Upload
whitney-atkins
View
27
Download
0
Tags:
Embed Size (px)
DESCRIPTION
Assessment of voluntary waiting period and frequency of estrus synchronization among herds R.H. Miller, 1, * H.D. Norman, 1 M.T. Kuhn, 1 and J.S. Clay 2 1 Animal Improvement Programs Laboratory, Agricultural Research Service, USDA, Beltsville, MD 20705-2350 - PowerPoint PPT Presentation
Citation preview
Assessment of voluntary waiting period and frequency of estrus synchronization among herds
R.H. Miller,1,* H.D. Norman,1 M.T. Kuhn,1 and J.S. Clay2
1Animal Improvement Programs Laboratory, Agricultural Research Service, USDA, Beltsville, MD 20705-23502Dairy Records Management Systems, Raleigh, NC
Abstr. W172
INTRODUCTION
New reproductive management regimes adopted in recent years Synchronization protocols (ES) Timed insemination
Voluntary waiting period (VWP) of 60 d assumed by USDA for genetic evaluation of pregnancy rate
Actual herd VWP and frequency of ES relative to traditional estrus detection need to be examined
OBJECTIVES
Determine variation in DIM at first service after calving (DFS) among and within herds to assess consistency of VWP
Identify ES herds with timed insemination and compare DFS and number of services between ES herds and those with traditional estrus detection
DATA
5.55 million lactation records (DRMS, AgSource) Inseminations from 1995 through August
2002 Identified service sires Holsteins and Jerseys Pregnancy status unknown
2529 herds on continual test from 1995 through 2001
Mean DFS and cows per herd
CONCLUSIONS
VWP Determination
Increase in mean DFS from 89 d in 1995 to 94 d in 1998 and then slight decrease
Within herd, reasonably consistent herd means for DFS from year to year (correlation = 0.67)
10% of cows inseminated before 60 DIM for 70% of herds
60-d VWP assumed by USDA for calculating pregnancy rate is conservative
Increase in VWP since 1995, but recent moderation
ES Herd Identification
Strong trend toward ES/timed AI regimes relative to traditional estrus detection
Steady increase from 0.9% in 1995 to 7.1% in 2001 in relative frequency of ES regimes (probable and ES)
Fewer DFS (16.4 d) and days open (9 d) for ES herds than for herds with traditional estrus detection but more services per cow (0.18)
METHODS
VWP Determination
Tabulate frequency distribution of herd-years based on DIM by which 10% of cows within herd-year received first insemination after calving 30 d 60 d 120 d 40 d 75 d 150 d 50 d 90 d
Evaluate consistency of DFS within herd over time by intraclass correlation for herds on continual test
ES Herd Identification
Calculate 2 for each herd-year to determine whether frequency of first insemination deviated from equal distribution among 7 week days
Evaluate effect of ES on days open available from lactation records in USDA national database
Not an ES herd 2 < 22.46 Possible ES herd 22.46 2 < 100 Probable ES herd 100 2 < 250 ES herd 2 250
RESULTS
VWP Determination
Cumulative frequency of herd-years based on DIM by which 10% of cows received first insemination after calving
Over 70% of herds with 10% of cows first inseminated by 60 DIM
Percentage of herds that had 10% of cows first inseminated by 60 DIM
Intraclass correlation of 0.67 for DFS and 0.54 for number of services
ES Herd Identification
Mean cows per herd by herd ES status
Within-year frequencies (%) of herd groups based on likelihood of ES
Least-squares differences within herd among ES herd-year groups for DFS and NS
Least-squares differences within herd among ES herd-year groups for days open
1995 1999
2001
Herd frequency (%) 77.5 70.5 72.3
Not ES Possibly ES Probably ES ES64 119 203 384
YearNotES
PossiblyES
ProbablyES ES
1995 91.2 8.0 0.80.1
1998 88.1 10.2 1.30.4
2001 77.2 15.7 4.42.7
VariableNotES
PossiblyES
ProbablyES ES
DFS 0.0 6.3 12.3 16.4No. of services
0.00 0.07 0.090.18
Days openNotES
PossiblyES
ProbablyES ES
Verifiedn=44,964
0.0 0.5 3.9 8.9
All datan=57,643
0.0 0.7 5.1 9.0
FUTURE RESEARCH
Studies underway to determine if reproductive regime should be considered in genetic evaluations of pregnancy rate