Page 78 - Hereford Magazine 2021

Genotyping

the keepers:

it’s all in

the timing

With NZ Herefords members accessing genomically
enhanced breeding values via the Hereford Single-
Step Breedplan analysis, Hereford breeders may be
considering when the best time is to genotype their
young animals and whether all animals should
be genotyped or just those replacement heifers
and/or sale bulls being kept. Catriona Millen from
Southern Beef Technology Services explores these
considerations in more detail.

ereford producers can collect DNA samples for better description of an animal’s genetic potential. This allows
genotyping very early in a calf’s life. Tissue Hereford producers to be more confident in their selection
sampling units (TSUs) can be used to collect a accuracy when identifying which animals to keep, and which
tissue sample when tagging and/or weighing the to cull.
Hcalf soon after birth. While it is recommended An example of the effect of genomic data in animal selection
hair samples are not taken until the calf is at least 60 days of can be seen in Figure 1. This figure shows 10 heifers from an
age, which allows time for the hair follicles to develop, hair Australian Hereford herd, born in 2020, and their selection
samples are commonly collected at marking/weaning. Even index values when a) their own genotypes are not included
allowing for the genotyping process – typically three to four (i.e. just pedigree and own performance) and b) their own
months – Hereford producers can have genotype information genotypes were included (along with pedigree and own
included in the Single-Step Breedplan analysis by the time performance). Let us assume that the Hereford breeder plans to
the calf is four to six months of age. For those who wish to keep 60% of the heifers as replacements, and, for simplicity, is
utilise genomically enhanced EBVs as part of their selection using the selection index as the sole selection criteria. Without
criteria, collecting DNA samples at birth or marking/weaning genomically enhanced EBVs, which contribute to the selection
is strongly encouraged. index, the Hereford breeder would select heifers 1, 3, 5, 6, 7 and
8. However, a month later, with genomic information included,
Why genotype young Hereford calves? the heifers have re-ranked and the Hereford breeder would now
select heifers 1, 2, 3, 4, 6 and 7. While not shown, the inclusion of
The major advantage to having genomic information on genomic information is also lifting the EBV accuracy of these
animals at such a young age is that this information, in the heifers. With the inclusion of genomic information, the Hereford
form of Single-Step Breedplan EBVs, can be utilised when breeder is able to make a more informed selection decision.
the Hereford breeder is making selection decisions. While There are several other benefits to genotyping Hereford
traditional Breedplan EBVs for young animals were calculated calves prior to animal selection. In addition to the ability to
from pedigree and the animal’s own performance, genomics use genomically enhanced EBVs for identifying replacement
provides an additional source of information for the Single- heifers and/or sale bulls, the Hereford DNA bundles allow
Step Breedplan analysis to use. This offers several advantages: Hereford breeders to do parentage verification and genetic
firstly, genomic information typically increases the variation condition testing of their animals. Both of these, in particular
(spread) observed between animals. This allows greater genetic condition status, may also be important factors in the
differentiation between the top (keeper) and bottom (cull) final selection of replacement animals.
calves, allowing easier selection decisions and greater selection
response. Secondly, genomics typically cause increases in EBV Should I genotype all my Hereford calves?
accuracy, which can cause re-ranking of animals. This increase
in EBV accuracy is usually more pronounced for animals with One of the barriers to genotyping the entire calf crop is cost,
a lower starting EBV accuracy, such as young animals with particularly for larger Hereford herds with several hundred
no progeny performance in the system. By lifting the EBV calves born each year. Understandably, some Hereford
accuracy, genomics is providing Hereford breeders with a producers may look to genotype just those animals they

76 HEREFORD MAGAZINE Year 2021