What
Amount of Brahman Influence Will Meet The Targets of Branded Beef Programs?[1]
M. A. Elzo, D. D. Johnson, D. L. Wakeman, R. L. West, J. G. Wasdin, and W. P. Dixon
Department of Animal Sciences, University of Florida,
Gainesville
Introduction
According to the United Stated Department of Agriculture (USDA, 2001),
in December 2001 there were 44 branded beef programs in the United States, and
40 of them (91%) imposed a restriction on the amount of Brahman breeding. Brahman and high-percent Brahman carcasses
were considered too variable in their degree of tenderness to be acceptable for
branded beef products. However,
environmental and management conditions in Florida and in other Southeastern
states of the USA favor the use of Brahman influenced cattle over completely Bos
taurus cattle of British and continental origin. It is likely that beef cattle containing some Brahman fraction
will continue to be the predominant type in the Southern region of the USA in
the foreseeable future. The purpose of
this paper is to objectively discuss the carcass characteristics of Brahman and
Brahman influenced cattle and of one Bos taurus breed (Angus) according to the
traits and restrictions imposed by branded beef programs, using information
from the Angus-Brahman multibreed herd of the University of Florida. Because Florida is primarily a cow-calf
state, growth traits will also be discussed.
Trait results will be presented in terms of actual values (phenotypes)
and of predicted genetic values.
Analyses of predicted genetic values of the parents of the Angus,
Brahman, Brangus, and various Angus ´ Brahman crossbreds calves produced in the
multibreed herd should help to better understand phenotypic values and shed
some light on the growth and carcass characteristics of Brahman influenced
cattle as a whole.
Main
Characteristics of Branded Beef Programs in the USA
Branded beef programs have a series of requirements that animals and
carcasses must meet to be accepted within each brand name (USDA, 2001). These requirements were grouped into six
categories: 1) live requirements, 2) carcass characteristics, 3) yield factors,
4) quality factors, 5) USDA information, and 6) management claims.
Live requirements are used by breed branded beef products (e.g., Angus,
Hereford) to include crossbred animals in their categories (70% of branded beef
programs). Live requirements are either
genetic or phenotypic. For example,
Angus branded beef programs require animals to be either progeny of one
registered Angus or grandprogeny of two registered grandparents. Certification by phenotype requires animals
to be 51% solid black. Hereford-branded
beef programs have similar requirements.
Carcass characteristics preclude carcasses with ribeye internal
hemorrhages and “dark cutting” characteristics (100% branded beef programs),
hump heights taller than 2 inches (91% branded beef programs), and except for
two branded beef programs, allow only steer and heifer carcasses (96% branded
beef programs).
Yield factors include yield grade (no requirement: 43%, 2.9 or less:
2%, 3.9 or less: 32%, and 4.9 or less: 23% of branded beef programs), fat thickness
(no requirement: 95%, .7 inches or less, or 1.1 inches: 5% of branded beef
programs), ribeye area (no requirement: 91%; larger than or equal to 11 square
inches, or between 11 and 17 square inches: 9% of branded beef programs),
muscling (no requirement: 20%; moderately thick: 80% of branded beef programs),
and hot carcass weight (no requirement: 82%; larger than or equal to 600 pounds
or between 600 and 950 pounds: 18% of branded beef programs).
Quality factors are quality grade (prime: 50%, choice: 82%, and select:
32% of branded beef programs), marbling (slightly abundant to abundant: 50%,
small to moderate: 82%, and slight: 32% of branded beef programs), marbling
texture (no requirement: 48%, and medium to fine marbling texture: 52% of
branded beef programs), and maturity (no requirement: 7%, A and A/B maturity:
89%, and A to E maturity: 5% of branded beef programs).
USDA information refers to a schedule number (a description of the
requirements of an specific beef program), the initial release date and
effective date of the beef program, whether the beef program is USDA certified
(98% are USDA certified) and USDA verified (5% are USDA verified).
Management claims are additional management (9%) and breed (7%)
requirements of some branded beef programs.
The
Angus-Brahman Multibreed Herd of the University of Florida
The Angus-Brahman multibreed herd was established in 1988 to conduct
intrabreed and multibreed animal breeding and management research in a herd
whose composition was a reflection of the types of animals commonly found in
Florida and in other Southern estates.
The herd is composed of Angus (A), Brahman (B), ¾ A ¼ B, ½ A ½ B, ¼ A ¾
B, and Brangus (5/8 A 3/8 B) interbreeding mating groups of sires and
dams. The term interbreeding here means
that a sire is mated to dams of all breed groups. That is, sires are mated across all breed groups of dams
following a diallel design. Sires come
from inside and outside the herd. In
particular, Angus, Brahman, and Brangus sires included in their national sire
evaluations were used in order to create connectedness with the national herd
of these breeds. This is a
self-perpetuating herd in that replacement females from all breed groups can be
produced within the herd.
