Genetic lag refers to the phenomenon where the genetic merit of farmed animals within a breed falls behind that of the breeding herd. This means that the animals raised for production, such as meat or milk, don't possess the same advantageous genetic traits as the animals specifically selected for breeding purposes.
Understanding Genetic Lag
This discrepancy isn't an error, but rather a natural consequence of breeding programs that aim for continuous genetic improvement. The best animals are chosen for breeding to pass down superior traits, while a larger group is raised for regular production, which leads to this lag.
How Does Genetic Lag Occur?
Here’s a breakdown of how genetic lag develops:
- Selective Breeding: Breeding programs focus on identifying and selecting animals with the most desirable traits. This leads to a breeding herd with a higher genetic potential for certain traits compared to the rest of the population.
- Time Delay: The superior genetics of the breeding animals are not immediately passed on to the production herd. It takes time for the offspring of the selected breeding animals to grow and reproduce, causing a time lag.
- Generational Difference: The production herd consists of animals from previous generations that do not benefit from the most recent genetic improvements. The next generation of production animals will benefit from the current improvements.
Impact of Genetic Lag
| Impact | Description |
|---|---|
| Reduced Efficiency | Farmed animals may not perform as well as they could if they had the most current genetics, leading to reduced production. |
| Slower Progress | The overall improvement in production can be slower if a significant genetic lag exists between the breeding herd and the production herd. |
| Economic Losses | Lower yields and increased costs can lead to economic losses for farmers. |
Addressing Genetic Lag
While genetic lag is inherent in breeding systems, here are a few ways to manage it:
- Efficient Breeding Programs: Optimize the selection process and use modern technologies like genomic selection.
- This means faster turn over rates with the selection of animals and faster generation times.
- Artificial Insemination (AI): Using AI can speed up the transfer of superior genetics into production herds.
- Embryo Transfer: Transferring embryos from genetically superior females can also accelerate the process.
- Data Management: Accurate and consistent record-keeping helps in better selection and faster genetic gain.
Example
Imagine a dairy farm that uses the best cows from their herd to breed the next generation of cows. The breeding cows are now the best in terms of milk yield and other desirable traits. When their daughters are born, they are also used to generate the next generation of calves, where some are kept as production animals and some are also selected to be part of the breeding herd. This continual selection and time delay results in the production herd having a genetic potential slightly behind the current breeding herd.
In summary, genetic lag is the time difference in genetic potential between breeding animals and production animals, a result of ongoing genetic improvement strategies. This lag is a normal process and is manageable with effective breeding strategies.
