I don't think I was born in a manger but my earliest memory involves sitting in one. I clearly remember the warm sweet cud-chewing breath of cow at my face. In those byre milking days, the manger was the safest place to leave a soft child while Mam and Dad milked the cows. The cows minded me then and cows look after me still.

I also remember how pleased I was when Dad told me that cows have four stomachs. Clearly, I thought, cows are very special if God gave them four stomachs! At every age since, I have gained new knowledge and new amazement at the workings of the ruminant stomach.

Mystery of nature

To me, one if the biggest mysteries in nature is why no higher organism ever developed the cellulase enzyme that enables cellulose to be digested. Cellulose is the building block of which all plants are made and yet no mammal can directly digest it. Amazingly, certain microbes got the cellulase enzyme. Even more amazing is the design of the ruminant stomach adapted to harness the needs of microbes to that of ruminant animals for the benefit of both. It is called symbiosis and its a wonder of nature.

I wonder how this amazing partnership began? For millions of years there was luxuriant growth of plants and forests due to the high CO2 levels in the atmosphere. At that time there wasn't enough oxygen to support a large animal population.

It was only when the plants, through photosynthesis, converted enough CO2 to Oxygen that animal life could really take off. Incidentally that missing carbon was buried in the ground back then. That stuff that we burn as fossil fuel, releasing the dinosaur carbon back into the atmosphere. More carbon equals warmer world equals higher sea levels. But that's another story.

Forests

I can only speculate that as the primeval forests became overcrowded with fruit and nut eaters such as our own ancestors, there was a need for some animals to feed on the cellulose in branches and leaves. Again, as CO2 levels fell, plant growth slowed and the animal population increased.

Thus spaces were opened in the forests which were colonised by plants like grasses that adapted to the regular browsing of animals which by then must have already sealed the contract with those microbes.

The cow's first and largest stomach called the rumen is home to billions of microbes that use their cellulase enzyme to break the woody and grassy cellulose into sugars. They are helped by the cow regurgitating it to chew and churning it around. After fermentation, it passes to the second stomach, the reticulum, which butchers call the honeycomb because of the lovely pattern of its lining.

Its purpose seems to be to stop undigested hard twigs etc from passing on to the delicate intestines. The third stomach, the omasum, butchers call the book because it has page-like tissues that squeeze the rumen fluid out and return it to the rumen. The final and fourth stomach is just an ordinary miracle like our own.

Grass

Cows love grass and grass loves cows. The cow's four stomachs are what enables her to live on grass but it also allows lots of nutrients pass through to feed the soil and grass. These nutrients are enhanced by the vigorous fermentation of the rumen. This enabled the herds of ruminants and natural grasslands to live in nutrient balance for millions of years. That cows need grass is obvious, but grass needs cows as well.

Grassland soils die if they are not periodically grazed, trampled and fertilised by sufficient numbers of grazing ruminants. Alarmingly, there are many "experts" in high places, who don't seem to know this. Some say ruminants are inefficient. Some say grasslands are healthier without cows. Some actually stop eating beef "to help the environment" or to be kind to cows. Some even think cows fart, God help us!

Sadly they missed the benefit of being gently belched over in a manger. Nevertheless, someone needs to put them straight about our own bovine contract obligations, but that's another story.