Ruminal fermentation, microbial growth and amino acid flow in single-flow continuous culture fermenters fed a diet containing olive leaves

Effect of a two-step fermentation method with rumen liquor on protein quality of wheat bran and rice bran to use as poultry feed

The availability of high quality protein rich feed in many developing countries is limited as well as expensive. Low-quality agro-industrial by-products, i.e., rice bran (RB) and wheat bran (WB), are therefore used as poultry feed irrespective of their low protein content. The main objective of the present study was to improve the protein content and the amino acid profiles of these by-products through rumen liquor mixed fermentation process. A two-step fermentation of some agricultural by-products (e.g., WB and RB) was performed in a controlled environment for 3 h and 6 h. In the 1st and 2nd steps, feedstuff (brans), McDougall buffer as well as collected rumen liquor were mixed with following the proportion of 1:2:3, respectively. After fermentation, brans were dried at 100 °C in an oven. Dried sample were used to analyze the crude protein (CP) as well as amino acid (AA) content. In 1st and 2nd fermentation of the WB, CP content increased 3.3 ± 0.2% (3 h), 4.3 ± 0.2% (6 h) and 7.7 ± 0.1% (3 h), 8.5 ± 0.1% (6 h), respectively compared to control. On the other hand, RB protein content increased by 3.3 ± 0.1% (3 h), 0.8 ± 0.1% (6 h) and 7.3 ± 0.3% (3 h), 4.0 ± 0.1% (6 h) in the 1st and 2nd fermentation step, respectively compared to control. Majority of the AA increased compared to control during the 1st fermentation step for RB and WB. However, In WB, some of the AA did not show significant difference. A number of AA were decreased after the 2nd step for both RB and WB except Methionine, which increased in both steps. In 1st and 2nd steps, Methionine increased by 24.9 ± 5.1% (3 h), 25.9 ± 5.8% (6 h) for WB and 12.2 ± 3.2% (3 h), 13.0 ± 4.5% (6 h) for RB, respectively compared to control. In conclusion brans protein and amino acid quality optimization might be possible through methodical rumen liquor mixed fermentation process for better utilization as poultry diet.

Metagenomic Characterization and Volatile Compounds Determination in Rumen from Saanen Goat Kids Fed Olive Leaves

The accumulation and disposal of by-products deriving from the agro-food industry represents a problem both from an economic and environmental point of view. The use of these matrices in zootechnical nutrition could represent a feasible solution. The aim of the study was to examine the effect of a diet containing olive leaves (OL), a by-product of the olive industry, on the ruminal microbial community of Saanen goat kids and on volatile organic compounds (VOCs) produced during the digestion. Twenty goat kids were randomly divided into two groups of ten goat kids each. The control group (CTR) was fed with a standard diet, while the experimental group (OL+) received a custom-formulated diet containing 10 % OL on a dry matter (DM) basis. After 30 days of trial, genomic DNA was extracted from the rumen liquor and prepared for 16S rRNA-gene sequencing to characterize the rumen microbiota; furthermore, rumen VOCs were also characterized by solid-phase microextraction coupled with gas chromatography-mass spectrometry. The Shannon’s alpha index was not significantly different between the two groups, on the contrary, Bray-Curtis (p < 0.01) and Jaccard (p < 0.01) distances evidenced that feed affected microbial community. Eleven genera were influenced by OL supplementation, with a significant increase (p < 0.05) in Paludibacter, Fibrobacter, Sphaerochaeta Christensenella, Rikenella, Oligosphaera, Candidatus Endomicrobium, Anaerovorax, and Atopobium was observed, while the percentages of Bacteroides and Selenomonas were reduced (p < 0.05). Differences were also observed between the two groups at the family level (p < 0.004). Fibrobacteriaceae, Christensenellaceae, Coriobacteriaceae, Oligosphaeraceae, Candidatus Endomicrobium, and Planctomycetaceae were significantly higher (p < 0.05) in goat kids fed OL diet compared to CTR, while the levels of other identified families, Succinivibrionaceae and Bifidobacteriaceae, were opposite (p < 0.05). Finally, results showed that the main phyla in both groups were Bacteroidetes and Firmicutes; however, no significant differences in the relative abundance of any phyla were observed between the two groups. In addition to what has been reported, the analysis of VOCs at the rumen level showed the ability of the OL integration to induce an increase in hexanoic acid and a parallel decrease in decanal. Furthermore, only in OL+ samples there was the accumulation of α-terpineol to which a wide range of interesting biological properties is attributed. The presence of VOCs associated with health status suggests a favorable role of OL in preserving and improving animal welfare.

Products derived from olive leaves and fruits can alter in vitro ruminal fermentation and methane production

BACKGROUND

The industrial processing of olive generates a high quantity of by-products. The objective of this study was to examine the effects of products derived from olive trees, i.e. leaves, fruits or kernels as a sole substrate (part A), and crude extract from leaves combined with a substrate (part B) on rumen microbial fermentation in an in vitro batch fermentation system. In this study, total gas production, methane production, and concentrations of volatile fatty acids (VFA) and ammonia in ruminal fluid were measured.

RESULTS

In part A, in vitro fermentation of leaves or fruits yielded a gas and total VFA production that were comparable with control substrate, while most of them produced significantly less methane (up to 55.6%) when compared to control substrate. In part B, amongst leaf extracts, only addition of chloroform extract reduced methane production, which was also associated with a decrease (P < 0.01) in gas production. This effect was associated with a significant reduction (P < 0.01) in acetate to propionate ratio and ammonia production, but not in reduction in VFA concentrations.

CONCLUSION

Olive leaf and olive leaf chloroform extract reduced ammonia production and increased the molar proportion of propionate in the rumen and can assist in developing novel feed additives for methane mitigation from the rumen. © 2016 Society of Chemical Industry.