Ruminal dry matter degradability of high concentrate diets with increasing levels of calcium soaps of tallow

Abstract

The present study measured the in situ digestibility and ruminal degradability of dry matter of rations with different levels of calcium soaps of tallow (CST). The samples of the four rations with CST at levels of 0% (T1), 1.5% (T2), 3.0% (T3) or 4.5% (T4) were incubated in the rumen of a fistulated yearling steer. The nylon bag technique was used to determine the in situ digestibility and ruminal dry matter degradability. A completely randomized design was used, with 4 treatment diets and 4 repetitions. Rapidly-soluble fraction (a) or in situ digestibility of DM at 0 h of incubation was higher in T1 than T3 (P<0.05). The non soluble but degradable fraction (b) and constant of degradation (c) were higher in T3 than T1 (P>0.05). Potential (a+b) degradability was similar (P>0.05) between treatments. Effective degradation modeled at low ruminal turnover (1%/h) was lower in T4 than T1 (P<0.05); however, at higher ruminal turnover (5 and 8% per h), CST did not influence effective degradation of dry matter (P>0.05). In conclusion, CST in the ration influenced ruminal fermentation during the first hours of incubation. However, effective degradability at medium and high ruminal turnover was not affected by CST level in diets.