اثر افزودني باكتريايي و پري بيوتيكي بر پروفايل تخمير و تجزيه پذيري شكمبه اي مواد مغذي سيلاژ ذرت

The effects of bacterial inoculant and prebiotic additive on fermentation characteristics and rumen degradability of corn silage

استفاده از برخي مواد افزودني به سيلاژ ذرت مي­ تواند بر پروفايل تخمير و تجزيه ­پذيري شكمبه ­اي مواد مغذي سيلاژ ذرت تاثير به ­سزايي داشته باشد. هدف:اين طرح به منظور بررسي اثرات افزودني ميكروبي تجاري با نام Lalsil Fresh (حاوي لاكتوباسيلوس بوكنري) و افزودني پري­بيوتيكي (پودر آب پنير) بر روي پروفايل تخمير و تجزيه­ پذيري شكمبه ­اي مواد مغذي سيلاژ ذرت صورت گرفت. روش كار: تيمارهاي آزمايشي بترتيب شامل 1) سيلاژ ذرت شاهد (بدون افزودني)، 2) سيلاژ ذرت تيمار شده با پودر آب پنير (يك درصد يا 10 كيلو بر تن)، 3) سيلاژ ذرت تيمار شده با افزودني باكتريايي Lalsil Fresh به ميزان 106×1/8 واحد تشكيل دهنده كلني به ازاي هر گرم علوفه تازه و 4) سيلاژ ذرت تيمار شده با پودر آب پنير (يك درصد) به همراه افزودني باكتريايي لالسيل (106×8/1 واحد تشكيل دهنده كلني به ازاي هر گرم علوفه تازه) بودند. نتايج: در پايان دوره آزمايشي 90 روزه تيمار پودر آب پنير و افزودني باكتريايي سبب كاهش توليد پساب و افزايش در ماده خشك سيلاژ نسبت به تيمار شاهد شدند (0/05< P). افزودن پودر آب پنير به علوفه ذرت سيلوئي سبب افزايش غلظت پروتئين خام و كاهش غلظت الياف در سيلاژ گرديد (0/05< P). افزودني لالسيل باعث كاهش pH سيلاژ ذرت شد (0/05< P). مخلوط افزودني ميكروبي و پري­بيوتيكي كمترين ميزان اسيدهاي چرب فرار و ازت آمونياكي را به خود اختصاص دادند (0/05< P). تيمار پودر آب پنير سبب افزايش معني­ دار تجزيه­ پذيري بخش محلول، بخش كند تجزيه و ثابت نرخ تجزيه گرديد (0/05< P). افزودني باكتريايي نيز سبب افزايش قابليت ناپديد شدن ماده خشك سيلاژ ذرت شد. نتيجه ­گيري نهايي: نتايج آزمايش نشان داد كه پودر آب پنير مي­ تواند سبب بهبود ارزش تغذيه ­اي، افزايش قابليت هضم و نرخ نجزيه پذيري سيلاژ ذرت گردد. همچنين افزودني باكتريايي با كاهش سريع pH موجب بهبود كيفيت سيلاژ حاصله مي­ گردد.

Introduction: Forages are used as hay, silage, hilage or soilage for ruminant nutrition. Ensiling is a widely accepted method for preservation forages or crops. Packing chopped forages and sealing the silo results in anaerobic conditions in the silo. Water soluble carbohydrates (WSC) are fermented into lactic acid by lactic acid bacteria (LAB) in anaerobic condition of the silo and consequently lead to pH falling. Low pH in the silo prevents bacteria or other microorganism’s development. However, low WSC concentration or lactic acid bacteria population in the forages or crops may results in bad fermented silages. Silage additives are a group of nutritive or non-nutritive substances which widely are used to enhancing fermentation, improving aerobic stability or increasing nutritive value of silages. This study was conducted to determine the effects of whey (as a WSC source) and Lalsil (containing Lactobacillus Buchneri) inoculants on chemical composition, pH, aeirobic stability and in vitro digestibility of corn silage. Material and methods: Corn crops were chopped at 25 mm of theoretical cut length. The four various treatments in the current experiment were as: 1. Control (corn silage without any inoculant), 2. Corn silage treated with whey (1% or 10 kg/T) 3. Corn silage treated with Lalsil Fresh (include Lactobacillus Buchneri) at 1.8 × 10 6 CFU/gr and 4. Corn silage treated with whey (1% or 10 kg/T) in addition to bacterial additive (at 1.8 × 10 6 CFU/gr of fresh forage). The corn crops were inoculated by spraying the Lalsil Fresh or whey over the crops and then were filled in laboratory mini silos (6 L capacity) for 90 days and were kept at room temperature. Dry matter content of corn silage was determined in oven-dry for 72 h at 60 °C. The dried samples were ground to pass through a 1-mm screen and then analysed for total nitrogen and neutral detergent fiber (NDF). Also, rumen degradability of dry matter (DM), crude protein (CP) and NDF were determined using rumen fistulated sheep. Silage extract were used for pH, ammonia-N, volatile fatty acids (VFA), lactate and WSC. Results and discussion: Concentration of DM was higher in both prebiotic and bacterial treatments at the end of experimental period (P<0.05). Application of whey or Lalsil Fresh reduced effluent production during ensiling period (P<0.05). Addition of whey to corn silage caused signifacant increase (P<0.05) in WSC and CP concentrations because of higher concentration of WSC and CP in whey when compared with corn forage. However, a reduction (P<0.05) was observed in NDF concentration of corn silage in response to whey supplementation. The pH of silages were lower in bacterial inoculated treatments (P<0.05) due to higher fermentation rate in silage in response to lactic acidproducing bacteria. The mixture of prebiotic and probiotic resulted in silages with least concentrations of volatile fatty acids and ammonia (P<0.05). This may lead to lower DM disapearance in ensilage period which consequently lead to lower nutrients losses and higher DM concentration. Concentrations of VFA and ammonia-N were lower in whey treated silages (P<0.05). Also, concentrations of VFA and ammonia-N were reduced in Lalsil Fresh treated silages (P<0.05) maybe due to rapid falling of pH in first days of fermentation phase in silage. In the in situ trial, adding of whey increased the DM disappearance (P<0.05) due to increase in WSC and CP and lower NDF and pH. Also a significiant increase were occurred in “a” and “b” fractions and degradability rate of DM in corn silage (P<0.05). Higher amount of rapidly or slowly degradable DM in whey treatments implies that whey treated silages had higher digestibility and nutritive value in rumen. DM disappearance was lower in Lalsil treatments in the last hours of incubation (P<0.05). Also, application of Lalsil fresh resulted in silages with higher NDF degradability (P<0.05) due to excessive proteolysis of NDF in silages due to lower pH which leads to rapid degradation of NDF in rumen environment. Conclusion: Results suggest that whey had a positive effect on nutritive value (DM, CP, WSC and NDF) and degradability of corn silage. Treating silages with bacterial inoculant (Lalsil Fresh) produced silage with good fermentation pattern and lower pH. Then, simultanous application of whey and Lalsif Fresh at ensiling corn crops may improve nutritive value, fermentation pattern and rumen degradbility of nutrients