Comparison of in-vivo and in-vitro degradability of different soy products

This research was carried out to determine the in-situ and in-vitro degradability of four different soy products [Soybean meal (SM), soy pass (SP), soy flake (SF), full-fat soybean (FFS)]. In the study, 3 Brown Swiss cow and 3 Crossbreed Buffalo (Murrah x Anatolian) (> 2 yearsold) were used to determine the in-situ rumen degradability of soy products. Constant cannulas were placed on left paralumbar fossa for all animals. Soy products samples were weighed into nylon bags for determination of dry matter (DM), crude protein (CP), crude fat (CF), organic matter (OM) and crude ash (CA) in rumen degradability at 4th, 8th, 12th, 16th, 24th hours. In addition, in the second stage of the study, a daisy incubator and NDF analyses were used to determine the in vitro true digestibility of soy products for 48 hours. At the in-situ experiments, the avarage of 24 hour DM digestibility values were found to be significantly different at cattle compared to buffalo in only SP (47,54% and 49,61%, respectively; P= 0,0001). The highest DM digestibility in situ at the 24th hour was found in SM at buffalo (86,16%) and the lowest in SP at cattle (63,30%). Diffrences were found between species in teoric passage rates of 2%, 5%, 8% in SF and 2% in SP among the kinetic digestibility values of DM. The avarage of 24 hour CP digestibility values were found to be significantly different at cattle than buffalo in only SF (50,47% and 42,92%, respectively; P= 0,03). The highest CP digestibility in situ at the 24th hour was found in SM at buffalo (83,04%) and the lowest in SP at cattle (45,25%). Differences were found between species in fractions b and c in FFS, UF in SF and fraction a in SP among kinetic digestibility values of CP. The avarage of 24 hour CF digestibility values were found to be significantly different at catlle than buffalo in FFS and SF (60,46%, 91,21%; P<0,0001 and 71,27%, 38,13%; P<0,0001). The highest CF digestibility in situ at the 24th hour was found in FFS at buffalo (99,1%) and the lowest in SM at buffalo (64,24). Differrences were found between species in fractions a, b, c in FFS and SP; a and b in SF in addition in teoric passage rates of 2%, 5%, 8% in FFS, 5% in SF, 5% in SP among kinetic digestibility values of CF. For all soy products we have used there was no differences detected between species in CA values. The highest CA digestibility in situ at the 24th hour was found in SM at buffalo (84,07%) and the lowest in SP at cattle (63,96%). Differences were found between species in fraction c in FFS, a in SF in addition in teoric passage rates of 5%, 8% in FFS among kinetic digestibility values of CA. A significant difference was observed between the species in SM and SF acorrding to the in-vitro digestibility results determined by NDF analysis performed after 48 hours of incubation in the Daisy Incubator. As a result, it was revealed that the digestibility of different soy products may be slower at buffalo than at cattle, and DM degradability in the previous hours of rumen is faster at cow than at buffalo. However, DM degradability was faster in the later hours at buffalo than cattle in the rumen. CP digestibility in rumen of the raw materials with high by-pass properties such as SP was determined lower than the other soy products at buffalo. CP digestibility positively increases towards the buffalo with the increase of incubation period of the samples in the rumen. In addition, FFS which have high fat content gave the very high digestibility values at buffalo than cattle. The use of low quality roughages together with soy products with high protein content in the rations of buffalo may increase the coversion rate of the feed to yield. Further studies are needed to determine the digestibility rates of soy products in ruminants and especially buffaloes by in-vivo, in-situ and in-vitro methods compared to other ruminants. Keywords: Buffalo, Cattle, Soy, in-situ, Daisy incubator, Degradability