Breeding the horns out of your herd
The following information was presented at the 2012 Kidman Springs Field Day by
Trisha Cowley, Department of Resources
Slide 1 – Background
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Improved production
Better welfare outcomes
Safety
Decreased labour
Slide 2 – Objectives
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But where does polledness rank in the selection process?
Breeding the horns out of your herd
Trisha Cowley, Department of Resources
Slide 3 - Where does polledness fit in?
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What are you selecting a bull to achieve?
Slide 4 - Before a bull is polled it needs to:
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Be reproductively sound
Be structurally sound
Have good temperament
Produce fertile daughters
Produce progeny that will make you money
Produce progeny that suit your market
Don’t buy a bull because he’s polled, buy a bull because he has all this AND he’s polled!
Slide 5 - Inheritance of polledness 101
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Controlled by 1 gene in many Bos Taurus breeds
Polled Gene
o Polled form (P)
o Horned form (H)
o Polled form is dominant
o (so PP and PH look polled)
Breeding the horns out of your herd
Trisha Cowley, Department of Resources
Slide 6 – PP
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Two copies of the Polled allele
Homzygous polled
“True polled”
Can only pass on a Polled allele to offspring
Slide 7 – PH
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Has one copy of the polled allele and one copy of the horned allele
Heterozygous polled
Passes on a polled allele to 50% of its offspring and a horned allele to 50%
Slide 8 - Polledness in Brahmans
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Not so simple in Brahmans
– Scur gene, African horn gene
Major difference in PH animals
– Scurred, polled or horned
Breeding the horns out of your herd
Trisha Cowley, Department of Resources
Slide 9 - PP versus PH
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Both can look polled!!
But PH will pass on a horned form of the polled to 50% of its progeny….
Desirable to be able to distinguish between them
DNA tests existed for use in Bos taurus cattle, but did not work well in Bos indicus
Slide 10
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Beef CRC set about developing gene markers for these hypothesised genes
Validated in Brahman, Hereford, Droughtmaster, Santa Gertrudis, Limousin, Brangus,
Tropical Composite, Simmental, Charolais, Shorthorn.
Slide 11 - Polled Gene Marker Test
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DNA test used to determine an animal’s horn/poll genotype
When gene is not isolated, markers help to tag a gene of interest
Works well in Brahman, Hereford, Simmental, Droughtmaster, Santa Gertrudis
Ambiguous results – 11% in Brahman
Slide 12 - Validation in Brahmans
Breeding the horns out of your herd
Trisha Cowley, Department of Resources
Slide 13 - PP versus PH – genotype
Slide 14 - PP versus PH – phenotype
90% of PP progeny won’t need dehorning, versus 50% of PH
Breeding the horns out of your herd
Trisha Cowley, Department of Resources
Slide 15 - Some practicalities…
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Complications of the interaction of the African Horn Gene
Slide 16 - Some practicalities…
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Frequency of polled animals in the Brahman
Availability of Polled Brahmans
Dangers of single trait selection
Are polled animals inferior?
– Spiral deviation NO
– Sheath structure NO
How long will it take?
– 35 years vs 8….
Slide 17 - Other options
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Controlled mating, segregation
PH bulls
Crossbreeding
– Belmont Red, Bonsmara, Senepol, Droughtmaster
Breeding own nucleus herd
Slide 18 - Summary
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Polled Gene Marker Test isn’t perfect – but best we’ve got
PP sires will get you there faster
Going to take long time so start now
Balanced selection is critical as always