Predictions of protein digestibility and lysine absorption in pigs

With 294 feedstuffs-classified into 22 feedstuff categories-, from which in the original literature besides the crude protein (CP) and lysine (lys) contents their precaecal (pc) and partly their total (t) digestibilities in pigs had been presented, assessments of the pc and t apparent digestibilities (AD%) were done by two different ways. Between the prediction possibility using the mean value of nondigestible CP resp. lys (mean ndCP, means ndlys, g/kg DM) and the usual way of calculating average digestive coefficients (mean ADCP%, mean ADlys%) there were with regard to the validity of predictions only small differences, with the tendency of partly more advantageous results by the first cited procedure. Good assessments of pc ADCP% and pc ADlys%, where 70 ... 100 per cent of the single feedstuffs showed prediction errors of only < or = 5 digestibility units, were got for the protein concentrates field bean, lupin, soybean meal, sunflower seed meal, rapeseed meal, yeast and casein as well as with some restrictions for sorghum, linseed meal, blood meal and poultry by-product meal. Less reliable and connected with more uncertainties are the pc digestibility predictions for cereals, peas, cottonseed meals, meat (& bone) meals and fish meals: only 20 ... 30 per cent of the single feedstuffs showed good appraisals with differences < or = 5 digestibility units. In the rule t digestibilities can be assessed more exactly than pc digestibilities, for lys these predictions are mostly less precise than for CP.