There is currently reproduction, management, growth, and carcass
information on 2910 calves (between 143 and 951 per breed group) born from 1989
to 2001. These calves were the progeny
of 153 sires (between 12 and 42 per breed group) and 1124 dams (between 113 and
293 per breed group). Figure 1 shows
the number of sires, dams, and calves by breed-group-of-sire ´ breed-group-of-dam
combination for the 1989-2001 period.
Notice that larger numbers of dams were mated to produce Angus, Brahman,
and Brangus replacements.
Figure 1. Number of
sires, dams, and calves by breed-group-of-sire ´ breed-group-of-dam combination in the Angus-Brahman
multibreed herd
The growth traits used to compare Angus, Brahman, Brangus, and A ´ B crossbred animals
will be: 1) birth weight, 2) weaning weight, 3) weaning weight adjusted to 205
days, 4) yearling weight, 5) yearling weight adjusted to 365 days, 6) feedlot
average daily gain, 7) slaughter weight, 8) slaughter age, and 9) 550-day
weight.
Carcass information was collected only on steers slaughtered when they
had between .35 and .55 inches of backfat thickness. Thus, all carcasses fell into the category of A maturity. Steers were slaughtered at the Meats
Laboratory of the Animal Science Department of the University of Florida, and
at other facilities in Florida and elsewhere.
The incidence of “dark cutting” characteristics was extremely rare (2
out 827 slaughtered steers), and there were no reports of internal hemorrhages of the ribeye
muscle. Marbling texture was not
measured. Thus, to compare Angus,
Brahman, Brangus, and A ´ B crossbred animals for carcass traits, only the following
requirements of the branded beef programs will be considered: 1) live
requirements: 51% black, when relevant for specific black Angus branded beef
programs, 2) carcass requirements: hump height less than or equal to 2 inches,
3) yield requirements: hot carcass
weight (600 to 950 pounds), dressing percent, fat over the ribeye (0 to 1.1
inches), ribeye area (larger than or equal to 11 square inches, or between 11
and 17 square inches), and yield grade (2.9 to 4.9), and 4) quality
requirements: marbling (small to medium: 400 to 699), slight: 300 to 399, and
traces: 200 to 299), and quality grade (choice: 600 to 699, select: 500 to 599,
and standard: 400 to 499). USDA
information and management claims will not be included in the discussion.
Results
and Discussion
Results will be entirely presented in graphical form. Graphs will be of two kinds: 1) Actual
records and moving averages (Investopedia.com, 2002) of 100 actual records (the
first moving average is computed using records 1 to 100, the second one using
records 2 to 101, and so on), and 2) multibreed genetic predictions. Graphs were created using Quattro Pro
version 9. Animals in graphs were
sorted by Brahman fraction of the calf, Brahman fraction of the sire of the
calf, and Brahman fraction of the dam of the calf. To simplify the notation, the abscissa of each graph contains
numbers 1 to 6, one for each breed group: 1 = Angus (100% to 81% Angus), 2 =
.75 A (80% to 61% Angus), 6 = Brangus (62.5% Angus), 3 = .5 A (60% to 41%
Angus), 4 = .25 A (40% to 21% Angus), and 5 = Brahman (20% to 0% Angus). The ordinate of each graph contains values
of traits expressed in the American system (inches, pounds), except for
Warner-Bratzler Shear Force (expressed in kg), and categories (e.g., 1 =
extremely tough to 8 = extremely tender, for tenderness).
Multibreed genetic predictions were obtained using single-trait
maternal grandsire multibreed models (Elzo and Wakeman, 1998). Fixed environmental effects were
contemporary groups and ages of dam.
Fixed genetic effects were additive and nonadditive intra and interbreed
genetic effects. Random effects were
sire additive and nonadditive genetic effects and residual. The model for growth traits included direct
and maternal effects, and only direct effects for carcass traits. Direct genetic effects measure an animal’s
ability to perform. Maternal genetic
effects refer to maternal care, especially milk production. Additive genetic effects were predicted as
deviations from average Brahman additive genetic effects. Nonadditive genetic effects were predicted as
deviations from the average of intrabreed Angus and Brahman intrabreed
interaction effects. Computations were
performed using the MREMLEM program (Elzo, 2002). The multibreed model used here differed from multibreed national
sire evaluation models in that 1) it used sires and maternal grandsires instead
of calves and dams, 2) it computed random nonadditive intra and interbreed
nonadditive genetic predictions, and 3) it computed total direct and maternal
genetic predictions. For simplicity,
graphs for growth traits only contain predictions for total direct and total
maternal genetic effects. Carcass trait
graphs show additive, nonadditive, and total direct genetic effects. Lastly, growth and carcass graphs show
nonadditive and total genetic predictions of sires mated to ½ Angus ½ Brahman
dams. This was done to make the
expected nonadditive fraction of Angus/Brahman interactions in all matings
equal to ½. This would make sire
comparisons more fair because progeny from all sires would have the same amount
of nonadditive interactions regardless of the breed composition of their sires.
