Genetic Disorders, Milk Hygiene, Fire, Lethal Alleles and Monsters… (Day 81)

Hydrocephalus skull anatomy and pathology genetic lethal gene

Considering Friday is the end of the week, it is one of my busiest action packed days, I am going to try and cover as much as I can from today however. This morning started with the Genetics lecture which today was on genetic disorders, which was pretty cool.

Basically a disease can be a mutation, hereditary (comes from the parents via genes) or environmental where external influences cause it. Now looking at the genetics for a disease to be a mutation something has to go wrong in the transcription or translation stages in the cell cycle. For a disease to be hereditary it must be genetically coded and passed on from the parents, and finaly environmental is where it is caused by outside influences such as heavy metals.

Visual comparison of cream with different fat content
Visual comparison of cream with different fat content

Milk Hygiene today was looking at cream and butter, we did titration tests to calculate the fat percentage in cream which is one of the most basic quality control checks. Then with the butter we attempted to measure the water content in the butter. This test basically involves using the weight and then melting the butter over a flame to evaporate the water before measuring it again. Now this was going fine until the butter caught fire, after putting this out it did leave a rather pleasant smell in the lab, which also spread under the door and down the corridor.

After this and a short break it was time for the genetics practical, todays practical was looking at lethal and semilethal genes. From a genetics perspective a lethal factor causes > 90% mortality, a semilethal factor causes over 50% mortality and a subvital factor is less than 50% mortality. Now these are clasified according to an international standard with each animal species having a letter code:

  • A : Cattle
  • B : Horse
  • C : Pig
  • D : Sheep
  • I : Goat

The specific disease/gene is then assigned a number, for example A24 is hydrocephalus where there is excessive accumulation of fluid within the brain causing an enlarged head and the animal being stillborn or dying within a couple of days.

Hydrocephalus skull anatomy and pathology genetic lethal gene
Hydrocephalus skull

Understanding how these diseases are linked to genetics is especially crucial when it comes to breeding males. This is because with the use of artifical insemination a single male may father 100’s of animals, ensuring that only genetically healthy males are used for semen it prevents the suffering of other animals. Today has been pretty gruesome with some of the images seen, and looking at genetic disorders. It has however been extremely useful as this knowledge is essential when it comes to breeding.

So so tired at the end of Week 2… (Day 18)

testing-milk-fat-content

Ok so its Friday so thats probably an excuse for me being so tired today, I also got stuck into Anatomy revision last night as I really am pushing myself for the A now. Its the end of my second week of lectures in Vet School and it has finally sunk in that I am really here and that it’s not just a holiday! I really am looking forward to getting some sleep this weekend, though realise I have a ton of stuff to catch up with fundraising for next semester, finishing some painting in my room and also got to get my residency permit sorted so that I can get a bank account here.

Anyways this mornings lecture was Genetics, this is definately somewhere I am going have to do my own additional reading. I lack the biology and chemistry A-Levels that many have so have to really get back to basic to understand the more advanced theories. This is also going onto my weekend reading list.

This was followed by the Milk Hygiene practical which this week was very interesting. Basically (in Slovakia at least) milk has to go through several different quality controls before it can enter the human foodchain. The basic tests for this look at fat content and protein content of the milk, this also helps ensure that milk has not been watered down. The first test for fat content uses a really strong concentration of Sulphuric Acid to seperate the fat molecules. Cue the first appearance of Health and Safety here with faceshields and massive aprons!!! Anyways the method that we used was the Gerber method which is used worldwide as its a very simple and extremely rapid way to determine the volume of the fat in the sample. It uses a special tube called a butyrometer in which the sulphuric acid is mixed with the milk sample and osoamyl alcohol before it is placed in a centrifuge and the result read by moving the stopper on the tube in and out.

testing-milk-fat-content
4 different milk samples in 4 butyrometers to determine the volume of fat contained in the sample

Yes that tarry looking black substance is in fact milk… The thin tube on the top actually contains the scale and the tube on the left has the most fat and the tube on the right the least fat content. One of the basic requirements for dairys is that the milk produced contains at least 3.5% fat. The other classifications of skinned and semi-skinned have their own margins which the reading has to fall between.

The next test of the day was for protein content and was carried out using Formol titration with the chemicals below (love how the only understandable thing on the bottles are the labels of doom!) and sodium hydroxide from a burette.

Chemicals with the labels of doomThis method relies on the neutralisation of the milk by adding sodium hydroxide and doing a calculation based on the quantity of sodium hydroxide actually used. Its actually pretty a pretty cool example of chemistry at work as sodium hydroxide is a clear liquid yet when added to milk turns a bright pink.

Adding sodium hydroxide to milk turns it pink
Adding the sodium hydroxide to the milk turned it pink

Pretty cool or what? The next practical of the day was for genetics where we used PCR to look at DNA, I will be doing a detailed post on this later on so will not include too many details here. Basically PCR allows for the rapid duplication of DNA and then the comparision of this DNA. By the end of this I was exhausted, vet school is definately tough and my weekend is going be very busy!