Adams, Nelson J.

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Texas A&amp;M Repository

l/Z.'I/ ~OL-2160Texas Agricultural Extension ServiceSELECTING REPLACEMENT FEMALES:Commercial Heifer SelectionNelson J. Adams*Selection, as it is used here, encompasses both thedirect selection for desirable traits and the indirecteffect of improving herds by culling individuals withundesirable characteristics. In the absence of perfor-mance records, producers must select animals based onphysical appearance. The three primary traits to em-phasize when evaluating heifers for use as replacementsare fertility, structural soundness and growth. Certainphysical characteristics are associated with these traitsin high performing cattle.FertilityFertility, or reproductive performance, is the mostimportant trait in beef cattle production. The primarygoal of every cow/calf producer should be to produce alive calf every 12 months from every cow exposed to abull. Fertility is low in heritability and difficult to recog-nize in young females. The best approach to improvingfertility is to select against obvious structural orreproductive problems and to cull based on reproduc-tive performance.Visually inspect all heifers for feminine character andsize of the vulva. Questionable heifers should be ex-amined by a qualified veterinarian for any internalreproductive tract problems such as infantile tracts; theovaries should be examined for functional status andestrous cyclicity: Avoid heifers from cows with low milkproduction, pendulous udders or balloon-shaped teats.Structural SoundnessA sound skeletal structure is necessary for the beefanimal to remain productive for several years. Ananimal with good body structure will stand with her legssquarely placed and the toes pointed straight ahead.Minor problems, especially with commercial replace-ment heifers, can be tolerated, but major ones should beavoided. Problems in the skeletal structure of the hindlegs are more serious than those of the front legs.Straight hind legs (post leggedness) can cause more* Extension livestock specialist, The Texas A&M University Sys-tem.problems than those with too much "set" to their hocks(sicklehocked). The latter may be unsightly and detractfrom visual appearance, but only in extreme situationsdo they result in unsoundness that affects performanceor longevity. Overly straight and/or open shoulders andbucked knees are other possible indications of unsoundstructure.GrowthGrowth is an important performance trait in beefcattle because rapid and economical gains are essentialfor profitable production. Research has shown thatlarger, heavier heifers born earliest in a calving seasonwill generally breed earlier, raise more calves andrebreed sooner after calving. Attention should be givento skeletal size and weight. Without records, the oldest,largest heifers should be retained as replacements.These heifers are from the earlier calving cows thatproduced optimum milk for a good weaning weight.Such heifers also may have had the genetic ability tocontinue to grow when they were independent of theirdams. All three characteristics--the ability to breed andvalve early, the ability to provide a sufficient milk supplyfor optimum growth, and the ability to grow rapidly--areimportant in selecting higWy productive females.In a practical production situation, a sequentialselection can be made without extra gathering of theherd. At weaning, retain approximately 10 to 20 per-cent more heifers than are required for actual replace-ments. Then re-evaluate and cull heifers that do notmeet set standards. This should be done prior to breed-ing,60 days after removing bulls and again after weaningthe first calf.Weaning SelectionWeaning selection involves removing any heifers thatare structurally unsound, undersized for their age,have a wild disposition or show signs of masculinity orcoarse-ness. For further herd reductions, select thelargest heifers of acceptable maturity for the environ-ment and cull the rest.Texas Agricultural Extension Service • Zerle L. Carpenter, Director • The Texas A&M University System • College Station, TexasBreeding Age SelectionBreeding age selection consists of removing anyheifers that have developed any structural problemssince weaning. This is also the opportunity to cull anyheifers that are smaller than others in the group becauseofgenetics. For accurate selection at this stage, compareheifers that have been managed alike and are on anutritional regimen adequate for optimum growth. Aguide for adequate heifer growth is that they should haveattained 65 percent of their mature body weight beforebeginning the fIrst breeding season.Selection After BreedingSelection after breeding