Growth Traits
Growth traits will be presented in the following order: 1) birth
weight, 2) weaning weight (unadjusted, 205-d), 3) yearling weight (unadjusted,
365-d), 4) feedlot average daily gain, and 5) slaughter weight, slaughter age,
and 550-d weight. For each trait there
are two graphs: one with phenotypic results (actual measurements and 100-record
moving averages), and another with multibreed genetic predictions. The purpose of the graphs with genetic
predictions is to help explain phenotypic results and to help understand the
connection between the actual trait measurements and the underlying additive
and nonadditive genetic effects.
Birth Weight. Figure 2
contains the graphs of phenotypic calf birth weights and moving averages, and
of total direct and maternal genetic predictions.
Figure 2. Calf birth
weights, moving averages, and sire total direct and maternal multibreed
expected progeny differences in the Angus-Brahman multibreed herd
The phenotypic graph in Figure 2 suggests a similar degree of
variability across all breed groups of calves, and the moving average shows an
upward trend from Angus to Brahman calves.
The genetic graph indicates that Brahman, 75% Brahman, and ½ Brahman
sires would tend to produce heavier calves at birth compared to Angus, 75% Angus,
and Brangus sires due to direct genetic effects, and that their maternal effect
would produce the opposite effect. This
means that, on the average, the heaviest calves will likely be those of Brahman
sires mated to Angus cows and the lightest ones will likely be straightbred
Angus. The largest phenotypic average
for birth weight was that of the F1 calves from the Brahman sires ´ Angus dams combination
(89.1 pounds), and Angus calves had the second smallest average (66.6 pounds),
which is close enough to the expected outcome given the small size of the
multibreed data set.
Weaning Weight. Figure 3
contains phenotypic and genetic graphs for unadjusted weaning weights, and
Figure 4 shows the corresponding graphs for weaning weights adjusted to 205
days of age. Calves from Angus and A ´ B crossbred dams were
weaned in early September, and those from Brahman dams in early October. This was done because Brahman dams were
mated approximately one month later than Angus and A ´ B dams.
Figure 3. Calf
weaning weights, moving averages, and sire total direct and maternal multibreed
expected progeny differences in the Angus-Brahman multibreed herd
Figure 4. Calf 205-d
weights, moving averages, and sire total direct and maternal multibreed
expected progeny differences in the Angus-Brahman multibreed herd
The moving average of the unadjusted and 205-d adjusted weaning weights
show a convex arch between Angus and Brahman calves. Straightbred Angus and Brahman calves had smaller phenotypic
unadjusted and 205-d adjusted weaning weights than crossbred calves. The smaller weights for Brahman calves in
the unadjusted weaning weight graph occurred largely because Brahman calves
were younger at weaning (about one month) than Angus and A ´ B crossbred
calves. Because most calves were older
than 205 days at weaning the 205-d moving average shows a drop of about 100
pounds relative to the unadjusted one.
In addition, there is a decrease in variability, which also appears in
the genetic graphs. The genetic graphs
also show that Brahman and 75% Brahman sires had higher predictions for direct
genetic effects for 205-d weights than Angus, 75% Angus, Brangus, and 50%
Brahman sires. This difference is less
evident in the sire predictions for unadjusted weaning weights. Predictions for maternal effects were
comparable across all breed groups of sires, although A ´ B crossbred and Brahman
sires showed more genetic variability than Angus sires. The largest average phenotypic unadjusted
weaning weight was for calves from the mating of Brahman sires and 75% Brahman
dams (581 pounds), and the smallest was for calves from the mating of 50% Angus
sires and Brahman dams (441 pounds).
The largest phenotypic average 205-d weight belonged to calves from
Brahman sires and Brangus dams (508.3 pounds), and the smallest was that of
Angus calves (426 pounds).
Yearling Weight. Calf
phenotypic values and multibreed sire predictions of unadjusted yearling
weights are presented in Figure 5, and those for 365-d adjusted weights in
Figure 6.
Figure 5. Calf yearling
weights, moving averages, and sire total direct and maternal multibreed
expected progeny differences in the Angus-Brahman multibreed herd
Figure 6. Calf 365-d
weights, moving averages, and sire total direct and maternal multibreed
expected progeny differences in the Angus-Brahman multibreed herd
The patterns of unadjusted and adjusted yearling weights and of genetic
predictions is similar to that observed for weaning weights. Crossbred calves continue to have larger
weights than straightbred Angus and Brahman calves. Brahman-sired calves continue to be heavier than calves from
other breed groups. Calves from Brahman
sires and 75% Brahman dams had the largest average unadjusted yearling weights
(697.4 pounds). Genetic predictions for
crossbred sires continue to show larger variability than straightbred sires.
