Hydroponic maize, barley, and cowpea fodder as partial replacements for conventional rabbit diets: A feeding trial approach

Abstract:

Replacing 20-30% of a pelleted rabbit ration with fresh hydroponic sprouts can reduce purchased feed costs without penalising growth-provided the right species is chosen. This research evaluated hydroponic maize (Zea mays), barley (Hordeum vulgare), and cowpea (Vigna unguiculata) as partial diet replacements for growing New Zealand White rabbits at São Paulo Research Institute, Brazil, between April and September 2022. Sprouted fodder was produced on plastic trays (seed density 3.0 kg m⁻²) under greenhouse conditions (26 ± 2 °C, 75% RH, 14 h photoperiod) and harvested on day 8. Proximate analysis showed cowpea sprouts contained the highest crude protein (24.1% DM), while barley had the lowest crude fibre (13.8% DM). Forty-five weaned rabbits (35 d old, 641 ± 21 g) were assigned to three groups (n = 15) in a completely randomised design. Each group received a basal pellet (17.1% CP) ad libitum, with 25% of daily DM replaced by one sprout species over 60 days. Cowpea-supplemented rabbits recorded the highest daily gain (25.2 g d⁻¹) and final body weight (2,153 g), whereas barley-fed animals achieved the best feed conversion ratio (3.28). Maize-fed rabbits showed intermediate gain (21.9 g d⁻¹) but the poorest FCR (3.71). Scatter-plot regression of cumulative feed intake against cumulative weight gain revealed a steeper slope for cowpea (0.33 kg gain per kg DM) than for maize (0.28) or barley (0.31), confirming that the legume sprout delivered greater growth per unit of feed consumed. Nutrient-balance calculations indicated nitrogen retention was 14.2 g per rabbit in the cowpea group versus 10.1 g in the maize group over the trial period. These data support the partial replacement of conventional pellets with hydroponic cowpea sprouts as a cost-effective strategy for improving protein supply and growth efficiency in small-scale rabbit production.