Dual-purpose cowpea (Vigna unguiculata (L.) Walp.) straw as sole diet for west African dwarf rams

Abstract

The study investigated straw quality of four cowpea varieties (Vigna unguiculata (L.) Walp.) (IT89KD-391; IT86D-716; IT86D-719; IT81D-994) using 24 West African dwarf (WAD) rams solefed the straw over a 60-d period. Voluntary dry matter (57 to 88 g kg-1 W0.75 d-1), organic matter
(OM) ranged from 50.5 to 78.9 g kg-1 W0.75 d-1, crude protein (CP) from 6.8 to 14.7 g kg-1 W0.75 d-1, and neutral detergent fibre (NDF) intake between 30 and 39 g kg-1 W0.75 d-1 (p<0.05) among the varieties; but acid detergent fibre (ADF) did not vary (p>0.05). In vivo digestibility values of DM (390 to 590 g kg-1 DM), OM (377 to 591 g kg-1 DM), and NDF (469 to 646 g kg-1 DM) varied (p<0.05) among the varieties. The soluble and degradable DM and the potential and effective degradability values also varied (p<0.05) among the varieties. Variety IT81D-994 gave the highest
metabolizable energy (ME) intake of 7.80 MJ, while variety IT86D-716 recorded the lowest ME intake of 3.15 MJ. Average daily gains of rams and grain yields varied significantly (p<0.05) from less than 10 g and 2,800 kg ha-1 in variety IT86D-716 to more than 50 g and 5,500 kg ha-1 in IT81D-994, respectively. Straw of cultivar IT81D-994 was found to have greater potential as sole diet for rams than the other varieties, based on grain yields and average daily gain which is a better measure of forage quality.

Keywords: Cowpea, fodder, grain yields, rumen degradation, West African dwarf rams