Angus Group Breedplan
Understanding Estimate Breeding Values (EBVs)
Estimated Breeding Values (EBVs) are predictions of an animal’s genetic merit, based on available
performance data on the individual and its relatives.
In the calculation of EBVs the performance of individual animals within a contemporary group is directly
compared to the average of other animals in that group. A contemporary group consists of animals of the same
sex and age class within a herd, run under the same management conditions and treated equally. Indirect
comparisons are made between animals reared in different contemporary groups, through the use of pedigree
links between the groups.
With the widespread use of artificial breeding and trading of genetics among seedstock herds an extensive
network of pedigree links has been established throughout the Angus breed. These pedigree links enable the
adjustment for environmental differences between herds, years and management groups. This allows
comparisons between animals from totally different environments and management conditions.
EBVs are expressed in the units of measurement for each particular trait. They are shown as +ive or -ive
differences from the breed base. For example, a bull with an EBV of +50 kg for 600-Day Wt is estimated to
have genetic merit 50 kg above the breed base of 0 kg. Since the breed base is set to a historical benchmark,
the average EBVs of animals in each year drop has changed over time as a result of genetic progress within
the breed.
While EBVs provide the best basis for the comparison of the genetic merit of animals reared in different
environments and management conditions, they can only be used to compare animals within the same breed.
The EBVs for different breeds have different bases and are subject to different rates of change over time.
Consequently, Angus GROUP BREEDPLAN EBVs cannot be validly compared with EBVs of any other breed.
The absolute value if any EBV is not critical, but rather the differences in EBVs between animals. Particular
animals should be viewed as being “above breed average” for a particular trait only if their EBVs are better than
the average EBVs of all animals born in their year drop. A useful “benchmark” is the average EBVs for calves
born in their year drop.
EBVs are published for a range of traits covering fertility, calving ease, maternal performance, growth
and carcase merit. When using EBVs to assist in selection decisions it is important to achieve a balance
between the different groups of traits and to place emphasis on those traits that are important to your herd,
your markets, and your environment. One of the advantages of having a comprehensive range of EBVs is that
you can avoid extremes in particular traits and select for animals with balanced overall performance
EBVs are provided for the following traits:
- Calving Ease (DIR)
- Calving Ease (DTRS)
- Gestation Length
- Birth Weight
- 200-Day Weight
- 400-Day Weight
- 600-Day weight
- Days to Calving
-
Scrotal Size
- Carcase Weight
- Eye Muscle Area
- Rump Fat
- Rib Fat
- Retail Beef Yield %
- Intra-muscular Fat % (Marbling)
Further details on each of the EBVs are listed below.
Calving Ease Traits
Calving ease is an important economic trait because of its impact on calf and heifer mortality, labour and
veterinary expenses at calving time, and subsequent re-breeding performance of heifers.
EBVs for calving ease are estimated from calving ease scores, birth weight data and gestation length
information provided by breeders. Due to the many non-genetic influences on calving ease the trait has a low
heritability.
Usually only proven bulls or cows with several progeny recorded have EBVs for calving ease with sufficient
accuracy to be reported. Two Calving Ease EBVs are provided – Calving Ease (DIR) and Calving Ease (DTRS).
Calving Ease (DIR) EBVs
Calving Ease (DIR) EBVs are estimates of genetic differences between animals in the ability of their calves
from two year old heifers to be born unassisted. The EBVs are reported as differences in the percentage
unassisted calvings.
Higher, more +ive, Calving Ease (DIR) EBVs are more favorable. For example, a bull with an EBV of +2.0 %
would be expected to produce easier calving progeny from two year old heifers than a bull with an EBV of
-2.0%.
Calving Ease (DTRS) EBVs
Calving Ease (DTRS) EBVs are estimates of genetic differences between animals in the ability of their two
year old daughters to calve without assistance. The EBVs are reported as differences in the percentage
unassisted calvings.
Higher, more +ive, Calving Ease (DTRS) EBVs are more favorable. For example, a bull with an EBV of +2.0 %
would be expected to produce two year old daughters that have less calving problems than the daughters of a
bull with an EBV of -2.0 %.
Gestation Length EBVs
Gestation Length EBVs are estimates of genetic differences between animals in the number of days from the
date of conception until the calf birth date. These EBVs are estimated from the joining and birth date records
for calves got by AI or Hand Mating. The analysis accounts for differences in the “maternal” effect of dams on
the gestation length.
