The biological efficiency of producing beef from the suckler herd is relatively low, with a large maternal cost to production. The suckler cow accounts for about half of the annual feed costs in suckler calf-to-beef systems. Some individual animals are more efficient, eating less for the same output. Scientists at Teagasc Animal and Grassland Research and Innovation Centre, Grange, Ireland, are now looking at new ways to identify the most efficient animals and build a beef breeding programme around it.
Researchers are now investigating Residual Feed Intake (RFI) as a measure of feed efficiency that is genetically independent of growth and body size. It is defined as the difference between an animal's actual feed intake and what its predicted feed intake should be, based on bodyweight and level of performance.
"Efficient animals eat less than expected and have a negative or lower RFI value. Whereas, inefficient animals eat more than expected and have a positive or higher RFI. Differences among individual animals have long been recognised but little is known about the causes of this variation in efficiency of energy utilisation by cattle," explains Dr Mark McGee, Teagasc Animal and Grassland Research and Innovation Centre, Grange, Ireland.
Teagasc and University College Dublin are currently jointly researching the links between RFI and genetic or biochemical markers of the trait. This collaborative project is examining biological control of RFI in cattle with a view to identifying some more easily measured indicators of the trait. Results to date show significant differences between efficient and non efficient animals in the expression of genes controlling the synthesis of cellular energy. "This work could help develop an early cost effective identification of genetically superior animals for feed efficiency," concluded Dr McGee.
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