In vitro Fermentation Parameters of Diets Containing Different Levels of Mint Pulp and Chicory Pulp

Introduction:

The world average yield of essential oil is around 50000 ton/year which means that large amounts of apparently useless plant residues are produced. These residues do not have a specific commercial use, so it would be a very interesting alternative to provide feed for livestock.Agro-industrial co-products, can be effectively consumed by ruminant species. Since, many parts of Iran have arid and semi-arid climate, and there is feed shortage during the year, hence agro-industrial co-products can be used as animal feed. This experiment was aimed to study the chemical compositions and in vitro rumen fermentation of mint pulp and chicory pulp and experimental diets containing different levels of mint pulp and chicory pulp.

Materials and Methods:

 Fresh mint pulp and chicory pulp were collected from an agro industry processing factory. Chemical compositions (dry matter, neutral detergent fiber, acid detergent fiber, crude protein and ash), in vitro gas production parameters, total protozoa population and N-ammonia concentration of mint pulp and chicory pulp were measured. Each pulp separately included at three levels (10, 20 and 30 % of DM) in a basal diet. Experimental diets were: 1- Basal diet, 2- basal diet containing 10% chicory pulp, 3- basal diet containing 20% chicory pulp, 4- basal diet containing 30% chicory pulp, 5- basal diet containing 10% mint pulp, 6- basal diet containing 20% mint pulp and 7- basal diet containing 30% mint pulp. Basal diet formulated for ewes and contained 12.5 % CP and 2.20 Mcal metabolisable energy (ME) /Kg of diet. In vitro gas production parameters, total protozoa population and N-ammonia concentration of diets were measured and ME, short chain fatty acids (SCFA) and organic matter digestibility (OMD) were estimated. For in vitro gas production tests, the rumen fluid was taken from two rumen fistulated Kurdish rams. For measuring kinetic parameters of gas production, 200 mg of samples were incubated with 40 ml of buffered-rumen fluid for 120 hours. The cumulative produced gas was recorded at different times of incubation and gas production parameters were fitted to an exponential equation. For estimating ME, OMD and total VFA, 40 ml buffered rumen fluid was added to 200 mg of diets and incubated at 39 °C for 24 hours. After 24 hours of incubation, gas production recorded and ME, OMD and SCFA were estimated. Rumen protozoa population were identified after 24 hours incubation. Five ml of buffered rumen fluid was pipetted into a screw-capped test tube containing 5 ml of formalin. Thereafter, two drops of brilliant green dye (2 g brilliant green and 2 ml glacial acetic diluted to 100 ml with distilled water) were added to the test tube, mixed thoroughly and allowed to stand overnight at room temperature. Total and differential counts of protozoa were made with five replications.  All in vitro gas production trials were carried out in three runs. Data were analyzed based on a completely randomized design using Proc GLM of SAS software. The differences among treatments were evaluated using Tukey adjustment when the overall F-test was P ≤ 0.05. Trends were declared when 0.05 < P≤ 0.10. In addition, independent comparisons were done for diets containing mint pulp vs. diets containing chicory pulp.

Results and Discussion :

The results showed that mint pulp contains 105, 500 and 345 g/kg of CP, NDF and ADF respectively and chicory pulp contains 69.7, 610 and 465 g/kg of CP, NDF and ADF respectively. Mint pulp had greater lag phase than chicory pulp (p < 0.05) and potential of gas production did not differ between two pulps. Mint pulp had greater estimated ME, SCFA and OMD in compare to chicory pulp (p < 0.01). Potential and rate of gas production, N- ammonia concentration, total protozoa population, estimated ME, SCFA and OMD were not different among all experimental diets (P>0.05). The constant rate of gas production when half the potential of gas is produced was different among experimental diets (P=0.05), so that basal diet and diet containing 30 % of mint pulp had the highest and lowest value, respectively.

Conclusion:

 Considering the obtained data regarding the chemical compositions and gas production parameters, it is concluded that mint pulp and chicory pulp could be used as a part of forage portion in ruminant nutrition. More experiments are needed to study the inclusion of mint pulp and chicory pulp in diets of productive ruminants.