A comparison of different methods which estimate nutritive value of forages

In recent years, the demand for forages in the world has greatly increased. In developing nations, the population increase is so rapid that more of the grain is used for human consumption, while in developed nations beef consumption is rising rapidly. For profitable cattle and sheep production an abundance of good quality forages is essential. In order to differentiate good forages from poor ones, it is mandatory to have good methods of determining forage quality. In the past, this has mainly been achieved with feeding experiments and digestibility trials. Recently, the amount of the forage that is voluntarily consumed by ruminant animals has been recognized as another important factor in determining its quality. Furthermore, several laboratory methods are becoming increasingly useful in the determination of nutritive value of forages, since they are less costly, less time-consuming, and require a smaller amount of test material. These laboratory (or in vitro) methods will probably not replace in vivo experimentation completely. They are only an estimation of the results obtained from animals, and the degree with which they estimate these animal results has to be determined carefully before they can be of general usefulness. The major objective of this investigation, therefore, was to determine how close various laboratory methods come to estimate results obtained directly from animals. Secondary objectives were to determine the nutritive value of three grades of alfalfa hay, to compare cattle and sheep in their ability to digest these three alfalfa hays, and to determine the relationship between the Total Digestible Nutrient (T.D.N.) and the Digestible Energy (D. E.) methods of feed evaluation, using these three alfalfa hays.