Utjecaj koncentracije inokulanta na promjene sadržaja kiselina i mikrobiološku kvalitetu silaže lucerne tijekom aeracije

master's thesis

• Title (english): THE EFFECT OF DIFFERENT INOCULANT CONCENTRATION APPLICATION ON CHANGES IN ACID CONTENT AND MICROBIOLOGICAL QUALITY OF ALFALFA SILAGE DURING AERATION
• Author: Vida Vertuš
• Mentor: Marija Duvnjak (mentor)
• Committee member: Marija Duvnjak (predsjednik povjerenstva)
• Committee member: Kristina Kljak (član povjerenstva)
• Committee member: Mirna Mrkonjić Fuka (član povjerenstva)
• Granter: University of Zagreb; Faculty of Agriculture; (Department of Animal Nutrition); Zagreb
• Defense date and country: 2023-09-11, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Agronomy

Abstract

Prilikom izuzimanja silaža i aeracije, dolazi do aktivnosti aerobnih mikroorganizama i kvarenja silaže, što se očitava razgradnjom mliječne kiseline i hranjivih tvari te povećanjem temperature silaža. Cilj rada bio je istražiti mikrobiološke karakteristike te promjene sadržaja mliječne kiseline i HMK u silaži lucerne siliranoj bez i s tri različite koncentracije inokulanta bakterija mliječne kiseline (BMK) tijekom sedmodnevne aeracije silaže. Silaža lucerne silirana je s tri koncentracije inokulanta koji je kombinacija homofermentativnih i heterofermentativnih BMK (T2: standardna, T3: 1,5x standardne i T4: 2x standardne) te kontrola bez dodatka BMK (T1) u vakuum vrećicama (SmartVac, Status d.o.o.) u peteroplikatu. Nakon 124. dana siliranja, silaže su aerirane tokom 7 dana. Promjena temperature u silažama mjerena je svakih 15 min tijekom cijelog razdoblja aeracije, dok su silaže uzorkovane 0., 3. i 7. dan i analizirane na broj BMK, kvasaca, plijesni i spora bakterija maslačne kiseline (BAB) te sadržaje fermentacijskih parametara. U cijelom periodu aeracije sve testirane silaže ostale su aerobno stabilne. Međutim, T1 i T4 na kraju aeracije imale su 3x veće vrijednosti mliječne kiseline nego T2 i T3 ukazujući na neočekivanu izrazitu homofermentativnu aktivnost u T4. Primjena inokulanta na silaže imala je pozitivan utjecaj na sadržaj octene kiseline na kraju aeracije u usporedbi s kontrolom (38 – 47 g/kg ST u T2 – T4 vs. 30 g/kg ST u T1) i sadržaj propionske kiseline (0,83 – 3,32 g/kg ST u T2 – T4 vs. 0,76 g/kg ST u T1). Najveći sadržaj maslačne kiseline na kraju aeracije bio je u T3 u kojem je bio i najveći broj BAB. Primjena inokulanta imala je pozitivan utjecaj na broj BMK na kraju aeracije (oko 1,16x više BMK u T2 – T4), dok su kvasci i plijesni bili ispod prosjeka u svim testiranim silažama (kvasci < 3,1 log10 CFU/g, plijesni < 4,1 log10 CFU/g). Rezultati istraživanja pokazuju kako je inokulant poželjno koristiti u koncentraciji preporučenoj od strane proizvođača jer ta koncentracija omogućava optimalnu aktivnost homofermentativnih i heterofermentativnih BMK te proizvodnju silaže s optimalnim sadržajem mliječne kiseline i HMK za aerobnu stabilnost.

Abstract (english)

During silage sampling and aeration, the activity of aerobic microorganisms leads to silage deterioration which is indicated by the degradation of lactic acid, nutrient loss and an increase in silage temperature. This study aimed to investigate microbiological characteristics as well as changes of content in lactic acid and VFA in alfalfa silage ensiled without and with three different concentrations of lactic acid bacteria (LAB) inoculant during a seven-day silage aeration. Alfalfa silage was ensiled with three combined concentrations of homofermentative and heterofermentative LAB inoculant (T2: standard, T3: 1.5x standard and T4: 2x standard) and control without LAB inoculant (T1) in vacuum bags (SmartVac, Status d.o.o.). All of the treatments were sampled in five repetitions. After 124 days of ensilling, the silages were subjected to aeration for 7 days. The change in silage temperatures were measured every 15 minutes during the whole aeration period and were sampled 0th, 3rd and 7th day to determine the number of LAB, yeasts, moulds, and spores of butyric acid (BAB), as well as fermentation parameters. During the entire period of aeration, all the tested silages remained aerobically stable. However, T1 and T4 had 3x higher lactic acid values when compared to T2 and T3, thus showing an unexpectedly pronounced homofermentative activity in T4. Inoculant application had a positive influence on acetic acid content at the end of aeration when compared to the control group (38 – 47 g/kg DM in T2 – T4 vs. 30 g/kg DM in T1) and propionic acid (0.83 – 3.32 g/kg DM in T2 – T4 vs. 0.76 g/kg DM in T1). The highest butyric content was in T3, which also had the highest number of BAB. Inoculant application showed a positive effect on LAB numbers at the end of aeration (about 1.16x more LAB in T2 – T4 ) while yeasts and moulds were below average in all tested silages (yeasts < 3.1 log10 CFU/g, moulds < 4.1 log10 CFU/g). The results show when using an inoculant, it is preferred to use the concentration recommended by the producer, because that concentration enables the optimal activity of homofermentative and heterofermentative LAB and the production of silage with an optimal content of lactic acid and VFA for aerobic stability.

• Keywords: aerobna stabilnost; silaža lucerne; koncentracija inokulanta BMK; fermentacijski parametri; broj mikroorganizama
• Keywords (english): aerobic stability; alfalfa silage; LAB inoculant concentration; fermentation parameters; number of microorganisms
• Language: croatian
• URN:NBN: urn:nbn:hr:204:124597
• Study programme: Title: Animal Nutrition and Feed Science; Study programme type: university; Study level: graduate; Academic / professional title: magistar/ magistra inženjer/inženjerka hranidbe životinja i hrane (magistar/ magistra inženjer/inženjerka hranidbe životinja i hrane)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Embargoed access; Embargo expiration date: 2024-09-15
• Created on: 2023-09-15 08:20:37