Feedlot Average Daily Gain. Yearling
steer calves were sent to a feedlot to be fed until their ultrasound backfat
thickness was between .35 and .55 inches.
The time steers spent in the feedlot ranged from 3 to 6 months. Angus and A ´ B crossbred calves tended to have somewhat higher
average daily gains (Figure 7) than Brahman calves. Genetically this amounted to a difference of about .2 pounds/day
between Angus and Brahman sire predicted total genetic values (Figure 7).
Figure 7. Steer
feedlot average daily gains, moving averages, and sire additive, nonadditive,
and total direct multibreed expected progeny differences in the Angus-Brahman
multibreed herd
Slaughter Weight and Slaughter Age. Steer calves
were slaughtered when they reached between .35 and .55 inches of ultrasound
backfat thickness. The objective was to
slaughter steers at a similar fat thickness endpoint. Thus, genetic background, ultrasound backfat measurement, and
slaughter age contributed to the steer phenotypic and sire genetic variation
found for slaughter weights (Figure 8).
Figure 8. Steer
slaughter weights, moving averages, and sire additive, nonadditive, and total
multibreed expected progeny differences in the Angus-Brahman multibreed herd
Crossbred steers were heavier on the average than straightbred Angus
and Brahman steers. In part, Brahman
steers had lighter average slaughter weights because, on the average, they
tended to be younger than A ´ B crossbred and Angus steers at slaughter (Figure 9). Age was probably the main reason for Brahman
steers to have had lighter slaughter weights than Angus. Brahman steers were 30 days younger at
slaughter than Angus calves (553 days vs 583 days). However, there were eight breed group combinations whose average
slaughter ages were younger and had slaughter weights comparable to Brahman
steers. The graph of multibreed sire
predictions for direct genetic effects for slaughter weight shows an upward
trend from Angus to Brahman, and the nonadditive line shows an advantage of
Angus/Brahman interaction of about 40 pounds over the mean of intrabreed Angus
and Brahman interactions. Thus,
crossbred steers with high percent of Brahman breeding will tend to be heavier
than crossbred steers with low percent Brahman, and straightbred Brahman
steers.
Figure 9. Steer
slaughter ages, moving averages, and sire total direct and maternal multibreed
expected progeny differences in the Angus-Brahman multibreed herd
550-day Weight. This
adjusted weight provides a clearer depiction of the growth potential of Angus,
Brahman, and A ´ B crossbred animals as replacement animals than do
similar-backfat-thickness slaughter weights.
Figure 10 shows a phenotypic pattern that is similar to earlier growth
stages (birth, weaning, yearling), with crossbred animals having larger weights
than straightbred animals, predicted direct sire genetic effects favoring
Brahman, and predicted maternal effects favoring Angus.
Figure 10. Steer and
heifer 550-d weights, moving averages, and sire total direct and maternal
multibreed expected progeny differences in the Angus-Brahman multibreed herd
Carcass Traits
Angus, Brahman, Brangus, and A ´ B crossbred animals will be compared using the
following carcass traits grouped according to the requirements of branded beef
programs: 1) carcass characteristics:
hump height less than or equal to 2 inches, 3) yield characteristics: hot carcass weight (600 to 950 pounds),
dressing percent, fat over the ribeye (0 to 1.1 inches), ribeye area (larger
than or equal to 11 square inches, or between 11 and 17 square inches), and
yield grade (2.9 to 4.9), and 4) quality characteristics: marbling (small to
medium: 400 to 699), slight: 300 to 399, and traces: 200 to 299), and quality
grade (choice: 600 to 699, select: 500 to 599, and standard: 400 to 499). The live requirement of 51% black will be
used only when discussing specific black Angus branded beef programs. As with growth traits, each carcass trait
will be discussed using two graphs: one containing phenotypic results (actual
measurements and 100-record moving averages), and another one showing
multibreed predictions for direct genetic effects.
Carcass Characteristics: Hump Height.
Hump Height. Hump height
was measured as the distance between the dorsal point of the ligament nuchae to
the dorsal most point of the rhomboideous muscle. This measurement is different from the USDA measure of hump
height (USDA, 1994), which measures the height of the lean muscle (excluding
fat) in the center of the hump that is perpendicular to a line formed by the
extension of the top line (including fat).
