Have you ever wondered how mares and stallions are placed in a particular Single Population Analysis & Record Keeping System (SPARKS) Band along with the total number of horses included?  Have you ever been curious how many of the SPARKS mares are in the Cleveland Bay Horse Society (CBHS) Grading Registry? With the publication of the 2010 SPARKS Sheets available on the Cleveland Bay Horse Society of North America (CBHSNA) website, I was able to obtain the answers to these questions and my research raised a few more questions.

As a quick review of the SPARKS Program for those new to the breed and possibly not familiar with the SPARKS Program, I have included a description from the CBHSNA website article “SPARKS, on the Cutting Edge of Rare Breed Management”.

What SPARKS… has enabled is a detailed genetic… analysis of the living population of Cleveland Bays and it provides guidance for managing genetic health in the future. The measure it uses is MEAN KINSHIP (MK).  This is the numerical value of how closely an individual horse is related to every other in the world population of Cleveland Bays.  This gives us an indication of just how rare an individual’s combination of genes is in the entire population.  Animals with a lower Mean Kinship have relatively fewer genes in common with the rest of the population, and are therefore more genetically valuable in a breeding program.  An individual animal’s MK number is a moving benchmark, which changes as the world population changes with births and deaths, and so every living Cleveland Bay’s MK number is recalculated every year and new data is issued. Using this information it is possible through a coordinated strategy to breed to minimize Mean Kinship and maximize the retention of genetic diversity.

The SPARKS Program places the horses, based on their Mean Kinship in Bands labeled A, B, C, D, E, F and G, with the lower MK values in Band A progressing to Band G for the higher MK values.  For the purpose of this article, I will call all of the horses listed in the 2010 SPARKS Sheets, the 2010 SPARKS Breeding Population. This review of the 2010 SPARKS Breeding Population does not take into account the location of these Cleveland Bays or their availability to be bred.

First, I counted the number of mares in each Band and calculated the percentage of the mare population represented in each Band.  The total number of mares is 512, including Graded mares.

DISTRIBUTION OF ALL MARES IN EACH SPARKS BAND

BAND	NUMBER OF MARES	PERCENTAGE OF MARE POPULATION
A	10	1.95 %
B	3	0.59 %
C	25	4.88 %
D	75	14.65 %
E	194	37.89 %
F	194	37.89 %
G	11	2.15 %

 

Second, I determined the number of Graded mares in each Band, finding a total of 12 Graded mares.  Then, I calculated the percentage of Graded mares in each Band.

DISTRIBUTION OF GRADED MARES IN EACH BAND

BAND	TOTAL NUMBER OF GRADED MARES	GRADE	GRADE C	GRADE B	GRADE A	PERCENTAGE OF GRADED MARES/BAND
A	2		1	1		20.00 %
B	1	1				33.00 %
C	3	1		1	1	12.00 %
D	0					0.00 %
E	5	1	4			2.58 %
F	1		1			0.52 %
G	0					0.00 %

 

Third, I counted the total number of stallions in each Band and calculated the percentage of the stallion population represented in each Band.  There are a total of 80 stallions which are alive and 6 dead stallions (available by frozen semen) for a total of 86 stallions.

DISTRIBUTION OF STALLIONS IN EACH BAND

BAND	NUMBER OF ALIVE STALLIONS	NUMBER OF DEAD STALLIONS	PERCENTAGE OF STALLION  POPULATION
A	0	0	0.00 %
B	2	0	2.33 %
C	4	0	4.65 %
D	19	2	24.42 %
E	25	2	31.39 %
F	29	2	36.05 %
G	1	0	1.16 %

 

Fourth, I determined the total number of horses, mares and stallions, in each band and the percentage of the total SPARKS Breeding Population represented.  There are a total of 598 Cleveland Bays in the 2010 SPARKS Breeding Population.

