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

Abstract

Six single-flow continuous culture fermenters were used to determine fermentation profile, microbial growth and amino acid (AA) flow promoted by olive leaves supplemented with barley grains and faba beans (OLSUP), and alfalfa hay (AH). Two incubation runs were carried out with three fermenters inoculated with ruminal fluid from wethers and three from goats. The inoculum source did not affect (p = 0.059 to 0.980) any of the parameters. Daily volatile fatty acid (VFA) production and carbohydrate digestibility were greater (p = 0.009 and 0.024, respectively) for AH, therefore the pH values were lower (p = 0.015) than for OLSUP. Acetate was greater (p < 0.001) and isobutyrate, isovalerate and caproate lower (p < 0.001 to 0.006) for AH with greater acetate/propionate (p = 0.014) and 'VFA/digested carbohydrate' (p = 0.026) ratios. Daily microbial N flow and efficiency were greater (p = 0.016 and p = 0.041) for diet AH. Individual AA flows were greater (p < 0.001 to 0.016) for AH, but microbial essential AA proportion was greater for OLSUP (p = 0.015). The results indicate that OLSUP promoted lower bacterial growth and AA flow than AH, which could have been partially due to a limitation of N availability to ruminal microbes.

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

“…This hypothesis is supported by low NH 3 ‐N concentration observed with addition of extracts to each of substrates. The results in our study are in line with the findings in wethers and goats fed dry olive leaves ad libitum , or with those previously reported in fermenters fed a diet containing olive leaves in comparison to alfalfa hay …”

“…In addition, olive leaf also stimulated some favourable pathways such as propionate production, which caused a significant reduction in acetate to propionate ratio. These findings were consistent with the result obtained by Molina‐Alcaide et al , who reported lower acetate to propionate ratio in continuous culture fermenters fed a diet containing olive leaves in comparison to alfalfa hay. The decrease in acetate to propionate ratio observed with olive leaves might be due to a reduced growth of cellulolytic bacteria in the rumen, which is in line with a previous study …”

Use of tomato and cucumber waste fruits in goat diets: effects on rumen fermentation and microbial communities in batch and continuous cultures

“…On days 6, 7 and 8 the effluents were removed, weighed and sampled for VFA, NH 3 -N and total N analyses as described in Expt 1. Each sampling day, 500 ml of effluent was used to isolate bacterial pellets by differential centrifugation as described by Molina-Alcaide et al (2010). Bacterial pellets were lyophilized, pooled by fermenter and analysed for purine bases (PB) and N content.…”

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

“…Shakeri et al [19] showed a reduction by 15-53% of methane production, an increase in propionate production, and a significant reduction in acetate to propionate ratio in the rumen when OL and the different parts of the fruit were added to the in vitro incubations compared with the two different substrates used as control (oaten chaff and commercial concentrate). Molina-Alcaide et al [20] reported a lower acetate-to-propionate ratio in continuous culture fermenters fed a diet containing OL (3.74 ratio) in comparison to a diet with olive leaves supplemented with barley grain (3.74 vs. 4.82 ratio, respectively). The addition of different concentrations of OL extract in the in vitro fermentation of a 50:50 forage:concentrate diet was tested by using a rumen simulation technique which evidenced a significant increase of 4-9% in the production of VFAs and propionate (11-14%), and a decrease in butyrate release (−8%) and total protozoa count (−8%) [21].…”