is based primarily onwhether or not heifers are pregnant. The breedingperiod should be kept short, about 60 days, for selectionof early, easy breeding heifers. Open heifers should besold because their chances of having high lifetime per-formances are lower than those that are already bred.Avoid purchasing open heifers from a group given thechance to breed.Selection Based on PerformanceSelection based on first calf performance is the finalstep in ensuring a high performing cow herd. Identifyingpairs (dam/calf) can be difficult, but obviously small,unthrifty calves can be paired with their dams and thepairs culled. Pregnancy checking is £mother tool forselecting first-calf heifers. It is often difficult to rebreedfirst-calf heifers because they are still growing and lac-tating and their reproductive systems require time toprepare for rebreeding. Culling open cows after aspecified breeding period will put additional selectionpressure on reproductive performance. Economicsusually dictates whether or not to sell open first-calfheifers after their calves are weaned.Improving by SelectionThe single most effective method of improving thecow herd is to select outstanding sires, based on perfor-mance records, to use on the cow herd. In most breedingherds, more than 80 percent of the genetic materialcomes from the last three generations of sires. To en-hance the improvement process, replacements shouldbe the best heifers available.The use of the following simple subjective and objec-tive selection procedures will allow for better decisionmaking and improve the productive capability of com-mercial cow herds.1. Identify heifer calves at weaning with an individualhot brand or ear tag number. Each heifer, andeventually every cow, is then identified and shouldbe viewed as an individual productive unit of theranching operation.2. At weaning, cull heifers that are structurally un-sound, undersized, display bad temperament orare otherwise undesirable for your operation.3. Shortly after weaning, weigh each heifer in-dividually under uniform and repeatable weighingconditions. Weaning weight is a combination ofthe milking ability of the cow and the calfs geneticability to grow. Both are important characteristicsin selecting replacement heifers. The weaningweight is the first measurement of growth rateduring the developmental stage. To minimize thepossibility of penalizing the fleshier heifers fromheavy milking cows, the heifers should be weighed4 to 6 weeks after weaning. This allows the groupto equalize and provides a more valid basis formeasuring post-weaning rate of gain. Selectionpressure on post-weaning gain alone may fosterpoor milking ability as thinner heifers at weaningmay make compensatory gains during the post-weaning growth period.4. Manage all heifers alike in the environment inwhich they are expected to perform. It ispreferable to give them access to the better forageand supplement during the winter months. It is notnecessary to achieve maximum gain on replace-ment heifers, but time and environment should beallowed to become part of the performanceevaluation process. If nutrition is sufficient toallow individuals to reach their genetic potentialfor growth, then the differences within the groupwill be evident. Depending on breed type, dailyweight gains of 1.25 to 1.75 pounds are neededduring the development period. For most breeds,this rate of gain will promote the onset of pubertyand allow heifers to conceive early in the breedingperiod.5. Weigh heifers two to three times during thedevelopment period and calculate the rate of gainbetween weighings. If gains are inadequate, in-crease feed levels. The final weight can be used inranking heifers according to their gaining abilityduring the post-weaning development period.6. Remove any heifers that may develop unsoundphysical characteristics and those with very lowpost-weaning growth rate.7. Expose the remaining heifers to bulls which willminimize calving difficulties. Limit exposure to a45- to 6O-day breeding period.8. Check all heifers for pregnancy 60 days after theend of the breeding season.9. Make the final selection from the pregnant heifers.Cull all non-bred heifers.AS1Educational programs conducted by the Texas Agricultural Extension Service serve people of all ages regardless of socioeconomiclevel, race, color, sex, religion, handicap or national origin.Issued in furtherance of Cooperative Extension Work in Agriculture and Home Economics, Acts of Congress of ~ay 8, 1914, as an:'ended,and June 30, 1914, in cooperation with the United States Department of Agriculture. Zerle L. Carpenter, DIrector, Texas AgricultureExtension Service, The Texas A&M University System.10M-5-90, Revision

