Effect of supplementation of urea on the nutritive value and fermentation characteristics of apple pulp silages

Abstract

The aim of current experiment was to determine the effect of supplementation of urea on the nutritive value and fermentation characteristics of apple pulp silage. Apple pulp obtained from apple with Granny Smith (Malus domestica) varieties was used in the research. Apple pulp were ensiled in special glass jars with 1.5 L capacity. Urea (0, 0.5, 1.0, 1.5, 2.0 and 2.5% on DM basis) was added homogeneously to apple pulp in triplicate. The experimental silos were placed in a room until opening after 45 day of preservation to determine chemical composition and silage fermentation parameters. The addition of urea to apple pulp reduced the water soluble carbohydrate (WSC), content of neutral detergent fiber (NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL) whereas the supplementation of urea significantly (P<0.01) increased crude protein (CP) contents of resultant silages. The addition of urea to apple pulp significantly (P<0.01) increased pH, lactic acid (LA), propionic acid (PA), butyric acid (BA) and ammonia nitrogen (NH3-N) contents of the resultant silages whereas the supplementation of urea significantly (P<0.01) reduced the acetic acid (AA) contents. Addition of urea to apple pulp increased in vitro gas production, digestible organic matter (DOM), metabolic energy (ME) and lactic acid bacteria (LAB), and significantly reduced yeast and mold count (P<0.01). The urea supplementation also increased the aerobic stability of the resultant silages. It can be concluded that supplementation of urea to apple pulp at 2.0 and 2.5% can be recommended to improve the nutritive value and fermentation parameters of the resultant silages.