Gastric Juices, Bird Digestion, and the end of Anatomy 1… (Day 94)

Snowy white owl bird digestion

Today waking up and thinking that it was my last Anatomy credit this semester was pretty weird. It feels like only yesterday that I arrived here in Slovakia yet I am now supposed to know all the different bones, parts of bones, muscles, joints and ligaments. Before Anatomy though I had to get through Physiology.

Today was my turn to present a short seminar to my group, and I had selected to this on the physiology of digestion in birds. Now birds are different to mammals in that their bones are hollow and their red blood cells are different and have a nucleus. In terms of digestion they have an extremely high metabolism, a different structure of digestive tract, and no teeth. This means that the average bird needs to eat 80% of its body weight each day just to maintain its bodyweight.

Snowy white owl bird digestion

The digestive tract for birds starts at the beak, which is adapated in shape and size to the birds environment and the type of food that the bird eats. Birds do not have teeth, though evolutionarily it is believed that they once did (this is backed up by research into their genetics). The next difference is that they have a widening of the eosophagus called the crop which allows birds to store food for later to eat themself or for their young. This also in some species such as pigeons is the milk glands and produces milk for their young.

The stomach organ within birds is called the ventriculus or gizzard and is split into two parts; the pro-ventriculus which is at the front is a chamber where acid is used to break down food, and then the ventriculus or gizzard is two strong muscles which break down food mechanically by grinding (as birds cannot chew). They then have small intestines where most of the absorption takes place, before two chambers at the join between the small and large intestines called the cecum (pl. ceca) where fermentation takes place.

Fermentation is the process by which plant matter is broken down as most animals struggle to break down the cellulose in the cell walls. Within birds this is done by microbiological fermentation where bacteria in the ceca excretes enzymes which can then break down these walls. The large intestine then reabsorbs the water content as this passes through before it is then excreted through the vent. In birds the large intestine is relatively short, however the actual length differs between different species of birds.

The physiology practical was looking at how gastric juice breaks down food, and we used boiiled egg to exam its breakdown in different solutions and under different temperatures.

This afternoon we had our final anatomy session for the Anatomy 1 module, as we had a bank holiday on one of the sessions todays exam was two credit tests combined into one as the joints and ligaments are actually normally taught seperately. There was however no practical other than the test. Todays test went really well with me being on the ball and getting every question correct, seems I can now say I know all the joints and ligaments which is a scary thought. Next semester is Anatomy 2 where we start looking at the organs, blood vessels and brain…

Crop Feeding Chickens, Taking Blood, Digestion, and the Joints…. (Day 87)

Chicken dissection tools and materials

Well today I got a suprise when I walked into Physiology and was told we were going to feed a cock starch solution and then take blood from it before we euthanised it and inspected the digestive tract.

Now the starch solution was to look at the different areas of absorbtion within the avian digestive tract which is important in our knowledge of animal nutrition. As with any practical in vet school anywhere it is important that animals are treated with respect and do not suffer unnecesarily. This is something that is at the front of my mind at all times as I am here to learn how to relieve suffering and each animal that helps me on this path will be remembered forever.

Now avian species (birds) have a different digestive anatomy to mammals, it starts with something called a crop. A crop is like a storage pouch at the end of the esophageus before the stomach (called a gizzard in birds) allowing it to store food for later, and also soften food before feeding it to their young. Within veterinary medicine birds are often fed by crop feeding, which is where a tube is passed down the esophageus into the crop (it is painless to the animal!!!) for liquid food to be directly given to birds too weak to feed themselves. This is the method that was used today to allow the starch solution to be inserted into the digestive system.

Crop feeding chicken a food solutionThe solution was given 20 minutes to pass through the digestive tract, during this time we took blood samples from the chicken to analyse for white blood cells. I was the first person to do this, and with my previous disasters was a little nervous. I attempted to collect blood from the metatarsal vein which is located on the foot of the chicken and shows as a really thin darker line. With this I was determined to get it first time! Following aseptic techniques I cleaned the area with antiseptic, before then inserting the needle at 45 degrees and with the point towards the skin. I was amazed when I immediately got the needle into the vein and was collecting blood for my sample. This really has been one of my highlights as I finally managed to collect blood first time!!!

After the 20 minutes required for the solution to pass through the entire digestive tract were up the chicken was then humanely slaughtered for dissection. Something at the forefront of our minds is animal welfare and we requested to observe this for ourselves and were allowed to watch. Whilst happy it was humanely done, one of the observations was it really is a humbling when considering how few people can relate the pack of meat obtained in a supermarket to having been a living breathing animal.

Chicken dissection tools and materialsSomehow I ended up being the person that dissected the digestive tract from the chicken, one of the things I was most suprised about was how much of the body cavity was actually given to digestion in relation to the size of the bird. Previously I had watched the dissection of a quail on my previous degree and remember the tract being a lot smaller and less defined then it was in this chicken.

The afternoon then was our anatomy practical with a different lecturer than usual, todays test was different as instead of being questioned using a cadaver we were asked to describe a area from memory. I did pass however after getting out realised that being put on the spot I had forgotten some things from my description which I knew but totally got distracted from. I think I am going change my revision stragety and get someone to question me each week before the exam from memory as its valuable being able to picture the anatomical structures in the mind.

During the practical we looked at the different ligaments of all the joints of the body, something I found really interesting was being able to see and touch an intervertebral disc as its something I had heard so much about. Something else that got me was just how difficult it actually is to get the cruciate ligaments, this has given me a much greater respect for the vets out there that do CCL repairs!

As the course gets more interesting something I’d like to do is be able to make it so people that want to can see the more graphic photo’s whilst keeping the main posts friendly for everyone. Anyways, until next time 🙂