EFFECT OF COWPEA VARIETY AND PHOSPHATE FERTILIZER RATE ON NUTRITIVE VALUE OF COWPEA HAULMS FED TO DJALLONKÉ SHEE

Abstract

Two experiments were conducted to determine the effects of cowpea variety (V) and phosphate (P) fertilizer application rate on nutritive value of cowpea haulms fed to Djallonké sheep. In Experiment 1, the effects of three levels of phosphate fertilizer application rate (30, 60 and 90 kg P2O5/ha) on the in vitro gas production characteristics, concentration of digestible organic matter (DOM), crude protein (CP), acid detergent fibre (ADF) and neutral detergent fibre (NDF) of haulms from five cowpea varieties (V) (Zaayura-SARC 4-75, Songotra-IT97K-499-35, Hewale-IT93K-192-4, IT- IT99K-573-1-1 and Asomdwe-IT94K-410-2) were studied using a 3 x 5 factorial treatment arrangements in a Completely Randomized Design. In Experiment 2, Djallonké rams grazing natural pasture were randomly assigned to haulms of two V (Zaayura-SARC 4-75 and Hewale IT93K-192-4) of cowpea and two P fertilizer rates (30 and 90 kg P2O5/ha) in a 2 x 2 factorial treatment arrangement, to determine the (1) intake, (2) growth performance, (3) blood profile and (4) carcass characteristics of the rams. In Experiment 1, there was a significant V x P interaction for CP, NDF and ADF. The CP for Zaayura-SARC 4-75 and Asomdwe-IT94K-410-2 increased (P<0.044) as the P rates increased from 30 to 60 kg P2O/ha but there was a declined, which was significant (P<0.044) for IT- IT99K-573-1-1 and similar (P>0.05) for the other varieties. The CP at 90 kg P2O5/ha for all V was lower (P=0.119) than that at 30 kg P2O5/ha. The NDF for Songotra-IT97K-499-35 and Asomdwe-IT94K-410-2 increased (P= 0.032) as the P rates increased from 30 to 90 kg P2O5/ha whilst the other V increased from 30 to 60 kg P2O5/ha and declined (P= 0.032) at 90 kg www.udsspace.uds.edu.gh iii P2O5/ha. Whilst all V declined in ADF with increase in P rates, Songotra-IT97K 499-35 and Asomdwe-IT94K-410-2 increased (P= 0.031). There was a significant V effect on DOM with the highest reported in Zaayura-SARC 4-75 (43.44%). The in vitro gas production characteristics did not differ (P>0.05) by interaction (V x P rates) or main effects (V or P). The V x P rates interaction was significant (P<0.05) for DM intake. Whilst intake increased (P=0.003) as P rate increased for Zaayura-SARC 4-75, there was a decline in Hewale-IT93K-192-4. There was a significant (P<0.05) V x P interaction for the blood urea nitrogen (BUN) and a V effect on globulin. There was a significant (P= 0.039) V x P rate on carcass length whilst live weight at slaughter, dressed weight, chuck, leg, loin, rib and flank and shoulder all differed by P rates only. Except for liver and lungs which differed (P= 0.029; P= 0.048) by P rates among the non-carcass parameters, the others were not affected (P>0.05) by the treatments. The CP, NDF and ADF of the V responded differently to the increasing P rates. The feed intake, carcass and non-carcass characteristics as well as BUN were also affected (P<0.05) by the treatments. It can be concluded that nutrient concentrations of cowpea haulms were influenced by different P rates and varieties with favorable effects on growth, haematology and carcass composition of lambs. Varieties Zaayura-SARC 4-75 and Hewale IT93K-192-4 at P rates at 90 kg/ha are recommended to enhance growth performance and carcass yield of the Djallonké lambs