Effects of the crushing and ensiling process of brown rice grain on in situ starch degradability

Abstract.

This study used an in situ technique to examine the effects of pretreatment (crushing vs non-crushing) and storage method (drying vs ensiling) on the ruminal starch degradability of rice grain. The rice grain was prepared for two treatments: non-crushed brown rice (NCB) and crushed brown rice (CB). After pretreatments, NCB and CB were ensiled or dried. The percentage of particles <2 mm was higher in CB than in NCB (67.7% vs. 2.1%, respectively). Ensiled CB (82.5%) had a significantly (P < 0.05) high rapidly degradable fraction of starch than the other sample, followed by dried CB (22.1%), ensiled NCB (1.9%), and dried NCB (0.1%).The slowly degradable fraction varied significantly (P < 0.05) in the opposite order: the highest value was seen for starch in dried NCB (99.3%) followed by ensiled NCB (98.1%), dried CB (76.1%), and ensiled CB (17.0%).The effective degradability of starch was significantly (P < 0.05) higher in ensiled CB (95.4%), followed by dried CB (78.4%), ensiled NCB (12.2%), dried NCB (11.3%). The ruminal starch degradability of NCB was low, regardless of whether it was dried or ensiled. The rapidly degradable fraction, slowly degradable fraction and effective degradability of starch were significantly affected by the interaction between pretreatment and storage method. These interactions indicate enhancement of starch degradability. On the other hand, ensiling and crushing changed the slowly degradable fraction to rapidly degradable fraction and increased the effective degradability. However, ensiling and crushing brown rice would enhance the risk of acidosis.