Reduction of plant fibers in the digestive tract of two pika species (Ochotona pallasi and O-dauurica, Lagomorpha, Ochotonidae)

The distribution of fibers of different sizes in the gastrointestinal tract in two species of pikas-Pallas' pika Ochotona pallasi and daurian pika O. dauurica-was studied. It was established that fibers of small-sized fractions dominated in all organs of the digestive tract of both pika species, the proportion of which in the stomach proved to be even higher than in fine-grinding voles. No distinct changes in the composition of the size fractions of fibers from organ to organ were observed in the studied individuals of both species, which may be due to frequent consumption of finely dispersed cecotrophs by pikas, which enrich the primary chewed food with small fibers.