Effects of bacterial silage inoculants on whole-crop maize silage fermentation and silage digestibility in rams

Bd Nkosi,T Langa,R Meeske,Rs Thomas

doi:10.4314/sajas.v41i4.5

Abstract

This study evaluated the effects of ensiling whole-crop maize with bacterial inoculants, Lactococcus lactis (LL) and Lactobacillus buchneri (LB), on the fermentation and nutrient digestibility in rams. Whole-crop maize (265 DM g/kg) was ensiled for 90 days in 210 L drums with no additive, or with LL or LB. After three months, the drums were opened and the silage was sampled for fermentation characteristics. Diets were produced by mixing the whole-crop maize silage with lucerne hay (90 : 10) on an “as fed” basis, and a digestibility study was conducted using five South African Mutton Merino rams (37.2 ± 2.2 kg live weight) per treatment. Inoculating maize silage with LL and LB reduced ammonia nitrogen concentration, but did not affect silage pH. The concentration of lactic acid was increased with LL compared to the other treatments. A higher concentration of acetic acid was obtained with LB inoculation compared to the other treatments. The aerobic stability of the silage was improved with LB while it was reduced with LL inoculation, as indicated by a higher CO 2 production than the latter. The intake and digestibility of dry matter, organic matter, crude protein and fibre were improved by inoculation. Furthermore, inoculations resulted in improved nitrogen retention. It was concluded that the inoculants improved silage fermentation and diet digestibility. Inoculation with LB improved aerobic stability and LL inoculation reduced it. Keywords: Alfalfa, lucerne, aerobic stability, Lactococcus lactis , Lactobacillus buchneri

Highlights

The ensiling of crops has been a preferential method in maintaining the energy nutrient content of crops, ensuring a good nutritional value when used as feed (Vervaeren et al, 2010)
This study evaluated the effects of ensiling whole-crop maize with bacterial inoculants, Lactococcus lactis (LL) and Lactobacillus buchneri (LB), on the fermentation and nutrient digestibility in rams
A pH range of 3.7 - 4.2 is generally considered to be beneficial for whole-crop maize preservation (Kung & Shaver, 2001) and in our study the pH was less than 3.9, which is indicative of well-preserved silage

Summary

Introduction

The ensiling of crops has been a preferential method in maintaining the energy nutrient content of crops, ensuring a good nutritional value when used as feed (Vervaeren et al, 2010). Whole-crop maize (Zea mays L.) is one of the most ensiled crops in the world, due to its ease of cultivation, high production rate, low buffering capacity and high concentration of WSC (McDonald et al, 2002). To ensure that there is enough LAB for the efficient fermentation of forages during ensiling, bacterial inoculants comprising mainly LAB are used. These micro-organisms have been reported to increase lactic acid concentration and cause a rapid decline of pH in silage (Weinberg & Muck, 1996). Hetero-fermentative LAB was developed to improve aerobic stability, as the conversion of lactic acid into acetic acid prevents rapid aerobic degradation of nutrients after silage opening (Driehuis et al, 2001, Danner et al, 2002)

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