Page 6 - Lochburn Shorthorn Catalogue eBook.pdf

INDEXES

The Self - Replacing Index

“The Self-replacing Index” ranks bulls on their ability to generate profit (profit per cow mated)
in a herd situation in which some females are retained for breeding and surplus females, along
with all males, are slaughtered.
The main drivers of profit addressed by the Index include (in order of economic importance):
• Direct and Maternal Calving Ease
• Growth
• Meat Yield
• Cow Survival
• Finishing Ability
• Fertility
• Cow Efficiency
In short, selection on the Index is expected to favour production of a cowherd with excellent
reproductive efficiency, rearing progeny with moderate-to-high growth rates and high yielding
carcasses.
• Comparing the lifetime profitability of two bulls:
The following example illustrates how potential differences in lifetime profitability can be
approximated between bulls with different Indexes. These estimates of value differences may
be conservative.
Two bulls with Self-replacing Indexes of $40 and $20 are mated to genetically similar cows.
If each bull mates 200 cows during its lifetime, the first bull will generate $2000 ($(40-20)/2
x 200) more profit during its lifetime than the second bull (the $20 profit advantage must be
divided by 2 because a bull only passes half his genes on to each of his progeny).
The Dairy Index
Estimates the genetic differences between animals in net profitability per cow joined for an
example commercial dairy herd targeting the production of dairy beef progeny from dairy
cows and heifers where all progeny are slaughtered. Steers are assumed marketed at 520 kg
live weight (280 kg carcase weight and 6 mm fat depth) at 20 months of age. While calving
ease is by far the most important profit driver in the Index, growth and to a lesser extant meat
yield also contribute.

INDEX VALUES ($)
Self Replacing +64
Dairy +36

The Australasian Shorthorn GROUP BREEDPLAN Estimated Breeding Values
contained in this Sale Catalogue were compiled by the Agricultural Business Research
Institute (ABRI) from data supplied by the breeders. Neither the New Zealand Beef
Shorthorn Association nor the ABRI oversee or audit the collection of this data.

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