Fodder productivity and nutritional quality of oat and vetch mixtures improved with application of NP fertilizers in Ethiopia

Abstract The fertilizer application rate is the same for different forage crops in Ethiopia. Thus, this study was conducted to determine the effect of nitrogen and phosphorus fertilizer application on fodder yield and nutritional quality of oat ( Avena sativa L.)/vetch ( Vicia villosa ) mixtures. The oat/vetch mixtures were sown with eight fertilizer rates (0%, 25%, 50%, 75%, 100%, 125%, 150%, and 175%), and sole oat (100 kg/ha diammonium phosphate [DAP] + 50 kg/ha urea) and vetch (100 kg/ha DAP) were also sown with their recommended fertilizer rates (100%) using a randomized complete block design with three replications. The system productivity increased with increasing fertilizer rates up to 150% and the second year gave higher yield. All the nutritive value except fiber contents were higher in the second year. Among mixtures, the highest ash, crude protein yield, digestible dry matter, dry matter intake, in‐vitro dry matter digestibility, digestible yield, total digestible nutrients, total digestible nutrient yield, relative feed value, and relative feed quality were recorded for 150% fertilizer. On the contrary, the neutral detergent fiber, acid detergent fiber, acid detergent lignin, and cellulose contents decreased with increasing fertilizer rates. Application of 175% fertilizer on oat/vetch mixtures gave the highest crude protein and digestible crude protein. Moreover, the digestible energy, metabolizable energy, and net energies for lactation, maintenance, and gain increased with increasing fertilizer rates up to 150%. Therefore, application of 150% fertilizer would increase the system productivity and nutritive value of oat/vetch mixtures in the study area.