It appears that the hump height measured here (heretofore UFL hump
height) is on the average 3 inches longer than the USDA hump height
measurement, and that this distance correspond to the distance between the
extension of the top line and the dorsal aspect of the ligament nuchae. Thus, regardless of the actual difference
between the two measures, if UFL hump heights from all steers are deviated from
the mean UFL hump height of Angus steers (about 3 inches, Figure 11), the
resulting difference should give a reasonably close approximation to the USDA
measure of hump height.
The graph of phenotypic values of hump heights shows a clear upward
trend between Angus and Brahman (Figure 11), suggesting a mostly additive mode
of inheritance. This is confirmed by
the graph of sire predicted genetic values, which shows an average nonadditive
genetic effect of less than .5 inches, compared to a difference of 1.5 inches
between Angus and Brahman. However,
there is a substantial amount of phenotypic variability for this trait. Phenotypically, animals with a 50%
difference in Brahman breeding may have similar hump heights. Genetically, differences in sire predicted
direct genetic values for hump height seem to be more distinct and predictable:
Angus and some Brangus sires would produce calves with the smallest humps, and
Brahman sires would generate calves with the largest humps.
Figure 11. Steer hump
heights, moving averages, and sire additive, nonadditive, and total direct multibreed
expected progeny differences in the Angus-Brahman multibreed herd
Crossbred and Brahman calves hump height deviations from Angus indicate
that branded beef programs that included the 2 inch-or-less restriction on hump
height would have excluded about 10% of 50% Brahman steers, about 60% of 75%
Brahman steers, and 80% of Brahman steers in the Angus-Brahman multibreed
herd. All Brahman steers would also
have been excluded because of phenotype and(or) genotype live requirements by
70% of branded beef programs.
Yield Characteristics: Hot Carcass Weight,
Dressing Percent, Fat Over the Ribeye, Ribeye Area, and Yield Grade.
Hot Carcass Weight. Phenotypically, hot carcass weights tended to be larger for
Brahman and A ´ B crossbred steers than for Angus steers (Figure 12). Genetically there was a clear upward trend
in sire additive direct and total genetic predictions for hot carcass weights
from Angus to Brahman. Interbreed sire
nonadditive genetic effects were about half the values of additive genetic effects
and less variable than sire additive and total direct predicted genetic
values. Phenotypic and genetic
variability were large however, indicating that carcasses of similar weight
ranges would exist in all steer breed groups.
Brahman, 75% Brahman, Brangus, and 25% Brahman sired steers tended to
have, on the average, heavier carcasses than Angus and 50% Brahman sired
calves. The restriction of 600 to 900
pounds imposed by a few branded beef programs (9%) would exclude a similar
fraction of carcasses across all breed groups.
Figure 12. Steer hot
carcass weights, moving averages, and sire additive, nonadditive, and total
direct multibreed expected progeny differences in the Angus-Brahman multibreed
herd
Dressing Percent. This trait
was included here for completeness, although it is not one of the yield traits
restricted by branded beef programs.
There was a small difference (Figure 13) in phenotypic
Figure 13. Steer
dressing percents, moving averages, and sire additive, nonadditive, and total
direct multibreed expected progeny differences in the Angus-Brahman multibreed
herd
dressing percent between Angus and Brahman steers (about 1% in favor of
Brahman). Genetically, this difference
was likely to be almost entirely due to additive direct genetic effects. Predicted nonadditive genetic effects were
close to zero for sires of all breed groups.
Fat Over the Ribeye. This trait
was included here because it is part of the set of restrictions on yield
traits, although its variability was highly controlled because animals were
slaughtered using a similar backfat thickness endpoint. Some phenotypic variability still remained
for this trait because animals were not slaughtered at exactly the same backfat
endpoint, but the genetic variability was tightly controlled as shown in the
graph of sire multibreed predictions (Figure 14). Most branded beef programs imposed no restrictions on backfat
thickness. The severest restriction (.7
inches or less) would have eliminated only a few A ´ B crossbred steers.
Figure 14. Steer fat
over the ribeye, moving averages, and sire additive, nonadditive, and total
direct multibreed expected progeny differences in the Angus-Brahman multibreed
herd
Ribeye Area. Phenotypically,
ribeye areas tended to be smaller for straightbred Angus and Brahman than for
crossbreds, although the difference was small (about 1 square inch on the
average). Phenotypic variation was
sizable, with values ranging from about 8 to 18 square inches. Genetically, there was a small difference in
sire additive direct genetic predictions from Angus to Brahman. Nonadditive sire genetic predictions were
all small (.25 square inches or less) and mostly on the positive side,
suggesting a small advantage of crossbred over purebred steers (Figure 15).
Figure 15. Steer
ribeye areas, moving averages, and sire additive, nonadditive, and total direct
multibreed expected progeny differences in the Angus-Brahman multibreed herd
Branded beef programs that imposed a minimum ribeye area of 11 square
inches would have eliminated approximately 25% Angus, 25% ¾ A, 27% Brangus, 17%
½ A, 27% ¼ A, and 26% Brahman carcasses.
