Abstract

The effect of wheat bran (WB) as a silage additive on chemical composition, in situdegradability and in vitro gas production of citrus pulp silage (CPS) was investigated.The whole fresh citrus pulp was manually chopped and used as untreated or treated with 6, 12, or 18 g WB/kg fresh citrus pulp for ensiling. The data were analyzed in a completely randomized design that showed experimental treatments had no significant effect on DM% of silages but with increasing WB, crude protein (CP%) linearly and quadratically increased (P < 0.05). Ammonia nitrogen, ether extract (EE%), ash% and pH were similar among treatments (P > 0.05). Result showed that with increasing WB, NDF concentration linearly increased (P < 0.05) but acid detergent fiber (ADF) concentration linearly and quadratically decreased among treatments (P < 0.05). Aerobic stability of silage exhibited a negative linear and quadratic relationship (P < 0.05), with increasing the level of WB. Data of flige point displayed that all treatments had very good quality. Data of in situ degradability indicated that soluble degradable fraction (a) was significantly higher in control group (P < 0.05) and with the addition of WB to silage, (a) parameter significantly decreased(P < 0.05). Non-soluble degradation fraction (b) was not affected by different treatments (P > 0.05). The fractional degradation rate (c) with increasing of WB significantly increased (P < 0.05). Potential degradability (a + b) of silages with increasing of WB linearly decreased (P < 0.05). Effective degradability (ED) of silages was not affected by different treatments (P > 0.05). Potential gas production (b) andfractional rate of gas production (c) demonstrated a linear and quadratic relationship (P < 0.05) with increasing WB. The organic matter digestibility (OMD), net energy (NEl), metabolisable energy (ME) and short chain fatty acids (SCFA)  were significantly different between control group and treatments with WB (P < 0.05). This data suggest that the addition of WB to CPS can improve the nutritional value of citrus pulp silage without any adverse effects on this by-product.

Key words: Aerobic stability, citrus pulp silage, silage additive, degradability.

Abbreviation

Abbreviations: ADF, Acid detergent fiber; NDF, neutral detergent fiber; WB, wheat bran; CPS, citrus pulp silage; DM, dry matter; CP, crude protein; EE, ether extract;OMD, organic matter digestibility; ME, metabolisable energy; SCFA, short chain fatty acids.