Beef Cattle Frame Scores

AS-1091, May 1995

John Dhuyvetter, Area
Livestock Specialist

Frame scores are an objective,
numerical description of cattle skeletal size which
reflect the growth pattern and potential mature size
of an animal. Frame score values typically range
from 2 to 9 and are calculated from hip height and
age. Frame scores are frequently reported as
supplementary information to weight and other
performance data. They can be used to project mature
size, provide an indication of composition, and
characterize performance potential and nutritional
requirements of an animal.

Considerable variation exists
among cattle for frame size. Optimum frame score and
desired body type will be different among production
situations which differ in feed resources, breeding
systems, and market endpoints. Low frame scores are
descriptive of cattle which are short in stature for
their age, tend to be early maturing, and finish for
slaughter and mature at lighter body weights. High
frame scores are indicative of cattle that are tall
for their age, have a slower rate of maturity, and
finish and mature at relatively heavy body weights.
Rate of gain is usually higher for larger framed
cattle; however, large differences in rate and
efficiency of gain exist in cattle of similar size.

For cattle developed under a
consistent and adequate plane of nutrition for
normal growth, a calculated frame score should be
similar regardless of when the animal was measured.
Theoretically an animal should have the same frame
score throughout its life. Inconsistent
environmental factors and management can alter
skeletal growth rate, which may result in cattle
developing slightly faster or slower than
anticipated. As a result animals may increase or
decrease a frame score over time depending on rate
of growth.

The Beef Improvement
Federation has recommended in its "Guidelines for
Uniform Beef Improvement Programs" that height
measurements for the calculation of frame score be
taken at the hip directly over the hook bones as
illustrated in Figure 1. Height measurements can be
collected through the use of hip height measuring
sticks marketed specifically for that purpose. Such
height sticks are constructed with a sliding arm
containing a bubble level on a pole scaled in height
increments. To make a measurement, the pole is held
vertically alongside the animal’s hip with the
sliding arm positioned level and directly over the
hook bones and a measurement read from the pole
where the arm attaches. For accurate height
measurements it is necessary for the animal to have
its legs set squarely and head in a normal position.
An alternative to using a height stick and where the
accuracy of individual measurements is not as
critical is to place a grid marked in height
increments inside a scale or working chute. As
cattle are being worked, a height can be read off
the grid by sighting across the animal’s hip.
Modifications can also be made to equip cattle
handling chutes with a moveable front to back
pull-down measuring device calibrated to obtain
height measurements.

Figure 1. Proper position for correctly measuring
hip height. Source: BIF Guidelines for Uniform
Beef Improvement Programs, 1990

Beef Improvement Federation
recommended procedures are available to adjust
actual height measurements to standard performance
testing 205-day weaning and 365-day yearling stages.
Hip heights adjusted to 205 days should be collected
between 160 and 250 days of age similar to the range
for calculating adjusted weaning weights. Cattle
should be at least 330 days of age for predicting
yearling height measurements that are adjusted to
365 days. Age of calf and age of dam adjustment
factors and formulas for calculating adjusted
205-day and 365-day hip heights are presented in
Table 1. As an example of adjusting an actual
height, the 205-day weaning height of a bull calf
born March 1 to a 4-year-old dam and weaned October
10 measuring 44 inches would be 43.4 inches. {44 +
[(205 - 224) * .033]} * 1.01 = 43.4

Table 1. 205 day and 365 day Height Adjustment Factors 
and Formulas
--------------------------------------------------------
205 day Height   
Adjusted Height = {actual height + [(205 - actual age)*                 
age of calf adjustment]} * age of dam adjustment
--------------------------------------------------------
Factors for Adjusting Weaning Height
                                bulls        heifers
        Age of Calf              .033    .025
        Age of Dam                      
          2 and 13 or older     1.02    1.02    
          3 and 12              1.015   1.015
          4 and 11              1.01    1.01    
          5 through 10          1.00    1.00
--------------------------------------------------------
365 day Height   
Adjusted Height = {actual height + [(365 - actual age)*                 
age of calf adjustment]}
--------------------------------------------------------        
Factors for Adjusting Yearling Height
                                bulls   heifers
        Age of Calf
          under 365 days        .033    .025
          over 365 days         .025    .025       
-------------------------------------------------------- 
--------------------------------------------------------        
Source: BIF Guidelines for Uniform Beef Improvement 
Programs, 1990

