Influence of 2,4-D and 2,4,5-T on In Vitro Digestion of Forage Samples

Abstract

The influence of 2,4-D [(2,4-dichlorophenoxy) acetic acid] and 2,4,5-T [(2,4,5-trichlorophenoxy) acetic acid] on in vitro digestion of dried ground corn silage (Zea mays L.) and bermudagrass (Cynodon dactylon L.) foliage was determined using a modification of the Tilley and Terry method for determining in vitro dry matter digestibility of forage plants. Neither herbicide influenced the digestion of plant samples when treated with a herbicide concentration range of 10-8 to 10-4 M. Solutions containing 10-4 M of either herbicide did not influence the growth of microbial populations in incubated rumen liquor. The influence of rumen microorganisms on degradation of 2,4-D and 2,4,5-T was also investigated. Samples containing sucrose or plant material, buffered rumen liquor, and 10-4 M concentrations of either herbicide were incubated for 10 day periods. Data from periodic quantification of herbicide remaining in the samples indicated that neither herbicide used in these experiments was degraded by the rumen microorganisms. Results indicate that: (1) 2,4-D and 2,4,5-T do not alter the rumen microbial functions or development and (2) these herbicides are not readily degraded in the rumen by the rumen microorganisms.