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Wisconsin Dairy Herd Improvement Association, et al. / Wisconsin D.H.I.A. record
Vol. IV (1937)

Factors used in adjusting records,   pp. 5-7 PDF (527.1 KB)


Page 5


FACTORS USED IN ADJUSTING RECORDS
The factors used in adjusting actual lactation records to the
"Standard Milking Period" basis are as follows:
1. Factors for Adjusting Records to a Two Milkings Per Day
Basis for Al Breeds. Worked out by H. W. Norton, Jr.,
Superintendent of Advanced Registry, Holstein-Friesian As-
sociation, from a study of 19,000 Holstein Semi-Official records.
Multiply records made under 3 milkings per day for more
than 90 days by .80.
Multiply records made under 4 milkings per day for more
than 90 days by .66.
2. Factors for Adjusting Complete Lactation Records For All
Breeds to a Standard Milking Period of 305 Days. Based on
a study of 600 Holstein complete lactation records obtained
from daily milk weights, by G. E. Dickerson, Departments of
Genetics and Dairy Records, University of Wisconsin.
Length of   Range      Conversion     Length of      Range Conversion
Lactation  in Class .    Factor        Lactation    in Class   Factor
-days      -days         .           -days        -days
245         240-249        1.19_.        395         390-399       .81
255         250-259        1.16          405         400409        .79
265         260-269        1.12          415         410419        .77
275         270-279        I.xQ          425         42D429        .76
285         280-289        1.06          435         430-439       .74
295         29D-299        1.03          445         440-449       .73
305         300-309        1.00          455         450459        .71
315         310-319        .97           465         460-469       .70
325         32D-329        .95           475         470479        .69
335         330-339        .93-          485         480-489       .67
345         340-349        .90           495         490499        .66
355         350-359         88           505         500-509       .65
365         360-369        .86          *515         510-519       .64
375         370-379         84           525         520-529       .62
385         380-389        .82           535         530-539       .62
545         540-549       .61
For complete and normal lactation records shorter than 240 days,
the 240-249 day factor is used, because practically never is a cow bred
back soon enough to prevent a lactation at least this long.
For complete lactation periods longer than 550 days (usually due
to breeding trouble or delayed breeding), the production during the
first nine months (275 days) is used as the equivalent of a complete nor-
mal lactation in which the cow carries a calf for seven months and is
dry 305 days after calving.
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