Survey of chemical composition, ruminal degradability and in vitro gas production of Mentha pulegium pulp silage with different levels of waste date

Ruminant feeding systems based on the available by-products of each region, are a useful method to provide animal feed. Among these agricultural wastes is oregano residue, which is the waste of oregano extraction factories. Due to their high moisture, storing such resources under normal conditions is difficult. Ensiling is one of the common methods of storing and processing forages with high moisture. On the other hand, adding easily degradable carbohydrates such as wasted date, improves the nutritional value of silage. The objective of this study was to investigate the chemical composition, ruminal degradability and in vitro gas production of Mentha pulegium L. pulp silage with different percentages of wasted date.

To perform this experiment, 400 kg of Mentha pulegium pulp ensiled with 0, 5, 10 and 15 percent of wasted date in 10 litters buckets. Experimental diets were: 1) dried Mentha pulegium pulp, 2) Mentha pulegium pulp ensiled without additive, 3) Mentha pulegium pulp ensiled with 5% waste date, 4) Mentha pulegium pulp ensiled with 10% waste date, 5) Mentha pulegium pulp ensiled with 15% waste date. Buckets were exposure after 45d and several samples were taken for determining chemical composition, in vitro gas production and ruminal degradability by nylon bag technique.

The results showed that dry matter content of Mentha pulegium pulp increased by ensiling and enhancing the percentage of waste date in silages. The neutral detergent fiber (NDF) and ether extract of Mentha pulegium pulp decreased by ensiling but addition of waste date to silage caused to an increase in their percentages. The lowest volume of gas produced among incubation time, was related to Mentha pulegium pulp silage without additive (100 mL). Gas production potential and gas production rate were reduced by ensiling Mentha pulegium pulp, but addition of waste dates to the silages increased these two components. The partitioning factor was the highest value in ensiled oregano pulp without additives (2.23 mg/mL). Rapidly degradable fraction (a) of dry matter (DM), crude protein (CP) and NDF and also potentially degradable fraction (b) of CP and NDF decreased by ensiling, but adding waste date to silages lead to an increase in the degradability of the soluble fraction. Slowly degradable fraction (b) of DM, increased by ensiling and also by addition of wasted date to silages. The degradation rate (c) of DM and NDF decreased by ensiling, but adding different percentages of wasted date up to 15% cause to a significant increase in this component (0.016 and 0.018 respectively).

The results showed that chemical composition and nutritional value of Mentha pulegium pulp decreased slightly by ensiling, but it seems that the best performance of silage production can be observed by adding 15% of waste dates for ensiling oregano pulp.