Effects of sprouted cowpea (vigna unguiculata) dietary inclusion with ronozyme ® ProAct supplementation on broiler performance

Abstract

The study evaluated the efficacy of maize-sprouted cowpea (Vigna unguiculata) diets when fed with supplementary exogenous enzymes on the growth (live weight, live weight gain, feed conversion ratio) and carcass parameters of Ross-308 broilers. Cowpeas were screened for viable seed and sterilised by 30-minute immersion in 2% sodium hypochlorite aqueous solution. Germinated by 12-hour soaking in tap water prior to 4-day open-air, 2-hourly irrigated sprouting on steel screens, and rapid, hot sun-drying to 35% DM spread on black plastic sheeting laid on a concrete surface. Balanced [160 g CP kg-1 DM] cowpea-based grower and finisher diets were mixed at 0, 50, 100% with iso-nutrient respective commercial feed mixes (controls). Duplicates of the experimental diets were fortified with 200 g/tonne of Rononzyme ® ProAct (75,000 PROT units g-1 serine protease). Nine hundred chicks were randomly allotted at 30 birds/pen in a 3 (diet) x 2 (enzyme) factorial experiment replicated five times. Random sample (8 birds/pen) live weight were evaluated on a weekly basis. Treatments were subjected to the analysis of variance using Minitab Statistical package version 18 (Minitab, 2017). Treatment means were separated using Tukey’s test at 5% level of significance. The maize-sprouted cowpea inclusion rate had no effect (P>0.05) on feed consumption (g/b/d). Grower feed with 100 maize-sprouted cowpea inclusion had a significantly (P<0.05) lower live weight gain (45.0 g/b/d) (LWG) and consequently live weight at day 35 (LW35) compared to SCG0 and SCG50 which were not different. Enzyme fortification had no effect on all growth parameters in both grower and finisher phases. During the finisher phase, birds on maize-cowpea diets had significantly higher (P<0.05) feed consumption (g/b/d) compared to the control diet (SCF0). Diet SCF100 had the lowest (P<0.05) live weight at day 42 (LW42) compared to SCF0 and SCF50, and eventually had the highest feed conversion ratio (FCR). Cumulatively, grower-finisher (day 22-42) live weight gain (LWG22-42) was in the dietary order SCG0> SCG50>SCG100 (P<0.05). The feed conversion ratio (FCR22-42) was in the dietary order SCG0< SCG50<SCG100 (P<0.05). Broilers on the SCG0-SCF0 dietary regime had larger carcasses and the proportionate breast (P<0.05). Broilers on the SCG100-SCF100 dietary regime had smaller proportions of wings and thighs (P<0.05). The treatments did not (P>0.05) affect the abdominal viscera. The enzyme had no effect (P>0.05) on the slaughter parameters except the proportional weight (%) of the heart. The maize-sprouted cowpea diets resulted in a low value for the meat redness coordinate (a) (P < 0.05). The yellowness coordinate (b) was in the order SCG0-SCF0>SCG50-SCF50>SCG100-SCF100 (P < 0.05). Meat water holding capacity and the shear force were higher on the SCG0-SCF0 compared to the SCG100-SCG100-SCF100 feeding regime (P<0.05). In conclusion, dilution of the control with the sprouted cowpea diet reduced the live weight gain, feed efficiency ratio and carcass weight, and caused adverse effect on meat quality, with more adverse effects at the 100%, compared to the 50% dilution level. Adverse metabolic and physiological effects were v indicated by the enlargement of the liver and gizzard at the high inclusion of sprouted cowpea in broiler diets.