Wydanie 367(66)2 2023

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http://hdl.handle.net/20.500.12539/1933

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    Effect of lactation number and average daily milk yield in complete lactation on the dry period length of Polish Holstein -Friesian cows
    (Wydawnictwo Uczelniane Zachodniopomorskiego Uniwersytetu Technologicznego w Szczecinie, 2023) Salamończyk, Ewa; Siedlce University of Natural Sciences and Humanities, Faculty of Agrobioengineering and Animal Husbandry, Institute of Animal Science and Fisheries, Siedlce, Polan
    The aim of the study was to determine the effect of average daily milk yield in complete lactation and lactation number in cows producing at least 8,500 kg of milk in 305-day lactation on the length of the dry period before the next lactation. A total of 1,965 complete, extended lactations in Polish Holstein-Friesian cows subject to use value assessment were analysed. The average complete-lactation daily milk yield was shown to influence the length of the dry period. The average dry period length was 44 days. Dry period length decreased in successive milk-yield groups, from 50 days (average daily yield up to 25 kg of milk) to 28 days (average daily yield over 35 kg in complete lactation). Thus it was confirmed that as milk yield increased, it was more difficult to end lactation. The shortest dry period (only 25 days) was recorded in the youngest cows (second and third lactation) with the highest average daily milk yield in complete lactation (>35 kg). In the oldest cows, i.e. those in their sixth lactation and higher, no statistically significant differences were shown in the length of the dry period depending on daily yield