Effect of dietary inclusion of cashew nut shell liquid on metabolic functions of rumen bacteria in West African dwarf goats

R Y Aderinboye,K O Olagoke,J Njuguna ,Eunice Machuka ,Kolawole Adebayo ,F Stomeo

doi:10.4314/njb.v34i1.15

Abstract

This study investigated the effect of dietary inclusion of cashew nut shell liquid (CNSL) on rumen microbial metabolic functions in West African dwarf goats. Twenty-four West African dwarf goats were divided into four groups of six animals each. Each group of animals was fed a basal diet of Panicum maximum and supplemented with one of four concentrate pellets containing CNSL at the rate of 0, 2, 4 and 6 ml/kg in a completely randomized design. Rumen fluid samples (n=6/animal) were collected from each animal after 60 days of feeding to assess the rumen metabolic functions in response to CNSL using the 16S rRNA metagenomic approach. Results revealed that the function of ammonia oxidizers was prominent while chitin degradation ranked least. The inclusion of 4 and 6 ml/kg of CNSL in supplemental diets for goats increased (P < 0.05) the function of xylan degraders while ammonia oxidizers, dehalogenation, nitrite reducers, methanogens amongst others were unaltered (P > 0.05). It can be concluded that 4 6 ml/kg of CNSL in supplemental pellets for goats enhanced xylan degraders implying higher hemicellulolytic functions which has implication for increased hemicellulose degradation in the rumen.

Highlights

Microorganism in the rumen can be assigned to different functional groups such as cellulolytics, amylolytics, proteolytics, which degrade the wide variety of feed components or further metabolize some of the products formed by other microbes (Henderson et al, 2015)
The operational taxonomic units (OTUs) were assigned to 33 different phyla and the dominant phyla included the Euryarchaeota, Actinobacteria, Bacteroides, Firmicutes, Proteobacteria, Spirochaetes and Verrucomicrobia which represented 96% of the total OTUs
In samples from the control group (Figure 1 a), taxonomic-tophenotype mapping revealed the presence of ammonia oxidizers (48.6%), bacteria associated with dehalogenation (44.5%), sulfide oxidizer (43.0%), nitrite reducers (30.9%), sulfate reducers (27.5%), cellulose degraders (15.5%), methanogens (13.9%), xylan degraders (13.3%) amongst other minute functions such as chitin degradation and nitrogen fixation

Summary

Introduction

Microorganism in the rumen can be assigned to different functional groups such as cellulolytics, amylolytics, proteolytics, which degrade the wide variety of feed components or further metabolize some of the products formed by other microbes (Henderson et al, 2015). Microorganisms have different metabolic functions within the rumen, these functions are specific to each group of microbes (DAF, 2017). According to McChann et al (2014), diverse microbial community adaptto a wide array of dietary feedstuffs and management strategies. Numerous dietary strategies have been employed to modify rumen function in order to improve animal performance (Dreux, 2017)and a number of plant extracts have gained interest in ruminant nutrition as rumen modifiers (Patra & Saxena, 2009; Patra, 2011; Flachowsky & Lebzien, 2012). CNSL, an extract from cashew nut shell has been studied in many in vitro trials with evidence for its regulatory effect on rumen metabolic processes methanogenesis (Watanabe et al, 2010; Oh et al, 2017)

Methods

Results

Conclusion