Most steer carcasses (76%) had ribeye areas between 11 and 16.5 square
inches. Thus, branded beef programs
that imposed an upper limit of 16.5 or 17 square inches would have eliminated
only one carcass (from a Brahman steer).
Yield Grade. The vast
majority of carcasses of steers of all breed groups had yield grades below
4. The moving average of yield grade
suggests that straightbred Angus and Brahman tended to have slightly lower
values of yield grade (hence higher percent of boneless, closely trimmed retail
cuts). Phenotypic values showed similar
range of values across all steer breed groups (between 1 and 4.2). Genetically, sires differed little in their
additive and nonadditive direct predicted ability (Figure 16).
Figure 16. Steer yield
grades, moving averages, and sire additive, nonadditive, and total direct
multibreed expected progeny differences in the Angus-Brahman multibreed herd
About 57% of the branded beef programs impose the restriction that
carcasses must have a yield grade of 2.9, 3.9, or 4.9. The program that required carcasses to have
yield grades of 2.9 or less would have accepted 63% of carcasses (75% Angus,
56% ¾ A, 64% Brangus, 64% ½ A, 53% ¼ A, and 54% Brahman), whereas those that
required yield grades of 3.9 or less would have accepted 98% of all carcasses
(98% Angus, 95% ¾ A, 97% Brangus, 98% ½ A, 96% ¼ A, and 99% Brahman), and those
that required 4.9 would have accepted all carcasses. It should be noticed that yield grade is heavily influenced by
fat over the ribeye. Thus, had steers
been slaughtered at a lower backfat thickness endpoint (e.g., .2 inches),
probably most carcasses would have been eligible for branded beef programs
requiring a maximum yield grade of 2.9.
Quality Characteristics: Marbling, Quality
Grade, WB Shear Force 5 Days, WB Shear Force 14 Days, and Tenderness.
Marbling and Quality Grade. Given a
degree of maturity (e.g., A maturity as in the Angus-Brahman multibreed data
set), marbling is the deciding factor in the categorization of animals for
quality grade. Thus, marbling
phenotypic and genetic graphs (Figure 17) showed trends very similar to those obtained
for quality grade (Figure 18). The
moving average lines for marbling and quality grade depict decreasing
phenotypic trends from 100% Angus to 100% Brahman steer carcasses. On the average, marbling scores dropped from
about 450 (small) to 350 (slight), and quality grade scores fell from 610
(choice) to 540 (select). Similar
trends occurred for sire direct additive and total genetic predictions. Nonadditive direct genetic effects appeared
to have played a minor role in the genetic determination of these traits. Although some predicted nonadditive genetic
variation existed, it was smaller than the additive genetic variation present
among sires of all breed groups.
Figure 17. Steer
marbling scores, moving averages, and sire additive, nonadditive, and total
direct multibreed expected progeny differences in the Angus-Brahman multibreed
herd
Figure 18. Steer
quality grades, moving averages, and sire additive, nonadditive, and total
direct multibreed expected progeny differences in the Angus-Brahman multibreed
herd
Most crossbred steer carcasses in the Angus-Brahman herd had marbling
scores between 300 (slight) and 500 (modest).
Some Angus, Brangus, and crossbred steer carcasses reached marbling
scores of 600 and higher (moderate).
All breed groups had some steer carcasses with marbling scores below 300
(traces, practically devoid). In terms
of quality grades, most carcasses had scores between 500 (select) and 650
(choice). No carcasses qualified for
prime, and all breed groups had carcasses with scores between 400 and 499
(standard). Branded beef programs that
require quality grades to be prime or choice would have accepted 47% Angus, 34%
¾ A, 31% Brangus, 23% ½ A, 15% ¼ A, and 13% Brahman carcasses, whereas those
requiring choice and select would have accepted 95% Angus, 95% ¾ A, 92%
Brangus, 89% ½ A, 83% ¼ A, and 76% Brahman carcasses. It should be noticed that the phenotypic variation among marbling
scores was substantially larger than that of quality grades. Thus, some animals (particularly Brahman)
that would have been eliminated because of branded beef marbling restrictions
would have been accepted under their quality grade restrictions.
WB Shear Force 5 Days, WB Shear Force 14
Days, and Tenderness. Warner-Bratzler shear force was substantially
more variable at 5 days postmortem (Figure 19) than at 14 days postmortem
(Figure 20) in steer carcasses of all breed groups. Further, the moving average line indicates a steeper upward trend
from Angus to Brahman carcasses at 5 days (approximate increase of 2 kg of
shear force) than at 14 days postmortem (about .5 kg increase in shear
force). Genetic prediction graphs were
in complete agreement with phenotypic graphs for these traits. Angus sires had predicted additive direct
and total genetic values that were approximately 1 kg below at 5 days and .5 kg
below at 14 days than those of Brahman sires.