Shorter gestation lengths are usually associated with lighter birth weights, easier calving and improved cow
re-breeding performance. Calves born with a shorter gestation length are often heavier at weaning due to more
days of growth compared to their contemporaries.
Lower, or more -ive, Gestation Length EBVs are generally more favorable. For example, a bull with an EBV
of -2.0 days would be expected to produce calves that are born earlier, with easier calving, than a bull with an
EBV of +2.0 days.
Birth Wt EBVs
Birth Wt EBVs are estimates of genetic differences between animals in kg of calf birth weight. Calf birth weight
is the biggest contributing factor causing calving difficulty in heifers. To minimise the risk of calving difficulty it
is recommended that you only use bulls over your heifers that have similar, or lower, Birth Wt EBVs to the
heifers.
While low Birth Wt EBVs are favored for calving ease they are also often associated with lower growth
potential. Consequently, birth weight and growth need to be carefully balanced.
Fortunately, animals do exist with moderate Birth Wt EBVs and above average EBVs for later growth.
Small, or moderate, Birth Wt EBVs are more favourable. For example, a bull with an EBV of +2.0 kg would be
expected to produce lighter calves at birth than a bull with an EBV of +6.0 kg, with a lower risk of a difficult
calving if joined to heifers.
Growth Traits
EBVs are provided for three growth traits: 200-Day Wt, 400-Day Wt and 600-Day Wt, enabling breeders to
tailor their selection decisions to achieve desired growth rates for particular market requirements.
In general, with all other things being equal, higher growth rates will lead to higher profitability. However, it is
likely that in most situations an optimum point is reached where less emphasis should be placed on further
increases in growth. One of the consequences of continued selection for increased growth EBVs is an
associated increase in body size at all ages, together with increases in herd feed requirements.
Growth EBVs are estimated from weight data submitted by breeders, adjusted to relevant age classes prior to
analysis. In addition, birth weight data also contributes to variation in growth EBVs due to its positive
relationship with later weights.
200-Day Wt EBVs
200-Day Wt EBVs are estimates of the genetic differences between animals in live-weight at 200 days of age.
This is a measure of an animal’s early growth to weaning. It is an important trait for breeders turning off
animals as vealers or weaners.
Larger, more +ive, 200-Day Wt EBVs are generally more favorable. For example, a bull with an EBV of +30 kg
would be expected to produce heavier calves at 200 days of age (or weaning) compared to a bull with an EBV
of +5 kg.
400-Day Wt EBVs
400-Day Wt EBVs are estimates of the genetic differences between animals in live-weight at 400 days of age.
This is an important trait for breeders turning off animals as yearlings.
Larger, more +ive, 400-Day Wt EBVs are generally more favorable. For example, a bull with an EBV of +50 kg
would be expected to produce heavier calves at 12 to 14 months of age compared to a bull with an EBV of
+30kg.
600-Day Wt EBVs
600-Day Wt EBVs are estimates of the genetic differences between animals in live-weight at 600 days of age.
This is an important trait for breeders targeting the production of animals suited for heavy weight grass or grain
fed markets.
Larger, more +ive, 600-Day Wt EBVs are generally more favorable. For example, a bull with an EBV of +70 kg
would be expected to produce heavier progeny at 18 to 20 months of age than a bull with an EBV of +40 kg.
Maternal Traits
Differences in calf growth are influenced by a combination of the genetic potential for growth among the calves
and the genetic differences in maternal ability of their dams. The differences in maternal ability can largely be
attributed to variation in milk production of the dams.
GROUP BREEDPLAN separates the growth and maternal components of 200-Day Wt and 400-Day Wt
records to produce EBVs for milk production. A bull’s Milk EBVs are based on the growth performance of his
daughter’s calves.
Mature cow weight is a new maternal trait in Angus GROUP BREEDPLAN. This EBV provides useful
information to assist breeders in matching cow size to the environment. It is also a useful indicator of later
growth performance for breeders targeting heavy grain or pasture fed bullock production.
Milk EBVs
Milk EBVs are estimates of the genetic differences between animals in milk production potential, expressed
through variation in calf growth performance.
