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Male traits and herd reproductive capability in tropical beef cattle. 2. Genetic parameters of bull traits

journal contribution
posted on 13.09.2018, 00:00 by Nicholas Corbet, BM Burns, DJ Johnston, ML Wolcott, DH Corbet, BK Venus, Y Li, MR McGowan, RG Holroyd
A total of 4063 young bulls of two tropical genotypes (1639 Brahman and 2424 Tropical Composite) raised in northern Australia were evaluated for a comprehensive range of production and reproduction traits up to 24 months of age. Prior to weaning, peripheral blood concentrations of luteinising hormone (LH) and inhibin were measured at 4 months of age. At weaning (6 months) blood insulin-like growth factor-1 (IGF-I) and flight time were recorded. Body composition traits of fat depth and eye-muscle area were determined by ultrasonography at 15 months of age when additional measurements of liveweight, hip height and body condition score were recorded. Bull breeding soundness was evaluated at ∼12, 18 and 24 months of age when measurements of scrotal circumference, sheath score, semen mass activity, progressive motility of individual sperm and percent morphologically normal sperm were recorded. Magnitude of heritability and genetic correlations changed across time for some traits. Heritability of LH, inhibin, IGF-I and of 18-month scrotal circumference, mass activity, progressive motility and percent normal sperm was 0.31, 0.74, 0.44, 0.75, 0.24, 0.15 and 0.25, respectively, for Brahmans and 0.48, 0.72, 0.36, 0.43, 0.13, 0.15 and 0.20, respectively, for Tropical Composites. Inhibin and IGF-I had moderate genetic association with percent normal sperm at 24 months in Brahmans but low to negligible associations in Tropical Composites. Body condition score in Brahmans and sperm motility (mass and individual) traits in both genotypes had moderate to strong genetic correlation with percent normal sperm and may prove useful candidates for indirect selection. There is scope to increase scrotal circumference by selection and this will be associated with favourable correlated responses of improved semen quality in both genotypes. The lack of genetic antagonism among bull traits indicates that selection for improved semen quality will not adversely affect other production traits. © CSIRO 2013.

Funding

Category 4 - CRC Research Income

History

Volume

53

Issue

2

Start Page

101

End Page

113

Number of Pages

13

eISSN

1836-5787

ISSN

1836-0939

Publisher

CSIRO

Peer Reviewed

Yes

Open Access

No

External Author Affiliations

Cooperative Research Centre for Beef Genetic Technologies; CSIRO Livestock Industries; University of Queensland; University of New England; Department of Employment Economic Development and Innovation

Era Eligible

Yes

Journal

Animal Production Science

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