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In August 2008 the United States Department of Agriculture released Sire Conception Rates (SCR) for the first time ever, replacing Estimated Relative Conception Rates (ERCR). The SCR evaluation has proven to be better than ERCR as it is a more accurate measure of a bull’s ability to actually get a cow in calf, as opposed to just measuring non-return rates. Repromax™, Semex’s lineup of high fertility sires, benefits from this new system, as the SCR evaluation is included, forming the world’s only international fertility information.



Semex sires rank well above average for SCR, adding to the confidence breeders can have in using our Repromax™ lineup. The Sire Conception Rate (SCR) rating is an important fertility figure, but should just be part of the decision making process when choosing a mating sire. Therefore, it’s important to keep in mind just what the SCR figure represents. With SCR, the average conception rate for the Holstein and Jersey breeds has been set at 0, therefore a bull that scores 1.0 SCR can be expected to have a 1% higher conception rate than the average bull. And, the opposite is true for a bull with a -1.0 SCR score.



Looking at the industry snapshot of numbers like 1.9… 2.0… 2.1… and 2.3… one wonders how much difference is there between these bulls?



There is a difference of less than half a percet separating the top four competitors in the Holstein breed, and an even smaller difference among the top four competitors in the Jersey breed. These small margins do not lend themselves for any one company to claim complete dominance in SCR rankings.



When is a Bull “Good” or “Bad”?

If only small differences separates so many bulls, technically it is difficult to label one bull better or worse than another for fertility unless the ranking is above +2 or below -2. Bulls scoring within 2% on either side of 0 for fertility are widely considered to be well within the average range for fertility.



Repromax™ & SCR

SCR is built into Semex’s Repromax™ sire lineup. Semex scientists have gathered SCR, Agri-Tech Analysis (ATA) and Non-Return Rates (NRR) to develop the industry’s first-ever international fertility evaluation.



The information and performance required to be considered a Semex Repromax™ sire is rigorous, encompassing much more than just the SCR score, as it also takes into consideration the bull’s history and performance outside of the United States.



Additionally, SCR scores do not always tell the full story of a bull’s fertility. It is important to recognize that sires may be used for different purposes, and the types of cows and their condition may have a definite impact on his SCR score.



For example, many elite sires may score higher for SCR than their contemporaries. A higher score may be the result of the positive effect of the elite sire being used heavily on cows that are in peak breeding condition in very controlled environments.



The opposite may also apply to sires used on problem breeders and reproductively challenged cows. These sires may actually show a decrease in their SCR score as they are considered for use on high service, clean up cows.



Neither situation indicates that the bull(s) in question is either a great or poor fertility bull (this difference in usage would not result in more than a percent or two difference), but it may account for a fair portion of the variation in the group of bulls with scores falling between -2 and 2.

Financial Considerations

The economic value of conception rate depends on several factors such as herd conception rate, heat detection rate, heifer price or replacement cost, the value of a new pregnancy and milk production. Based on current industry averages, the value of an increase of one percent of SCR can be estimated at about $3.00 US per dose of semen. A more accurate way to look at SCR value is to calculate the return per cow per year.



The table below shows the extra value of using Repromax sires per cow per year, compared to using sires with an average SCR value of 0, assuming initial herd conception rate is around 35%, heat detection is 50% with a resulting pregnancy rate (before Repromax™) of 17.5%. Herds with a pregnancy rate below 17.5% will see a greater return on increased SCR than herds with pregnancy rates greater than 17.5%. (Herds with low pregnancy rates have more room for improvement, thus greater incremental financial gains than herds closer to optimum performance.) The average value of the Semex Repromax™ line up is $22.22 US.





Note: Because Repromax™ sires will increase your conception rate, you will need less semen to breed the same number of cows, gaining you significant savings in semen costs, especially for higher priced semen.





Quick Points

1. There is less than one half of 1% difference between the averages of the active lineups of the top four studs.

2. Keep in mind that only bulls scoring 2.0 or greater should be considered great fertility bulls, and that bulls less than -2.0 are bulls to be weary of.

3. Sires ranking -2.0 to 2.0 for SCR are all considered to be in the average range for fertility.