>Demonstration 1- Absorbency<

Wood pellets are designed to absorb moisture and retain it- basically they are made from compressed wood fibres. This demonstration illustrates how absorbent they are, and what might happen to pellet matter inside a degu's stomach.

As with all experiments, a control is needed to compare with. Here, an alfalfa pellet is used as the control, since it is the same size and shape as a wood pellet and these are often found in degu feeds (therefore clearly safe to ingest). Pictured below is the experimental setup, showing the wood pellets (left), alfalfa pellets (right) and a 1 ml syringe of water. Two five pence pieces are used to represent the relative size of a degu's stomach, but any similar sized coin will do. These are placed on an absorbent sheet of kitchen paper.


Next, one of each of the pellets is crushed and sprinkled on the top of the coin (see below). Crushing the pellets simulates what would pass into a degu's stomach after chewing and ingestion.


Now to each of the coins is added 0.5 ml water, dripped carefully from above. This quantity represents the fluid level inside a degu stomach. You will see in the image below that the majority of water is not retained by the alfalfa pellet as it runs off the top of the coin and onto the kitchen paper. In contrast, all the water is retained by the wood pellet as none of it runs onto the kitchen paper.


We can therefore conclude that wood pellets are much more absorbent than alfalfa pellets. We can speculate that the effect inside a degu stomach will be similar to this, with a wood pellet absorbing the stomach fluid in a similar way. Remember that the stomach continually secretes fluid during digestion.

>Demonstration 2- Expansion<

Wood pellets also expand on contact with moisture as the fibres increase in size and break apart when hydrated. This demonstration illustrates the degree to which wood pellets expand, and what this would mean to pellet matter inside a degu's stomach.

Again, an alfalfa pellet is used as a control. Pictured below is the experimental setup, with wood pellet (right), alfalfa pellet (left) and 1 ml syringe of water. Also pictured are two small bottle caps to hold a small quantity of water (2 ml each).


Next, each pellet is added to the 'bath' of water; The image below shows the setup immediately after adding the pellets.


After only a few seconds, the wood pellet starts to expand and take up the moisture (see below). The alfalfa pellet remains intact.


After just 10 minutes, the wood pellet has increased in size dramatically (see below), while the alfalfa pellet still appears relatively intact.


Time lapse images of the two pellets taken at the start and 10 minutes in to the experiment detail just how each pellet has changed on contact with the liquid (below):


We can therefore conclude that wood pellets expand a lot more than alfalfa pellets on contact with liquid. This may have severe consequences for a degu ingesting a wood pellet, as the expansion is rapid enough to occur inside the stomach before the pellet can be passed through into the intestines and later excreted. While a degu stomach can stretch to a certain degree, this type of expansion could easily lead to stomach rupture, which would be fatal for the degu. It may also cause other problems such as constipation and/or intestinal blockage.

>Demonstration 3- Breakdown<

By nature, fibre is not completely broken down during digestion and as it it, fibre is an essential element to every degu's diet as it helps keep the intestines in good working order, just as it does in humans. However, fibre needs to be broken down to some extent inside the degu's digestive system in order to prevent intestinal blockage, which could be very dangerous for the degu. Here we test how well wood pellets break down as they might be during digestion.

As before, an alfalfa pellet is used as a control. Pictured below is the experimental setup, with wood pellet (right), alfalfa pellet (left) and two glass vessels, each holding 10 ml of liquid (5 ml water, 5 ml vinegar) which simulates a slightly acidic environment similar to that found in the stomach.


Next, each pellet is added to the liquid. The image below shows the pellets immediately after being placed in the vessels.


Now the pellets are agitated thoroughly for 5 minutes, then left to sit in the bath for 12 hours before being vigorously agitated again. This simulates how food is processed and stored in the stomach before passing through to the intestines. After several hours the vessels now look like this:


Next, we need to see how much the remaining matter has broken down. To do this, we filter off the liquid from the vessels and leave the remaining fibre to dry for a few hours. Here's what we have left over:


The picture on the left is the remains of the alfalfa pellet. You can see the fibre has completely broken down into tiny particles. On the right, the remains of the wood pellet can be seen. Although some of the pellet has crumbled down into particles of similar size to the alfalfa, there are still larger particles left. It is these larger particles that risk becoming lodged and packing inside the intestines on the way through the degu body. In conclusion, the wood pellet poses more risk of causing intestinal blockage than the alfalfa pellet.