ObjectiveAn experiment was conducted to investigate the effects of a specific mixture of essential oils (MEO), containing thyme, clove and cinnamon EO, on rumen microbial fermentation, nutrient apparent digestibility and blood metabolites in fistulated sheep.MethodsSix sheep fitted with ruminal fistulas were used in a repeated measurement design with two 24-d periods to investigate the effect of adding MEO at 0 (control), 0.8, and 1.6 mL/d on apparent nutrient digestibility, rumen fermentation characteristics, rumen microbial population and blood chemical metabolites. Animals were fed with a 50:50 alfalfa hay:concentrate diet.ResultsRuminal pH, total volatile fatty acids (VFA) concentration, molar proportion of individual VFA, acetate: propionate ratio and methane production were not affected with MEO. Relative to the control, Small peptides plus amino acid nitrogen and large peptides nitrogen concentration in rumen fluid were not affected with MEO supplementation; while, rumen fluid ammonia nitrogen concentration at 0 and 6 h after morning feeding in sheep fed with 1.6 mL/d of MEO was lower (p<0.05) compared to the control and 0.8 mL/d of MEO. At 0 h after morning feeding, ammonia nitrogen concentration was higher (p<0.05) in sheep fed 0.8 mL/d of MEO relative to 1.6 mL/d and control diet. Ruminal protozoa and hyper ammonia producing (HAP) bacteria counts were not affected by addition of MEO in the diet. Relative to the control, no changes were observed in the red and white blood cells, hemoglobin, hematocrit, glucose, beta-hydroxybutyric acid, cholesterol, total protein, albumin, blood urea nitrogen and aspartate aminotransferase and alanine aminotransferase concentration. Apparent total tract digestibility of dry matter, crude proten, organic matter, and neutral detergent fiber were not influenced by MEO supplementation.ConclusionThe results of the present study suggested that supplementation of MEO may have limited effects on apparent nutrient digestibility, ruminal fermentation and protozoa and HAP bacteria count, blood cells and metabolites.

Eighteen natural medicinal plant essential oils and garlic oil obtained from semi-arid climate were conducted to evaluate their effects on in vitro rumen microbial fermentation and their effectiveness for decrease in vitro ruminal methane production. 50 ml of buffered rumen fluid (1:2; rumen fluid: buffer solution) were introduced in 125 ml serum bottles containing 500 mg of 80:20 alfalfa hay to concentrate as basal diet and or basal diet plus 1 µ/ml of medium of medicinal essential oils or garlic oil (6 replicates for each treatment) and incubated for 24 h at 38.7°C. Head space gas pressure of each bottle was recorded using a pressure transducer at 2, 4, 6, 8, 10, 12, 16 and 24 h of the incubation and a sample was collected to determine methane concentration. In the end of incubation pH measured and samples were collected for ammonia nitrogen concentration and dry matter (DM) and crude protein (CP) disappearance were recorded and feed fermentation efficiency (FFE = mg IDMD/ ml accumulative gas produced at 24 h post incubation) were calculated. Medicinal plant essential oils which caused an increase in FFE and decrease in gas production in-contrast with those in control were selected as the candidates for gas analysis and determine their effects on methane concentration. All essential oils resulted in a significant decrease (P < 0.05) in total gas production (except in Rosemary, Dill, Clove, Fennel, Pistachio hull and black pepper) and both IDMD and ICPD (except in Black pepper, Rosemary and Dill). Of the 19 samples tested coriander, rosemary, cinnamon, red basil, oregano 2, black pepper, cumin, caraway and dill that selected as the candidates for gas analysis and determine their effects on methane concentration increase in FFE and decrease in gas production in contrast with those in control. Increase in FFE was more noticeable for thyme, lemon pulp and cinnamon essential oils (22, 21.95 and 3.2 times more than those of control, respectively). Results indicated that coriander, cinnamon, red basil, oregano 2, cumin, caraway and dill essential oils caused a significant decrease (P < 0.05) in total methane production (1. 5, 0.3, 1.0, 1.3, 1.1, 1.1 and 2.0 compared with 2.3 in control as mmol/g DM incubated, respectively).

The aim of the study was to determine the effects of different heat-processing methods of flaxseed on the in situ effective dry matter degradability (EDMD) and the in situ effective crude protein degradability (ECPD). The treatments included roasting, steep roasting, rolled roasting, rolled steep roasting, microwave irradiation and extrusion. Three rumen-fistulated sheep were used for in situ incubations. Furthermore, the effects of heat-processing methods on post-ruminal in vitro nutrient disappearance and total tract disappearance were measured by a three-step in vitro technique. The seeds were roasted and extruded at 140°C to 145°C. One lot of roasted seeds was gradually cooled for about 1 h (roasting) and another lot was held in temperature isolated barrels for 45 min (steep roasting). Moreover, roasted and steep roasted flaxseed was rolled in a roller mill. The lowest and highest EDMD was observed for unheated and extruded flaxseed, respectively (p < 0.05). The highest ECPD was observed for extruded flaxseed (p < 0.05). Roasting and microwave irradiation reduced ECPD of flaxseed (p < 0.05). In vitro post-ruminal disappearance of crude nutrients including fibre fractions was highest for rolled-roasted and rolled steep-roasted flaxseed (p < 0.05). The lowest and highest total tract disappearance rates of crude nutrients and fibre fractions were estimated for unheated and extruded flaxseed, respectively (p < 0.05). The post-ruminal disappearance of crude nutrients was also increased by roasting, in which rolling enhanced this effect. In conclusion, all investigated heat treatments had significant effects on in situ and in vitro degradability of nutrients. As well, rolling of roasted flaxseed enhanced the respective effects. Therefore, different methods of heat processing can be used to modify the feed value of flaxseed for specific purposes.

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