How can Humans Eat Grass?

Every summer I mark GCSE Biology examinations, and every year I end up really depressed when I mark the agriculture or food question.  In a nutshell, the average British 16 year old – if what they write in this national examination is to be believed – has learnt that livestock farming has nothing good to offer society.  According to the 1500 or so exams I have read in the last three years, the majority of British 16 year olds believe that

  • farmers rear animals indoors because they enjoy (or at best don’t care) making animals unhappy,
  • everyone, human and livestock, would be better off if we were all vegetarian because then food would not be wasted on animals:  humans could eat animal food and that would be much more efficient,
  • possibly best of all would be if we grew all our protein in large silos in the form of fungus (this is what makes Quorn) because it protects farmland and has a much higher protein content than meat.

As is so often the case, there are grains of truth in all these which have been grotesquely distorted.  Some may be put down to adolescent inattention or intellectual incapacity, but strikingly similar arguments crop up in batches and frequently, which implies that the teacher has at best a poor understanding of the topic and at worst an ‘agenda’.

Aberdeen Angus in the water meadow, Lleyn sheep on the hill

Aberdeen Angus in the water meadow, Lleyn sheep on the hill

This photograph would not be possible in a society where no one ate meat.  I have read exam scripts in which it appears young people are being encouraged to think that if no one ate meat then farm animals would be left to live to a ripe old age in bucolic bliss.  They are also being given the impression that all livestock are fed entirely on grains which could also feed humans.  This may be true of the great stockyards of the United States, but in this country a significant part of the nutrient intake of cows and sheep is grass.

Feeding livestock with grass is a way of using land which could not be used for anything else.  The water meadow could flood.  The hill in the background is rather steep.  So both would probably be unsuitable for arable crops.  And even arable fields periodically need a rest:  a grass ley provides this as part of a crop rotation.

There is a ‘grain’ of truth in the argument that feeding grain to livestock is not the most energy-efficient (in terms of calorific content) way of growing food.  Dairy cattle in particular need extra inputs to enable them to make the many litres of milk that they produce each day.  Maybe the best compromise would be to keep using these excellent converters of grass into human food, but moderate our meat and dairy product intake whilst doing a better job of consuming the ‘5 a day’ of fruit and veg!

Not Just Any Old Grass

Now that the spring barley has been cut, you can see the grass coming through.  This was ‘undersown’ when the barley was planted in the spring.  A specially bred variety is used:  it is called Festulolium because it is actually a hybrid of Festuca (fescue) and Lolium (ryegrass).  There is more about selective breeding of grasses here and more about the particular uses of the many varieties of ryegrass here.

festulolium growing up through spring barley

festulolium growing up through spring barley

The process of crossing two grasses which are not closely related means that the hybrids are tetraploid.  ‘Tetraploid’ means that the cells contain 4 of each type of chromosome:  normally in both plants and animals there are only 2 of each type of chromosome.  Having twice as many chromosomes means that each cell is much larger:  this in turn means that the leaves are larger.  (Modern wheat is ‘octoploid’, ie it has 8 of each type of chromosome.  This happened as a natural mutation thousands of years ago, but partly explains why a grain of wheat is so much larger than a grass seed.)

The reason that these two are hybridised is that each parent species bring a particular set of desirable characteristics.

The fescue (Festuca) brings high yield and durability:

  • high dry matter yield
  • resistance to cold
  • drought tolerance
  • persistence

The ryegrass (Lolium) brings rapid growth and tastiness!

  • rapid establishment
  • good spring growth
  • good digestibility
  • high sugar content
  • good palatibility

There are many varieties of this same hybrid, and each has slightly different traits so farmers can be very specific about the qualities of the grass they grow for a particular purpose.  The various varieties are created by ‘backcrossing’ the hybrids with either the ryegrass or fescue parent species.

This spring barley was undersown so that there would be a grass ley in place when the barley was harvested.  It will be grazed over the autumn and winter, and so the fescue’s resistance to cold will complement the ryegrass’s palatibility and digestibility well for this purpose.

What do cows eat in the Winter? Part 2 Eating outdoors

cow winter grazingEvery year in the UK one hears stories about the RSPCA or police being called by a concerned member of the public because’there are cows standing in a muddy field with no grass’.

Of course cows can be, and are, put out into grassy fields in the winter.  These are usually sown with a ryegrass ley and this download can tell you more about the management of this.

agri_arable_roots_forage_rape1However, the alternative ‘fresh’ food is provided by brassica crops which are sown as part of the crop rotation.  There are a variety of these, and you can learn more about them in this download.  The ones currently being grown in the valley include forage rape, kale, and turnips.  The cows eat the foliage and, in the case of turnips, the roots as well.  

An electric fence is used to partition off strips in order to be able to periodically provide fresh strips of pasture.  So if you see cows in a muddy field, look closely at what has been planted there.  It may be that they are at the end of a day grazing kale.  

Or it may be that they are grazing a root forage crop, have eaten the foliage, and are now down to the sweetest part of the plant – the root!