Volume 42, 245-251

Tropical Grasslands (2008) Volume 42, 245–251

Studies on sweet potato forage and dried brewers’ grains as supplements to green panic for Bunaji cows

I. ETELA¹, U.I. OJI², G.A. KALIO³ AND G.O. TONA⁴

¹ Department of Animal Science and Fisheries, University of Port Harcourt, Choba, Port Harcourt
² Department of Animal Science, Rivers State University of Science and Technology, Nkpolu, Port Harcourt
³ Department of Agriculture, Rivers State College of Education, Ndele
⁴ Department of Animal Production and Health, Ladoke Akintola University of Technology, Ogbomosho, Nigeria

Abstract

Growth of sweet potato (Ipomoea batatas) was examined in a plot study. Forage yield and leaf: stem ratio decreased (P<0.05), while harvest index (tuber yield:tuber+forage yield) increased, as harvesting was delayed from 12 to 20 weeks after planting (WAP). Tuber yields increased but not significantly (P>0.05) as harvest age increased, while leaf yields declined. In a feeding study with Bunaji cows in mid-lactation, dried brewers’ grains (DBG) and sweet potato forage (SPF) were compared as supplements to a diet of green panic (Panicum maximum) (9.3% crude protein). Dry matter (DM) intake of green panic was similar (P>0.05) in both groups, while intakes of supplement, total DM, crude protein and ME for DBG were higher (P<0.05) than for the SPF-supplemented group. Milk yield for the DBG group was 22% higher (P>0.05) than for the SPF group but milk composition was similar in both groups. Rumen dry matter (DM) degradation characteristics were similar (P>0.05) for the two rations. The study suggests that sweet potato foliage could be used as an alternative supplement to DBG for feeding lactating cows but that low levels of milk yield could result. Similar studies covering a full lactation are needed to verify whether the lactation levels could be sustained for long periods or improve with time.