vetschool | Ileana Berezanski

I’m writing this blog post as a half procrastination-half studying tool because I really like theriogenology and reproductive technologies (and I may have a quiz tomorrow on this stuff…). They are relatively new and there is so much advancement and growth in that field! And so much more work to be done there as well…

Here are 3 of reproductive technologies that can be used for genetic improvement.

Artificial Insemination (AI) is a reproductive technology where semen is harvested from male animals and stored in semen straws that can then be deposited into chosen females. It is used to increase male selection and can therefore potentially increase the accuracy of the Estimated Breeding Values (EBVs). Semen can be sourced from all over the world and can potentially increase the effective population size (amount of genetically unrelated animals in a population). However, using a dairy bull from the USA may not be a great choice for an AUS dairy farmer as environmental interactions may pop up! AI is not used as often in the beef industry because it is more costly and labour intensive. AI is too expensive to do on commercial sheep farms as the procedure is different, it involves surgical insemination of the females. However, sheep stud farmers may use AI as they are selling the offspring for a lot more money (thus more cost effective). The benefits of using AI in your industry include:

Increases the accuracy of EBVs and male selection
Allows commercial breeders to access genetic information that previously would have been too expensive (and used only at a stud level)
Allows great genetics to be rapidly spread throughout a population (because many semen straws can be made from one male)
Technically forms a ‘world flock/herd’ of animals

Multiple Ovulation Embryo Transfer (MOET) is used to increase female selection and can therefore potentially increase the accuracy of the EBVs. However, this is a very expensive procedure as it involves taking a superior female animal, using hormones to get her to produce more eggs and then harvesting the eggs. MOET allows the female genetics to be spread farther/faster into the population. MOET is best used in species who usually only produce one egg at a time like cows.

Inbreeding can be a big problem with MOET, so farmers need to develop a good breeding scheme/plan to avoid this. It is best to use females with good genetics and semen from males with good genetics (as opposed to fresh semen and females that harvest/flush well).

This leads to a concept which I find exciting (and ethically interesting!) which is called Juvenile In Vitro Embryo Transfer (JIVET). Since all females are born with the total number of eggs they need in life, these can technically be harvested at a very young age (juvenile). These harvested eggs can then be in vitro fertilized and develop into offspring. This reduces the generation inverval and increases selection intensity. There are current issues with this reproductive technology that have not been worked out yet—and so it is not common.

I apologize if some of the terms and concepts were a bit too confusing for some of my non-vet friends; however if you are interested in food or wool production this is a vital part of the industry. Feel free to pose any queries you might have and I’ll try my best to answer 🙂

At work in my old University dairy barn

Every week we have several practical classes. These are the classes where we have hands on contact with animals, or are looking at microscope slides, or handling and assessing preserved tissues, etc. This year we have mostly had pathology practical classes. We spend a few hours in a cold room wearing our labcoats and gloves and handling tissues. Some of the tissues/organs we have been looking at are: digestive tracts (rumens, stomachs, esophagus), livers, kidneys, hearts, lungs (they have all been preserved). We look for signs of diseases, different presentations, abscesses, parasites, cancer, infection, inflammation, abnormalities…the list goes on! Usually the classes are long and overwhelming with information!

This week we did something a bit different than handling cold preserved organs. In the first half of prac we did some hematology work. Did you know that red blood cells are also called erythrocytes? We practiced blood smears; this is a common diagnostic test done in clinics. A blood smear lets you examine which cells are present, if they look normal, if there is too many cells or too few. This can give a veterinarian a lot of valuable information on a case!

My blood smears; practice makes perfect!

We also checked packed cell volume (PCVs) of different animal bloods. PCV tells you the percentage of red blood cells in a sample (the other 2 parts of blood are plasma and a buffy coat (white blood cells and platelets). If there is not enough blood cells seen on a PCV, the animal might be anemic. We also spent some time looking at cells under the microscope to see if we could identify all the different types.

From: http://www.biosbcc.net/doohan/sample/htm/Blood%20cells.htm

In the second half of prac class we got to practice bone marrow sampling. Did you know that red blood cells are made in the bone marrow and then move out of the bones into the blood? The bone marrow is sampled to check for signs of infection, disease, or other problems. We learned the correct way to use a bone marrow needle and the specific locations on the body that the needle need to be placed. The needle needs to be inserted through the skin and into the center of a bone in order to suck up bone marrow. After a few tries (on deceased animals) I was starting to get the hang of it!

This was a really fun and practical afternoon of practicing some clinical skills. I wanted to share with everyone so you could have a bit more of an understanding of what I do in uni!

A bone marrow aspiration needle. Image from: http://www.kimal.co.uk/products/bone-marrow-aspiration-needle/

Ileana Berezanski

Vet Student

Tag Archives: vetschool

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Blood smears and bone marrow