DISTRIBUTION OF TOTAL NUMBERS OF HORSES IN THE SPARKS BREEDING POPULATION

BAND	TOTAL HORSES	NUMBER OF MARES	NUMBER OF STALLIONS	PERCENTAGE OF TOTAL POPULATION
A	10	10	0	1.67 %
B	5	3	2	0.84 %
C	29	25	4	4.85 %
D	96	75	21	16.05 %
E	221	194	27	36.96 %
F	225	194	31	37.63 %
G	12	11	1	2.00 %

 

The Cleveland Bay breed is perilously close to losing the genetic material in Bands A, B, C and G.  Band D is not far behind. Keep in mind that horses with the lower Mean Kinship values, Bands A, B, and C, have fewer genes in common with the rest of the population making them genetically valuable in a breeding program.  Band G, which has horses with the higher Mean Kinship values, have more genes in common with the rest of the population. In Andy Dell’s 2004 Presentation of SPARKS, which is available on the CBHSNA website, he notes the identification of 182 founder horses for the Cleveland Bay breed.  In 2004, Mr. Dell stated the Cleveland Bay breed had lost the genetic equivalent to almost 180 of these founder horses.  As I write this, the Winter Olympics are in progress in Canada.  Let’s pretend that Bands A, B, C, and G are downhill skiers.  Each is racing downhill at breakneck speed, and then losing their concentration for the briefest moment, each loses their balance tumbling out of control to the bottom of the hill.  This ends in loss individually, for their team and for their country.   For each skier representing a Cleveland Bay Band, the result would be a permanent, irreversible loss for the Cleveland Bay breed.

From a genetic standpoint the mares, not the stallions, passes on the genetic material to maintain the genetic diversity and characteristics of the breed.  The CBHS Grading Registry for mares provides a venue for new genetic material to be introduced to the breed while maintaining the breed characteristics and standards.  In 1997 the current CBHS Grading registry was implemented, replacing the previous Grading Program.  Based on the information in the 2010 SPARKS Sheets there are only twelve Graded mares out of a total of 512 mares.  Mares are placed in the CBHS Grading Registry for a number of reasons. This means they are listed in the CBHS Studbook, but not have full studbook status. Detailed information about the Grading Registry is available at http://www.clevelandbay.com/rules_and_regulations.htm It is beyond the scope of this article to research the pedigrees of these twelve mares.  With only twelve Graded mares, representing 2.34% of the 512 mares, it becomes easy to surmise that very little new genetic material is being introduced to the Cleveland Bay breed.

One way of preserving the Cleveland Bay is by freezing eggs from mares. What could this mean for the Cleveland Bay breed if eggs from mares, especially from the more genetically valuable mares, were frozen? Before you begin the litany of the usual objections, simply contemplate the possibility. Semen from stallions is frozen, originally not a common practice, yet is now considered common. In lieu of freezing eggs, what can be done to preserve DNA from not just the rare, but all mares in the 2010 SPARKS Breeding Population?

In Andy Dell’s 2004 Presentation of SPARKS, he states, “Small populations loose genetic diversity more quickly than large populations”.  Certainly, the 598 Cleveland Bay horses in the 2010 SPARKS Breeding Population, is a small population. Of the 598 Cleveland Bay horses there are 44 horses in Bands A, B and C, comprised of six stallions and 38 mares, which represent 7.36% of the 2010 SPARKS Breeding Population.  In Band G there are 12 horses, comprised of 11 mares and one stallion, which represents 2.00% of the 2010 SPARKS Breeding Population.  What can be done to encourage owners of mares, eligible for the CBHS Grading Registry, to pursue this venue as a means of introducing new genetic material to the breed?

Currently, the Cleveland Bay breed is maintaining its present genetic makeup and increasing its genetic diversity, utilizing the SPARKS program, while maintaining the breed characteristics and standards. The concern is how much longer can the breed survive if proactive and preventative measures are not taken?

Have you been surprised, enlightened or intrigued by the information obtained from the 2010 SPARKS Breeding Population?  Thinking outside the box, what can you do to make a positive difference for the survival of Cleveland Bay breed?

By Carlene Kerr
February 2010*

*On March 3, 2010, the 2010 SPARKS sheets on the CBHSNA website were updated with the addition of two stallions.  The data in this article has been updated to include these two stallions.