Modeling Extended Lactations of Dairy Cows
نویسندگان
چکیده
منابع مشابه
Modeling 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...
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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...
متن کاملModeling daily energy balance of dairy cows in the first three lactations.
Daily energy balance was calculated for 111 Holstein cows in their first 3 lactations, based on combinations of smoothed preadjusted phenotypic records for milk yield, feed intake, live weight, and body condition score. Two energy balance traits were defined: one based on milk yield and feed intake (EB1) and the other on live weight and body condition score change (EB2). Bessel functions (BF), ...
متن کاملEnergy balance profiles for the first three lactations of dairy cows estimated using random regression.
Daily animal solutions were predicted using random regression analysis for feed intake, milk yield, live weight, and condition score recorded on 189 cows at the Langhill Dairy Cattle Research Centre. All cows had three successive lactations. Energy balance for days 1 to 305 of each of the three lactations was calculated both from daily measures of feed intake and milk output and from weekly mea...
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: Journal of Dairy Science
سال: 2000
ISSN: 0022-0302
DOI: 10.3168/jds.s0022-0302(00)75005-3