Przeglądaj wg Autor "Cwynar, Marzena"

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  • Miniatura
    PozycjaOpen Access
    Production parameters of PHF cows depending on varying housing conditions during lactation
    (Wydawnictwo Uczelniane Zachodniopomorskiego Uniwersytetu Technologicznego w Szczecinie, 2017) Mróz, Piotr; Wójcik, Piotr; Cwynar, Marzena; Department of Animal Genetics and Breeding, National Research Institute of Animal Production Krakow; Department of Animal Genetics and Breeding, National Research Institute of Animal Production Krakow; KR Kietrz Ltd., Kietrz
    The aim of the study was to determine the effect of varying housing conditions on production parameters of Polish Holstein-Friesian cows. The animals from the Experimental Station of the National Research Institute of Animal Production in Chorzelow were divided into three groups differing in housing conditions. The differentiating variables were access to outdoor areas and area per animal. Cows were also subjected to changes in stocking density and regrouping. The results showed that among cows without outdoor access, those with a space allowance of 3.8 m2/cow produced 2 kg less milk than those with a floor space of 7.74 m2/cow. Increasing stocking density from 3.8 to 2.71 m2/head reduced milk production by 8.9 kg. In cows with outdoor access, decreasing floor space allowance from 7.74 to 5.35 m2/head reduced milk production by 7.46 kg. Two changes in the living area, including increased floor space (in another group) from 6.24 to 17.6 m2 also caused milk yield to decrease by 6 kg. The decreases in milk yield increased the solids content per litre of milk. The study found that housing system and stocking density determine the level of milk production. Too frequent changes in stocking density, as well as regroupings have a negative effect on milk yield.
  • Miniatura
    PozycjaOpen Access
    The Use of Lactation Persistence as an Indicator in the Selection of the Maternal Lines of HF Cows
    (Wydawnictwo Uczelniane Zachodniopomorskiego Uniwersytetu Technologicznego w Szczecinie, 2022) Wójcik, Piotr; Cwynar, Marzena; Pankowski, Mateusz; National Research Institute of Animal Production, Department of Cattle Production, Poland; Kombinat Rolny Kietrz Ltd., Poland; Alta Genetics Ltd., Poland
    The research material for this study consisted of a group of 163 Polish Holstein Friesian cows (PHF). For the study, the cows were assigned to 14 maternal lineages covering three generations. The aim of this study was to indicate possibilities for selecting cows with the goal of maintaining lineages on the farm which are characterised high productive qualities based on lactation persistency index. Basic milk parameters were analysed over a 305-day lactation cycle and information on somatic cell content was also gathered based on sample milkings. A characterisation of lactation persistency for a given lactation was generated as a percent difference between milk yield in the 2nd and 10th month of lactation, and a lactation persistency curve was developed for particular lineages in successive lactations, representing changes in the productivity of the cows. It was determined that together with increasing numbers of lactations among the cows studied, the average lactation persistency index also increased. For younger cows, this index did not exceed 30%, while in the older group this index amounted to 70%. Cows with the highest lactation persistency values 70.1–80% were also characterised by the highest milk production in average daily milk yields during peak lactation, amounting to 56.14 kg at values of for the index. Cows which began their milk production stage with a high persistency index in the 1st and 2nd lactations, in successive lactations saw a significant decrease in this index. Breeding cattle within maternal lines characterized by a high and stable level of lactation persistence index can ensure a high level of milk production in this line of cows.