Effects of source and concentration of NDF from roughage on performance and carcass characteristics in finishing feedlot diets

Abstract

A meta-analysis was performed to investigate the effects of neutral detergent fiber from various dietary constituents (total, TNDF, forage, FNDF, co-products, CNDF, and grain, GNDF) on performance and carcass characteristics in finishing feedlot cattle. Backward elimination procedures were used on mixed models to determine effect of concentration and source of NDF on feedlot and carcass performance. Significant effect (P < 0.05) covariates representing use of growth technology (implants and ionophores), gender, days on feed and initial BW were permitted in the model. Models containing total, co-product and grain NDF concentration and source were least useful (based on reductions in AIC values) in describing the relationship between NDF and performance than forage NDF. Feeding any forage increased DMI (P < 0.03) compared to feeding no forage, and increasing concentration of FNDF tended to increase DMI quadratically (P =.10). Increasing concentration of FNDF decreased ADG (P = 0.02) and gain-to-feed ratio. (P = 0.01). Concentration of FNDF was quadratically related to quality grade (P < .0001). Yet, feeding a greater FNDF concentration was positively correlated to decreasing liver abscesses (P = 0.001). Fiber constituents associated with forage NDF were more consistently associated with finishing and carcass performance response than those constituents associated with total NDF.