The most obvious strategy for using sexed semen is to grow your herd from within, decreasing reliance on purchasing replacements. The herd can then raise its overall herd female calf percentage to approximately 63 percent by using sexed semen in the heifer pens.
This increase gives the herd the advantage and peace of mind in getting genetics from cows whose production and disease history is already known. With the current quota policy in Canada, however, there is little pressure to grow herds from within compared to other countries. So this strategy isn’t currently being heavily deployed in Canada.
Using sexed semen as part of a larger genetic strategy is where this technology provides the greatest opportunity. Deploying a genetic selection strategy means taking the extra pregnancies generated by the herd and leveraging them for a higher level of genetic gain and additional revenue streams for your herd.
A herd running a pregnancy rate above 20 percent and using sexed semen in the heifer pens can generate 20 percent more pregnancies than needed to sustain the herd. The question then becomes: What you do with the extra pregnancies?
A cushion of extra heifers opens up opportunities to push genetic gain by increasing selection pressure. A tactic that has been successfully employed by a few progressive dairy herds is to sell extra heifers before they make it to the pipeline. With this strategy, herds set a genetic criteria their heifers must meet in order to stay within the herd.
This is normally a combination of traits such as LPI or TPI indexes as well as future inventory needs. Heifers that meet the criteria stay, and heifers that are below their threshold are sold off.
By creating extra heifers, producers are able to increase selection pressure on the herd’s core traits and speed up genetic improvement. When utilizing this method, herds often use genomic testing to help increase the accuracy of genetic traits.
Another genetic strategy that some progressive herds have adopted is using a combination of sexed semen and beef semen as part of their breeding program. These herds take extra heifers created by sexed semen and balance them out by breeding a selected group of cows to beef semen.
Basically, this means that for every extra heifer pregnancy created from a cow whose genetics they want to keep in the herd, they’re also creating a beef pregnancy from the cows with the genetics they don’t want to repopulate.
Using this sexed semen/beef strategy has a couple of advantages. One, it helps manage the inventory in the current milking herd, as you’re not removing any of the cows carrying pregnancies.
Two, you create some extra meat value from a beef-cross calf whose dam’s genetics you do not want to carry on within your herd. Again, this strategy involves the herd setting up genetic criteria regarding which cows are bred to beef, conventional dairy or sexed semen.
Often, the beef semen ends up in cows with fertility problems or cows with obvious issues that develop during lactation. While the sexed semen is used in the heifers, the conventional semen is used across the rest of the herd.
Using sexed semen as part of a wider genetic strategy will help to improve your herd’s overall performance. In the next decade, the majority of herds will be using sexed semen as an integral part of their genetic improvement program. PD
- Mark Carson
- Herd Reproductive Analyst
- EastGen