Selecting Replacement Females:  Commercial Heifer Selection.

Texas A&M University

l/Z.'I/ ~O
L-2160
Texas Agricultural Extension Service
SELECTING REPLACEMENT FEMALES:
Commercial Heifer Selection
Nelson J. Adams*
Selection, as it is used here, encompasses both the
direct selection for desirable traits and the indirect
effect of improving herds by culling individuals with
undesirable characteristics. In the absence of perfor-
mance records, producers must select animals based on
physical appearance. The three primary traits to em-
phasize when evaluating heifers for use as replacements
are fertility, structural soundness and growth. Certain
physical characteristics are associated with these traits
in high performing cattle.
Fertility
Fertility, or reproductive performance, is the most
important trait in beef cattle production. The primary
goal of every cow/calf producer should be to produce a
live calf every 12 months from every cow exposed to a
bull. Fertility is low in heritability and difficult to recog-
nize in young females. The best approach to improving
fertility is to select against obvious structural or
reproductive problems and to cull based on reproduc-
tive performance.
Visually inspect all heifers for feminine character and
size of the vulva. Questionable heifers should be ex-
amined by a qualified veterinarian for any internal
reproductive tract problems such as infantile tracts; the
ovaries should be examined for functional status and
estrous cyclicity: Avoid heifers from cows with low milk
production, pendulous udders or balloon-shaped teats.
Structural Soundness
A sound skeletal structure is necessary for the beef
animal to remain productive for several years. An
animal with good body structure will stand with her legs
squarely placed and the toes pointed straight ahead.
Minor problems, especially with commercial replace-
ment heifers, can be tolerated, but major ones should be
avoided. Problems in the skeletal structure of the hind
legs are more serious than those of the front legs.
Straight hind legs (post leggedness) can cause more
* Extension livestock specialist, The Texas A&M University Sys-
tem.
problems than those with too much "set" to their hocks
(sicklehocked). The latter may be unsightly and detract
from visual appearance, but only in extreme situations
do they result in unsoundness that affects performance
or longevity. Overly straight and/or open shoulders and
bucked knees are other possible indications of unsound
structure.
Growth
Growth is an important performance trait in beef
cattle because rapid and economical gains are essential
for profitable production. Research has shown that
larger, heavier heifers born earliest in a calving season
will generally breed earlier, raise more calves and
rebreed sooner after calving. Attention should be given
to skeletal size and weight. Without records, the oldest,
largest heifers should be retained as replacements.
These heifers are from the earlier calving cows that
produced optimum milk for a good weaning weight.
Such heifers also may have had the genetic ability to
continue to grow when they were independent of their
dams. All three characteristics--the ability to breed and
valve early, the ability to provide a sufficient milk supply
for optimum growth, and the ability to grow rapidly--are
important in selecting higWy productive females.
In a practical production situation, a sequential
selection can be made without extra gathering of the
herd. At weaning, retain approximately 10 to 20 per-
cent more heifers than are required for actual replace-
ments. Then re-evaluate and cull heifers that do not
meet set standards. This should be done prior to breed-
ing,60 days after removing bulls and again after weaning
the first calf.
Weaning Selection
Weaning selection involves removing any heifers that
are structurally unsound, undersized for their age,
have a wild disposition or show signs of masculinity or
coarse-ness. For further herd reductions, select the
largest heifers of acceptable maturity for the environ-
ment and cull the rest.
Texas Agricultural Extension Service • Zerle L. Carpenter, Director • The Texas A&M University System • College Station, Texas
Breeding Age Selection
Breeding age selection consists of removing any
heifers that have developed any structural problems
since weaning. This is also the opportunity to cull any
heifers that are smaller than others in the group because
ofgenetics. For accurate selection at this stage, compare
heifers that have been managed alike and are on a
nutritional regimen adequate for optimum growth. A
guide for adequate heifer growth is that they should have
attained 65 percent of their mature body weight before
beginning the fIrst breeding season.
Selection After Breeding
Selection after breeding is based primarily on
whether or not heifers are pregnant. The breeding
period should be kept short, about 60 days, for selection
of early, easy breeding heifers. Open heifers should be
