Page 21 - Silverstream 2021 Catalogue eBook

PP
PP
PP
PP
P

PP
PP

P
P
PP
PP
P
PH
H
P

PH P

H
PH
P
PP
PH PP
P
P

P
PP
PP
H
PH
PH
P

P
P P P P P P P P
H PH PH
P PP PP P P PP P PP

PH PH
P PP PP H H PH PH
Homozygous polled bull (PP) mated to Heterozygous polled bull (PH) mated to
P
P
P
P
homozygous horned cow (HH) H heterozygous polled cow (PH)
PH
PH
P PP PP P PP PP
P P Phenotypes: P H Phenotypes:
P PP PP 100% polled H PH PH 75% Polled and
H PH PH progeny P P PP P PH 25% horned
progeny
H PH PH P H PP PH PP HH
P P P H
H PH PH
Diagram 2 PH PH Diagram 3 PH
H
P
PP
P P P H
H PH PH H PH HH
PP
PP
P Homozygous polled bull (PP) mated to Heterozygous polled bull (PH) mated to

HH
H
PH H
P
heterozygous polled cow (PH) homozygous horned cow (HH)
H PH PH P H PP PH PH
HH
P P Phenotypes: P H Phenotypes:
100% polled H PH HH 50% polled progeny
P PP PP progeny H PH HH and
P H H H 50% horned progeny
H PH PH H PH HH
P PP PH H P HH H HH

H PH HH
HH
H
PH
Diagram 4 Diagram 5 HH HH
H
P H H H
H PH HH
HH
H
HH
H PH
P Homozygous polled bull (PP) mated to Homozygous horned bull (HH) mated to
P PP
homozygous polled cow (PP) homozygous horned cow (H)
H H PH HH H HH HH
PH
HH
P P Phenotypes: H H
H PH HH 100% polled Phenotypes:
P PP PP progeny H HH HH 100% horned
P H progeny
P PP PP H HH HH
H H PH H HH

HH
H H
PH
HH
Diagram 6 HH Diagram 7
P P
H HH HH

H PH PH

Scur Condition H H

H PH PH

H
HH
HH
Horn growth would make it impossible for scurs to develop at the same spot but horned animals can carry the gene for scurs. Unlike the

poll/horn trait, scurs is not a simple recessive trait and is not completely understood! It has been shown that, regardless of the cause, the
H
HH
HH
scur condition can only happen in heterozygous polled cattle, of either sex (Asai-Coakwell and Schmutz 2002; Wiedemar, et al. 2014). The
P
P

data also support that males develop the scur condition at a higher rate than females. The condition that is obvious is that horned cattle (HH)
PP
PP
P
cannot have the scur phenotype. If cattle have the genotype for the horned condition (HH) they will always be horned. For cattle to develop

scurs, it must be a horn allele carrier (PH) and have some other unknown genetic influence, realizing that male calves will tend to develop
H
PH
PH
scurs at a higher rate than females. For cattle to be smooth polled it must be either homozygous (PP); or heterozygous polled (PH) without

the unknown genetic influence that allows scurs. A smooth polled heterozyogous bull has the same geneotype as a scurred heterozygous

polled bull so just because a bull has scurs doesn’t mean he will leave less polled progeny than his clean polled counterpart.
P H
P PP PH
GLOSSARY
H
PH
HH
Alleles – The possible forms of genes (i.e. poll and horn alleles) at a locus. Because genes occur in pairs, one gene of a pair may have one allele and the other may
have a different allele.

Carrier – An animal that has two different alleles to make up its pair for a gene, both the polled and horned alleles (PH). The dominant allele (polled) masks the
existence of the recessive allele (horned) so it is polled, but it carries the horn allele and can pass it on to its calves.
P
H

Dominant – Masks the characteristic of the recessive allele. Characteristic is expressed in full if either homozygous or heterozygous (i.e. polled is dominant to
horned).
PH
HH
H
Double Polled – Refers to mating a polled bull to a polled cow, and producing a polled calf. It is incorrect to assume that this calf is homozygous polled; one or both
parents could be carriers, and if only one horn allele gets passed to the calf it will be a carrier.
PH
HH
H
Gene – A gene is a specific section of DNA on a chromosome that serves a biological function. Two copies of each gene exist in an animal. Only one allele of each
pair is randomly passed on to the offspring; the offspring gets one from each parent, thus giving it a pair.

Genotype – The genetic makeup of the animal.
Heterozygous – The gene has different alleles.
H

H
Homozygous – The gene has matching alleles.
Horned – The presence of horns that are attached to the skull.
H
HH
HH
Phenotype – The physical appearance of the cattle. For the purposes of this article there are 3 possibilities: smooth polled, scurred or horned.
Polled – Absence of horns (can be scurred).
HH
HH
H
Recessive – Is completely masked if paired with a dominant allele. Is only expressed if homozygous (both alleles are recessive).
Scurs – Horn-like tissue that are attached to the skin rather than the skull. Can vary in size from small growths to small hornlike structures.

Smooth Polled – Absence of both horns and scurs.

Poll testing: Silverstream Charolais bulls have been tested by Neogen Australasia at the University of Qld, Australia with a SNP based poll test to identify their poll status.

While this is the most accurate poll test available to determine if an animal is PP ( homozygous polled) there is no guarantee by Silverstream that this is 100 % accurate.
We rely on Neogen to determine an animals poll status so therefore we cannot bear direct liability or any consequential losses incurred by the purchaser should this test
deemed to be incorrect.