The technical stuff
When hay is analysed in a laboratory to determine its feed value, it is assessed for levels of ADF (Acid Detergent Fibre), NDF (Neutral Detergent Fibre and CP (Crude Protein).
ADF is the percentage in the hay of difficult to digest or indigestible material such as cellulose, lignin and pectin. The higher the ADF, the less digestible the hay is and the lower its feed value. ADF is equivalent to the term ‘crude fibre’ used by feed manufacturers in the UK.
NDF is the percentage of plant cell wall or fibre in the hay or other forage. It includes ADF and hemicellulose.
There is a direct relationship between the level of fibre in hay and the digestibility of the hay or other feed. At a fibre content pf 35% of Dry Matter (DM) the food is only 40% digestible compared with 90% digestible where no fibre is present.
According to John Sandford in his book The Domestic Rabbit, “..as the proportion of fibre increases, so the total digestibility falls. Furthermore, as the proportion of fibre rises, the individual digestibilities of the various constituents of the food fall. The reason for this is that the fibre tends to protect the more digestible constituents from the digestive juices.”
The simple version!
Having bored and baffled you with the technical lowdown on hay, what does it mean in practice? Given free choice, rabbits, guinea pigs, chinchillas and other pet herbivores, for example degus, prefer sweet, green, leafy hay, or gold/green cereal hay rather than the dry, brown-golden, stalky hay often sold in pet shops. Orchard Grass or Cocksfoot hay is green/gold and extremely palatable for all species.
The green colour indicates higher levels of chlorophyll, vitamin C and vitamin A. More golden hay has more vitamin D. Leafy hay tends to be higher in protein, lower in fibre and higher in calcium than stalky hay.
Green, soft, leafy hay is used as an alternative to replace hard feed (pellets or mix) (for example if you are already feeding vegetables as part of the diet); coarser hay is used to complement or balance the hard feed fed.
The seed heads of the coarser 1st cut Timothy hay provide variety in the diet and are particularly welcomed by chinchillas who have a strong foraging instinct.
If you feed good hay ad-lib, and especially if you feed green, leafy hay such as 2nd cut Timothy, you will inevitably find that your animals show less of an interest in their pellets or mix. This is especially true if you also offer other foods such as fresh vegetables, fresh grass or dried grass.
There have been some concerns that the Hay & Veggie diet advocated by many in the US could be low in vitamins such as A and E. Carrots and marigold flowers are good sources of vitamin A. Green leafy vegetables contain vitamin E and if there are concerns about the level, a few shelled sunflower seeds or some wheatgerm will provide extra vitamin E.
A rabbit’s eye view
Now and again you will hear that someone’s rabbit “Won’t eat hay”. That might be because they have been provided with a less healthy but perhaps tastier alternative (rabbits have a preference for sweet foods); that they don’t like the particular hay they’ve been given; or even that it isn’t ‘where’ they want it.
Try putting the hay in a rack where the rabbit can reach it from its litter tray. Gently tap the rabbit on the nose with a stiff strand of the stuff. In grunting and grabbing it in annoyance, the rabbit might just get a taste for it.
Once a rabbit starts eating one type of forage, it is more likely to show an interest in other types of forage. Cereal grass hays such as oat hay, wheat hay or spelt hay are a great way to wean rabbits off of an addiction to the biscuits and flakes in mixed feeds. Their lower calcium and higher phosphorous levels means they should ideally be balanced by high calcium legume hay such as clover and alfalfa or herb forage.
If your rabbit suddenly stops eating hay where he previously enjoyed it, you should check his mouth for dental problems or soreness of any kind. Rabbits do not normally ‘go off’ a food without good reason. Any rabbit which suddenly displays a preference for only soft food should be checked for dental problems.
Hay for guinea pigs
Guinea pigs have a serious need for hay. In the wild they create tunnel like passageways through the long grass where they can hide from predators as they go about their foraging activity. Barging through to bury themselves in a great bundle of hay and munching away is what a guinea pig likes best. Hay for them is not so much a bedding, more a way of life!
Not only do they share the general herbivore preference for sweeter, greener, leafier hay, they also need to be safe when they bury themselves in it. 1st cut Timothy hay is an excellent source of fibre and a good boredom buster but not so good for snuggling into the guinea pig way. Coarse stalks can also, if caught at the wrong angle by a guinea pig dodging for cover in the hay, cause eye injuries.
2nd cut hay can also be coarse but provided it forms a cave or tunnel if you plunge your fist into it, it can be considered a good guinea pig hay. In their natural habitat guinea pigs create tunnels through the older, dried grass, in order to forage on the new undergrowth as described above.
Hay may not have the same ‘green shoot’ appeal of undergrowth grass, but with a good, young, greenish hay, however coarse, if it holds its shape and the nutritional value is good, guinea pigs will thrive on it.
If feeding coarse hay, such as 1st cut Timothy hay, it is best fed from a hay rack, stuffed into a hollow log, or tied to the cage roof or bars in a bundle. These methods also add to the boredom busting benefits.
Chinchillas & Degus
Chinchillas and degus live on a particularly sparse diet in the wild. They both have a bit of a sweet tooth which must not be overindulged as they cannot tolerate sugar and too much will make them extremely ill.
Chinchillas are extremely active when they are awake and benefit from having their hay stuffed into hollow logs, or Galen’s Garden’s Grassy Logs, just like guinea pigs.
Degus like soft hay such as the German mountain meadow hays, for bedding as well as munching on.
Chinchillas, on the other hand, benefit from the coarser hays such as Orchard Grass, meadow hay or Timothy 1st cut with some 2nd cut for variety. They are especially fond of the Timothy seed heads.
Hay for chinchillas must be properly cured. Poorly produced hay can kill a chinchilla so it is very important to buy from a good source. This often happens when hay is sold straight ‘off the field’ and used right away rather than being allowed to further cure in the bale. The best hay for chinchillas is pale green to light gold. Feed small amounts of herb forage, berries, flowers roots and shoots to add variety.