AIPL RESEARCH REPORTCULL1 (9-09) |
Reasons that Cows in Dairy Herd Improvement Programs Exit the HerdH.D. Norman,1 J.R. Wright,1 and J.E. Lombard21Animal Improvement Programs Laboratory, ARS-USDA, Beltsville, MD 20705-2350 301-504-8334 (voice) ~ 301-504-8092 (fax) ~ inquiry@aipl.arsusda.gov ~ http://aipl.arsusda.gov 2National Animal Health Monitoring System, APHIS-USDA, Fort Collins, CO 80523-8117 970-494-7245 (voice) ~ 970-494-7228 (fax) ~ Jason.E.Lombard@aphis.usda.gov |
Reasons that dairy producers report for individual cows' exiting the herd have been provided by dairy records processing centers (DRPCs) to the Animal Improvement Programs Laboratory for decades. Unfortunately, the data were rarely summarized to show changes in the national situation. Two pieces of information available when cows complete lactations or are removed from a herd are destination categories and more descriptive reasons for leaving the herd, which are referred to as termination codes (TCs). The TCs have been revised as needed to improve predictions of genetic merit. Currently, a producer can assign 1 of 10 TCs for why a cow exits the herd or an additional 2 codes if the cow completed her individual lactation. Using Dairy Herd Improvement data, lactation records were examined to summarize the destination categories and TCs assigned for each dairy cow that is permanently removed from the herd:
| Destination category | Termination code |
| Remained in herd | 0, 8 |
| Sold for dairy purposes | 2 |
| Sold for slaughter or salvage | 1, 3–5, 7, 9, A, B |
| Died | 6 |
Two of the 4 destination categories have more than 1 TC to allow reporting of more detailed information. For the "remained in herd" group, the TC indicates whether the cow's lactation ended normally (i.e., without an abortion; TC = 0) or as the result of an abortion (TC = 8). For the "sold for slaughter or salvage" group, 8 TCs provide more specific information to indicate the reason that the animal was sold:
| Reason sold for slaughter or salvage | Termination code |
| Locomotion problems (feet, legs, lameness) | 1 |
| Low production (not caused by other reasons) | 3 |
| Reproductive problems | 4 |
| Mastitis or high somatic cell count | 7 |
| Udder problems (udder conformation or injury) | 9 |
| Undesirable conformation (other than udder) | A |
| Aggressive behavior (undesirable temperament) | B |
| Unspecified other reason or no reason given | 5 |
A comparison of the frequencies of those codes across DRPC revealed considerable uniformity (not shown), but total uniformity should not be expected because of different input software accessible to dairy producers for different DRPCs.
Historical studies of survival of U.S. dairy cattle have been reported by Nieuwhof et al. (1989) and Hare et al. (2006). Those studies grouped and examined records of cows by calving year and followed them through removal from the herd. Unfortunately, that method of data analysis provided information that was fairly dated before publication. An alternative approach that provides more current information on why cows exit the herd is to summarize TCs for all cows that left the herd in recent years. Results from the latter method are likely to be impacted more by yearly changes in the dairy economy (milk and feed prices) and thus are subject to more annual fluctuation than would summarization by calving year. Either method should provide somewhat similar information that would be of benefit for economic studies on dairy management decision-making.
This report is based on recent TCs for cows that exited the herd so that information would be current and could be provided annually. Data were all Dairy Herd Improvement records with completion dates between January 1, 2007, and December 31, 2008, including those removed by edits prior to calculation of USDA-DHIA genetic evaluations. Allowing adequate time between lactation completion and the cutoff date for extracting data from the national dairy database provided an opportunity for updated codes to be received for cows that left the herd after completing their lactations and for those who calved but left the herd prior to a herd test, thus providing a more complete and accurate assessment.
