Preliminary beef carcass composition data from breed-crosses in
a genetic marker trial
C.A.Morris, N.G.Cullen, C.D.K. Bottema, A.M.Crawford, D. Hyndman
and W.S.Pitchford
AgResearch, Ruakura Research Centre, Private Bag, Hamilton, New
Zealand
Proceedings of the New Zealand Society of Animal Production.
2000 60: 113-114
A collaborative project has been established in AgResearch and
at the University of Adelaide to identify genetic markers for carcass
composition and meat quality traits in beef cattle. Two extreme breeds
were used, Jersey (J) and Limousin (L). First-cross Jersey x Limousin
bulls (X) were mated to cows of both breeds to produce three-quarter
Jersey (XJ) and three-quarter Limousin (XL) animals. A total of 261 and
155 back-cross cattle of both sexes were slaughtered as 2-year-olds at
Ruakura in the springs of 1998 and 1999, respectively. A further 400
cattle of the same back-crosses are under evaluation in Australia.
Relative to the mean off-pasture weight and hot carcass weight of the XJ
cattle slaughtered at Ruakura in 1998 (404 and 202 kg), the
corresponding XL means were 472 and 262 kg respectively, 1.8 and 2.6
phenotypic standard deviations (s.d.) heavier. A series of carcass
composition traits was obtained from the weights of saleable meat,
trimmed fat and bone from individual joints on the right side of each
animal, after 24 h in the chiller. Over all joints, the weights of meat,
fat and bone (as a % of their total) were 66.6, 9.6 and 23.8 for XJ and
71.7, 7.1 and 21.2 for XL, representing differences of 2.8, 1.4 and 2.2
s.d. units respectively. Weights of high value cuts (% of side weight)
were 50.4 for XJ and 52.7 for XL, a 2.3 s.d. difference. Ratios of meat
to bone were 2.80 for XJ and 3.93 for XL, a 5.5 s.d. difference.
Standard errors of all the above differences in s.d. units were 0.16.
The largest differences between the two breed crosses for the above
traits were 2.8 and 5.5 s.d, for meat percent in the side, and for meat
to bone ratio, providing good opportunities for genetic marker studies.
In the AgResearch animals, consisting of progeny from three sire groups,
markers from over half of the genome have been analysed so far. A
significant marker has been identified for meat percent in the side. The
two informative sires had the same genotype for this marker, and the
difference between sire-derived alleles in their effect on meat percent
averaged 0.99 s.d. (F statistic for each sire, 45.47 and 8.84).
Keywords: NZSAPAB;
cattle; breeds; carcass composition; genetic marker.
Last Updated 12-07-2000
