et al [2] compared liver mitochondrial respiration to estimated differences in heritability of milk production in Holsteins and growth and milk production in beef breeds. They found no correlation for beef breeds. Proton leak kinetics could account for differences in mitochondrial respiration rates but was not measured in either study. Lancaster et al [4] found higher liver mitochondrial respiration rates in low RFI cattle in one of the two experiments but no difference in proton leak kinetics. Proton leak kinetics are used to represent the uncoupling of hydrogen ion passage with ATP production and to assess changes in mitochondrial

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