The only lecture I had today was Genetics this afternoon as Milk Hygiene is finished pending the exam and there was no power on campus this morning because they were doing work on the mains. Campus today was looking very nice yet was practically deserted when I arrived for the lecture…
To understand why HHC is important we need to consider how genetics are managed now. Previously where dairy farms each had their own bull (which is a dangerous animal to keep and work with!) many farms now use artificial insemination. Artificial Insemination (AI) is safer, faster and also gives the benefit of widening the gene pool as semen can be collected the other side of the world to be used if necessary. The question is how do you know that the animal that donated this semen doesn’t carry a genetic disease? This is where HHC comes in, and most countries have very strict legislation here, this can be based on four basic principles:
- Phenotypic (physical) expression of the disease
- Pedegree Analysis
- Health Status of the Progeny (children)
- Cytogenetic and DNA tests
The downside to genetics is that it is just not the sire that needs to be tested, but for the offspring as well for a minimum of at least two generations (some diseases skip a generation).
Within the Czech Republic and Slovakia the HHC testing is based upon the health status of the progeny, this means that breeding of a test group of animals (this is usually 1000 animals) is required. These then need to be grown on to sexual maturity and a second group inseminated to test for diseases that skip a generation This not only takes time (in cows gestation is around 9 months, plus 2 years for sexual maturity) so this process takes around 4 years before the collected semen can be used in production animals.
During this testing the fertility of the semen is checked, offspring for genetic diseases and fertility, and the pregnancy and delivery of the calves are monitored. The semen is then graded on a scale of C – A depending on the outcome of this.
- C – Is pretty bad with lots of problems in pregnancy and with diseases in the calves. The sire is not used for AI and the offspring are sent to slaughter
- B – The sire is acceptable to be used as a father for non-breeding stock only
- A – The sire is breeding standard, and progeny is suitable for further development of the breeding line
One of the most important things that I have taken away from this is the great responsibility that vets have. When looking at this testing it is important to consider the entire population and not just a single animal, and the wording used when reporting is also crucial. Neglecting the word “suspected” when dealing with a uncomfirmed animal with a genetic disease can send a thousand animals to slaughter unnecessarily.
With that week 12 has ended, I have one more week of lessons remaining, and just weeks left to find the tuition that I need to raise to continue in vet school. Please if you can help, whether it is just £1 of more, please do! You can make a one off donation on the right of the page or set up a monthly donation securely by paypal. If you want to do a bank transfer or direct debit please contact me for banking details.