Nutritional value, fermentation losses and aerobic stability of elephant grass (Pennisetum purpureum Schum.) silage treated with exogenous fibrolytic enzymes

Maikon Figueredo Lemos,Aurielle Silva Medeiros,Pedro Mouzinho De Oliveira Neto,Camila Oliveira Santos,Caio Felipe Barros Souza,Pedro Henrique Ferreira Da Silva,Marcos Antonio Vanderlei Silva,Alexandro Pereira Andrade

doi:10.4025/actascianimsci.v42i1.48272

Abstract

The aim of this study was to evaluate nutritional value, fermentation losses, and aerobic stability of elephant grass silage (Pennisetum purpureum Schum.) treated with exogenous fibrolytic enzymes. The experiment was conducted in a completely randomized design with four replicates (experimental silos) and five levels of fibrolytic enzymes (0, 1.5, 3.0, 4.5 and 6.0%). For this, the elephant grass was ensiled at 70 days of age in plastic buckets with 20L capacity. Silos were opened 60 days after sealing. Analyses were made for chemical composition, in vitro dry matter digestibility (IVDMD), effluent losses (EL), gas losses (GL) and dry matter recovery (DMR), as well as the aerobic stability of the silage. Data were analyzed with PROC REG of SAS® University, at 5% probability. There was an increase in IVDMD content (p < 0.0001) and reduction in NDF and ADF contents (p < 0.0001) according to enzyme levels. These results were related to the increase in the degradation of fiber fractions. There were higher EL (p = 0.0062) as a function of enzyme levels and aerobic deterioration after silo opening, at all levels tested. Thus, it can be concluded that the exogenous fibrolytic enzymes change the chemical composition of elephant grass silage, and increase its digestibility and nutritional value. Moreover, when used alone as an additive, fibrolytic enzymes are not able to recover all dry matter of this silage (with effluent and gas losses), and are not able to maintain aerobic stability in the first hours after opening the silos.

Highlights

The goal of the study was to evaluate the nutritional value, fermentation losses and aerobic stability of elephant grass silage treated with levels of exogenous fibrolytic enzymes
The levels of fibrolytic enzymes increased linearly effluent losses, as already highlighted above. These results are similar to those of Nolan, Doyle and O’Kiely (2018), who observed an increase in effluent production in silages of annual ryegrass (Lolium multiflorium L.) treated with fibrolytic enzymes (163 and 320 g kg-1 for control and fibrolytic enzyme, respectively)
The authors reported that fibrolytic enzymes were not able to promote total recovery of dry matter, observed in the present study and which corroborates Andrade et al (2012), who suggest that tropical grass silages without absorbent additives are subjected to significant effluent losses

Summary

Introduction

The uneven distribution of rainfall in Brazil causes many rural producers to adopt food conservation practices, so that they can maintain the performance of their herds during periods of low forage production, usually in the dry season (Rassini, 2004). In this sense, silage is one of the alternatives for the conservation of forage through anaerobic fermentation (Veriato, Tolentino, Alves, Jayme, & Moura, 2018). The ensiling of these grasses has some advantages: high forage production, better use of the cultivated areas of the property, with a reduction in the areas destined to crops; in addition to lower forage losses in the dry period of the year (Bonfá et al, 2015)

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Results