Genetic and phenotypic parameters of lactations longer than 305 days (extended lactations)
نویسندگان
چکیده
منابع مشابه
Genetic and phenotypic parameters of lactations longer than 305 days (extended lactations).
Test-day milk yield and somatic cell count data over extended lactation (lactation to 540-600 days) were analysed considering part lactations as different traits and fitting random regression (RR) models. Data on Australian Jersey and Holstein Friesian (HF) were used to demonstrate the shape of the lactation curve and data on HF were used for genetic study. Test-day data from about 100 000 cows...
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Modeling extended lactations for the US Holsteins is useful because a majority (>55%) of the cows in the present population produce lactations longer than 305 d. In this study, 9 empirical and mechanistic models were compared for their suitability for modeling 305-d and 999-d lactations of US Holsteins. A pooled data set of 4,266,597 test-day yields from 427,657 (305-d complete) lactation recor...
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Alternative measures of productive life (PL) were compared, and life expectancy factors were updated to replace estimates from 1993. Alternatives were proposed with extra credits for lactations longer than 10 mo and beyond 84 mo of age and for each calving so that an extremely long lactation would not receive more credits than multiple shorter lactations with dry periods between. Maximum credit...
متن کاملModeling extended lactations of dairy cows.
Nine mathematical models were compared for their ability to predict daily milk yields (n = 294,986) in standard 305-d and extended lactations of dairy cows of Costa Rica. Lactations were classified by parity (first and later), lactation length (9 to 10, 11 to 12, 13 to 14, 15 to 16, and 16 to 17 mo), and calving to conception interval (1 to 2, 3 to 4, 5 to 6, 7 to 8, and 9 to 10 mo). Of the nin...
متن کاملEconomics of extended lactations in dairying
Introduction Whole-farm analysis of alternative lactation regimes Case study farm number one Description of farming system one Whole-farm results of farming system one Case study farm number two Description of farming system two Whole-farm results of farming system two General discussion of results Conclusions References Appendix Abstract. This paper deals with the economic analysis and managem...
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ژورنال
عنوان ژورنال: Animal
سال: 2008
ISSN: 1751-7311
DOI: 10.1017/s1751731107001425