Brangus and crossbred sires had intermediate values between Angus and
Brahman sires. The same as with other
carcass traits, nonadditive direct genetic effects were close to zero, with
some variation among sires of all breed groups. Larger amounts of variation among sires of all breed groups
existed for additive direct and total genetic effects. Consequently, there were Angus, 75% Angus,
Brangus, and 50% Angus sires that had similar direct and total predicted
genetic values for shear force at 5 days postmortem, whereas 75% Brahman and
Brahman sires had somewhat larger values.
Figure 19. Steer WB
shear force at 5 days, moving averages, and sire additive, nonadditive, and
total direct multibreed expected progeny differences in the Angus-Brahman
multibreed herd
Figure 20. Steer WB
shear force at 14 days, moving averages, and sire additive, nonadditive, and total
direct multibreed expected progeny differences in the Angus-Brahman multibreed
herd
At 14 days postmortem however, differences among direct additive and
total predicted genetic values decreased dramatically. Thus, at 14 days postmortem, there were sires
of all breed groups that had similar predicted differences. There was still, however, a small but
noticeable difference suggesting that progeny of Angus sires would yield
carcasses with lower shear force values at 14 days than those from progeny of Brahman
sires. Crossbred and Brangus sires
continued to have intermediate predicted additive genetic values at this aging
time.
The increasing trend in shear force between Angus and Brahman steer
carcasses translated into a downward trend in tenderness scores (taste-panel
evaluated 14 days postmortem) from Angus to Brahman (Figure 21). The tenderness moving average went from
approximately 6 (moderately tender) for Angus steers to 4 (moderately tough)
for Brahman steers. This Angus to
Brahman downward trend was supported by the trend obtained for the predicted
additive and total direct genetic effects.
Angus sires had predicted additive and total genetic values that were,
on the average, about 1 point larger than Brahman sires. Crossbred sires had intermediate values, and
Brangus sires had values closer to those of Angus sires, but they were
substantially more variable. Phenotypic
variability was large for all steer breed groups, and because of it there were
steer carcasses with tenderness values between 4 (slightly tough) and 3
(moderately tough) in all breed groups.
At the other end of the scale, only some Angus, 75% Angus, Brangus, 50%
Angus, and 75% Brahman carcasses had tenderness values of 6 (moderately tender)
and 7 (very tender). Tenderness in Brahman
steers ranged from 3 to 5.5. It should be noticed that the downward trend
in tenderness from Angus to Brahman is a closer reflection of the upward trend
for WB shear force between Angus and Brahman at 5 days than at 14 days
postmortem. Thus, WB shear force at 5
days postmortem appears to be a better indicator of tenderness than WB shear
force at 14 days postmortem.
Figure 21. Steer
tenderness scores, moving averages, and sire additive, nonadditive, and total
direct multibreed expected progeny differences in the Angus-Brahman multibreed
herd
Specific Branded Beef Programs
Branded beef programs in the USA could be grouped into two categories
depending on whether; 1) they have live requirements (phenotypic or genotypic)
and they require animals to have hump heights lower than or equal to 2 inches,
and 2) they do not have either live or hump height requirements. Certified Angus Beef (USDA, 2002a) falls
into the first category, and Nolan Ryan’s All Natural Tender Aged Beef (USDA
,2002b) belongs to the second category.
The acceptability of the steer carcasses of the Angus-Brahman multibreed
herd will be discussed considering only the deciding factors from each program.
Certified Angus Beef. The most
critical conditions of this program are live requirements and hump height. Live requirements (51% black) would exclude
all Brahman steers, and hump height requirements (less than or equal to 2
inches) would eliminate 2% Angus, 2% Brangus, 10% ½ Angus, and 61% ¾ Brahman
steers. Interestingly, 19% of all
Brahman steers had hump heights lower than or equal to 2 inches. Quality grade (prime, choice) and(or) marbling
requirements: 500 (modest) and above would eliminate the majority of the
remaining carcasses. Approximately 47%
Angus, 34% ¾ A, 31% Brangus, 23% ½ A, and 15% ¼ A would be accepted according
to these two criteria. When all four
criteria (live requirements, hump height, quality grade, and marbling) are
considered together approximately 22% of steer carcasses (45% Angus, 32% ¾ A,
29% Brangus, 20% ½ A, and 6% ¼ A; Figure 22) will be accepted. If, in addition, tenderness is included as
an additional criterion, and only tender steers (tenderness score 5 and higher)
were acceptable, this fraction would drop to 16% (40% Angus, 21% ¾ A, 20%
Brangus, 13% ½ A, and 3% ¼ A).