Selected summaries are provided by parity and breed (including separate summaries for crossbreds). Crossbreds were categorized into 2 groups depending on the extent of heterosis: those with heterosis of >90% (CB90) and those with heterosis of 50 to 90% (CB50). The CB90 group was primarily first-generation crosses between 2 breeds (F1s) or offspring of a third breed from a crossbred dam of 2 other breeds; the CB50 group was crosses of either 1 of the 2 F1 breeds back onto the F1s. The frequency of the various types of crossbreds born in the United States in 2005 was documented by Powell et al. (2008). They reported that no single breed combination accounted for a majority of crossbreds, but the largest sources of genes in crossbreds were from Holsteins (44%) and Jerseys (26%). The most frequent sire breeds for crossbreds in 2005 were Jerseys (42%) and Holsteins (27%).
Table 1 shows the frequency of destination categories and TCs by breed disregarding parity. The percentage of purebred cows that completed their lactations and remained in the herd varied from 64.8 to 72.3%, with the highest percentage for Jerseys and the lowest for Guernseys. Holsteins were intermediate at 68.4%. Crossbreds groups had the greatest staying power with 74.9% of CB90s and 73.1% of CB50s remaining in the herds for another lactation.
| TABLE 1. Percentages by destination category, reason for termination, and breed for cows completing lactations between January 1, 2007, and December 31, 2008. | |||||||||
| Destination category and reason for termination | Ayrshire (n = 19,950) |
Brown Swiss (n = 48,077) |
Guernsey (n = 18,200) |
Holstein (n = 6,195,521) |
Jersey (n = 407,049) |
Milking Shorthorn (n = 10,378) |
Red and White (n = 10,349) |
CB90 (n = 80,481) |
CB50 (n = 26,183) |
| Stayed in herd | 70.9 | 68.1 | 64.8 | 68.4 | 72.3 | 69.8 | 67.8 | 74.9 | 73.1 |
| Lactation ended normally (TC = 0) | 70.6 | 67.7 | 64.3 | 67.7 | 71.7 | 68.9 | 67.5 | 74.4 | 72.5 |
| Lactation ended with abortion (TC = 8) | 0.2 | 0.4 | 0.4 | 0.7 | 0.5 | 0.9 | 0.3 | 0.5 | 0.5 |
| Sold for dairy (TC = 2) | 6.2 | 6.1 | 5.6 | 3.1 | 6.3 | 6.9 | 4.7 | 3.7 | 4.8 |
| Sold for salvage/slaughter | 18.6 | 20.1 | 22.5 | 22.5 | 16.1 | 19.2 | 22.2 | 16.8 | 17.5 |
| Sold for locomotion (TC = 1) | 0.7 | 1.1 | 0.8 | 0.9 | 0.3 | 0.2 | 1.0 | 0.7 | 0.6 |
| Sold for low production (TC = 3) | 2.5 | 3.0 | 2.9 | 4.1 | 3.1 | 2.6 | 2.7 | 3.0 | 3.4 |
| Sold for reproduction (TC = 4) | 5.3 | 5.5 | 5.3 | 4.5 | 3.0 | 5.0 | 6.4 | 3.1 | 3.6 |
| Sold for mastitis (TC = 7) | 2.5 | 3.0 | 3.2 | 3.6 | 2.9 | 2.9 | 3.6 | 3.6 | 3.5 |
| Sold for other reasons (TC = 5) | 7.7 | 7.6 | 10.3 | 9.4 | 6.8 | 8.6 | 8.5 | 6.3 | 6.4 |
| Died (TC = 6) | 4.4 | 5.7 | 7.2 | 5.9 | 5.3 | 4.0 | 5.4 | 4.7 | 4.7 |
Because of breed differences in the percentage of cows that remained in the herd, percentage sold for various other reason was rather consistently reversed. For example, percentages of Holsteins and Jerseys sold was 0.9 and 0.3%, respectively, for feet, legs, or lameness (locomotion); 4.1 and 3.1% for low production; 4.5 and 3.0% for reproduction; 3.6 and 2.9% for mastitis, and 9.4 and 6.8% for unspecified other reasons. The percentage that died was 5.9% for Holsteins and 5.3% for Jerseys. Holsteins had 0.7% of lactations terminated by abortion, and Jerseys had 0.5%. In contrast, 3.1% of Holsteins and 6.3% of Jerseys were coded as sold for dairy purposes.
