Understanding Roughage
by Diederick Labuschagne
It is an undeniable fact that your horse needs roughage. It is just the way their gut and digestive system operates. If you deprive them of this important feed stuff the gut function will progressively deteriorate resulting in mal nutrition causing colic, laminitis and various other ailments. When these conditions prevail the animal will eventually perish.
But what is roughage? By simple definition it is any fibrous material such as pastures, hays, silage and other by-products like hulls and husks of various seeds and grains. However, not all roughage sources are the same and for the purpose of this exercise we will focus on hay which is the most commonly used source in the majority of feed regimes.
The average daily consumption of your horse should equal 2,5% of its body weight. At least 1 – 1,5% of this should be roughage. Considering this proportion you may as well ensure that the quality is of such nature that it makes a significant contribution to the animal’s requirement. In fact, under most circumstances, good quality roughage will meet the daily nutrient requirement for maintenance. So if you going to spend the money, spend it wisely!
So how do I know if I have spent my money wisely? Like with most things in life you can either view it subjectively or objectively, or both. In the case of hay we do both.
To understand and apply this evaluation process we need to look at the basic attribute of roughage. In simple terms roughage are made up of a structural and non structural portion. The structural portion represents the fibre content or cell walls consisting of lignin, cellulose and hemicelluloses, lignin being the least digestible and hemicelluloses being the most digestible. The non structural portion is termed the non structural carbohydrates (NSC) comprising of sugar and starch. These are readily available to and digestible by most animals.
The subjective evaluation is a sensory one. That which you can see, taste and smell.
The objective evaluation is that which can be derived from a laboratory analyses. There are two important analyses that pertain to the fibre portion of the roughage.
Acid detergent fibre (ADF) refers to the cell wall portion that is made up of cellulose and lignin. This is an indication of the amount of digestible dry matter (DDM) of the roughage i.e. the percentage of the roughage that is digestible. The following equation is used to calculate this.
Neutral detergent fibre (NDF) refers to the total cell wall comprising of the ADF portion plus hemicelluloses. This is an indication of the dry matter intake (DMI) or how much of the roughage the animal will be able to eat. The following equation is used to calculate this.
The figure below illustrates the relationship between the various analyses.
But what is roughage? By simple definition it is any fibrous material such as pastures, hays, silage and other by-products like hulls and husks of various seeds and grains. However, not all roughage sources are the same and for the purpose of this exercise we will focus on hay which is the most commonly used source in the majority of feed regimes.
The average daily consumption of your horse should equal 2,5% of its body weight. At least 1 – 1,5% of this should be roughage. Considering this proportion you may as well ensure that the quality is of such nature that it makes a significant contribution to the animal’s requirement. In fact, under most circumstances, good quality roughage will meet the daily nutrient requirement for maintenance. So if you going to spend the money, spend it wisely!
So how do I know if I have spent my money wisely? Like with most things in life you can either view it subjectively or objectively, or both. In the case of hay we do both.
To understand and apply this evaluation process we need to look at the basic attribute of roughage. In simple terms roughage are made up of a structural and non structural portion. The structural portion represents the fibre content or cell walls consisting of lignin, cellulose and hemicelluloses, lignin being the least digestible and hemicelluloses being the most digestible. The non structural portion is termed the non structural carbohydrates (NSC) comprising of sugar and starch. These are readily available to and digestible by most animals.
The subjective evaluation is a sensory one. That which you can see, taste and smell.
- Stage of maturity is directly related to the lignin content of the plant. The more mature the plant the higher the lignin content will be and the less digestible it will be. The amount of seed, flowers or pods is an indication of maturity. Ideally these should not exceed the 10% level.
- The leaf to stem ratio is an important indication of quality. A high proportion of leaves and thin pliable stems would indicate good quality. Stocky thick stems with little leaves would be the converse.
- Although colour in itself is not a good indicator of quality, green roughage is an indication that it is either a fresh cut or has been store properly to prevent oxidation and that the vitamins are intact.
- Roughage should be free of foreign objects such as twine, wire, cans, weeds, mould and roots.
- Good quality roughage has a fresh clean grassy smell. Avoid roughage that smells musty or mouldy.
The objective evaluation is that which can be derived from a laboratory analyses. There are two important analyses that pertain to the fibre portion of the roughage.
Acid detergent fibre (ADF) refers to the cell wall portion that is made up of cellulose and lignin. This is an indication of the amount of digestible dry matter (DDM) of the roughage i.e. the percentage of the roughage that is digestible. The following equation is used to calculate this.
- DDM and ADF
- % DDM = 88,9 – (0,779 X % ADF) so if the ADF analyses of a roughage is 30% then the digestibility would calculate to 65.55%
- The ADF norm for good quality roughage is lower than 35
Neutral detergent fibre (NDF) refers to the total cell wall comprising of the ADF portion plus hemicelluloses. This is an indication of the dry matter intake (DMI) or how much of the roughage the animal will be able to eat. The following equation is used to calculate this.
- DMI and NDF
- % DMI = 120 / % NDF so if the NDF analyses of a roughage is 45% then the potential daily intake will calculate to 2,66% of body weight
- The NDF norm for good quality roughage is lower than 50%
The figure below illustrates the relationship between the various analyses.
