1	Factors that impact longevity of Holsteins in the United States H. D. NORMAN and J. R. WRIGHT Animal Improvement Programs Laboratory Agricultural Research Service, USDA Beltsville, MD 20705-2350 dnorman@aipl.arsusda.gov
2	Previous Findings An overview of the survival rate to various parities and herd life by breed and year was reported previously. Hare, E., Norman, H.D., Wright, J.R. “Survival rates and herdlife of dairy cattle in the United States”. J. Dairy Sci. (accepted)
3	Mean number of parities
4	In-progress Report A recent study shows how producers value yield and fitness traits when culling cows. Norman, H.D., Hutchinson, J.L., Kuhn, M.T., Wright, J.R., Lawlor, T.J. “Selection on yield and fitness traits when culling Holsteins during the first three lactations”. J. Dairy Sci. (submitted)
5	Emphasis given to traits when culling during 1st lactation compared to milk Relative emphasis on trait Milk Fat Protein Days Dystocia Final Year yield yield yield SCS open score score 1984 100 83 97 -- -21 -9 29 1988 100 82 99 -19 -18 -8 26 1992 100 76 101 -25 -23 -9 24 1996 100 74 100 -26 -30 -9 23 1997 100 83 91 -31 -61 -11 33 2000 100 78 95 -33 -74 -15 33 From: Norman et.al., J. Dairy Sci. (submitted)
6	Current Objective To examine some additional factors to determine how they impact herd life in Holsteins.
7	Data edits Herd participated in DHI testing for 1 year prior to cow’s first calving and remaining on test throughout the cow’s lactations Cows first calving 1980 to 1995 and remaining in same herd Cows culled for dairy purposes excluded No missing lactations (required 270–650 days between lactations)
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9	Mean parities by region Region Mid- Mid- Mtn.- North- North- South- South- Year east west Prairie east west east west 1980 3.24 3.09 3.03 3.43 3.23 3.14 3.22 1984 3.03 2.91 2.95 3.23 3.04 3.01 3.14 1988 2.90 2.74 2.81 3.06 2.91 2.82 2.97 1992 2.80 2.71 2.78 2.95 2.83 2.67 2.90 1995 2.72 2.67 2.69 2.92 2.82 2.58 2.85
10	Mean parities by herd size Cows in herd (no.) 51– 101– 201– 501– 1001– 2001– Year 5–50 100 200 500 1000 2000 5000 1985 3.05 3.02 2.99 3.03 3.02 2.87 2.82 1987 2.95 2.94 2.92 2.95 2.96 2.86 2.60 1989 2.85 2.85 2.85 2.92 2.88 2.84 2.73 1991 2.83 2.82 2.82 2.85 2.89 2.80 2.64 1993 2.82 2.79 2.77 2.80 2.89 2.81 2.77 1995 2.81 2.78 2.73 2.77 2.81 2.75 2.71
11	Mean parities by level of inbreeding Inbreeding coefficient (%) 0.1- 1.1- 2.1- 3.1- 4.1- 5.1- 7.1- 10.1 Year 0 1.0 2.0 3.0 4.0 5.0 7.0 10.0 15.0 >15.0 1980 3.33 3.14 3.26 3.31 3.24 3.13 3.09 2.98 2.88 2.91 1984 3.15 3.04 3.02 3.00 2.96 2.98 2.90 2.87 2.74 2.78 1988 2.98 2.91 2.86 2.84 2.82 2.81 2.79 2.74 2.59 2.60 1992 2.96 2.89 2.82 2.79 2.80 2.80 2.73 2.65 2.55 2.61 1995 3.02 2.92 2.83 2.76 2.74 2.76 2.70 2.64 2.60 2.49
12	Edits for analysis of terminal lactations Only data from Dairy Records Processing Centers reporting complete data (DIM >305) Cows culled for dairy purposes excluded Cows exiting herds during 2002-2005
13	Lactation length of exiting cows (2002-2005)
14	Lactation length of exiting cows for 3 parities (2002-2005)
15	Probability of exiting cows leaving by lactation length (2002-2005)
16	Probability of exiting cows leaving by lactation length for 3 parities (2002-2005)
17	USDA termination codes (%) for Holstein cows exiting herds (2002-2005)
18	USDA termination codes (%) for Holstein cows exiting herds by parity (2002-2005)
19	Mean DIM for cows exiting herd by USDA termination code (2002-2005)
20	Conclusions
21	Conclusions
22	Conclusions