sold because their chances of having high lifetime per-
formances are lower than those that are already bred.
Avoid purchasing open heifers from a group given the
chance to breed.
Selection Based on Performance
Selection based on first calf performance is the final
step in ensuring a high performing cow herd. Identifying
pairs (dam/calf) can be difficult, but obviously small,
unthrifty calves can be paired with their dams and the
pairs culled. Pregnancy checking is £mother tool for
selecting first-calf heifers. It is often difficult to rebreed
first-calf heifers because they are still growing and lac-
tating and their reproductive systems require time to
prepare for rebreeding. Culling open cows after a
specified breeding period will put additional selection
pressure on reproductive performance. Economics
usually dictates whether or not to sell open first-calf
heifers after their calves are weaned.
Improving by Selection
The single most effective method of improving the
cow herd is to select outstanding sires, based on perfor-
mance records, to use on the cow herd. In most breeding
herds, more than 80 percent of the genetic material
comes from the last three generations of sires. To en-
hance the improvement process, replacements should
be the best heifers available.
The use of the following simple subjective and objec-
tive selection procedures will allow for better decision
making and improve the productive capability of com-
mercial cow herds.
1. Identify heifer calves at weaning with an individual
hot brand or ear tag number. Each heifer, and
eventually every cow, is then identified and should
be viewed as an individual productive unit of the
ranching operation.
2. At weaning, cull heifers that are structurally un-
sound, undersized, display bad temperament or
are otherwise undesirable for your operation.
3. Shortly after weaning, weigh each heifer in-
dividually under uniform and repeatable weighing
conditions. Weaning weight is a combination of
the milking ability of the cow and the calfs genetic
ability to grow. Both are important characteristics
in selecting replacement heifers. The weaning
weight is the first measurement of growth rate
during the developmental stage. To minimize the
possibility of penalizing the fleshier heifers from
heavy milking cows, the heifers should be weighed
4 to 6 weeks after weaning. This allows the group
to equalize and provides a more valid basis for
measuring post-weaning rate of gain. Selection
pressure on post-weaning gain alone may foster
poor milking ability as thinner heifers at weaning
may make compensatory gains during the post-
weaning growth period.
4. Manage all heifers alike in the environment in
which they are expected to perform. It is
preferable to give them access to the better forage
and supplement during the winter months. It is not
necessary to achieve maximum gain on replace-
ment heifers, but time and environment should be
allowed to become part of the performance
evaluation process. If nutrition is sufficient to
allow individuals to reach their genetic potential
for growth, then the differences within the group
will be evident. Depending on breed type, daily
weight gains of 1.25 to 1.75 pounds are needed
during the development period. For most breeds,
this rate of gain will promote the onset of puberty
and allow heifers to conceive early in the breeding
period.
5. Weigh heifers two to three times during the
development period and calculate the rate of gain
between weighings. If gains are inadequate, in-
crease feed levels. The final weight can be used in
ranking heifers according to their gaining ability
during the post-weaning development period.
6. Remove any heifers that may develop unsound
physical characteristics and those with very low
post-weaning growth rate.
7. Expose the remaining heifers to bulls which will
minimize calving difficulties. Limit exposure to a
45- to 6O-day breeding period.
8. Check all heifers for pregnancy 60 days after the
end of the breeding season.
9. Make the final selection from the pregnant heifers.
Cull all non-bred heifers.
AS1
Educational programs conducted by the Texas Agricultural Extension Service serve people of all ages regardless of socioeconomic
level, race, color, sex, religion, handicap or national origin.
Issued in furtherance of Cooperative Extension Work in Agriculture and Home Economics, Acts of Congress of ~ay 8, 1914, as an:'ended,
and June 30, 1914, in cooperation with the United States Department of Agriculture. Zerle L. Carpenter, DIrector, Texas Agriculture
Extension Service, The Texas A&M University System.
10M-5-90, Revision


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Selecting Replacement Females: Commercial Heifer Selection.

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Texas A&M University

Selecting Replacement Females: Commercial Heifer Selection.

Abstract

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Full text

Available Versions

Texas A&amp;M Repository

Texas A&M University

Texas A&M Repository