This Diploma thesis deals with the identification of microorganisms in samples of experimentally produced cheese. Model samples of cheese were produced in association with a private manufacturer. Raw organic milk was used to make the cheese. The theoretical part provides an overview of the issues such as the characteristics of the cheese, its properties and compounds. A special chapter is dedicated to molecular diagnostic methods, which serve for identification of microorganisms. In the experimental part of the thesis were identified some microorganisms in the samples. A polymerase chain reaction was used. The DNA was isolated from coarse lysates using phenol extraction; it was amplified using specific primers and demonstrated by gel electrophoresis. DNA of lactic acid bacteria (Lactobacillus spp., Lactococcus spp.) and yeast was ascertained in the cheese. The samples do not contain DNA of pathogenic genera Bacillus and Salmonella.

While forage plays an important role in equine nutrition, little research has been conducted evaluating fiber utilization by young horses. Therefore, studies were conducted to compare in vivo digestibility and digesta passage in weanlings and mature horses (Exp 1) and yearlings and mature horses (Exp 2). All horses were fed forage-based diets at the same rate (on a metabolic BW basis; Exp 1: 67% alfalfa cubes, 33% concentrate; Exp 2: 75% timothy cubes, 25% concentrate). Ytterbium labeled hay and cobalt-ethylenediaminetetraacetic acid were used to estimate digesta mean retention time (MRT), while in vivo digestibility (DM, OM, and NDF) was measured using a total fecal collection method. Feed and water intake was similar between young and mature horses in both experiments. In Exp 1, there were no differences in digestibility or MRT due to age. The results suggested that weanling horses are capable of digesting a relatively high quality diet as efficiently as mature horses and that most of the development of the gastrointestinal tract occurs before 6 mo of age. In Exp 2, digestibility estimates were greater (P < 0.0311) for the yearlings than for the geldings. The increased digestive capacity of the yearlings was likely due to the longer MRT observed for the particulate phase in the yearlings (P = 0.0190). A third study was conducted to compare the microbial profiles of the feces of mares and foals. Fecal samples were collected from mare-foal pairs as the foal matured. The profiles of each pair, obtained using polymerase chain reaction-denaturing gradient gel electrophoresis, were compared and used to describe bacterial colonization in the foal. Mean similarity between mares and their foals on the day of parturition was low, but rapidly increased. Within 2 wk of parturition, similarity among mares and their foals was higher than among mature mares, suggesting that by 2 wk of age the bacterial species found in the foals’ gut are similar to those found in the mature horse. Collectively, the results from this series of experiments describe the early development of the foal’s digestive capacity.

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