Effects of Lactobacillus plantarum and hydrolytic enzymes on fermentation and ruminal degradability of orange pulp silage

ISSN: 1314-6246 Paya et al. J. BioSci. Biotechnol. 2015, 4(3): 349-357. RESEARCH ARTICLE Hamid Paya 1 Akbar Taghizadeh 1 Saman Lashkari 2 Authors’ addresses: 1 Department of Animal Science, Faculty of Agriculture, University of Tabriz, Tabriz, Iran. 2 Department of Animal Science, Faculty of Agriculture, University of Kurdistan, Sanandaj, Iran. Correspondence: Saman Lashkari Department of Animal Science, Faculty of Agriculture, University of Kurdistan, Sanandaj, Iran. e-mail: Article info: Received: 19 April 2015 Accepted: 5 October 2015 Effects of Lactobacillus plantarum and hydrolytic enzymes on fermentation and ruminal degradability of orange pulp silage ABSTRACT The current study was carried out to examine the effect of inoculants, enzymes and mixtures of them on the fermentation, degradability and nutrient value of orange pulp silage. Orange pulp was treated with water (control), inoculant (Lactobacillus plantarum), enzymes (multiple enzyme) or inoculants + enzymes prior to ensiling (denoted C, I, E and I+E). For ensiled orange pulp, 84 kg of orange pulp were mixed with 16 kg of wheat straw as an absorbent. Three minisilos were prepared for each treatment and ensiled for 90 days. Data of each silo within each silage treatment was averaged and used as an experimental unit in a completely random design. Silage pH, total fatty acid and ammonia nitrogen were determined. Silage pH and lactic acid concentration were lowest and highest respectively for I and I+E (p<0.01), while the lowest (p <0.01) NH3N concentration (49.8 g/kg total N) was observed in I compared to the control. The lowest acetic and butyric acid concentrations were observed in I and I+E compared with the control (p <0.01). The highest metabolizable energy (ME), net energy lactation (NEl), digestible organic matter in dry matter (DOMD), short chain fatty acid (SCFA) and microbial protein (MP) values were observed for I+E (p <0.01). The in vitro degradability of dry matter (IVDMD) was highest (P<0.01) in I+E, while the highest (P<0.01) effective degradability of DM (EDDM) was observed for E and I+E treatments. These results indicated that the bacterial inoculants and combination of enzyme and bacterial inoculants clearly improved silage fermentation characteristic. In addition, the ME, DOM, MP and IVDMD of I+E were significantly improved. Key words: orange pulp silage, degradability, enzymes, Lactobacillus plantarum Introduction Orange pulp is the by-product obtained when orange fruits are pressed to make juice. Orange pulp is a proper energy source, and also has high potential rumen degradability, high apparent digestibility and it is considered as pectin-rich feeds (Lashkari & Taghizadeh, 2015). Orange pulp can be fed fresh, ensiled or dried. Storage of fresh orange pulp is difficult due to its high moisture content. The process of drying is costly and often inconvenient, but using the ensiling orange pulp is cheaper than dry processing and can be easily done by the farmer. The ensiled orange pulp has been fed successfully to dairy cattle (Volanis et al., 2006, Volanis et al., 2004) and fattening lamb (Gado et al., 2011). Using of bacterial inoculants as starters for silages have been recommended to ensure rapid fermentation during the early stages of ensiling, to minimize the loss of nutrients, dry matter and to accelerate the decline of pH by promoting homo-fermentation of major water soluble carbohydrates (WSC) to lactate. Rapidly decreasing pH conserves WSC and declining proteolysis and deamination by inhibiting prolonged fermentation (Muck, 1993). Positive outcomes such as higher lactate: acetate ratios, lower ammonia N, decreased DM losses (Henderson, 1993), increased http://www.jbb.uni-plovdiv.bg 349 ISSN: 1314-6246 Paya et al. J. BioSci. Biotechnol. 2015, 4(3): 349-357. RESEARCH ARTICLE digestibility and degradability, improved aerobic stability and enhanced growth performance (McAllister et al., 1998; Muck, 1993) have been reported by adding microbial inoculation. Most biological additives contain homofermentative lactic acid bacteria to obtain the highest possible amount of lactic acid in silage. Exogenous fibrolytic enzymes can improve the rate of ruminal degradability of dry matter and neutral detergent fiber and also increase the availability of WSC to use as a substrate for lactic acid producing bacteria (LAB) (McDonald et al., 1991; Weinberg et al., 1995). Gado et al. (2011) investigated the effects of addition of exogenous enzymes during ensilage of orange pulp on performance of lamb and reported that growth of fattening lamb was improved by enzyme addition. Nadeau et al. (2000) evaluated effects of inoculants and enzymes and reported that quality of legume and grass silage was improved. However, information is rare on effects of addition of exogenous enzymes, inoculants, and inoculants plus enzyme mixtures during ensilage of orange pulp. The objective of this experiment was to evaluate the effect of inoculants, enzymes and enzyme plus inoculants mixture ensiled with orange pulp on silage fermentation characteristics, in vitro digestibility and DM disappearance. Materials and Methods Silage preparation and treatment Orange pulp (OP) was collected from a food industrial company in Northwestern Iran. The average dry matter content of OP was 170 g/kg. Due to the high moisture content and the physical property (after chopping) of OP (approximately 900 mm3), wheat straw was added as an absorbent. Eighty-four kilograms of chopped OP were mixed with 16 kg of wheat straw (fresh weight basis). The mixture was divided into equal portions for application of four treatments: (1) distilled water (control), denoted as treatment C; (2) inoculant (Lalsil containing L. plantarum MA-18/5U, 3×106 and Propionibacterium acidipropionici MA-26, 3×106 CFU/g of fresh silage. The inoculants were dissolved in distilled water before application to the silage), treatment I; (3) enzymes (Natuzyme Plus; a mixture of enzymes: cellulase, xylanase, β-qlucanase, α-amylase, pectinase, phytase, proteases and lipase activities of 6000000, 10000000, 700000, 700000, 70000, 500000, 3000000 and 30000 U/kg, respectively), treatment E. Enzymes were applied at a rate of 1 g/kg of fresh forage; (4) inoculants plus enzymes, treatment I+E. Treatment I+E was applied in a 350 manner that achieved the same concentrations of inoculants and enzymes as in treatments I and E. An appropriate amount of each product was dissolved in 50 ml of distilled water and applied to 25 kg of freshly mixed OP and wheat straw using a hand sprayer. Three mini-silos were prepared for each treatment and silages were ensiled for 90 days. Chemical composition Silage samples were taken from each silo after opening and mixing of contents. For measurement of pH, silage (15 g) was blended with 135 ml of deionized water for 30 s. The homogenate was filtered through two layers of cheesecloth and pH was immediately measured (Zahiroddini et al., 20 (...truncated)