20/09/2022
Calming the Clover Commotion.......
Our previous post certainly stirred up a lot of ‘discussion’ - which is a good thing!
Pastures for horses NEED to be different to pastures meant for other livestock. The following information actually applies to the horse’s entire diet.
One thing everybody would agree on is that horses should be fed ‘appropriately for the species’.
It really boils down to the C:N ratio of their forage where C is carbon from fibre (structural) carbohydrates: N refers to the protein content. Efforts to ‘improve’ pasture for horses are ONLY beneficial when they foster a high C:N ratio. (HIGH fibre LOW protein)
Horses are ‘Graminivores’ – herbivorous animals who feed primarily on GRASS, specifically "true" grasses, plants of the family Poaceae, also known as Graminae which includes tussocks, and sedges (along stream-sides). *“Equids select graminoids over other species when available and consume large quantities of low quality forage”
Over millions of years, equids evolved on the world’s grasslands and steppes – regions where it is TOO DRY FOR TREES.
This means both they and their microbiota (which is an ‘ecological community’ in itself), have evolved in LOW NITROGEN habitats. *****“Horses appear not only to be highly successful herbivores but also ones that select a diet with the highest fibre, lowest protein content within the grazing community”
The equine species survives in some of the harshest habitats on earth. Relatively recently, both with and without the help of humans, they occupy a wider range of habitats.
Wherever they thrive, it is invariably on forage that is high in fibre relative to protein. (Has a high C:N ratio)
Consequently horses have ‘thrifty genes’ – they have evolved to be metabolically efficient - an adaptive advantage needed for survival in harsh, NUTRIENT SPARSE environments – which turns out to be a DISADVANTAGE when you are in a domestic environment grazing comparatively nitrogen-rich pastures.
Clovers naturally have Crude Protein levels of 18-20%. When combined with other high production species like rye-grass or under certain environmental conditions, overall CP of the pasture can rise significantly up to 36%! (As CHH has found in multiple forage analyses of pasture that horses were consuming when they tipped over into laminitis, head-shaking and had multiple bouts of colic). Potassium is involved here too – another closely related story.
The trouble is this CP is not the quality protein that horses need. While some of this Nitrogen is part of the make-up of true protein – the rest is what is known as NPN (Non-Protein Nitrogen) or free-floating Nitrogen which horses are not designed to handle.
Such plants have an inverted C:N ratio ie too much Nitrogen relative to fibre carbohydrate. This happens especially when grass is grazed short all the time and doesn’t get a chance to grow any structure.
If horses were meant to be consuming such forage they would have the RUMINANT STYLE digestive system rather than the MONO-GASTRIC STYLE.
Many people commented that ‘clover is good for the soil and good for the pasture growth’. There are other ways of achieving this.
CHH promotes Pasture Management that advocates waiting for grasses to mature (until they naturally have more fibre less CP) before allowing access and feeding grass AS HAY in the meantime.
We have found this to be one of the dietary principles which work best to resolve the vast array of ‘grass-affected’ issues in horses all over the world. A critical component is removing clovers from the diet as the correlation between the presence of clovers and all the issues listed in the previous post is very strong.
Most horse owners never meant to have clover in their pastures but ‘it just grows’ and tends to out-compete the grasses if not controlled in some way.
Next Post: How can you improve the C:N ratio of your horse’s diet?
Just some of the References:
Wild Equids – Ecology Management and Conservation - Jason I Ransom and Petra Kaczensky - Multiple observational studies have shown that grass species make up 83% -91% of the feral horse diet in all seasons, shrubs (about 8%) and herbaceous plants (1%) play a limited role, primarily in winter.
NRC Mineral Tolerance of Animals, Second revised edition 2005.
****The Evolutionary Strategy of the Equidae and theOrigins of Rumen and Caecal Digestion. Evolution 757:754 (Janis, c. 1976)
