My rabbits are getting about 50:50 at the moment.
The thing is its REALLY hard to get enough grass every day for a rabbit; remember, it has to be unlimited! It has to be hand cut, or given to them directly as any form of motor cutting (lawnmower etc) causes oil contamination as well as fermentation that makes it dangerous for buns. During spring and summer it isnt as hard, but during the winter grass stops growing (a minimum of 4 degress celsius to grow, 10 degrees to grow well)

You need to take into account that fresh grass isn’t as high in fibre as hay, so added forage would be required. An additional note is that you would have to have an untreated source-weeds and grasses are constantly exposed to chemicals, toxins and parasites.

Grass also needs to be introduced very slowly, it can and does cause stasis very easily- its the only thing that my girl has ever had stasis over.

Personally I would never remove hay from my rabbits diet, I treat grass like a hybrid food- its one of their five a day greens, but doubles as a hay supplement.

this time of year, my five rabbits are outside, eating grass, in enclosed runs every day. At night they have access to unlimited hay, but are barely eating it, in winter they scoff down loads, but they way prefer grass, and come in with full tums. mine eat the grass from the ground, but I do sometime gather the long grasses from around the edge of the garden too, plus the bun safe weeds, the weeds count as their daily greens, and the long grasses get chomped overnight, indoors.

As Dface says, any change in diet, such as from hay to a hay grass mix has to be done gradually.

grass can definitely be used alongside hay, but never to totally replace it

Grass is fine, but wild herbs can’t replace grass and hay. This is because herbs don’t wear the teeth as grass and hay does. My Bam was put on a basically hay/grass only diet about a year ago by his rabbit savvy vet. I said he wouldn’t eat hay, not in the amounts that he needs. My vet then said grass was fine.

So I foraged grass for him all through winter, we had a mild winter so it worked. He lost weight, his teeth got better, his tummy has been working fine.

I’d have gone on with this diet, if it weren’t for the drought. There were more grass in January than there is now. Bam has gradually become better at eating hay though.

In order to grow grass to cover your bun’s needs, you’d have to have some land or a garden/ an allotment garden. You could never grow enough in containers indoors. A bun is supposed to eat a pile of hay the size of himself every day. The same goes for grass, only it weighs more than hay (moisture content).

The thing about grass not being as rich in fibre as hay – someone else mentioned something similar recently but I think there might be a misconception arising. Weight for weight, grass won’t have as much fibre as hay because of the high water content. But calorie for calorie, the fibre content will be the same.

(This wouldn’t be true if you were comparing, say, timothy hay with oat grass – if you dried out the oat grass it would have less fibre than the timothy. But assuming you’ve got suitable grass species, then there’s similar amounts of fibre per calorie.)

As others have said, it’s best to introduce it slowly, as with all changes to buns’ diets.

Terra- I think the issue is a rabbit is likely to eat the same amount weight/weight of grass as hay-
the water content is likely to help make them feel full, which is why its considered lower fibre, in 10kg of grass, only 1.7kg is dry or ‘food’ weight, the remaining 8.3 kg is water.

So it is the logical progression is that the rabbit will receive less fiber content on a pure grass diet

A bun that eats lots of hay drinks more than a bun that gets fresh veg. You can compare volume hay to volume grass and get a rough estimate of how much the bun needs -grass doesn’t shrink a lot when it dries, but it does lose about 85% of its weight. So you can’t go by weight without measuring the contents of moisture in both the grass and the hay and then compare. Farmers test their hay for moisture content to know when the hay is dry enough to be harvested and then for when it should be baled.

A bun-sized pile per day is a rather good estimate. My Bam lost weight on grass only but when he was at his ideal weight, I started complementing his grass with pellets and veg so he’d maintain his perfect weight.

Bam IS perfect (just sayin’…)