COOPERATIVE E X T E N S I O N
AN
U N I V E R S I T Y OF CALIFORNIA
Number 146
September 1993
EGG ECONOMICS UPDATE
FLOCK PERFORMANCE INDEXING - A NEW ECONOMIC EVALUATION TECHNIQUE
In the October, 1991 Egg Economics Update, we discussed the concept of placing
Performance Traits in Their Proper Perspective”. We stated “Emphasis on only one
or a few measurements can often lead to the incorrect evaluation of a strain, a
program or a product being tested. Oftentimes, one positive trait is partially offset by
an accompanying negative trait”.
Since then, at least one major consulting firm has incorporated this concept into their
programs, one major breeder is using it to illustrate net product worth, and two other
consulting firms are studying the technique.
Flock Performance Indexing, or whatever you want to call it, is merely a way of
placing multiple traits into one measurement. Hen housed egg production to 60
weeks considers two items - eggs and mortality. Feed efficiency (Ibs of feed per lb
of eggs) considers three measurements - feed, eggs and egg weight. The Flock
Performance Index considers six measurements - eggs, egg weight, feed consumption,
mortality, typical egg prices, and typical feed costs. More importantly, it is more
closely related to true profitability than any other single measurement.
The input required to make a weekly index analysis include: egg numbers, case
weight, mortality, feed consumption and beginning count of layers. A formula is used
to convert case weights to value per dozen based upon the normal distribution of sizes
for each case weight and standardized values (55 cents for large and above, 46 cents
for medium, 30 cents for small). For example, a 40 pound case values out at 43.1
cents per dozen while a 48 pound case is valued at 54.5 cents per dozen. Feed price
is also standardized at $7.50 per 100 pounds.
Since 1991, we’ve analyzed more than 130 flocks totaling 8 + million hens with this
program. A typical index from 20 to 60 weeks of age would be $5.14 with a range
between companies of $4.68 to $5.35. Even though flock data represented five or
more years, the indexing system (with fixed prices and feed costs) allows for valid
performance evaluation over this period. Individual flocks, of course, will vary more
than companies.
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I
Table 1. Comparison of Strains - Importance of Traits
Strain
Number of flocks
Weeks of 90+ % EP
Av. EP% (25-60 wksl
Eggs/HH to 60 wks
Total Lbs of eggs/HH
Av Feed intake (25-60 wks)
Av Weekly Mortalitv (Oh
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indicates best strain for trait
Although flock indexing can be used to evaluate the effects of any program change,
its use in strain comparison is very effective. Today’s breeders select their strains
for trait superiority in those economic traits they feel are most important. In one case,
a strain has superior hen housed egg production. Another strain may have very low
mortality. A third strain may have very big egg size.
The best strain for a particular company is the one that has all traits in the best
economic balance to meet its needs. Table 1 illustrates how performance superiority
shifts from one strain to another and how this is reflected in their performance index.
This includes 97 U.S. flocks.
Note that superiority by trait shifted between strains D,E & F but that the performance
index chose strain E as being best economically. Strains D & E were very good when
the index was used, but were not best in any single trait.
The Relationship of Various Performance Traits to The Performance index
When we analyze the relationship of various standard performance traits to the
Performance Index, we can see how well each trait measures potential profits. The
analysis is called a “regression analysis”. Since many factors affect profits, a person
can determine the relative importance of various traits to the overall objective. Table
2 lists the R squares (1 .O is a perfect relationship) for a wide range of traits.
For example: The total weight of eggs produced to 60 weeks accounts for 62.6%
of the variability we measure with the Performance Index. This means that other
traits are having an effect on profits -the significant trait left out is feed consumption.
Eggs per hen housed to 60 weeks only accounts for 51.6% of the variability in profits
because it leaves out feed and egg weight effects.
This table should not be interpreted that all of these traits are unimportant, but only
that traits further down the list are better predictors of the true value of the flock or
program. The last item, or course, incorporates several of the traits further up the list.
Figures l-3 illustrate the “degree of fit” that each trait contributes to the Performance
Index. You will note that as the R square increases (approaches 1 .O) the fit to the
straight line improves.
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Hen day egg production from 20 to 60 weeks is one of the more traditional
measurements of flock performance but represents only 42.3% of the variability in the
Performance Index rankings of the individual flocks studied. Egg production rates
during this period ranged from 73.3 to 87.1% (average 80.6) with each 1% increase
in egg production rate associated with an increase in the index of $.072 (Figure 1).
Eggs per hen housed to 60 weeks has become the standard measurement for
comparing flock performance. Our studies indicate that this measurement accounts
for 51.6% of the variation in Index results. Individual flocks varied from 204.3 to
242.7 eggs (average 222.3). Each one egg improvement was associated with an
increase in the Index of $.028. This reflects the net returns from the value of an egg
minus the feed cost to produce it (Figure 2).
Finally, the best non-economic measurement correlating performance to the Index was
shown to be the total weight of eggs per hen housed to 60 weeks of age. This
measurement merely adds egg weight to the previous measurement, but now the trait
represents 62.6% of the variability of the Index. Total egg weight (egg mass) ranged
from 26.4 to 31.3 pounds (average 29.0) per hen housed. Each additional pound of
eggs increased the Index by s.22 (Figure 3).
Any measurement involving sampling (egg weight, body weight, house temperature,
etc.) must be representative of the majority of the flock in question. Samplings must
be of sufficient size and frequency to reflect real change. The use of breeder
standards in place of real data is not acceptable. Your flock performs the way it does
because of the multitude of management systems you impose upon your flock.
Breeder standards are only a guide to what may be expected. Your ability to improve
upon these standards is the measure of success you have as a flock manager.
NOTE: A copy of a more complete discussion of this subject is available from the
author and a Lotus l-2-3 template is available for $25. If you wish either of these,
please contact this office ((909) 787-4555).
I
Donald Bell, Poultry Specialist
Cooperative Extension
Highlander Hall
University of California
Riverside, CA 92521
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