Volatile Solids Prediction

[paradox3206]

Digestible volatile solids in feces were calculated as the sum of fecal starch, soluble fiber, NDF, protein, and lipid (kg DM/d) predicted using NDS where digestion is estimated based on rates of digestion and passage of nutrient fractions.

RuFaS documentation (page 111) states that dVS (kg/d) equals (-1.201 + 0.402OMI + 0.036NDF%-0.024*CP%). I am not saying that the NDS/CNCPS model is perfect but it should certainly give a better prediction of nutrient digestion and waste than this fairly crude equation of Appuhamy. Why is RuFaS using this simplistic equation which does not consider digestibility or rates of passage?

	GL0BP	GL31BP	GL42BP	GL45BP	NE0BP	NE23BP	NE41BP	NE48BP
NDS Manure VS, kg/d	6.60	6.67	7.15	6.90	6.28	6.37	6.57	6.93
NDS Manure dVS, kg/d	5.64	5.79	6.10	5.94	5.39	5.52	5.62	5.96
RuFaS Manure VS, kg/d	8.64	8.66	8.65	8.60	8.31	8.36	8.34	8.36

	W0BP	W37BP	W48BP	W51BP
NDS Manure VS, kg/d	6.28	6.95	6.97	6.88
NDS Manure dVS, kg/d	5.41	5.92	5.92	5.96
RuFaS Manure VS, kg/d	8.51	8.53	8.49	8.55