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Penn State Cooperative Extension
Capitol Region Dairy Team
GENETICS OF FEET
AND LEGS
AND IMPORTANCE OF
BULL SELECTION
Mary Beth Grove
Daiiy/Environmental Agent
Lancaster County
How important is it to select bulls
that transmit good (above-average)
feet and legs for your herd? How
should these bulls be selected?
Common sense tells us that when
deciding which A.I. bulls to use for
the dairy herd, the traits we select
should have a definite economic
value. Everyone knows the economic
value of milk pounds and butterfat
percentage in most cases, more
milk means more money in your
pocket. Unfortunately, the relation
ship between foot and leg traits and
production or cow longevity is much
more difficult to measure.
Dr. Ben McDaniel at North Caro
lina State University conducted in
teresting research to evaluate the im
portance of feet and legs on
production. Much of this work was
done at several state-owned dairy
herds in the Carolinas. The research
ers actually measured the hoof angle
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and hoof length on several thousand
cows to determine if these measure
ments could be associated with pro
duction traits. Table 1 exhibits the
finding of this study.
These results showed that as foot
angle increased (became steeper) by 5
degrees in first calf heifers, there was
an associated 503-pound increase in
second lactation milk production. A
decrease in 10 mm of toe length in
first calf heifers equated to a
1,475-pound increase in second-lac
tation milk production. Steeper foot
angles and shorter claw length were
associated with fewer days open,
earlier breedings, and a greater sur
vival to five years of age. Deeper
heels tended to increase days open,
but also increased longevity of that
cow in the herd. Cattle with deeper
heels did exhibit more sole ulcers.
Longer claws and lower angles
were also associated with lower sur
vival rates. It was also suggested that
legs that are neither too straight
(posty) nor too crooked (sickled) are
apparently the best for increasing
longevity in cattle.
As you can see from this research,
there is an economic value in steeper
foot angles in dairy cattle. Unfortu
nately, this does not mean that they
are easily improved by using better
genetics.
There is another important factor
in making bull breeding decisions
the “heritability” of that trait. What
is heritability? In simple terms, it is
the portion of the “visible” differ
ences in a trait that are due to genet
ic factors. The higher the heritability.
Table 1. Correlations between measured foot traits and production/longevity characteristics of
dairy cows in North Carolina institutional herds.
Trait
Milk.
Fat.
Da'
Survival to 5
the greater is the genetic control on
the trait, and the more rapidly selec
tion will result in genetic progress.
Some traits are highly heritable.
For example, stature has a heritabili
ty of about .42 or 42 percent. This
means genetics accounts for 42 per
cent of the variation in stature (mea
sured at hip height), and the environ
ment (or the way the animal was
raised) accounts for the remaining 58
percent Unfortunately, foot and leg
traits are not nearly as heritable, in
part because the animal’s environ
ment can easily affect the feet on a
cow. In Table 2, you will see the line
ar score and heritabilities for the foot
and leg traits.
This data suggests that, while in
creased foot angle and proper leg set
are very important for cow longevity,
much of the improvement to be made
on feet and legs on individual cows
will be through environmental
changes. These environmental
changes might include grooved con
crete and more stall bedding, allow
ing cows access to pasture, and an
adequate nutritional program.
Unfortunately, with these “low to
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moderate” heritability values, bull se
lection to improve feet and legs
through genetics will be a long, slow
process. This also explains why you
may not always be able to see mea
surable changes from generation to
generation in regards to foot confir
mation. This does not mean you
should ignore foot and leg composite
or foot angle PTAs on bulls just
that you may want to make it a sec
ondary trait to select.
Why not choose bulls that meet
your production goals first, and then
choose from this pool of bulls for
those with higher foot angle and
more intermediate leg set traits?
When attempting to correct a “two
way” trait such as rear legs (side
view), select an intermediate (+. 00)
Table 2. Heritabilities for Foot and Leg Traits of Dairy Cattle
Trait
Foot angle
Rear Legs (Side)
Rear Legs (Rear)
AY
Claw Lent
.18
.24
.26
-.01
-.34
bull this bull will tend to sire
daughters with legs of an intermedi
ate set. Using a bull that tends to sire
daughters with straight “posty” legs
will not correct a “sickled” cow fast
er.
There are also some indexes that
include the sire’s genetic merit for
foot angle in the overall index. One
such index is Net Merit. According to
many industry leaders, the top Net
Merit bulls transmit the best combi
nation of superior genes for produc
tion, longevity, 'Somatic cell score,
and type traits for most commercial
dairy herds.
For more information on sire selec
tion for improved feet and legs, call
Beth Grove at (717) 394-6851 or con
tact your local extension office.
Heritability
.10-.15
.15-.21
.10-.15
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The next issue of Lancaster Farming’s Grower & Marketer
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’ I Included will be features on several area vineyard managers
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tips on selecting proper grape varieties, and
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and a calendar of events.
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