Do You Know What Is In Your Horse’s Forage?

Although hay is the foundation of most equine diets, horse owners rarely ask for nutritional analysis and the routine practice is to choose hay based on its ‘perceived ‘nutritional value. However, how reliable is human perception for good quality forage?

Why do we analyse forage?

With forage forming the biggest portion of the horse’s diet, forage analysis can be beneficial when creating a diet for any horse, but particularly those with metabolic, muscular or digestive issues.

Whilst horses have evolved to browse on selected forage sources, domesticated horses and their owners rarely have a wide range of choice in terms of the forage source that is available to them. When given the option, horse owners typically select forages based on their physical or sensory characteristics, which more commonly have a higher energy (calorie) content (Julliand et al, 2019). For horses or ponies who maintain their weight well on very little, these forage sources of course may not be the most suitable as they may lead to unwanted weight gain and an increased risk of other health issues.

One study has shown that when presented with 3 hay types (A, B and C) over the course of 6 days, 30% of owners selected ‘hay A,’ as the preference. Hay A had the lowest amount of energy and protein and a higher proportion of stem and fibre. When horses within the trial were then given free access to the forage types however, 0% of horses selected hay A across any of the study periods, and instead chose option B (58%) which had a higher fibre, energy and protein content (Holzer et al, 2022). This suggests of course that owner perception is not the most reliable indicator for a suitable forage source for horses.

What factors influence the nutritional value of forage?

Season – It's important not to assume a certain nutritional value based on season as this can be highly influenced by differences in weather or temperature. Temperatures above 9 degrees with sufficient water supply will mean that grass will grow regardless of the season. Winter daylengths and colder climates delay the speed the plant ages, leading to an associated decline in nutritional value. In contrast, high temperatures increase the speed the plant ages, leading to an increased lignification of the cell wall.

Species – Few paddocks will contain just one species of plant, and so the plants contained within the pasture are likely to be at differing stages of growth. This will mean the overall nutritional value of the field could vary greatly, and should not be assumed based on one species of known plants within the field. Plant species will also hold an influence over the type of horse you are feeding. For example, Ryegrass hay will typically have a higher feed value than timothy / meadow grasses and has a seasonally higher protein content. Timothy hay is made specifically from one type of grass and is typically lower in protein and digestible energy, making it a popular choice for people managing laminitics.

Age / Maturity - Forage quality reduces with age as the cell wall of the plant increases. Young, growing plants may be up to 80-90% digestible, whilst mature grasses will be closer to 50%. For horses who may be poor doers, being able to select a hay from an early or first cut hay may help to provide more energy and calories in the diet.

Pasture management - The time of cutting and whether it is taken from a 1st or 2nd cut will affect the feed value.

Storage - Long-term hay storage will result in some nutritional losses. Most will occur in the first couple of months with overall dry matter losses up to about 5% in the first year. About 75% of vitamin A disappears within the first 24 hours of cutting and then loses another 10% monthly.

Using a balancer to balance forage.

The variability of forage will of course lead to a great deal of variability in the vitamin and mineral provision it will supply. For horses or ponies who are maintaining their weight well on a forage only ration, the use of a feed balancer is essential to ensure that important nutrients are not being lost.