Effect of different levels of Foeniculum vulgare and Nigella sativa powder on rumen fermentation parameters and protozoa population of Sanjabi sheep by in vitro and in vivo methods

Introduction: Rumen fermentation manipulation aims to maximize the feed efficiency and increase the usefulness of rearing ruminants; in simpler words, the goal of rumen manipulation is to increase processes in rumen fermentation that are beneficial for the host animal and to reduce, change, or eliminate inefficient or harmful processes in rumen fermentation. In this regard, trying to use natural products such as medicinal plants has been widely accepted. The desire and demand of consumers to use healthy meat and livestock products has increased the research to search for natural compounds and additives of plant origin that are beneficial for animal health. The positive effects of medicinal plants on the process of microbial fermentation and reduction of greenhouse gases through their active compounds (such as anthole in fennel or thymoquinone in black seed) have been shown. The present study was designed in two experiments to evaluate the effect of different levels of Foeniculum vulgare and Nigella sativa powder on rumen fermentation parameters and protozoa population of Sanjabi sheep by in vitro and in vivo methods. Materials and methods: The present study was designed and carried out in two experiments, in vitro and in vivo. In the first experiment (in vitro), 18 Sanjabi lambs (four to six months of age) with an average weight of 30.8 ± 6.7 kg were randomly divided into three groups with six replicates. Treatments included: control (basal diet without additives), fennel (basal diet plus 20 grams of fennel per kilogram of concentrate), and black seed group (basal diet plus 20 grams of black seed per kilogram of concentrate). In the second experiment (in vitro), 0, 5, 25, and 50 mg of fennel and black seed powder were added to the rumen liquor collected from six Sanjabi lambs (the control group of the first experiment). In both experiments, rumen liquor was taken through the esophageal tube. Gas production, pH, ammonia nitrogen concentration, total volatile fatty acids, in vitro digestibility of organic matter, and protozoa count were measured. In the in vivo experiment, the amount of excrement of sheep was measured by installing nets under the boxes of the animals. Data analysis was done using SAS statistical software. The normality of the counting data (population of protozoa) was first checked by a non-parametric Kolomogorov-Smirnov test and then analysis was done. The experimental design used in this research was completely randomized and for the first experiment, it was repeated measurements in time. Duncan's multiple range test was used to compare the mean of the treatments. Results and discussion: The results of the in vivo experiment showed that the use of fennel and black seed increased the amount of digested organic matter in the rumen significantly compared to the control (P<0.05). In the in vivo experiment, all studied protozoa populations decreased in all treatments (P<0.05). In the in vitro experiment, the addition of fennel caused a significant decrease in gas production (P˂0.0001), organic matter digestibility, and microbial mass at the levels of 25 and 50 mg compared to the control (P<0.05). Ammonia nitrogen concentration at all levels of black seed and the level of 50 mg of fennel had a significant decrease compared to the control (P<0.05). Total protozoa population and Entodinium spp. subfamily was affected by both fennel and black seed treatments in vitro and showed a significant decrease (P˂0.0001). The results of this study showed that black seed and fennel have anti-protozoa properties and can reduce different protozoa populations both in vitro and in vivo. Also, low levels of fennel can improve the fermentation efficiency by increasing the degraded organic matter and reducing gas production. In addition, the results obtained from this research showed that fennel and black seed medicinal plants had the potential to manipulate and change the process of rumen fermentation, and their anti-protozoal effects were evident and significant in both experiments. However, the effects of these plants on the fermentation process in vitro and in vivo did not follow the same process in most of the fermentation parameters, and in vitro results cannot be fully and reliably generalized to the conditions inside the rumen of live sheep. Conclusions: The levels of fennel and black seed used in this study can reduce different protozoa populations and improve the process of rumen fermentation, although more researches are needed with different levels of these herbs to get more results.