The nutritional value and yields of amaranth (Amaranthus hypochondriacus) cultivar silages compared to silage from corn (Zea mays) harvested at the milk stage grown in a hot-humid climate

Amaranth forage requires less water than corn forage. Moreover, the yield and nutritional value of plants grown in different geographical areas may vary. Therefore, the aim of this study was to compare silages from amaranth cultivars (Maria, A28, A14, A12, and A5), grown in hot-humid conditions, with corn forage (Zea mays) (CS) in terms of yield, chemistry, silage characteristics, in vitro fermentation, and in situ degradability. The crops were harvested at the mid-milk stage, chopped, and ensiled in five-liter containers for a 45-days period. The yield, chemical composition, and silage characteristics of the plants were determined. In vitro gas production, organic matter disappearance (OMD), methane production, microbial crude protein (MCP), ammonia-N, volatile fatty acids (VFA), cellulolytic bacteria and protozoa populations, and in situ dry matter (DM) and crude protein (CP) degradability were measured using fistulated sheep. Data were analyzed using PROC MIXED of SAS in a randomized complete block design. Average DM yield of amaranth forages from different varieties was lower (P < 0.01) than corn forage. Among amaranth forages, the highest (P < 0.01) DM yield was observed for A12. Compared to CS, amaranth silages (AMS) had lower (P < 0.01) mean values of DM, OM, and metabolisable protein (MP) yields. The AMS contained higher (P < 0.01) concentrations of CP, ash, calcium, phosphorus, nitrate, and total phenolics, but lower (P < 0.01) neutral detergent fiber, lignin, non-fiber carbohydrates, and lactic acid. Compared to CS, the in vitro incubation of AMS resulted in lower (P < 0.01) OMD, methane production, total VFA, cellulolytic bacteria, and protozoa population, but higher (P < 0.01) MCP. The in situ protein effective degradability, digestible undegradable protein, and MP of AMS were higher (P < 0.01) than CS. Overall, amaranth cultivars made a medium-quality silage when grown in hot-humid conditions, though, silage of A12 cultivar could be used instead of CS.