West Coast girls efficient

It's all in the genes: one of a herd of 60 high-efficiency and 60 low-efficiency heifers trucked from Trangie to Western Australia in March 2006.
It's all in the genes: one of a herd of 60 high-efficiency and 60 low-efficiency heifers trucked from Trangie to Western Australia in March 2006.

Maidens bred for feed efficiency in NSW and now living on the coast of southwest Western Australia, 3700 kilometres away, are showing that it is what they carry in their genes that’s important.

Recently completed feed efficiency testing in WA shows those bred from geneticallyhigh efficiency parents grow just as well as the heifers from genetically-low efficiency parents, but they eat less and have a superior (lower) feed conversion ratio.

The Angus heifers were bred at NSW DPI’s Trangie Agricultural Research Centre by Dr Robert Herd, principal research scientist with NSW DPI.

Their parents were selected as having either negative or positive Net Feed Intake Estimated Breeding Values (NFI EBV) to produce genetically high-efficiency or low-efficiency offspring.

Net feed intake (NFI) is the measure of feed efficiency adopted by the Australian beef industry for the purpose of genetic improvement in efficiency.

Estimated Breeding Values (EBV) for NFI, an expression of genetic merit for NFI, are currently available within the Angus and Hereford breeds, with other breeds to become available when more test records for NFI are accumulated.

Previous research in Australia has shown steer progeny from parents with negative (more efficient) EBV for NFI are more feed efficient at pasture and in the feedlot than steer progeny from parents with positive EBV for NFI.

In March 2006, 60 high-efficiency and 60 low-efficiency Trangie heifers were trucked to the WA Agriculture Research Station at Vasse, in the Mediterranean climate of coastal southwest WA.

Under the supervision of Dr Jeisane Accioly, they underwent a standard post-weaning NFI test.

The high-efficiency parents of the heifers had an average EBV for NFI of -0.43 kilograms per day and the low-efficiency parents had an average EBV of +0.61kg/day meaning their progeny should differ by about 1kg/day in NFI if reared and tested under similar conditions to their parents.

Tested on the other side of Australia, the difference in NFI in the progeny was 0.85kg/day (-0.41 v. +0.44kg/day) and very close to the expected difference based on the NFI EBV of their parents.

Dr Accioly also tested some of the heifers for their economy in using protein nitrogen in their diet.

Compared with low-efficiency heifers, she found the high-efficiency heifers retained more dietary nitrogen in their body tissues, and excreted less of the nitrogen in their urine.

Not only is this another mechanism contributing to the improved feed efficiency, but also gives an environmental benefit in the form of less nitrogen being lost onto pasture.

These Trangie heifers are part of research by the Co-operative Research Centre for Beef Genetic Technologies to provide the answers on the value of breeding for improved feed efficiency to increase the sustainability and profitability of the cow herd.