A redundancy analysis of the relative impact of different feedstuffs on nitrogen use efficiency and excretion partitioning in beef cattle fed diets with contrasting protein concentrations

Abstract Diet composition and intake are the main determinants of nitrogen (N) use efficiency (NUE) in beef cattle. Accounting for interactions comparative effects different feedstuff types on NUE N losses urine faeces can inform development financially environmentally sustainable feeding protocols This study aimed to assess impact various individual feedstuffs types/groups partitioning cattle, diets with contrasting crude protein (CP) concentrations. Partial multivariate redundancy analysis (pRDA) was used associate influence intakes by using results from 59 published trials growing finishing The data were split into three sub-sets, according diet CP concentration (low CP, 47−120 g CP/kg DM, n = 73; medium 121−150 90; high 151−269 74). In low diets, that improved shifted outputs fresh-cut grasses legumes, grass hay, straws, brans pulps. grasses, straws; while legume hays, pulps hulls also excretion faeces. silage, meals; straws meals present highlighted selection provide adequate digestible fibre energy supply rumen microbes, as well minimizing oversupply could be improve shift cattle; effectiveness providing might influenced overall concentration.