The Suffolk Punch draught horse

– Running out of time?

Worldwide, there are only around 2,500 Suffolk Punch horses.   The greater percentage of these are in North America, approximately 2000, with only around 440 in their original homeland of Great Britain.  There is believed to be a tiny herd in Pakistan and now only ten in Australasia.

The following article, titled Running out of time? was published in the Summer 2009 issue of the Heavy Horse World magazine.   It called for the recognition that with such small numbers (and thus the real risk to genetic diversity) remaining Suffolk Punch horses should be viewed as a global herd.  The views expressed then are as valid now in 2017 as they were in 2009.

As a member of both the UK Suffolk Horse Society (SHS) and the American Suffolk Horse Association (ASHA), an owner of a UK registered Suffolk mare, and engaged in a grading up programme where we have produced three equivalent Type B (50%) fillies, I, and others here in Australia and New Zealand, are interested in the ongoing debate on what was termed the American Mare Import Policy, with the now January 2009 Suffolk Horse Society revised requirements for Stud Book entry.1 I offer some thoughts for consideration.

 

Think Globally as well as Nationally

Perhaps in the 21st Century we should be thinking globally and not just nationally. Certainly the British Percheron Society has been doing this since its inception over 90 years ago, with imported Percherons able to enter the Stud Book provided they are already in their national registries of France, Canada and USA. As reported in HHW News (Spring 2009) a Clydesdale stallion has been imported to Scotland (the second one in two years) and a further Shire to England from Germany.

 

The latest FAO Bulletin on Animal Genetic Resources Information, succinctly states:    “Move it or lose it” – Enabling access to and the safe movement of animal genetic resources within and between countries, regions and continents is a key factor in use, development and conservation of animal genetic resources globally. (p4)2

 

Many of the arguments against enabling American imports to the UK herd just do not stack up against what has occurred historically, both in the UK and North America, and what is possible using DNA analyses to “regulate ingress.”

 

The American Suffolk Horse Association (ASHA) began DNA testing in 2003. DNA and Parentage Verification was made a condition of entry to their Stud Book since 1st January 2003 for all foals and their dams (and prior to DNA recording, ASHA began blood typing all breeding stallions in 1996). Almost all of the American breeding herd is DNA tested, with just a few mares left who have not bred or foaled since 2003.3, 4

 

The Suffolk Horse Society (SHS) is catching up, although it is not certain just how many of the UK Suffolk herd have been tested. By the end of 2002, 50 Suffolks had been tested by SHS in conjunction with the Rare Breeds Survival Trust and it was hoped to continue testing in 2003.5

 

By 2007 DNA testing was in place for all potential stallions and from 2008 for all other foals. Just recently the Animal Health Trust has instigated a project “to develop a sustainable breeding programme for the Suffolk horse based upon genetic analysis of the current breeding population”. 1

 

Running out of Time?

Officially designated a Category 1: Critically Rare and Endangered Species by the Rare Breeds Survival Trust, the Suffolk horse with its small UK population records 440 registered animals in the April 2008 census.

 

In terms of breeding stock, the figure is lower once the 108 geldings and the 25 mares aged 18 and over are subtracted. Eight Australian and New Zealand mares and three stallions also need to be subtracted, since, although UK registered, these Suffolks and their progeny are unlikely to contribute to the UK herd at least in the foreseeable future. In the UK, this leaves a breeding nucleus of approximately 296 Suffolks : 64 males (25 Licensed and awaiting Licences) and 180 females (over 3 and under 18 = 150: 3 years and under = 57).

 

Of course not all colts born become serving stallions, not all remaining stallions cover mares, certain prize winning stallions cover many more mares than other stallions and not all fillies become mares with foals at foot.

 

With the latest revised rules for entry into the Suffolk Horse Society Stud Book to take effect from 1 January 2009, the preamble states:

“The rules governing these sections will have their critics but provide for the long term standing of the breed as it has currently been developed whilst allowing ingress of new blood in a controlled way.” 1

Since the review and redefinition of the rules was prompted by the question of importation of American Suffolks, and since the revised rules continue to exclude American registered stallions (both USA and UK born), the ingress of new blood can only come from mares entered on the grade register.

Allowing for the earliest covering at age three years, foaling at age four, working through the grades before any new blood can achieve the Pedigree (aka Pure-Bred) Register will take a minium of 8-10 years. This minimum requires that each grade mare foals a filly every time. A time scale of 12-16 years might be more realistic.

Meanwhile, the UK Suffolk genetic pool continues its non replenishment with its tiny breeding population. It also relies on a less than ideal number of stallions for genetic diversity.

Figure 1

Between 1993 and 2007, 71 registered and licensed stallions appear on the Stallion (or Breeding) Lists for those years. The total number of progeny from the foaling seasons to 2007 is 466 live foals. Some 19 of the 71 stallions, however, either never covered registered mares, nor produced registered foals. This reduces the registered and licensed stallions producing mares within this period to 52.

