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Sex Balance

Pedigrees 360 report on Secretariat

Sex Balance: The Key to Successful Mating

Assisting a Breeder in Idaho

Yesterday, I assisted a breeder in Idaho with his breeding plans for his broodmare band and looked at the pedigrees of his yearlings to determine which ones to sell and which ones to keep. As is usually the case, I was able to share some good news and some not-so-good news. But in one instance, I was able to share some outstanding news. This breeder owned several very well-bred mares, but one was an absolute standout when I ran her Pedigrees360 report. In fact, it was one of the best mares I had ever seen on paper. I was shocked when he told me he paid $1,000 for her from a trainer because she was injured and her racing career, although very short, was over.

It is rare that I speak with a breeder who has such high-quality mares assembled at a relatively small purchase price.

I asked him his secret, and he shared that he looks for duplication of ancestors, including brothers and sisters in the pedigree, in all the mares he bought. I then asked him if he was familiar with Federico Tesio, and of course, he said he was. I was sure he did know who Tesio was, as his process of selecting mares was Tesio’s biggest secret of his time – one he would not share with his competitors.

The Importance of Sex Balance

We then began talking about the Pedigrees360 reports and the importance of sex balancing (which is a major part of the Pedigrees360 reports). It is so important that when the sex balance is good, the box in the report is highlighted in blue, so when viewing a report, you immediately see how much sex balance of genetics from the daughter and son is present in the pedigree. The more blue boxes on a report, the better.

Tesio's Secret

When the pedigree genius Tesio was studying hereditary trends as an extension of Mendelism, he observed that when the best and most desirable forebears were duplicated in any union, they were carried through both a son and a daughter of the common ancestor. He further discovered that when the genetics were passed down through generations largely through the son, the resulting foal would usually be a plodder. This was a secret that Tesio kept from his competitors.

It was not until after his death that various pedigree experts were able to recognize what he was doing to achieve such great success.

As mentioned in previous blog posts, Tesio ran a very small breeding operation of 12 broodmares and 2 stallions. Yet, today, I would suggest that 70% or more of the horses at any track can be traced back to Tesio’s small breeding operation. Without Tesio, there is no Northern Dancer, Mr. Prospector, and all the progeny that followed. In short, Tesio and his methods are certainly worthy of our attention.

Methods of Sex Balance

The basic method to use the sex balance is by breeding back to influential forebears through a son and a daughter. But there are other options. Tesio’s most popular approach was to use brothers and sisters (or half-brothers and sisters), carrying one sibling in each parent. Examples of this were Hyperion and Nasrullah, who would go into orbit when they pick up with the sisters and half-sisters. The following rhyme was popular in the days of Nasrullah:

Match Nasrullah through a son
And Nasrullah through a daughter
To make it really blister
Match Nasrullah with his sister

Modern Application

As I have stated in previous blogs, I decided to look at the top 50 stallions in the United States based on their Average Earnings Index (AEI) as compared to the mares' Comparable Index (CI). What I discovered was the top stallions all had significant sex balancing in their pedigree. Specifically, their pedigree showed at least 5 instances through generations 7-9 in which the genetics were passed down at least 33% of the time through the daughters. When I looked at the bottom 25 stallions in the United States, more than 70% had 4 or fewer instances in which the genetics were passed down at least 33% of the time through the daughters, and the majority of these low-producing sires had only 2 instances.

Keep in mind also that these Stallions became Sires because they were very successful on the track, so not only does sex balance matter in the breeding shed, it matters on the track as well.

Evaluating Genotype and Phenotype

When I run mating reports for breeders, the sex balance report is the first thing I look at, and if it is not up to par, I do not recommend the mating. The sex balance is extremely important; it is part of the horse's genotype. You must also look at the phenotype – the physical characteristics of the horse, the conformation, size, muscle, and bone structure.

A horse can have a great genotype, but the phenotype may be lacking or faulty. Recently, a horse sold as a yearling for a great deal of money (not saying who). His genotype was pure greatness, some may even say royalty. However, one quick look at his physical appearance, and he had extremely long pasterns that sloped back, which indicates potential problems of putting too much stress on the ligaments, sesamoids, etc. In other words, my first thought was, “This horse will never make it to the track”. I was shocked at the price for this obvious flaw in the conformation. I thought maybe it was just the picture and angle I was looking at, so I looked at different pictures of this high-priced colt at different angles – Nope, this was a very concerning pastern.

Also, it is important to match physicals between the sire and dam. One of my stallions is very tall, with heavy bone, and I try not to breed him to another very tall, big-boned horse for fear I am breeding the next Budweiser Clydesdale. If you have a fine-boned mare, look for a thick-boned sire, etc.

Conclusion

It is not all about genetics, but genetics is where it starts. The bloodline combination has to work, and then look at the physical. With the correct genotype and phenotype, your odds of success will soar! We can certainly help you with the genotype portion of the equation!

If you are interested in looking at your mares' or sires' sex balance, click HERE and provide the information on your horse(s). We will have a detailed report back to you within 24 hours. Looking to purchase at a sale? Let us weed out the prospects that have poor sex balancing in their pedigree.

Curious about how your mare(s) match up with our stallions? We offer FREE pedigree analysis reports utilizing state of the art software tools like G1 Goldmine and Pedigrees 360.
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