A hip height measurement can
be converted to a frame score if the animal’s age is
known. Frame scores can be approximated from "height
for age" frame score tables or calculated by
mathematical formulas. Separate charts and formulas
exist for bulls and heifers due to differing rates
of skeletal growth between sexes. Beef Improvement
Federation frame score charts and calculation
formulas are presented in Table 2. As an example of
determining a frame score, a bull measuring 48
inches at 330 days of age would be estimated to be
about a frame score 5 from the chart or calculated
to have a frame score of 4.98 by the formula.
[-11.548 + (.4878 * 48) - (.0289 * 330) + (.0000947
* 330 * 330) + (.0000334 * 48 * 330)] = 4.98.
Several beef cattle breed associations have
developed their own frame score formulas and charts
which are based on average growth and development
within their specific breed and vary slightly from
BIF calculations.

Table 2. Frame score formulas and charts for bulls and heifers. Values 
within the tables are reported in inches.
---------------------------------------------------------------------------
BULLS      
Frame Score = -11.548 + .04878 (Height) - 0.0289 (Days of Age) +
              0.00001947 (Days of Age)2 + 0.0000334 (Height) (Days of Age)
---------------------------------------------------------------------------
Age in   -------------------------- Frame Score ---------------------------
Months   1      2       3        4      5       6        7       8       9
---------------------------------------------------------------------------
  5    33.5    35.5    37.5    39.5    41.6    43.6    45.6    47.7    49.7
  6    34.8    36.8    38.8    40.8    42.9    44.9    46.9    48.9    51.0
  7    36.0    38.0    40.0    42.1    44.1    46.1    48.1    50.1    52.2
  8    37.2    39.2    41.2    43.2    45.2    47.2    49.3    51.3    53.3
  9    38.2    40.2    42.3    44.3    46.3    48.3    50.3    52.3    54.3
 10    39.2    41.2    43.3    45.3    47.3    49.3    51.3    53.3    55.3
 11    40.2    42.2    44.2    46.2    48.2    50.2    52.2    54.2    56.2
 12    41.0    43.0    45.0    47.0    49.0    51.0    53.0    55.0    57.0
 13    41.8    43.8    45.8    47.8    49.8    51.8    53.8    55.8    57.7
 14    42.5    44.5    46.5    48.5    50.4    52.4    54.4    56.4    58.4
 15    43.1    45.1    47.1    49.1    51.1    53.0    55.0    57.0    59.0
 16    43.6    45.6    47.6    49.6    51.6    53.6    55.6    57.5    59.5
 17    44.1    46.1    48.1    50.1    52.0    54.0    56.0    58.0    60.0
 18    44.5    46.5    48.5    50.5    52.4    54.4    56.4    58.4    60.3
 19    44.9    46.8    48.8    50.8    52.7    54.1    56.7    sa.7    60.6
 20    45.1    47.1    49.1    51.0    53.0    55.0    56.9    58.9    60.9
 21    45.3    47.3    49.2    51.2    53.2    55.1    57.1    59.1    61.0
---------------------------------------------------------------------------
HEIFERS    
Frame Score = -11.7086 + 0.4723 (Height) - 0.0239 (Days of Age) +
              0.0000146 (Days of Age)2 + 0.0000759 (Height) (Days of Age)
---------------------------------------------------------------------------
Age in   -------------------------- Frame Score ---------------------------
Months   1      2       3        4      5       6        7       8       9
---------------------------------------------------------------------------
  5    33.1    35.1    37.2    39.3    41.3    43.4    45.5    47.5    49.6
  6    34.1    36.2    38.2    40.3    42.3    44.4    46.5    48.5    50.6
  7    35.1    37.1    39.2    41.2    43.3    45.3    41.4    49.4    51.5
  8    36.0    38.0    40.1    42.1    44.1    46.2    48.2    50.2    52.3
  9    36.8    38.9    40.9    42.9    44.9    47.0    49.0    51.0    53.0
 10    37.6    39.6    41.6    43.7    45.7    47.7    49.7    51.7    53.8
 11    38.3    40.3    42.3    44.3    46.4    48.4    50.4    52.4    54.4
 12    39.0    41.0    43.0    45.0    47.0    49.0    51.0    53.0    55.0
 13    39.6    41.6    43.6    45.5    47.5    49.5    51.5    53.5    55.5
 14    40.1    42.1    44.1    46.1    48.0    50.0    52.0    54.0    56.0
 15    40.6    42.6    44.5    46.5    48.5    50.5    52.4    54.4    56.4
 16    41.0    43.0    44.9    46.9    48.9    50.8    52.8    54.8    56.7
 17    41.4    43.3    45.3    47.2    49.2    51.1    53.1    55.1    57.0
 18    41.7    43.6    45.6    47.5    49.5    51.4    53.4    55.3    57.3
 19    41.9    43.9    45.8    47.7    49.7    51.6    53.6    55.5    57.4
 20    42.1    44.1    46.0    47.9    49.8    51.8    53.7    55.6    57.6
 21    42.3    44.2    46.1    48.0    50.0    51.9    53.8    55.7    57.7
---------------------------------------------------------------------------

