Interrelationships between herd-level reproductive performance measures based on intervals from initiation of the breeding program in year-round and seasonal calving dairy herds

Morton, J. M. (2010) Interrelationships between herd-level reproductive performance measures based on intervals from initiation of the breeding program in year-round and seasonal calving dairy herds. Journal of Dairy Science, 93 3: 901-910. doi:10.3168/jds.2009-2045


Author Morton, J. M.
Title Interrelationships between herd-level reproductive performance measures based on intervals from initiation of the breeding program in year-round and seasonal calving dairy herds
Journal name Journal of Dairy Science   Check publisher's open access policy
ISSN 0022-0302
1525-3198
Publication date 2010-03
Sub-type Article (original research)
DOI 10.3168/jds.2009-2045
Volume 93
Issue 3
Start page 901
End page 910
Total pages 10
Place of publication New York, NY, United States
Publisher Elsevier
Collection year 2011
Language eng
Abstract In year-round calving herds, reproductive performance has traditionally been described in relation to each cow's calving date. This research described reproductive performance in year-round and seasonal calving dairy herds using herd-level measures based on interval from each cow's initiation of breeding program date, and assessed interrelationships between such measures. A large, prospective, single cohort study, implemented in 1997 and 1998, included 29,327 cows from 167 Australian dairy herds. Herd reproductive performance was described using 2 measures of primary importance to herd managers: the proportion of cows that became pregnant by 6. wk after their initiation of breeding program date (6-wk pregnancy rate) and the proportion of cows that were nonpregnant 21. wk after their initiation of breeding program date (21-wk nonpregnancy rate). Measures that contribute to these primary measures (secondary measures) were calculated for each herd for both the first and second 3-wk periods of each cow's breeding program; submission rates were calculated as proportions of cows that were inseminated at least once in the 3-wk period, and conception rates were calculated as the proportions of inseminations in the 3-wk period that resulted in pregnancy. The individual herd was the unit of analysis. The study results indicate that high submission rates are essential if herd reproductive performance is to be achieved. Six-week pregnancy rate was predicted to increase by 6 to 8 percentage points following a 10-percentage-point increase in submission rates in both 3-wk periods, and by 6 to 10 percentage points following a 10-percentage-point increase in conception rates. Submission rates were more variable than conception rates, indicating that managers may be able to achieve large increases in submission rates more easily than substantial increases in conception rates. However, the predicted benefits of increasing submission rates were greatest when conception rates were high and vice versa, highlighting the need to improve both submission and conception rates when both are low. The study results indicate that some herd managers can concurrently achieve high submission and conception rates. © 2010 American Dairy Science Association.
Keyword Reproductive performance
Fertility
Dairy cow
Dairy herd
Artificial-insemination
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2011 Collection
School of Veterinary Science Publications
 
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Created: Sun, 14 Mar 2010, 00:03:44 EST