Evaluation of Parameters of Degradability of Dry Matter and Neutral Detergent Fiber of Three Forages Alfalfa, Wheat Straw and Corn Silage using Norfur System

The Norfur system developed in Island, Norway, Sweden and Denmark for predicts nutrient supply and requirement for maintenance, milk production, growth and pregnancy in cattle. Due to the diversity in ruminal degradation of NDF and its effect on animal performance, knowledge of NDF digestibility in forage is critical to the effective feeding of ruminants. The aim of this study was to compare the degradability of alfalfa, wheat straw and corn silage and to estimate the concentration of  indigestible neutral detergent fiber (iNDF) and potential digestible NDF (pdNDF) using the Norfur system.

Degradability parameters of dry matter and neutral detergent fiber with in situ method using three ruminal fistulated sheep at intervals of 0, 2, 4, 8, 16, 24, 48 and 96 h was evaluated in  a complete randomized design. To measure of iNDF, three grams of samples were incubated in nylon bags for up to 288 h.

there was a significant difference between the three alfalfas, corn silage and wheat straw in the degradability of dry matter and NDF. Rumen disappearance of DM and NDF during incubation periods of 0 to 96 h was highest in alfalfa forage and lowest in wheat straw. Rapid and slow degradable fractions of dry matter in alfalfa, wheat straw and corn silage were 24.50, 6.57 and 22.20% and 48.30, 41.43 and 45.00%, respectively. There was no significant difference in rate of degradation between the experimental treatments at the 5% level. Effective degradability at 2, 5 and 8% rates of outflow from the rumen was also significantly different between experimental treatments (p<0.0001). Effective degradability and potentially digestible NDF concentrations were highest in alfalfa and lowest in wheat straw. There was a significant difference between pdNDF and iNDF parameters in wheat straw compared to corn and alfalfa silage and alfalfa forage had a higher potential for digestibility (p<0.0001). The highest concentration of iNDF was in wheat straw and then in corn silage and the lowest concentration were in alfalfa after 288 hours of incubation (55.31, 28.81 and 12.94% of NDF, respectively).

According to the results of this study, using the Norfur system to determine the degradability of neutral detergent fibers, the lowest amount of iNDF and the highest amount of pdNDF belonged to alfalfa compared to corn silage and wheat straw, which indicates higher digestibility of alfalfa forage.