Frame score provides an
indication of an animal’s growth curve, which can be
used to project expected finishing weight for
slaughter cattle, or mature weight for breeding
cattle. Table 3 provides an estimate of mature cow
weight and expected slaughter weight at finish for
steers and heifers by frame score. These projections
are for average cattle; actual weights will also
vary due to differences in muscling, body length,
condition and other factors.

Table 3. Relationship of frame size to projected 
mature cow weight and slaughter weight at Choice 
Quality Grade.
----------------------------------------------------
  BIF                   
Numerical  USDA         Mature    Steer      Heifer
 Frame     Feeder Calf   Cow    Slaughter  Slaughter
 Score     Frame Size   Weight    Weight     Weight
----------------------------------------------------
   2       Small          955      850        700
   3                     1030      950        800
----------------------------------------------------
   4       Medium        1100     1050        900
   5                     1175     1150       1000
----------------------------------------------------
   6       Large         1250     1250       1100
   7                     1320     1350       1200
   8                     1395     1450       1300
   9                     1470     1550       1400
----------------------------------------------------
Source:  Adapted from Boggs, South Dakota State 
University, 1991

Greater mature cow weight is
associated with increased frame scores, which
results in additional feed required for maintenance
because of a larger body mass. Stocking rates and
quantities of feed need to be adjusted to meet the
demands of larger cows. Provided necessary feed is
available, larger cows generally meet their higher
requirements. Under favorable management,
reproductive rates tend to be similar across frame
size; however, when the availability of feed becomes
restricted, larger framed cattle are more
susceptible to reproductive failure. Increasing
mature size is a concern and may require adjusting
replacement heifer development programs in order to
insure they reach heavier prebreeding weights
necessary to attain puberty.

Large frame size is also
associated with greater growth potential, longer
finishing periods, and heavier slaughter weights.
The generally preferred range for carcass weights of
650 to 850 pounds suggests the need to produce
feeder cattle with a 5 to 7 range in frame scores.
The current USDA feeder cattle grading system is
based on the factors of frame size and muscle
thickness. Three frame score designations are
included: large, medium, and small, which relate to
an evaluation by appearance of an animal’s skeletal
height in relation to its age and the weight at
which an animal will produce a choice quality
carcass with about .5 inches external fat at the
12th rib. Large frame steers and heifers would not
be expected to produce choice carcasses until their
live weight exceeds 1200 and 1000 pounds,
respectively. Medium frame steers would be expected
to produce choice carcasses at live weights of 1000
to 1200 pounds, and heifers at 850 to 1000 pounds.
Small frame steers and heifers would produce choice
carcasses at live weights of less than 1000 and 850
pounds, respectively.

An indication of frame size is
very important when estimating growing and finishing
cattle nutrient requirements and projected feed
intake. Although larger framed cattle will generally
have increased intakes, energy concentration in the
feed that is used for gain (NEg) is lower than that
of medium framed cattle. Furthermore, protein
requirements for large framed steers have been based
on medium framed steers that weigh 15% less. This
results in a greater protein requirement for large
compared to medium framed cattle.

Frame score is considered to
be moderately to highly heritable. As such, frame
score can be significantly changed through
selection, primarily achieved through sire
selection. With an heritability estimate of .40,
about 40% of a bull’s difference in frame score from
herd average will be passed on to progeny.

Frame score measurements are
descriptive of animal type and growth patterns in
beef cattle. They are useful in evaluating animal
nutritional requirements, characterizing target
market weights, and aid in selection decisions.

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