Comparison and Digestibility of Four Tropical Grasses Grown in Nigeria

Abstract

In a study of four tropical grass species: Cynodon plectostachyum (star grass), Cynodon Ib 8 (Ibadan strain), Pancium maximum (Guinea grass) and Pennisetum purpureum (Napier or Elephant grass) chemical composition, in vivo and in vitro digestibility were measured at three stages of growth. Digestion trials were conducted with African sheep. Lignin and plant cell wall were highly associated with in vitro digestibility but not with in vivo digestibility. Cellulose, hemicellulose and silica were not significantly associated with in vitro digestibility, and none of them were related to in vivo digestibility which was higher than in vitro digestibility particularly in the older grasses. The differences between in vivo and in vitro digestibility was highly related to cell wall composition. Significance of these findings in relation to the peculiarities of tropical grasses are indicated. Amount of hemicellulose and silica were highly associated with species differences.