 

In this time, 14 stallions produced 10 or more foals each, accounting for 295 live foals. Within this group and period, two stallions produced 97 foals – just over 22% or just over a fifth of all live foals born 1994-2007. Both stallions stood in 2008. One is standing for 2009 and also appears as either the sire or the dam’s sire in the pedigree of seven of the 25 stallions for 2009. The other stallion only appears once in the pedigrees of the 2009 stallions. Further analyses of the Stallion Lists and foals produced for same period shows that 373 foals are the progeny of only 24 stallions (just over 75% of foals produced).

 

In 2007 the FAO stated that within-breed genetic diversity is being undermined by the use of a few highly popular sires for breeding.6 This has been problematic for the UK Suffolks as a scan through the Stud Books from 1960 onwards reveals.

 

An axiom of genetics is that the smaller the breeding population the higher the risk of degrees of inbreeding.

 

There are divergent views on the number of sires required within a national or local equine herd to avoid inbreeding depressions. Professor Twink Allen of the then Equine Research Unit at Newmarket (UK) maintained 25 would be required. Professor John Bowman (University of Reading) in a 1969 lecture stressed “that any breed of stock with less than 30 males was in danger of extinction” (p.29, quoting Noel Linge)7.

 

Between 1988 and 2005, the average number of Licensed Stallions per year is 18.8. Using the actual numbers of stallions used (and thus producing foals), the average number is 16.27. Using Professor Twink Allen’s figure of 25 sires, stallion numbers have been only at 65% of the required number to ensure genetic stability. Using the slighter higher figures of 30 sires, this falls to 52.23%.

 

This problem was recognized by the SHS: with the Preface to Vol.80 2003 of the SHS Stud Book :

“By the end of 2003 the …registered stallions stood at 17, which, while not drastic is uncomfortably low for maintenance of a viable gene pool.”

and again in 2006, when the then Chairman of SHS was quoted in HHW (p.11Summer 2006) as saying:

“The gene pool of UK Suffolks could be higher, but it could be lower as well, and we are not at crisis point”

 

The American Suffolks

Up until the beginning of WW2, North America received the largest number of exported Suffolk horse worldwide. The USA required a more pure bred Suffolk than did the UK Stud Book.   Vol.XX published 1915 states:

 

“In order to meet the views of the American Suffolk Horse Stud-Book it has been resolved that no Export Certificate shall be granted with any animal purchased for the United States having a pedigree which does not contain four straight crosses recorded in the Suffolk Stud-Book in the case of Mares and five recorded crosses in the case of Stallions. Thus a mare to be admitted duty free shall be registered and have also a registered Sire, Dam Sire, g. dam Sire and g.g. dam Sire. With Stallions it is necessary to show an additional generation with a registered Sire.” (My emphasis)

 

By contrast, Conditions of Entry to the UK Stud Book (1915) stated:

“No Stallion which is known to have a cross of any other breed in the direct male line with four generations and no mare within two generations shall be admitted…”      (My emphasis)

Further from 1919 up until 31 December 1946 when the Clause was rescinded, a filly foal not having a registered dam …could be registered if :

a) the sire and dam’s sire were registered

b) approval to be by inspection

c) the dam had to be approved by inspection.

 

A cursory inspection of many of the SHS Stud Books through to 1982 will show that many took advantage of this and, surprisingly, it was applied to stallions as well.

 

Resurgence of the Suffolk Herds in both UK and USA

The SHS Stud Book Compilation 1986 (Vols 55- 62 1960-1985) shows via the List of Studs that the UK herd stood at 41 Stallions and 70 Mares in 1985/86.

There is no mention of geldings or if, within the 41 stallions, how many were colts.

This gives a total of Registered 111 horses. This number also included five mares entered into the Stud Book “Approved by Inspection” and three mares in the Supplementary Register (grading up mares).

Using the April 2008 Census of maximum numbers 440, this gives an increase of 329 horses in 23 years.

The Compilation Stud Book also states:

“…a survey in 1985 showed 311 pure Suffolk Horses in the United States and Canada, together with 53 grading-up horses.” ( p.26)

 

The Grading-up American Mares

The phrase “53 grading-up horses” is somewhat misleading. In 1973 ASHA instituted a grading up programme which ran for seven years. Their Stud Book was closed to new percentage mares in 1983. There were only 16 Foundation Mare (Suffolk type) who, with their subsequent progeny, were crossed with registered Suffolk stallions.8 A break-down of the total produced American mares is shown in Table 1. 

TABLE1

Since 1st January 2009, the new SHS rules for entry to the Stud Book state:

The female progeny of a Grade D mare, the product of a union with a registered and licensed Suffolk stallion, will equate to 87.5% Suffolk blood and may be admitted to the Pedigree register following inspection. “

Using the SHS criteria for Grading-up, (the previous 4-generation and the now 3-generation requirements) all progeny of the US grade mares would now be regarded as ‘pedigree’.

