Effect of replacing corn grains with date palm kernels on ruminal fermentation, feed degradability, and methane production under different initial in vitro pH conditions.

ABSTRACT

Date kernels (DK) are cheap by-products rich in energy and phenolic compounds. It can be used as an alternative to the conventional sources of energy in ruminant diets while reducing methane (CH4) production. Using a semi-automated gas production (GP) system, the initial pH of buffered rumen liquor was adjusted to 5.5 and 6.8. Five experimental diets were evaluated, control (0% DK), and DK25, DK50, DK75, and DK100 presented 25, 50, 75, and 100% replacement of maize by DK, respectively. Of the 16 phenolic compounds detected in DK, protocatechuic, p-hydroxybenzoic and catechin were the most abundant. At pH 6.8, the control diet recorded higher (p < 0.05) GP values throughout the first 12 h incubation than all other DK diets, while at 5.5 pH, DK50 displayed the highest (p < 0.05) GP at 3 and 6 h compared to all other diets. At either pH conditions, all DK diets reduced (p < 0.05) CH4 compared to the control without affecting protozoal counts. At 5.5 pH, DK diets showed enhanced (p < 0.05) nutrients degradability compared to control. DK modified (P < 0.05) the fermentation patterns toward more propionate than the control under either pH conditions. Substitution of maize by 50% DK was highly recommended in ruminant diets.