Effect of balanced supplementary feeding in winter on qualitative and quantitative changes in the population of microbes colonizing the rumen of red deer

Abstract

Gnat S., Dziedzic R., Nowakiewicz A., Zięba P., Trościańczyk A., Majer-Dziedzic B., Ziółkowska G., Beeger S., Wójcik M.Effect of balanced supplementary feeding in winter on qualitative and quantitative changes in the population of microbes colonizing the rumen of red deer Summary Ruminants are a group of animals that process and assimilate their food in a unique manner. The functioning of the digestive tract of these animals is closely related to the abundance and composition of microbes in the forestomach, which is a complex ecosystem of bacteria, protozoa and fungi. Microorganisms present in the rumen, and in particular their effect on physiological processes in the body, influence the animal's physical condition and state of health. Microbiological examination of rumen microbiota ecology is hindered by a lack of selective growth media, as well as by difficulties in isolating bacteria in vitro and accurately identifying them. The aim of the study was to evaluate the effect of food consumed by red deer (Cervus elaphus) on the diversity of their rumen microbiota. Microbes were compared in two study periods. In autumn the animals' diet came exclusively from natural plant sources, while in winter, supplementary feeding was introduced, including specially prepared fodder. The study showed that in deer that did not receive the special fodder in winter, but only natural plant components, the abundance of bacterial flora decreased significantly compared with what it was in autumn, unlike in animals that did receive the fodder, whose composition and caloric value substantially increased the activity of rumen microbes. In winter, changes in proportions of different morphological forms of rumen bacteria were observed, as well as a decline in their total number, particularly in the animals that did not receive the pellets. A similar decline was also observed in the populations of yeasts and protozoa in winter. To sum up the results of the study, the use of the specially prepared high-calorie fodder in winter was shown to influence the rumen ecosystem of red deer. The most significant factor improving the condition of deer receiving supplementary fodder during this period is the stabilization of bacterial flora in the rumen, which directly contributes to the efficiency of digestion.

Impact of winter enclosures on the gut bacterial microbiota of red deer in the Bavarian Forest National Park

“…Particularly the phylum Firmicutes was present in higher proportions in red deer in enclosures than in free‐ranging red deer. This is in concordance with a study in Poland in which red deer that were not fed with supplementary food during winter had a lower abundance of bacteria than red deer that were fed with supplementary food (Gnat et al 2018). Recent studies on the microbiota of silage (Duniere et al 2017, Peng et al 2018) have revealed that certain bacterial taxa within the Firmicutes increase during ensiling when aerobic spoilage occurs (Driehuis et al 2018).…”

“…Thus, the close contact to humans at winter enclosures might also increase the likelihood of zoonosis transmission. In addition, in contrast to the vast amount of research on dietary effects on the human gut microbiota and dysbiosis‐associated diseases (David et al 2014, Althani et al 2016), surprisingly little work has been carried out on the impact of supplementary feeding on the gut bacterial community of our most abundant large herbivores (but see: Li et al 2017a, Gnat et al 2018).…”

Influence of Farming Conditions on the Rumen of Red Deer (Cervus elaphus)

“…In our study, farmed deer did not differ for total rumen protozoa concentration from their wild conspecifics; however, they did for the community composition. The average total number of rumen protozoa (3.29 × 10 6 /mL of rumen fluid) in this study was higher than that reported by other studies on red deer [35,37,38], but similar to the number reported by Hobson et al [36]. Rumen fluid of farmed animals was characterized by a lower percentage of protozoa belonging to the Diplodininae subfamily, and by the presence of protozoa of the Isotrichidae family (or holotrichs), totally absent in wild animals; Entodiniinae and Epidininae protozoa were present at a similar concentration in the two groups, with the Entodininae subfamily having the highest concentration.…”

“…Bacterial population in the rumen of domestic cattle occurs at a concentration of 10 10–11 cells/g of rumen content [34], while other authors reported a total count of 10 9 in red deer [35,36]. Our results show a concentration of anaerobic and aerobic bacteria in a range of 10 5–6 cells/g.…”

“…According to the literature, there is no consistency in the rumen protozoa composition of the red deer. Prins and Geelen [37] and Dehority [39] reported the presence of protozoa belonging to the subfamilies of Entodiniinae, Diplodininae, Epidininae, and the family Isotrichidae in confined and domesticated red deer, while Gnat et al [35] did not find any Isotrichidae protozoa in wild red deer. This is consistent with our results, where the holotrich protozoa were present only in farmed animals.…”