 

Rebuilding the Herds

Both in the UK and USA, the 1970’s saw the beginnings of a rebuilding of the respective herds. Suffolks were exported again to the North America and their contribution to the modern day American Suffolk herd is significant.

 

Between the early 1970’s up to 1984, ASHA members imported 6 stallions and 15 mares. Two mares left the UK already in foal and produced a further 2 stallions: a total of 23 animals. ASHA members then increased this English stock by breeding within the imports resulting in 37 foals, thus effectively increasing their “English” Suffolks to 60 animals. At the same time, they were using  the stallions and mares over American stock. Between 1989 and 2000 a further infusion to genetic diversity came with the later imports of five more stallions, and four mares. A total of 224 American registered foals were produced by the imported UK stallions.8

Fig2Present Day North American Herd Size

The American Suffolk Horse Association (ASHA) reports each year on the total number of registered horses born within the last decade, rather than registered foals by year.9 Thus:

TABLE2

In 2006 the Board of Directors of the American Suffolk Horse Association said in a letter to the editor of the Heavy Horse World:

“There are presently approximately 2000 Suffolks in the United States and Canada. We are registering on average about 100 foals per year, a far cry from the 30+ foals being registered from the approximately 150 Suffolk in the early 1970’s.”

Historical Grading-up in the UK Herd

Conditions of entry to the SHS Stud Book did enable grade horses to enter the SHS Stud Book relatively quickly: take any random section of SHS Stud Books and these mares are surprisingly easy to find. There are many 75% mares and 50% mares. One 50% mare produced 14 progeny:10 all of her 75% (or 3/4 foals) were registered and are in the SHS Stud Books.

The early 1950’s SHS Stud Books are much smaller than the 1940’s and 1930’s, and thus quicker to extract the 7/8 and 15/16 grade horses. The 1950’s records are interesting since although the total UK herd numbers were in decline, they were still far higher than for the current UK herd. There is also a much higher proportion of graded up stallions than mares (half as many mares as stallions). The following table shows the grade entries to the three Volumes.11 12 13

TABLE3

One of these 7/8 grade stallions went on to produce around 42 registered progeny.

Even as late as 1982, three colt foals were entered into the Stud Book, two with records only to the 1st Dam, and one with records to the 2nd Dam: equivalent to ¾ and 7/8.   One of the ¾ colts went on to be a Registered Licensed stallion under the SHS Stallion Licensing Scheme.10 Under the revised rules for entry to the Stud Book today, none of these stallions, nor their progeny, would be eligible for entry.

In essence the Suffolk breeders were continuously introducing genetic diversity into the UK herd in a small but constant trickle with the entry into the Stud Book. This particularly applied not only to fillies who were not pure Suffolk (but Suffolk like in appearance and had a Suffolk Sire) but, as can be seen, also to colts.

This enabled one breeder at least to filter in his requirement of added height. In Edward Hart’s Book, The Suffolk Punch, An Illustrated History of the Breed, he discusses the Chickering Stud and Charlie Saunders:  

“Shires were his first interest but in 1932 he began breeding Suffolks. He told George Ewart Evans that he put a Suffolk over a Shire mare, and her offspring came clean legged, some chestnuts, some bays. He would sell eight or ten yearly to a coal firm in Colchester. By crossing the halfbred fillies back to a Suffolk, he got the three-quarter Suffolk females into the Stud Book. He fielded a big team of horses when such hitches were rare. In other words, he bred the Shire into the Suffolk, and then bred it out again.” 7

 

A geneticist view of Grading up

Geneticist, Frank Nicholas, in his text, Introduction to Veterinary Genetics states:

“A selection programme with a population can lead to a steady improvement in average breeding value and hence in profitability. However the average level of inbreeding also shows a steady increase, even if mating is entirely at random among the selected candidates. In addition the greater the selection applied, the greater is the increase in average level of inbreeding. Thus, successful selection programmes in closed populations incur inbreeding depression which has greatest effect on traits associated with viability and reproductive ability”

Selection and regular crossing

“….the traits that show the greatest inbreeding depression are those that also show the greatest heterosis when different populations are crossed. …suggests a solution to the dilemma: we can get the best of both worlds by continually selecting within each of several populations and by making regular crosses between them in order to produce the final commercial product.” 14              (My italics)

Some Final Food for Thought

All UK and North American Suffolk Horse owners, breeders and supporters are dedicated in their commitment to see the perpetuation of this unique breed.

Based on the respective Suffolk herd sizes in 1985/86 and the 2006/2008 populations, and excluding the 12 Suffolks in Australasia as well as the few in Pakistan, the global populations is approximately 2440 horses: 18% in the UK, and 82% in North America.