Rebuilding Project Overview
In March of 2012, The California Red Sheep Registry, Inc.
contacted the National Animal Germplasm Program for an assessment of the status
of their breed. The assessment concluded that "Over the long term with no changes in breed wide mating strategies
the observed trend will continue eventually resulting in a substantial decrease in performance due to inbreeding
depression." Since the California Red Sheep is not a heritage breed (having been developed in the 1970’s), Dr.
Blackburn offered the following recommendation: "the California Red Association to re-open its herd book and allow
the registration of newly formed California Reds (Tunis x (Tunis X Blackbelly Barbados)). This strategy can drive
inbreeding levels back to zero, depending on how widely breeders use the new composite animals." And, Dr. Blackburn
further concluded, "Not only does this allow inbreeding to be controlled it allows breeders to take advantage of
the hybrid vigor generated."
For these reasons, the California Red Sheep
Registry Board of Directors on November 3, 2012 voted as follows: "The registry is re-opened for the purpose of
permitting registration of new foundation stock through a ‘California Red Sheep Rebuilding Program’. A committee is
established to oversee the ‘California Red Sheep Rebuilding Program’ and to establish protocol and help to vote on
approval of new registry candidates and develop forms tracking this program."
If you would like to participate in this program,
please complete the Intent to Participate in California Red Sheep Rebuilding Project form. Once the Registry has
received your Intent to Participate, we will send you a guidebook for the Rebuilding Program
An Inbreeding Assessment of California Red Sheep
H. D. Blackburn and C. S. Welsh
National Animal Germplasm Program
Agricultural Research Service USDA
1111 S. Mason St. Ft. Collins, CO
March 27, 2012
An evaluation of the California Red sheep
was performed to determine the level of inbreeding that has accumulated since the association started maintaining
pedigree records. In general, all breeds with closed herd/flock books experience an increase in inbreeding over
time. The rate the inbreeding accumulates in a breed is a function of animal numbers, selection intensity, and how
well breeders manage inbreeding levels via mating choices.
Inbred individuals are the result of
mating parents that share a common ancestor (e.g., a common grand sire or grand dam). The genetic makeup of an
individual tends to be more homozyogous than non-inbred individuals. While increased inbreeding tends to make
individuals within a subpopulation more similar in performance and appearance it can also increase the frequency of
mutant or lethal recessive genes. In fact, intentional inbreeding of mating sons to mothers or brothers to sisters
is a common strategy livestock breeders’ have used to determine if a bull or ram carries an undesirable allele. The
livestock sector has developed and used inbred lines at various points in time. If it is the intention to develop
inbred populations this can be achieved with close management by the breeder. However, in general unplanned
inbreeding levels can result in depressed performance. In general performance decreases are not particularly
noticeable until inbreeding levels exceed 0.20 to 0.25.
The association’s pedigree file contained
2032 animals. Of these animals there were 215 unique sires and 847 unique dams. The
pedigree records were used as input to the program Animal Breeder’s Tool Kit to estimate the genetic relationship
between animals and compute inbreeding levels for each animal in the file. The results were summarized and put in
the following figures.
1 reports the number of animals registered by birth years. In 2004 and 2005 registrations peaked and then entered a
period of substantial decrease. Registrations for 2011 are not complete, so it is anticipated that 2011
registration may be similar to 2010.
2 illustrates the number of registered animals by birth year that had some level of inbreeding. The first year
where 100% of all registrations were inbred was in 1997. This level of inbred individual did bounce some in
subsequent years but by 2004 and continuing forward all sheep being registered were
3 gives the average inbreeding level for animals born in a specific year. Clearly as time has progressed the
average inbreeding level has increased. During the last four years average inbreeding level per birth year ranged
from .12 to .15. The regression line in Figure 3 is provided to illustrate the rate that inbreeding is increasing.
