The article presents the development of author’s concept of a diesel/hydraulic propulsion system for inland watercraft. Due to specific nature of vessel navigation on rivers, classical propulsion systems with shaft lines can be effectively replaced by systems with hydraulic power transmission. A solution is also presented of a hybrid design with extra electric port having the form of a pumping system driven from a battery of accumulators. Strong and weak points of the proposed solution are discussed and its energy efficiency is assessed
The aim of the study was to analyse the effect of non-genetic factors on fertility indices in high-yielding Black-and-White Polish Holstein-Friesian cows. The analysis covered 2414 reproductive periods in 1063 cows born in the years 1999-2008. Fertility indices of the cows were evaluated. The age of heifers at first calving was found to decrease in successive years in the population analysed. A shorter rearing period for heifers was not found to negatively affect fertility indices during their later productive life. A significant decrease in reproductive efficiency was observed in the case of yield exceeding 3600 kg over 100 days of lactation in primiparous cows. However, milk yield in the previous standard lactation had the strongest influence on fertility indices. Where milk yield exceeded 9000 kg, each increase of 2000 kg had a significant (P≤0.01) negative effect on all the fertility indices evaluated in the study.
The paper compares the chemical composition of milk from Polish Holstein-Friesian Black-And-White (PHF HO) and Montbéliarde (MO) high-yielding cows. The research was based on the results of 36,796 test-day milkings: 25,617 from PHF HO and 11,179 from MO. The analysis included the influence of the successive lactation and its phase, the daily milk yield, the cytological quality of milk, and the season on the content of basic compounds and the fat/protein proportion in milk. The milk from Montbéliarde cows contained significantly more fat (by 0.05%) and protein (by 0.38%) than the milk from the Polish Holstein-Friesian Black-And-White breed. The milk from Montbéliarde cows also had a better proportion of fat to protein (by 0.11). With regard to the fat and protein content, as well as the fat/protein proportion in milk of PHF HO cows, the most important factor was the daily milk yield, whereas the most important determinant of lactose was the level of somatic cells. The factors included in the analysis had less influence on the basic chemical composition of milk from Montbéliarde. The greatest differences in the fat content were related to the daily milk yield, in the protein content to the successive lactation month, in the lactose content to the level of somatic cells, and in the fat/protein proportion to the successive lactation.
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