Various microorganisms and chemical compounds might be added to forage, maintain or improve the nutritive value of a crop ensiled. The aim of the present experiment was to evaluate the fermentation characteristics and in situ rumen degradation of whole crop barley ensiled with Lactobacillus plantarum or ammonium propionate and its effect on feed intake and milk production of lactating dairy Holstein cows. Whole crop barley was harvested (32.5% DM), chopped and then ensiled alone (UT) or with Lactobacillus plantarum (8 × 1010 CFU g-1 fresh forage; LP) or ammonium propionate (1 g kg-1 DM; AP). Chemical composition, silage extract pH, NH3-N concentration and in situ ruminal degradation parameters of dry matter (DM), crud protein (CP) and neutral detergent fiber (NDF) were determined. Microbial inoculant had a significant (P < 0.05) effect on NDF content (LP = 545 vs. UT = 525 and PA = 522 g kg-1 DM) of whole crop barley silage (WCBS). In situ dry matter degradable coefficient of fraction (b) was affected by the treatments (LP = 0.48 ± 0.01 and PA = 0.47 ± 0.02 vs. UT = 0.45 ± 0.02). Use of LP caused to a decrease in CP degradability in fraction (b); (LP = 0.39 ± 0.02 and PA = 0.43 ± 0.05 vs. UT = 0.43 ± 0.04 % DM), and enhanced effective degradability of CP about 0.04 in contrast with the untreated silage. Treatment had no significant effect on dry matter intake, milk yield, milk fat and lactose concentrations, but milk protein yield for cow fed LP increased significantly compared with those of the other animals.

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