June/July 2013 - What determines the nutritive value of roughages?
Roughages make up the major part of most horse diets. Since most roughages are grown locally, and do not have strong commercial interests behind them, information on the nutritional value of individual roughages is much scarcer than for commercial concentrates. This article discusses factors that influence the nutritional value of roughages, and argues that a roughage analysis can benefit your horse’s wellbeing as well as reduce its feeding costs.
By Dr. Eric Clausen, Advisor on Horse Nutrition and Management
Videncentret for Landbrug, Denmark
Based on the analysis of forages, haylage and hays produced for horses that we encounter in our advisory work in Denmark, it is clear that there are large differences in terms of content of the various nutrients.
In order to make the best use of your roughages, and to obtain balanced rations providing the nutrients your horse needs, it is necessary to know the value for all critical nutrients in the feed. With rising prices for grain and feed mixtures, a feed analysis of your roughage can also be invaluable in improving the economy of your horse feeding, simply because roughage of a good quality can effectively substitute for more costly, commercial feeds.
The nutrient composition of herbage depends on:
• The botanical stage of the grass and legumes at harvest.
• The botanical composition, i.e. the proportions of different grass species, of clover and of various other plants.
• Harvest, i.e. whether it is it the first, second or possibly third cut.
• The amount of nitrogen fertilizer (fertilizer) used.
Young leafy grass can be difficult to dry for hay, whereas it is suitable for haylage. Therefore, grass harvested for haylage is usually cut at an earlier stage than grass cut for hay-making. As the grass grows older it becomes more fibrous and coarse, and the content of digestible nutrients decreases. Typically, grass cut for hay at the later stages of development will have a larger share of stems, a smaller percentage of leaves and a lower nutritive value.
The distribution of the different grass species involved is not the same in the case of a first or second harvest. Timothy is usually more dominant in the first than in the second cut, because it will develop more stems and smaller leaves as the growth season progresses. Meadow fescue, smooth meadow grass and white clover, however, continue to develop new shoots with many leaves throughout most of the summer.
Applying fertilizer (nitrogen) has a powerful effect on both crop yield and nutritional content. In particular, protein content is strongly increased by nitrogen fertilization.
Shorter chewing time needed for early cut haylage
Horses that are fed haylage from early harvests use less time chewing (number of minutes used per kg dry matter) and consume more roughage per unit of time than horses that are fed haylage or hay harvested at later development stages, when the fibre content in the diet is higher.
As later cuts result in longer eating time and lower nutritive value, it may be advantageous to use such roughages for horses that do not have particularly high nutritional requirements, such as adult horses in moderate use, or ponies that can easily become too fat.
Use of forage analyses in PC-Horse.
If you have access to a nutrient analysis for your roughage, you can easily enter it as a user-defined feed in the PC-Horse program. PC-Horse has made an agreement with one of the leading analytical laboratory in Europe (Eurofins) which now will supply their analysis certificate as a data file, in addition to the usual printed page. The latest version of PC-Horse will import the data file, and make the feed available for planning rations for your horses, thus greatly simplifying the process of entering complicated nutritional data. You may also save money when buying hay or haylage of above average quality.