Abstract
Fifty samples of leaf and stem of Sorghum stipodeum, Themeda australis, Iseilema vaginiflorum, Brachyacne convergens, and Dicanthium fecundum with different stage of maturity were used to study the relationship between their chemical components and in vitro dry matter digestibility (IVDMD). The IVDMD was performed by two stage of digestion; the first stage was digestion in rumen inoculum and the second stage was digestion of protein using neutral detergent solution. The relationship between chemical components and IVDMD was analysed using regression method. There was a negative correlation between fiber component [neutral detergent fiber (NDF), acid detergent fiber (ADF), and lignin] and a positive correlation between water soluble extract (WSE) or crude protein with IVDMD. Water soluble extract was the best predictor of IVDMD with r = 0.71 and residual standard deviation of 8.4 unit. Since the method of WSE is simple and inexpensive, it can be used as a predictor of dry matter digestibility of most forages. Although there were large variation exist among the species, however, the stage of maturity was an important factor affecting IVDMD showed in four out of five species tested. In two of the five species measured, the IVDMD were higher in leaf than that in stem.
Highlights
Forage is a basic feed for ruminant animal; knowledge of forage quality is required by farmers so that they can select the best quality forage offerred to their livestock
This paper reports the in vitro dry matter digestibility (IVDMD) of some tropical grasses and its relationship with the chemical component
There was a large variation among the species studied, on average the IVDMD tended to decrease with advancing maturity and the leaf had higher IVDMD than the stem fraction (Table 2)
Summary
Forage is a basic feed for ruminant animal; knowledge of forage quality is required by farmers so that they can select the best quality forage offerred to their livestock. Reid (1994) defined forage quality as the product of voluntary intake, digestibility and the efficiency of nutrient used by the animal. The efficiency of ruminant production based on forage as the main protein and energy sources are highly dependent on forage maturity, which is often considered to be the primary factor determining its nutritive value (Nelson & Moser 1994). Assessment of forage quality which include the measurement of animal performance that have production potential, requires significant amounts of feed, is expensive, laborious, and unpractical for screening large numbers of feeds. Most methods of feed evaluation involves the determination of chemical composition and digestibility, followed by calculation of energy values. Methods of determination of chemical composition have been developed which give some reliable results. Determination of feed digestibility by animal trial gives reliable results this method is expensive, time consuming and laborious. In vitro digestibilty methods have been developed using small quantities of feed (< 1 g) to simulate in vivo digestion (Tilley & Terry 1963; Van Soest et al 1967; Orskov & McDonald 1979)
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