Selecting browse plants to supplement cassava peel-based diet for peri-urban small ruminants

Cassava (Manihot esculanta) peel is routinely fed to ruminants in Ghana and most parts of Africa, but the low protein content and lack of suitable protein supplements limits its full exploitation in small ruminant production systems. This study assessed the suitability (degradation characteristics and synchrony between nitrogen release and organic matter degradation) of the leaves of three browse plants, chaya (Cnidoscolus aconitifolius), ficus (Ficus exasperata), and terminalia (Terminalia catappa), as supplements for sheep fed a cassava peel-based diet. Four ruminally fistulated Djallonké wethers were used in a randomized complete block design experiment to determine ruminal disappearance of dry matter (DM), organic matter (OM) and nitrogen (N) from the three leaves and from cassava peels. For chaya, ficus and terminalia, OM content was 93.1%, 83.8% and 90.3% (P < 0.05), respectively, whereas N was 3.4%, 3.1% and 1.7% (P < 0.05, DM basis). The OM and N content in cassava peel was 95.3% and 1.0%, respectively. Ruminal DM disappearance of chaya, ficus, terminalia and cassava peel after 24 h of incubation was 79.0%, 36.4%, 48.0%, and 43.0% (P < 0.05), respectively. The ratio of N released from chaya leaves to OM from cassava peel was 1:16 or lower during 24 h ruminal incubation, compared to 1:31 during the first 8 h and 1:25 after 12 h of incubation of ficus leaves. The ratio for terminalia leaves from 4 to 24 h of incubation ranged between 1:51 and 1:63. The high N content and ideal synchronous release of N and OM ratio of 1:33 (N:OM) made ficus leaves the most suitable supplement among the three browse leaves, with the potential to supply adequate N to optimize ruminal microbial protein synthesis in sheep on a cassava peel-based diet.