Adapted by Fernanda C. Ferreira, UCCE Herd Health & Management Economist Specialist
include: labor training and use of standard operating procedures, use of robotic milking machines, prudent use of antibiotics. Presentations will be made about farm labor and immigration, legal aspects of big data, nitrogen management and the producer/nutritionist relationship.
One of the great opportunities at this conference is the networking. As always, lunches, breaks and evenings provide ample opportunity to reconnect with old friends and/or make new ones. For more information check out the program http://wdmc.org/
When purchasing semen, producers usually rank bulls based on their predicted transmitting ability (PTA) for different indexes such as lifetime net merit (NM$), cheese merit, fluid merit, etc., depending on their market. In addition to differences in semen PTA, there are also price differences. The difference in semen prices, PTA, and the number of doses of semen necessary to produce a female offspring (sire conception rate) make the decision of choosing the most profitable semen a little challenging.
This article introduces a tool developed by Dr. Albert De Vries which addresses the question of comparing the value of semen from sires with different prices and different genetic merits. The tool allows the user to vary the inputs according to their own reality, providing farmers information on how much they can afford to spend on a dose of semen (which varies from farm to farm), and to compare semen from sires with different genetic merits and prices.
To run the calculations, the user needs to add the conception rate (CR) of the female being inseminated, the sire conception rate, the risk of abortion, and the risk of culling. Once a calf is produced, the risk of death before first calving is also required for the calculations, as the calf must be alive for the genetic merit of the semen to have value. Only female calves benefit from differences in genetic merit, so if sexed semen is used, the probability of getting a female calf increases, and the farmers can account for that in the tool. Dr. De Vries’ calculations also consider the NM$ that a superior female passes to her daughters, granddaughters, and all later generations (gene flow), which depends on the number of future female offspring of the daughter.
Finally, it is possible to compare the genetic merit difference of two units of semen, as well as the maximum price a farmer can afford to pay for different sires’ semen. This value depends on the CR of the females; better reproductive performance herds can afford to pay higher prices for semen. Other factors can also affect the value of the semen: reliability, response to selection, and the cow cull rate. The NM$ and other USDA indexes are standardized at 2.78 lactations. This corresponds to a cow cull rate of approximately 33%. In California, the average cull rate was 44% for Holstein herds in 2017 (CDFA), which means that on average California cows have fewer lactations to express their genetic merit, and will have fewer daughters, which decreases the value of semen. The tool allows the user to change the cull rate (which will change the average number of lactations of the herd), to have a realistic scenario of their farm.
If you have any questions about the spreadsheet, how the calculations were done, or if you need a demonstration of this tool, please contact Fernanda Ferreira at fcferreira@ucdavis.edu.
The tool is available at the University of Florida website: http://dairy.ifas.ufl.edu/tools/
Link to PDF Version: A Tool to Evaluate the Real Value of Semen