Fish farms and the function of glucose… (Day 170)

Fish Farm production fish farming systems

Today’s Diary Entry is sponsored by Pet Webinars

This week the bee’s lecture was cancelled so this morning I got a little extra time to work on my Emergency First Aid for Animals book which was pretty cool and is coming along nicely. I didn’t make my goal however will also be selling the electronic version of the book through this website very shortly, in the meantime you can get it here:

Anyways this week we still had a diseases of fish lecture looking at fish production systems (very cool!) and the problems associated with this. The common misconception here is that fish farming is just putting some fish into tanks, letting them grow and then selling them. I remember when I was very young visiting a salmon farm near Aviemore in Scotland and thinking it was more fun than that it was producing food to eat. This however is not the case as when a single tank may contain half a million fish getting things right is essential with complex infrastructure and processes. I am planning some individual diary entries on specific fish so for today will keep it to general information.

Fish Farm production fish farming systemsNow the production process starts with the design of the facilities, fish at different life stages require different conditions with water temperature and space. On farms these may be on separate buildings or tanks, each having an isolated water supply. One of the farms we looked at today spent years getting permits before even starting to allow them to source some of their water from a local river, and discharge water back into the river – even like this they still discharged more than they took!

The problems with the production systems include temperature, water filtration and feeding, the failure of one of these systems can be catastrophic for the animals causing the death of tens of thousands of fish in a single tank! Common problems with farmed fish is that they are not encouraged to move and recently there are new circular tank systems that have been developed producing a current and so encouraging the fish to swim against it causing a better quality of meat.

The biggest problem here however is the economics of production, farm owners are constantly asked for certain native fish, however these may take longer to grow which means higher food costs meaning the fish is unaffordable to buy. Even worse I believe is where it takes more little fish to feed the bigger fish during production (for example salmon takes 3 tonnes of little fish as food to produce 1 tonne of salmon to sell). Anyways this was the diseases of fish lecture today.

After this we had a physiology practical where we were looking at the absorption and digestion of glucose in the body systems though the Oral Glucose Absorption Test. For this we used rabbits checking the blood glucose before than after giving the rabbits a drink of glucose solution and then measuring the blood glucose at 30 minute intervals to produce a glucose curve. This is one of the most basic tests of insulin production and can be used to identify problems which is pretty cool.

Histology of the complex ruminant stomach (Day 162)

Vet School Diary Histology Bovine Rumen Section under the Microscope

Today’s Diary Entry is sponsored by Find Pet Boarding

Start of my second week of my second semester, last week vanished in a blur and this week I have tried to plan my time better to get a lot more of the research for my Emergency First Aid for Animals book completed.

Now I think I have previously said before how the stomach with ruminants is divided into four different compartments; the rumen and reticulum, omasum and the abomasum. Each of these has a specific role to play in digestion and specific structure to match. This is known as the complex stomach and the esophagus enters this between the reticulum and rumen. The rumen is the largest stomach compartment and is connected to the reticulum with a large opening allowing food to be passed back and forth between the two. Remembering that ruminants eat plant matter the rumen is where fermentation takes place with a large amount of bacteria and protozoa act on the contents breaking it down. The surface of this is covered in small papillae (low conical projections) and looks like this.

Vet School Diary Histology Bovine Rumen Section under the Microscope
Bovine Rumen Histology

The reticulum has a honeycomb like structure and sits next to the rumen and starts the mechanical breakdown of food into fine particles. This compartment is usually involved in “hardware disease” where cows swallow screws, nails wire or other hardware and it embeds into the lining. Occasionally this will completely penetrate the reticulum lining causing disease and as the reticulum sits next to the diaphragm will head into the thorax towards the heart.

Vet School Histology Section of Bovine Reticulum with Honeycombe structure
Histology of Reticulum showing a cell from the honeycomb structure

The last structure unique to compound stomach is the omasum which is where the final stage of mechanical digestion takes place before the plant matter enters to Abomasum which is basically the same as a simple stomach. The lining of the omasum consists of really large muscular folds which help the mechanical breakdown of food into tiny particles suitable for digestion in the stomach and intestine. Below you can see the size of these folds in relation to the Rumen and Reticulum (its so big I’ve had to put multiple different pictures together to make it!)…

Histology section of the bovine omasum showing the folds in the mucus tissue
Histology section of the folds in the omasum of the cow

After this the food then enters the abomasum which is the same as the simple glandular stomach and enzymes and gastric juices start to digest the food here before it then enters the small intestine.

This afternoon in Physiology we finished up looking at the endocrine system which is responsible for controlling the body systems using chemical messengers (aka hormones). There are several different hormones and I do have plans to do a diary entry in depth on each hormone in the near future so will leave this here until then.