There are several unique features in the anatomy of the stomach in African ostrich in comparison with other birds. The goal of this study was to determine changes in the main morphometric parameters and histological features of gastric mucosa in ostrich chickens from the 38th day of embryonal development until 60 days of age. For the study, 6 embryos (38th day of development) and 36 chicks (1, 3, 7, 14, 30, and 60 days post hatching; 6 chicks per time point) of both sexes were obtained from African ostrich farm in Latvia during May - October, 2009. Tissue samples were investigated in Preclinical Department, Faculty of Veterinary Medicine. The total area of proventricular mucosa (cm2) and surface area of deep glands (cm2) was measured. Tissue sections for histological assessment were stained with: hematoxylin and eosin and alcian-blue pH 2.5 - periodic acid – Schiff reaction. Thickness of proventricular and ventricular mucosa, depth of proventricular superficial glands as well as surface area of parenchyma occupied by deep glands were measured in histologic sections. As the chick age increased, there were changes in the ratio of areas occupied by proventricular superficial and deep glands with relative decrease in area occupied by deep glands. Proventricular deep glands developed rapidly after hatching; at the age of 30 days deep glands histologically resembled glandular structure of adult birds. Gastric mucosal epithelial cells of 38 days old ostrich embryos and of just hatched ostrich chicks contained neutral, acidic, and mixed mucopolysaccharides. Meanwhile, in the pyloric region of ventriculus acidic mucopolysaccharides predominated.

Rangifer tarandus (reindeer) – is actively bred in the northern regions of different countries. Therefore, an urgent task is to deepen information about the features of reindeer adaptations. Rumen symbiotic microorganisms play an important role in the life of Rangifer tarandus, allowing animals to efficiently use scarce nutrient resources of the tundra and forest-tundra. The microbial community of the reindeer rumen, as well as its age-related changes, are the least studied compared to other ruminants. The comparative analysis results of rumen bacterial community composition of calf (4 months), young animals (1–2 years) and adults (3–6 years) Rangifer tarandus of the Russian Arctic are presented for the first time. The reindeer ruminal bacterial community composition was analyzed in the laboratory of the ‘BIOTROF+’ Ltd by T-RFLP method. In the ontogenesis, significant changes in the microorganism representation were noticed, the greatest of which was noted in microorganism involved in carbohydrate fermentation. The content of cellulolytic Clostridia and the acid-utilizing species of the Negativicutes (P is less than 0.05) decreased with age, but bacteria with the amylo- and cellulosolytic properties of the phylum Bacteroidetes increased (P is less than 0.05). A wide range of microorganisms which traditionally belong to the pathogens of various animals and humans diseases was revealed. With age, a tendency to increase the number of pathogens, including the bacteria of the families Campylobacteraceae, Burkholderiaceae, phylum Fusobacteria, and the genus Staphylococcus was noticed. The greatest percent of opportunistic microorganisms, including phylum Actinobacteria and the family Enterobacteriaceae, were detected in young animals.

It is well known that secretion of gastric acid is regulated neurally by the stimulation of n.vagus and humorally by the activation of histamine H2 receptors in parietal cells. The purpose of the investigation was to clear up neural and humoral regulation mechanisms of gastric acid secretion in the postnatal ontogenesis of calves. Four calves from 5 to 14 weeks of age with chronical fistulae in abomasum have been investigated. Two electrode pH-probe has been used for measures. Atropine sulphate (0,06 mg kg*[-1) IV infusion) has been used to stop function of n.vagus, and cimetidine (0.16 mg kg*[-1) IV infusion) to block humoral regulation. The results clearly show that both, atropine sulphate and cimetidine, demonstrate some blocking influence on the HCL of abomasum in calves of different age.