It was found that inbreeding was increasing .004 per year. The equation provided can also be used to project future
inbreeding levels assuming mating plans continue as in the past. Therefore by 2020 the average inbreeding level
will be 0.216. At this level the potential for observing reduced performance due to inbreeding depression
4 reports the percent of animal born in 2006-2011 with varying categories of inbreeding. Approximately 75% of the
population has inbreeding levels ranging from 0.06 to 0.15. It is important to note that under current management
conditions the peaks observed in Figure 4 will shift to the right. In-other-words inbreeding will continue to
Conclusions and Recommendations
analysis would suggest that inbreeding is increasing in the California Red sheep breed. The results obtained are
typical for small livestock populations. Over the long term with no changes in breed wide mating strategies the
observed trend will continue eventually resulting in a substantial decrease in performance due to inbreeding
depression. The following are some general recommendations the association may wish to consider.
to the existing levels of inbreeding all breeders will need to monitor the genetic relationships between potential
sires and dams and inbreeding levels of potential offspring computed before mating. This will allow breeders the
opportunity to predetermine how much inbreeding will occur in future generations. However, this process will not
stop the accumulation of higher inbreeding levels. As part of such a strategy breeders may want to decrease the
ratio of rams:ewes. As this ratio nears 1.0 more genetic diversity will be maintained and inbreeding will proceed
at a slow pace. However, this will greatly decrease selection intensity. It has been suggested that ram circles be
formed as a tool to slow rates of inbreeding. However, this again is a stop gap measure and requires a substantial
number of association members to act in a unified manner, which can be difficult to organize and
alternative strategy would be for the California Red Association to re-open its herd book and allow the
registration of newly formed California Reds (Tunis x (Tunis X Blackbelly Barbados)). This strategy can drive
inbreeding levels back to zero, depending on how widely breeders use the new composite animals. This strategy has
been successfully used by a number of cattle breed associations, some with annual registrations of approximately
10,000 head per year. For example, the Brangus association allows a continual influx of newly formed animals into
the herd book and they maintain the parentage of the animals as they go through the upgrading process. Not only
does this allow inbreeding to be controlled it allows breeders to take advantage of the hybrid vigor generated.
California Red breeders could also modify the Brangus approach and allow the formation of new California Reds for a
number of years and then reclose its herd books. Either way breeders will how more options in how they may want to
manage the breed’s genetics than trying to work within the confines of the existing population.
Rebuilding Plan for California Red
will be re-opened to accept new foundation stock bloodlines approved by the registrar.
California Red Sheep Heritage Registry, separate and apart from the main registry, will be established to record
the Tunis, Barbados Blackbelly and first crosses used to establish new foundation lines for the breed.
foundation lines must meet all California Red Sheep breed standards and be 62.5% to 75% Tunis and 25% to 37.5%
Barbados Blackbelly (polled). American Barbados are not acceptable
bloodlines for this program. Any Tunis or Barbados Blackbelly animals being used in this
program must be registered with the California Red Sheep Heritage Registry prior to being used to establish new
California Red Sheep foundation stock.
sheep used in this program must be registered with the National Tunis Sheep Registry, Inc.
sheep used in this program must be devoid of wool forward of the horn line.
sheep used in this program must not have dewlaps.
Blackbelly sheep used in this program must be registered with the Barbados Blackbelly Sheep Association
International in the Barbados Blackbelly (polled) book.
Blackbelly sheep used in this program must be devoid of wattles.
Blackbelly sheep used in this program should not have white.
Those participating in this rebuilding program should be cognizant that both Tunis and Barbados Blackbelly breeds
are rare and animals used in this program should be used for 2-3 years and then returned to a breeder in their own
breed. Be respectful of the fact that these animals are needed by their respective
Participation in the Rebuilding Plan is limited to CA Red Sheep breeders in good
standing for the past two years. However, a CA Red Sheep breeder may sponsor an independent non-member, provided
that member joins the CA Red Sheep Association while in the rebuilding program. The sponsor would be required to
verify in-person all applications for registration. Members of the California Red Sheep Registry participating in
this program must submit five photos and a copy of the breed registration papers for any Tunis or Barbados
Blackbelly used in this rebuilding program for the animal to be included in the Heritage registry. Both
parents must be in the Heritage Registry for a First/Intermediate Cross to qualify for application.
First cross animals do not have to meet the breed standards of any of the breeds
of the California Red Sheep Registry participating in this program will submit an annual breeding report listing
the ewes covered and indicating the covering ram.
of the California Red Sheep Registry participating in this program will submit an annual lambing report which
includes flock numbers, genders, birth type (single, twin, triplet, etc), birth weight and color descriptions with
1-3 photos of each lamb.
a member has a candidate that meets the California Red Sheep Registry Standards and falls into the breed
percentages outlined in line 3 above, they may submit an application for registry following the regular
registration requirements for mail in registry.
program can be temporary or permanent. The Board of Directors of the California Red Sheep
Registry will review this program every five years beginning with 2017 to evaluate progress and assess need for
continuation or changes to this program.