USING A CELLULOLYTIC COMPLEX TO ESTIMATE IN VITRO DIGESTIBILITY OF BIRDSFOOT TREFOIL

Abstract

Digesting forages with a prepared cellulase solution (PCS) has been shown to be a rapid method of obtaining dry matter digestibility (DMD) estimates in many species. This procedure has not been previously used to obtain DMD estimates of broadleaf birdsfoot trefoil (Lotus corniculatus L.). A broad based population consisting of 19 accessions, representing 11 countries of origin, three germplasm pools, and two domesticated cultivars of birdsfoot trefoil was evaluated. The PCS was produced from culturing Trichoderma reesei Simmons culture number QM9414. Fiber and PCS determinations were compared to an in vitro rumen fermentation (IVDMD) procedure. The fiber components measured were; neutral detergent fiber (NDF), acid detergent fiber (ADF), and hemicellulose (HEMI). The PCS procedures involved digestion using a PCS without any pre- or post-treatment (CS), acid-pepsin digestion followed by a single-stage digestion in PCS (APCS), acid detergent solution (ADS) followed by a two-stage digestion in PCS (ADSCS), and neutral detergent solution (NDS) followed by a two-stage digestion in PCS (NDSCS). All of the fiber and PCS procedures were significantly (P ≤ 0.001) correlated with IVDMD except HEMI. The CS procedure underestimated IVDMD by 199 g kg−1; however, it had the best regression coefficient (b = 0.99), had the second best correlation coefficient (r = 0.86), and required less time than the other PCS procedures. The APCS procedure provided the best estimate of IVDMD. It overestimated the IVDMD mean of birdsfoot trefoil by only 30 g kg−1 and was the most accurate (residual standard deviation (RSD) = 22 g kg−1) approach. The CS procedure is recommended when a ranking of samples is desired and actual values of DMD are not of primary interest.Key words: Fiber digestion, germplasm, in vitro dry matter digestibility, Lotus corniculatus L., Trichodenna reesei Simmons