Old Blood, New Champions: The rise of ICSI-bred sport horses from late stallions

Breeding doesn’t stand still — quite the opposite. Thanks to ICSI (intracytoplasmic sperm injection), breeders today can still produce foals from stallions that passed away years ago. Stallions like Chacco-Blue, Cumano, and Heartbreaker continue to sire offspring that are active at international level. But how much real impact do these posthumously conceived horses have in sport?

In this article, we analyse which late stallions still appear to be producing sport horses through ICSI, how many young offspring they have competing internationally, and whether they still hold their place at the top?

We cannot say with absolute certainty which horses were conceived through ICSI — this is rarely explicitly recorded — but it is reasonable to assume that foals born after 2017–2018 from stallions who had already passed away or were no longer available by that time were almost exclusively produced via ICSI. In the case of stallions like Chacco-Blue (who died in 2012), this assumption is particularly justified: conventional insemination or embryo transfer was no longer possible, and the limited supply of frozen semen has since been used almost exclusively for ICSI.

Is ICSI just a way to preserve valuable genes? Or is it really the bridge to a new generation of top horses?

The 'immortal' stallions

Although they’ve long been absent in the flesh, some stallions remain remarkably active in modern sport horse breeding — thanks to frozen semen and advanced reproductive technologies. In this article, we focus on stallions who are no longer alive in 2025 but still produce young (max. 10 years old) offspring competing at international level. These horses were likely conceived via ICSI, especially those born after 2017–2018. Why that cutoff point? Because from then on:

• Stallions had been deceased or were no longer actively breeding for several years,

• ICSI became commercially widely available at specialized centers,

• and classical use of frozen semen was rarely still efficient.

The table below shows the number of foals registered with Hippomundo between 2017 and 2024 for four stallions that have since died: Chacco-Blue, Cumano, Heartbreaker and Carthago Z.

Certified by Hippomundo © 2025

Chacco-Blue shows an explosive increase from 2019 with a peak in 2023 - a clear result of large-scale ICSI use. [Heartbreaker]](https://www.hippomundo.com/pedigree/performance/16067-heartbreaker) shows a steady increase until a preliminary peak in 2024 - The use of ICSI has allowed breeders to extend his influence in breeding, resulting in a significant group of young offspring. Cumano and Carthago Z are producing fewer offspring, but remain registered annually - probably through more selective ICSI combinations.

Chacco Blue (2003–2012)

Passed away for more than 10 years, but every year dozens of new foals are registered from this top sire. His offspring still dominate young horse competitions and international rankings. A new generation is ready to advance in the rankings!

Eight-year-olds: 60% sports - seven-year-olds: 55% sports - six-year-olds: 37% sports - five-year-olds: 12% sports

The seven-year-old mare Celeana Des Joanins Z, is one such young emerging talent by Chacco Blue with the highest Hippomundo Rating (HR60p) among his young international offspring. A palmares with several victories in international young horse trials, under the saddle of French rider Olivier Perreau, is the result of a thoughtful breeding choice.

Celeana's dam, Lavina van den Bisschop, is a daughter of Vigo d'Arsouilles' full sister and belongs to a genetically valuable dam line. Because of that strong lineage, Lavina has been repeatedly combined with stallions available only via ICSI, including Chacco Blue. Celeana is thus a textbook example of how ICSI offspring are not only genetically interesting, but also perform effectively on the international stage.

Even in the six-year-olds we already see some notable talents performing internationally at 1.30m level. For example, there is Champione Blue Z, another offspring of Chacco-Blue out of an interesting dam line. In fact, his dam is a sister to the stallion Vingino. Also Cha-Cha-H, bred out of the mare MoM's Dalida vd Heffinck in combination with Chacco Blue (bred by Wens Stud), appears to be a hit. Both young horses are already active in international competition and confirm that the combination of top genetics produces not only prestige, but also real sport results!

Certified by Hippomundo © 2025

A new generation of Chacco Blue offspring is also advancing in the five-year-olds.

Moreover, not only does Chacco-Blue remain numerically dominant, he continues to top the Hippomundo Stallion Ranking based on the percentage of Black Type offspring.

The latest figures show that as many as 66.8% of his offspring aged four and older are active in the international sport, and 68.6% of his eight-year-olds and older achieve Black Type status. In addition, there is a remarkably large group of offspring between the ages of four and eight who are already running internationally.

That holds promise for the coming years: the next generation of Chacco Blue sport horses is clearly on the rise.

Certified by Hippomundo © 2025

Cumano (1993–2015)

eight-year-olds: 60% sport - seven-year-olds: 43% sport - six-year-olds: 41% sport - five-year-olds: 20% sport

Cumano, world champion under Jos Lansink, has a limited number of offspring, many of which were sired via ICSI. Although his offspring are rare, they are often of high quality. In the overall stallion ranking he achieves a Black Type of 50%. The highest scoring offspring of the young generation is Rotterdam De Muze with a rating of HR58p. Here Cumano was paired with Sara van het Parelshof, who is the dam of the top jumpers HH Carlos and Don VHP Z, among others. A well-considered breeding choice!

Heartbreaker (1989–2021)

eight-year-olds: 57% sport - seven-year-olds: 50% sport - six-year-olds: 52% sport - five-year-olds: 23% sport

Although Heartbreaker did not die until 2021, his semen quality had been limited for many years, so his recent progeny were presumably conceived primarily via ICSI. There were still 82 foals registered in 2024, and of those registered between 2017-2020 (5- to 8-year-olds), 38% are active in the sport. His young offspring find their way to the international ring through quality breeding combinations. An example is Howla Paula Tk Z, who has the highest ratings (HR48p) of his young generation. This 6-year-old mare is out of the 1.50 mare KN Costa Rica, who is a sister to the famous Chesall Zimequest. Heartbreaker thus remains an influential name in this generation as well.

Carthago Z (1987–2013)

Although Carthago Z died back in 2013, in recent years we see more and more foals registered from him, almost certainly via ICSI. Often still too young for the sport, yet there are already some notable horses within his new young generation, such as: Carthouille Philyra V.V. Z (HR37) who at the age of six is already jumping at 1.30m level, bred out of the 1.60m mare Gribouille du Lys, this is again a thoughtful choice associated with ICSI breeding.

A new generation on old valuable genes

What once began as a technical solution to still utilize limited semen from deceased or hard-to-avail stallions has since evolved into a full-fledged strategy in modern breeding. Thanks to ICSI, top stallions such as Chacco Blue, Heartbreaker and Cumano not only remain genetically present, but continue to produce sporthorses that live up to international standards. Data shows that these offspring are not only numerous, but also perform effectively at a young age - from 1.30m to even as early as 1.45m.

ICSI enables carefully selected combinations between proven mares and valuable stallions long after they have physically disappeared from breeding.

It remains to be seen whether ICSI will eventually take a dominant place in sport horse breeding, but one thing is clear: the technique opens up new possibilities for purposefully retaining and utilizing top genes in the sport.

ICSI is not only a matter of the future - it is already jumping today!