12th January 2012
We have updated the values used to calculate
our Terminal and Self Replacing index values to reflect the recent
upturn in finished cattle prices, the value of cull cows and general
values of livestock.
Breed average values are now +57(+20) for Terminal
index and +58(+24) for the Self Replacing index however the ranking
of animals within the breed or movement in ranking is minimal.
indexes are designed to show the financial viability of each animal
on a commercial farm.
The Society is pleased to release
a second selection index – the Self Replacing Index - to
complement the Terminal Sire index. Selection indices integrate
EBVs with costs and returns of production while focusing on meeting
market specifications. The whole production system is considered – not
just the sale animal. Feed costs are considered throughout the
production system while accounting for costs and returns. The Society
now has two selection indices which are focused on different sections
of the industry – terminal sire production systems and self
replacing herds. The indices will help you select animals suited
to your production system and market requirements. The indices
are independent, although some animals may rank well for both indices.
The BSCS Terminal index is aimed
at a commercial herd using Simmental bulls over large framed, mixed
breed cows to breed steers and heifers to turn off at 16 months
of age. All progeny are destined for slaughter and no replacement
females are selected from within the herd. There is some emphasis
on calving ease while finishing steers at around 630 kg live weight
(335 kg carcase weight) using a pasture based production system
supplemented with extra rations during the finishing phase.
this index in a commercial herd to produce progeny for slaughter.
The index has moderate emphasis on easier calving (ie getting a
live calf with minimal human interference) while producing calves
that will then grow quickly to market specifications at around
16 months of age. The index is focused on slaughter animals and
does not account for maternal traits and is therefore not suited
to breeding replacement females.
If you are using smaller framed
cows or heifers in your herd, then you should also put extra emphasis
on a higher calving ease direct EBV when selecting a sire using
Self Replacing Index
The BSCS Self Replacing index
is aimed at a Simmental herd selecting replacement females from
within the herd while breeding steers and excess heifers to turn
off at 16 months of age. There is emphasis on calving ease and
maternal traits while also looking to finish steers for slaughter
at around 680 kg live weight (350 kg carcase weight) using a pasture
based production system supplemented with extra rations during
the finishing phase.
This Self Replacing index is also suitable
to using Simmental sires over mixed breed cows where replacement
females are sourced from within the herd. There may be some hybrid
vigour expressed in the progeny depending on the breed type of
the cows used. Therefore you should consider placing extra emphasis
on the Calving Ease EBVs (more positive) of the sire to allow for
possible heavier birth weights of his calves due to hybrid vigour.
Use this index in both commercial and pedigree herds
where you are balancing the requirements of selecting replacement
females while also producing animals for slaughter.
Growth and Mature Size
Any selection index is trying to balance
costs and returns. Calving problems are seen as a cost (man hours
supervising during the calving period, assisting cows while calving,
etc; calf and cow losses; lower production due to calving stress;
potential re-breeding problems; etc). Growth and carcase attributes
are return or income focused (although there is also a cost in
feeding the animals, etc). Given that big animals at say 600 days
of age were also likely to be big at birth (ie this is the “average” biology of cattle), then it is
not surprising that both indices have a calving ease component.
What can be surprising to some people is that an animal with a
good index can still have a poor (low or negative) Calving Ease
EBV. In such a case, this indicates that the costs of likely calving
problems are more than compensated by the subsequent extra returns
from the calves that are slaughtered. That is, you may not get
as many calves and you may spend a lot of time getting them, but
the ones you do get will knock your socks off.
The “average” biology
of cattle also indicates that big calves tend to grow to be big
adults; they will tend to eat a proportional amount of their body
weight to maintain that weight which is critical when maintaining
condition for mating and calving; and they tend to be older when
they reach sexual maturity. Conversely, bigger cows tend to have
less calving difficulties and have a better salvage value when
culled than smaller ones.
The self replacing index is trying to
balance all these traits using available information on genetics
and economics to focus on profit.
Use the correct index
select replacement females from the calves you produce, you should
use the Self Replacing index as your main index. The SR index does
look at the maternal components as well as targeting the market
requirements of the slaughtered animals. The Terminal index is
just focused on getting a calf and then growing it out to market
requirements. However, the indices are not mutually exclusive and
some animals will have good values for both the Self Replacing
and the Terminal indices.
Each index is a complete index in itself.
The Self Replacing index is not like the old Calving Value. Calving
Value attempted to just look at the calving component, whereas
the Self Replacing index looks at calving, growth, carcase and
fertility from both the direct and maternal perspective. That is,
costs and returns are accumulated over the whole life of the animal,
not just a small component of it. If you are looking at buying
a cow, not only does she need to do the cow stuff (be fertile and
have a calf each and every year, calve un-assisted, rear the calf
to weaning, not be too expensive to maintain, etc.), but she needs
to have the genes to give to her calves so that they will grow
to market specifications and make a good profit – for whoever
sells the calf to slaughter. That is, the index is based on the
whole production chain.
Look at the Index, EBVs and Accuracies
The index is a means of weighting the relevant EBVs to focus on
profit within the defined production system and market specifications.
Therefore, the more information you have on the candidate animals
(ie more accurate and more extensive range of EBVs), the better
the potential ranking of these animals based on the index. Hence
use the relevant index to give a broad ranking of animals, then
look at the component EBVs (and accuracies) of the key traits in
the index to fine tune your selection to animals that best suit
your management and market requirements.
When using the index as
an aid to buying replacement animals, also look at the key traits
of the index and check that the herd selling the animals records
the relevant traits. For example, if you focus on easier calving
cattle, then ensure the selling herd routinely records calving
ease and birth weights. For carcase traits, the selling herd should
routinely scan all their animals (not just a couple of sale animals).
Does the herd take scrotal measurements and weigh the cows when
they weigh their calves for the 200 day weight? The quality of
recording in the selling herd affects the quality of your decision
in purchasing the animal.