In vivo digestibility and voluntary intake by sheep of five lines of Cenchrus ciliaris selected on the basis of in vitro digestibility

Abstract

A study is reported on the voluntary intake and digestibility by sheep of five lines of Cenchrus ciliaris when grown as swards and cut at five different stages of growth. Previous studies with C. ciliaris grown in small plots had shown large differences between lines in in vitro digestibility of plucked samples: high-digestibility line 1,63.6%; medium-digestibility lines 9, 59.9%, and 14, 61.3%; and low-digestibility lines 17, 55.9% and 29, 55.7%. When these five lines were grown as swards and fed to sheep, their mean dry matter digestibilities ranged from 60.3% for line 1 to 56.3% for line 29. There was a 0.95 correlation between the in vitro digestibility of the selections and the in vivo digestibility when grown as swards. Voluntary intake of line 1 was 9% higher than that of line 29, while intake of digestible dry matter was 16% higher. Line 1 had the highest leaf and lowest lignin percentage. It was concluded that Cenchrus ciliaris selected on the basis of a higher in vitro digestibility in small plots had superior in vivo digestibility of the dry matter and superior voluntary intake when grown in large areas.