Nolan Ryan’s
All Natural Tender Aged Beef. Carcasses from all breed groups can be
considered for this program. The
crucial requirements are yield grade: 2.9 or less, ribeye area: 11 to 16.5
square inches, and quality grade (choice, select) and(or) marbling: 300
(slight) to 699 (moderate). Considering
these requirements, 41% of all carcasses in the Angus-Brahman multibreed data
set would have been eligible to participate in this program (54% Angus, 40% ¾ A, 44% Brangus, 47% ½ A, 32% ¼ A,
and 30% Brahman). If tenderness is added as a further
criterion, and only tender animals were acceptable, then the fraction of
acceptable carcasses in the multibreed data set would drop to 25% (48%
Angus, 26% ¾ A, 30% Brangus, 30% ½ A, 16% ¼ A, and 8% Brahman; Figure 22).
As indicated in the yield grade section above, had animals been
slaughtered at a lower backfat endpoint, it is likely that a substantially
higher percentage of carcasses would have been eligible to participate in this
program.
Figure 22. Fraction of
acceptable steer carcasses by two branded beef programs in the Angus-Brahman
multibreed herd considering phenotypic, hump height, yield grade, ribeye area, quality
grade, and tenderness factors
Implications
The results presented here indicate that
from a growth trait standpoint it is advantageous to use Brahman in cow-calf
crossbreeding production systems in Florida.
Genetically Brahman sires had generally higher predicted values than
Angus, Brangus, and Angus ´ Brahman sires for direct
genetic effects, but the opposite occurred for maternal effects. From the point of view of carcass traits the
situation is less favorable to Brahman.
Most branded beef programs excluded Brahman and Brahman crossbred calves
using primarily specific requirements of phenotype, genotype, and hump
height. Results here suggest that these
two requirements alone would eliminate about 60% of 75% Brahman and all 100%
Brahman carcasses. Branded beef
programs that impose no restrictions on phenotype, genotype, and hump height
will accept all A and B maturity steers that meet their yield grade, quality
grade, and ribeye area restrictions.
This last type of programs might be more rewarding to Brahman crossbred
production systems in Florida and the Southern region than breed oriented
branded beef programs.
Acknowledgments
The authors would like to express their
appreciation to the beef cattle producers in Florida for their continued support
of this research and to the personnel of the Beef Units and the Meats
Laboratory of the University of Florida for their efforts. The authors thank T. A. Olson and R. S. Sand
for useful discussions and for reviewing this manuscript.
Literature Cited
Elzo, M. A. 2002. Manual for MREMLEM (version 12/15/2001): A
program for the estimation of covariance components, genetic parameters, and
genetic predictions of additive and nonadditive intra and interbreed genetic
effects in multibreed populations. Animal Breeding Mimeo Series, No. 52, University of Florida,
Gainesville, pp 1-54.
Elzo, M. A. and Wakeman, D. L. 1998.
Covariance components and prediction for additive and nonadditive
preweaning growth genetic effects in an Angus-Brahman multibreed herd. J. Anim. Sci. 76:1290-1302.
Investopedia.com. 1998.
Using the moving average.
Available: http://www.investopedia.com/university/technical/technical5.asp. Accessed Feb. 15, 2002.
USDA,
1994. USDA specification for
certification of beef carcass quality and yield characteristics of officially
graded beef. Schedule G1-May 1994. Available: http://www.ams.usda.gov/lsg/certprog/Schedules/schedG-1.htm. Accessed Mar. 18, 2002.
USDA,
2001. Comparison of certified beef
programs – PDF Version – Updated 12/07/01.
Available: http://www.ams.usda.gov/lsg/certprog/speccomp.pdf. Accessed
Mar. 22, 2002.
USDA,
2002a. Certified Angus Beef. Available: http://www.ams.usda.gov/lsg/certprog/beef/cab.htm. Accessed Mar. 18, 2002.
USDA,
2002b. Nolan Ryan’s Tender Aged
Beef. Available: http://www.ams.usda.gov/lsg/certprog/beef/nolan.htm. Accessed Mar. 18, 2002.
Appendix
Yield Grade Formula
Yield Grade = (2.5 + {2.5 *
Adjusted FOE} + {.20 * KPH} - {.32 * REA} + {.0038 * HCW})
Marbling Codes
Abundant (A) - 900 to 999
Moderately abundant (MA) - 800 to 899
Slightly abundant (SA) - 700 to 799
Moderate (Md) - 600 to 699
Modest (Mt) - 500 to 599
Small (Sm) - 400 to 499
Slight (Sl) - 300 to 399
Traces (T) - 200 to 299
Practically
Devoid (D) - 100 to 199
Quality Grade Codes for A and B maturity
Quality Grade Code Marbling
Required