Nutrient digestibility and in situ degradability of alternatives to soybean meal protein sources for sheep

Abstract

An in situ degradability and three in vivo (by difference) digestibility trials were conducted. The feeds tested were, soybean meal (SBM; control), lupin seeds (LS), rapeseed meal (RSM), sunflower meal (SFM), faba bean seeds (FBS), vetch seeds (VS), pea seeds (PS), flax seeds (FS), and chickpea seeds (CS). Feeds were weighed into nylon bags for incubation in the rumen of three ruminally cannulated Chios breed rams for 0, 3, 6, 12, 24 and 48h to measure DM and N degradability using a 3×9 incomplete Youden square design. Furthermore, three in vivo digestibility trials were conducted, by the use of a latin square (3×3 for the first trial and 4×4 for the second and the third trial) experimental design with castrated Chios rams, to estimate nutrient digestibility coefficients of these protein supplements. The results showed that RSM, PS and FS had similar N and dry matter (DM) digestibility compared to SBM. Even though PS had higher N degradability than SBM, the digestibility of N was similar for these two protein sources. The FS had the lowest effective protein degradability (EPD) compared to all other tested feeds, whilst VS, LS FBS and CS had higher EPD. This study reveals that RSM, PS and FS compared to SBM did not have adverse effect on DM and N digestibility. All tested seeds, but FS, have to be treated in purpose to reduce their N degradability, if they are to be used as main protein sources in highly productive diets for ruminants.