A bull with a Milk EBV of +10 would be expected to sire daughters with higher milk production than a bull with
Milk EBV of +2 kg. This higher milk production should be reflected through higher weaning weights among the
daughter’s calves. There is a considerable time lag before a bull obtains a reasonable accuracy for its Milk
EBVs due to the time taken before growth performance data is available from his daughter’s calves. If a bull is
to be used as a terminal sire with no daughters kept as female replacements then his Milk EBVs can
generally be disregarded.
The optimum level of milk production potential in beef cows is dependent upon the production system and
environment in which the cows are run. Selection for increased milk production might be warranted when cows
are run under good nutritional conditions and calves are sold as weaners or vealers. However, not all
environments will support high milking cows.
Larger, more +ive, OR moderate, 200-Day Milk EBVs can be more favorable, depending on the environment.
Mature Cow Wt EBVs
Mature Cow Weight EBVs are estimates of the genetic differences between animals in cow weight at 5 years
of age.
Mature cow weight EBVs for sires are based weights recorded on their daughters (following the weaning of
their calves), plus consideration of overseas genetic information and the genetic relationships known to exist
between cow weight and earlier growth performance.
While moderation in cow weight is desirable for reducing herd feed costs, it is also often associated with lower
overall growth potential. Consequently, mature cow weight and early growth performance need to be carefully
balanced to optimise overall herd productivity.
Sires with above average EBVs for 400-Day Wt. or 600-Day Wt. will also tend to have above average mature
cow weight EBVs. However, following the analysis of weight records on their daughters, some sires have
been identified that tend to have smaller (or larger) mature weights relative to that predicted from their early
growth performance.
Smaller, or moderate Mature Cow Weight EBVs are generally more favorable. For example, a bull with an EBV
of +50kg would be expected to produce daughters with lighter mature weights and lower feed requirements
than a bull with an EBV of +80kg.
Fertility Traits
Fertility is a critical component influencing the profitability of a breeding herd. EBVs are provided for two fertility
traits - Days to Calving and Scrotal Size. These traits contribute important information to assist in making
breeding decisions to maintain herd fertility. Days to Calving EBVs are estimated from the joining and calving
date records provided by breeders. Scrotal Size EBVs are based on measurements recorded on yearling bulls
and known genetic relationships with recorded growth traits.
Days to Calving EBVs
Days to Calving EBVs are estimates of genetic differences between animals in female fertility, expressed as
the number of days from the start of the joining period until subsequent calving.
Variation in Days to Calving records is mainly due to differences in the time taken for females to conceive after
the commencement of the joining period. Females with shorter Days to Calving EBVs tend to commence
cycling earlier after calving and conceive earlier in the joining period. They also tend to attain puberty at a
younger age as heifers.
Days to Calving EBVs for bulls are based on the performance of their daughters and female relatives.
Differences in scrotal size among bulls can also contribute to variation in Days to Calving EBVs.
Lower, or more -ive, Days to Calving EBVs are more favorable. For example, a bull with an EBV
of -3.0 days would be expected to produce daughters that conceive earlier in the joining period, and
subsequently calve earlier, than the daughters of a bull with an EBV of +3.0 days.
Scrotal Size EBVs
Scrotal size EBVs are estimates of the genetic differences between animals in scrotal circumference at 400
days of age.
Increased scrotal size is associated with increased semen production in bulls, and earlier age at puberty of
bull and heifer progeny. Scrotal size also has a favorable relationship with Days to Calving, such that bulls with
larger scrotal size EBVs tend to have daughters with shorter Days to Calving intervals.
Larger, more +ive, Scrotal Size EBVs are more favorable. For example, a bull with an EBV of +4.0 cm would
be expected to produce sons with larger scrotal size at yearling age and daughters that reach puberty earlier,
than the progeny of a bull with an EBV of -4.0 cm.
Carcase Traits
Angus GROUP BREEDPLAN uses data obtained from ultrasonic real-time scanning of live animals and
abattoir chilller assessment data to estimate EBVs for carcase weight, eye muscle area, rib and rump fat
cover, percentage retail beef yield, and intra-muscular fat percentage (marbling).
To date, the majority of the data used in the calculation of carcase EBVs has come from ultrasound scan
measurements taken by accredited scanning technicians. GROUP BREEDPLAN can now use relevant
abattoir carcase data collected on animals in structured progeny test programs, together with suitable
overseas genetic information.
EBVs for carcase traits can be used, together with visual assessment for muscularity and maturity type, to
assist in breeding cattle for specific market requirements.
