The Effect of Myrtle (Myrtus communis) Leaves on Digestibility, Some Blood and Rumen Metabolites and Protozoa Morphology in Arabi Sheep

Myrtle is from Myrtaceae family with scientific name, Myrtus communis. Myrtle leaves mainly containing terpynolen, cineol, linalool, terpineol and acetate lynalyl. Also including the active ingredients as phenolic acids such as galic acid, vanillic acid and ferulic acid, tannins such as galotannin and flavonoids such as, myrcetin, catechin and quercetin. Many plants synthesis secondary metabolites that have antimicrobial activity, regulation of ruminal fermentation and subsequently improve nutrient intake. Information on the use of myrtle leaves in ruminant nutrition is rare, so this experiment was designed to investigate the effect of myrtle leaves on digestion, some blood and rumen parameters and protozoa species in Arabi sheep.   At first step, the appropriate level of myrtle leaves between the levels 0.2, 0.4 and 0.6 % with diet 70:30 concentrate to forage was determined by in vitro methods (gas test and tilly and terry method). Rumen fluid was collected from sheep before the morning feeding. About 200 mg sample (1.0 mm screen) incubated in 100 ml vials with 35 mL buffered rumen fluid under continuous CO2 reflux for 2, 4, 6, 8, 10, 12, 16, 24, 48, 72 and 96 h, at 39°C. Cumulative gas production data were fitted to the exponential equation Y=B (1−e−ct). Partitioning factor, microbial biomass and truly digested organic matter was calculated. For determination of partitioning factor at the end of each incubation period, the content of vials was transferred into an Erlenmeyer flask, mixed with 20 mL neutral detergent fiber solution, boiled for 1 hour, filtered, dried (in oven at 60 °C for 48 h) and ash. Digestibility of dry matter and NDF of samples were determined using tilly and terry method. Rumen fluid was collected from animals, and were mixed with McDougall buffer in a ratio 1:4. After gasifying with CO2, tubes were incubated at 39 ˚C. After 48 h of fermentation, 6 mL of 20% HCl solution and 5 mL pepsin solution were added and the incubated for 48 h, simulating post-ruminal degradation. After incubation, the residual substrates of each tube were filtered and used to determine digestibility of DM and NDF.
At the second step of experiment, the appropriate amount of myrtle leaves; 0.4 %; was used in feeding 8 Arabi sheep (23±1.5 kg) for 30 days. In the end of experiment, feed intake, digestibility, protozoa morphology, some blood metabolites and rumen parameters were measured. Data were subjected to analysis as a completely randomized design using the General Linear Model (GLM) procedure of SAS. version 9.1. The Duncan multiple range test was used to compare means at P< 0.05.   The results of in vitro step showed that the best fermentation, gas production and digestibility were for 0.4% the myrtle leaves. On the base of the result of in vivo step, using of myrtle leaves had not any effect on dry matter and organic matter intake (P>0.05). Treatment containing myrtle leaves had the highest protein intake in compared with control treatment (P<0.05). Digestibility of crude protein and NDF in diet with myrtle in comparison to control significantly increased (P<0.05). But there was no significant difference between the dry matter, organic matter and ADF digestibility of sheep’s (P>0.05). Protozoa population was significantly not affected by inclusion myrtle leaves in the diet (P>0.05). Ammonia levels in diets treated with myrtle (8.29) significantly reduced in compared with the control (16.5) (p<0.05). The myrtle leaves treatment decreased triglyceride and blood glucose of sheeps (P<0.05). Factors such as period of adaptation to medicinal herbs and interaction with other dietary components and their amounts in the diet, can influence the amount of dry matter intake. Essential oils according to chemical structure, resources and activities have different effects on rumen fermentation and animal performance. The negative effect of active ingredients of medicinal plants on ammonia-producing bacteria caused to decrease of rumen ammonia production, also reducing protozoa and swallowing of bacteria that can be other reason for ammonia decrease. Polysaccharides, flavonoids, glycoproteins, polypeptides, steroids, alkaloids and pectin in plants such as myrtle can justify the hypoglycemic properties of these plants. Medicinal plants and their extracts are effective in reducing blood cholesterol and other lipids. It is reported essential oil reduces pH of intestinal tract through production of degrading enzymes of bile, also inhibit the activity of HMG-COA enzyme.   According to the results, it seems 0.4 % myrtle leaves has beneficial effects on digestibility and can reduce blood glucose and triglyceride; therefore, maybe it can be used as an herbal supplement in Arabi sheep diet.