Genetics of heifer puberty in two tropical beef genotypes in northern Australia and associations with heifer- and steer-production traits

Johnston, D. J., Barwick, S. A., Corbet, N. J., Fordyce, G., Holroyd, R. G., Williams, P. J. and Burrow, H. M. (2009) Genetics of heifer puberty in two tropical beef genotypes in northern Australia and associations with heifer- and steer-production traits. Animal Production Science, 49 5-6: 399-412.


Author Johnston, D. J.
Barwick, S. A.
Corbet, N. J.
Fordyce, G.
Holroyd, R. G.
Williams, P. J.
Burrow, H. M.
Title Genetics of heifer puberty in two tropical beef genotypes in northern Australia and associations with heifer- and steer-production traits
Journal name Animal Production Science   Check publisher's open access policy
ISSN 1836-5787
1836-5787
Publication date 2009
Sub-type Article (original research)
DOI 10.1071/EA08276
Volume 49
Issue 5-6
Start page 399
End page 412
Total pages 14
Place of publication Collingwood, Vic., Australia
Publisher CSIRO Publishing
Language eng
Abstract A total of 2115 heifers from two tropical genotypes (1007 Brahman and 1108 Tropical Composite) raised in four locations in northern Australia were ovarian-scanned every 4–6 weeks to determine the age at the first-observed corpus luteum (CL) and this was used to define the age at puberty for each heifer. Other traits recorded at each time of ovarian scanning were liveweight, fat depths and body condition score. Reproductive tract size was measured close to the start of the first joining period. Results showed significant effects of location and birth month on the age at first CL and associated puberty traits. Genotypes did not differ significantly for the age or weight at first CL; however, Brahman were fatter at first CL and had a small reproductive tract size compared with that of Tropical Composite. Genetic analyses estimated the age at first CL to be moderately to highly heritable for Brahman (0.57) and Tropical Composite (0.52). The associated traits were also moderately heritable, except for reproductive tract size in Brahmans (0.03) and for Tropical Composite, the presence of an observed CL on the scanning day closest to the start of joining (0.07). Genetic correlations among puberty traits were mostly moderate to high and generally larger in magnitude for Brahman than for Tropical Composite. Genetic correlations between the age at CL and heifer- and steer-production traits showed important genotype differences. For Tropical Composite, the age at CL was negatively correlated with the heifer growth rate in their first postweaning wet season (–0.40) and carcass marbling score (–0.49), but was positively correlated with carcass P8 fat depth (0.43). For Brahman, the age at CL was moderately negatively genetically correlated with heifer measures of bodyweight, fatness, body condition score and IGF-I, in both their first postweaning wet and second dry seasons, but was positively correlated with the dry-season growth rate. For Brahman, genetic correlations between the age at CL and steer traits showed possible antagonisms with feedlot residual feed intake (–0.60) and meat colour (0.73). Selection can be used to change the heifer age at puberty in both genotypes, with few major antagonisms with steer- and heifer-production traits.
Keyword Beef
Fertility
Puberty
Ultrasound
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: Queensland Alliance for Agriculture and Food Innovation
 
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