Oregano dietary supplementation modifies the liver transcriptome profile in broilers: RNASeq analysis.

Intensive farming of broilers involves stressful conditions that reduce animal welfare and performance. New dietary strategies to improve performance and meat quality include the administration of plant extracts. Oregano (Origanum vulgare L.) is known for its antimicrobial, anti-fungal, insecticidal and antioxidant properties. However, studies on diet supplementation with oregano are mainly focused on the evaluation of animal performance, while partial information is available on transcriptomics and nutrigenomics and, in particular, Next Generation Sequencing (NGS) is not widely applied. In this study we tested the effect of an oregano aqueous extract supplemented diet on gene expression in broiler chickens. Whole liver transcriptome of 10 birds fed with a supplemented diet versus 10 controls was analyzed using the RNA-Seq technique. One hundred and twenty-nine genes were differentially expressed with an absolute log fold change >1. The analysis reveals a massive down-regulation of genes involved in fatty acid metabolism and insulin signaling pathways in broilers fed with the oregano aqueous extract supplementation. Down-regulated genes could be associated to chicken lean line, suggesting the potential beneficial effect of oregano supplementation in reducing both abdominal and visceral fat deposition. Down-regulation of insulin signaling pathway related genes suggest that dietary oregano supplementation might be an option in obesity and diabetes conditions.

Critical evaluation of essential oils as rumen modifiers in ruminant nutrition: A review.

Ruminant livestock systems contribute significantly to emission of methane, a potent greenhouse gas as they waste a portion of the ingested energy (2-15%) as methane and a large proportion (75-95%) of the ingested nitrogen as ammonia. Recently, numerous researches have been conducted to evaluate plant secondary metabolites, including essential oils (EO), as natural feed additives in ruminant nutrition and to exploit their potential to improve rumen fermentation efficiency. Essential oils appeared to be very promising compounds as they selectively reduced methane production and protein breakdown in both in vitro and in vivo studies. However, in some studies, the use of EO as feed additives was accompanied with decreased feed degradability and lowered volatile fatty acid. These adverse effects could be attributed to their broad and often non-specific antimicrobial activities within the rumen. Future research should be directed to identification of the active and useful EO compounds, optimization of EO doses, and use of a whole-farm approach with a focus on animal welfare, performance and economic benefits.

Dietary supplementation of Rosmarinus officinalis L. leaves in sheep affects the abundance of rumen methanogens and other microbial populations.

BACKGROUND: Rumen microbiome has a great influence on ruminant health and productivity. Different plant extracts have been tested for their ability to modulate the rumen microbiome to improve feed digestion and fermentation. Among the evaluated plant extracts, essential oils, tannins, and saponins appeared to have positive effects on rumen protein metabolism, volatile fatty acids production, and methane and ammonia production. METHODS: The objective of this study was to evaluate the effect of rosemary (Rosmarinus officinalis L.) leaves and essential oils on rumen microbial populations. Four ruminally cannulated sheep were used in a 4×4 Latin square design fed (21 d/period): 1) a control diet composed of alfalfa hay and concentrate pellet (CTR), 2) CTR supplemented with 7 g/d/sheep of rosemary essential oil adsorbed on an inert support (EO), 3) CTR with 10 g/d/sheep of dried and ground rosemary leaves (RL), and 4) CTR with 10 g/d of dried and ground rosemary leaves pelleted into concentrate (RL pellet). Abundance of total bacteria, archaea, protozoa, and some select bacterial species or groups was quantified using qPCR, while the community of bacteria and archaea was profiled using denaturing gradient gel electrophoresis. RESULTS: No difference in abundance was noted for total bacteria, protozoa, or Ruminococcus flavefaciens between the control and the treatments, but the rosemary leaves, either in loose form or in pellet, decreased the abundance of archaea and the genus Prevotella (P < 0.001). The rosemary leaves in loose form also decreased (P < 0.001) the abundance of Ruminococcus albus and Clostridium aminophilum, while the EO increased (P < 0.001) the abundance of Fibrobacter succinogenes. The community of bacteria and archaea was not affected by any of the supplements. CONCLUSIONS: Being able to affect the abundance of several groups of rumen microbes that are known to be involved in degradation of protein and fiber and production of methane and ammonia, rosemary leaves may be used to modulate rumen microbiome and its function.