Carcase Weight EBVs
Carcase weight EBVs are estimates of the genetic differences between animals in untrimmed hot carcase
weight at 650 days of age.
Differences in carcase weight EBVs are estimated from available abattoir carcase weight records and known
genetic associations with growth traits. Animals with high 400 and 600-day weight EBVs will also tend to have
high carcase weight EBVs.
Larger, more +ive, Carcase Weight EBVs are more favorable. For example, a bull with an EBV of +40kg would
be expected to produce progeny with heavier carcases at 650 days of age than a bull with an EBV of +10 kg.
Eye Muscle Area (EMA) EBVs
EMA EBVs are estimates of the genetic differences between animals in eye muscle area (cm2) at the 12/13th
rib site on a 300kg carcase. EMA has a positive relationship with retail beef yield.
Larger, more +ive, EMA EBVs are generally more favorable. For example, a bull with an EBV of +2.0 cm2
would be expected to produce progeny with a greater degree of muscle expression and higher retail beef yield
at any particular carcase weight, than a bull with an EBV of -2.0 cm2.
Rib Fat EBVs
Rib Fat EBVs are estimates of the genetic differences between animals in fat depth (mm) at the 12/13th rib
site, on a 300kg carcase.
The use of Rib Fat EBVs depends on your goals relating to the finishing ability of your animals. Breeders
aiming to breed leaner cattle may select for lower fat values, whilst a breeder aiming to use a bull over dairy
cross cows to produce vealers may need to choose a bull with higher fat EBVs to ensure meeting market
demands. Fat depth has a negative relationship with retail beef yield.
Recent analyses of the Angus database indicate a general tendency for animals with positive fat EBVs to have
shorter days to calving intervals. Consequently, breeders should be cautious about applying intense selection
for lower Fat EBVs in situations where female replacements are kept.
More positive (+ive), OR more negative (-ive), Rib Fat EBVs may be more favorable, depending on your
breeding goals. For example, a bull with an EBV of –1.0 mm would be expected to produce leaner carcases at
any particular carcase weight than a bull with an EBV of +1.0 mm.
Rump Fat EBVs
Rump Fat EBVs are estimates of genetic differences between animals in fat depth at the P8 rump site on a
300kg carcase.
There is a strong positive genetic relationship between rump fat and rib fat. Animals with extreme (high or low)
Rib Fat EBVs also tend to have extreme Rump Fat EBVs. Differences between Rib and Rump Fat EBVs for
individual animals may indicate differences in carcase fat distribution.
More positive (+ive), OR more negative (-ive), Rump Fat EBVs may be more favorable, depending on your
breeding goals. For example, a bull with an EBV of –1.0 mm would be expected to produce leaner carcases at
any particular carcase weight than a bull with an EBV of +1.0 mm.
Retail Beef Yield % (RBY%) EBVs
RBY% EBVs are estimates of genetic differences between animals in percentage retail beef yield in a 300kg
carcase.
RBY% reflects economic differences in carcase value and refers to the bone-out yield of a carcase, with 2-3
mm fat trim, adjusted to 85% chemical lean. Currently, variation in RBY% EBVs is determined largely from
differences in ultrasound fat and EMA measurements between animals and a small negative relationship with
growth and carcase weight EBVs.
Larger, more +ive, RBY % Index values are more favourable. For example, a bull with an EBV of +1.0 % would
be expected to produce calves with higher yielding carcases at any particular carcase weight than the calves
sired by a bull with an EBV of -1.0 %.
Intra-muscular Fat % (IMF%) EBVs
IMF% EBVs are estimates of genetic differences between animals in percentage intra-muscular fat (marbling)
in a 300kg carcase.
For markets where marbling is important (e.g. Japanese B2/B3 market, high quality domestic hotel/restaurant
and specialist butcher trade) differences in IMF% can contribute significantly to carcase value.
Differences in IMF% EBVs are estimated from information obtained from overseas genetic evaluations of
marbling (i.e. American Angus Association Marbling EPDs), together with IMF% data obtained from animals
sampled in the Beef CRC progeny test program, and genetic relationships found to exist with ultrasound scan
fat depth measurements.
Depending on your market targets, positive IMF% EBVs may be more favorable. For example, a bull with an
EBV of +1.0 would be expected to produce calves with higher average marble score at any particular carcase
weight than a bull with an EBV of –1.0.
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