The other breeds were culled less frequently for low production but more often for reproduction than were Holsteins or Jerseys; they generally were intermediate or equal to Holsteins and Jerseys for percentages sold for locomotion, mastitis, or other reasons. However, culling for locomotion problems was low (0.2 to 1.1%) for all breeds. Guernseys had the greatest percentage of cows coded as died (7.2%), but other purebreds were intermediate to Holsteins and Jerseys or had smaller percentages of cows that died. Cows aborting but remaining in the herd accounted for the smallest portion of records completed (0.2 to 0.9%).
Crossbreds were intermediate to Holsteins and Jerseys in percentage reported culled for reproduction, mastitis, and locomotion problems. A smaller percentage of crossbreds ended lactations with death than did Holsteins, Jerseys, Brown Swiss, Guernseys, and Red and Whites, and fewer were sold for an unknown or nonspecified reason than were any of the purebreds. Percentages of crossbreds sold for dairy or for low production were similar to percentages for Holsteins and Jerseys.
Table 2 shows corresponding percentages based on only animals that left the herd except for those sold for dairy purposes. This latter gives the relative importance of the various reasons for exiting. Unfortunately, for nearly a third of all cows leaving the herd, an unspecified or unknown reason was given (28.9 to 36.9%). Died was generally the second most frequent code causing cows to exit the herd (17.4 to 24.8%), followed closely by reproduction problems (14.0 to 23.1%). These causes were reversed for Ayrshire, Milking Shorthorn, and Red and White, where percentage leaving for reproduction problems exceeded those coded died. Mastitis and low production were about equal as causes for removal (10.7 to 16.9 and 9.7 to 15.5, respectively).
| TABLE 2. Percentages by reason for termination and breed for cows leaving the herd except for dairy purposes between January 1, 2007, and December 31, 2008. | |||||||||
| Reason for termination | Ayrshire (n = 4,582) |
Brown Swiss (n = 12,430) |
Guernsey (n = 5,398) |
Holstein (n = 1,762,642) |
Jersey (n = 87,185) |
Milking Shorthorn (n = 2,417) |
Red and White (n = 2,851) |
CB90 (n = 17,267) |
CB50 (n = 5,809) |
| Sold for locomotion (TC = 1) | 2.9 | 4.3 | 2.6 | 3.1 | 1.6 | 1.0 | 3.7 | 3.2 | 2.7 |
| Sold for low production (TC = 3) | 10.8 | 11.5 | 9.7 | 14.5 | 14.4 | 11.0 | 9.9 | 14.0 | 15.5 |
| Sold for reproduction (TC = 4) | 22.9 | 21.1 | 17.7 | 15.7 | 14.0 | 21.5 | 23.1 | 14.7 | 16.0 |
| Sold for mastitis (TC = 7) | 10.7 | 11.4 | 10.8 | 12.7 | 13.4 | 12.3 | 13.0 | 16.9 | 15.7 |
| Sold for other reasons (TC = 5) | 33.4 | 29.5 | 34.9 | 33.1 | 31.9 | 36.9 | 30.7 | 29.5 | 28.9 |
| Died (TC = 6) | 19.2 | 22.2 | 24.2 | 20.9 | 24.8 | 17.4 | 19.5 | 21.8 | 21.2 |
More detailed information by parity is in Table 3 for Holsteins, Table 4 for Jerseys, Table 5 for other breeds, and Table 6 for crossbreds. Purebreds other than Holsteins and Jerseys were combined because of small numbers for later parities as were the 2 crossbred groups. Clear differences across parity are apparent for all breeds. Although 77.4% of Holsteins were coded as staying in the herd at the end of parity 1, that percentage dropped to 70.3, 62.4, 56.0, 51.1, and 45.6 at the end of parities 2 through ≥6. Likewise, Jerseys dropped from 78.8 to 76.3, 70.6, 64.0, 59.9, and 53.6%. Other breeds and crossbreds declined as well from 74.7 to 51.7% and from 80.8 to 51.4% of cows staying in the herd, respectively.
| TABLE 3. Percentages by reason for termination and parity for HOLSTEIN cows completing lactations between January 1, 2007, and December 31, 2008. | |||||||
| Reason for termination | Parity 1 (n = 2,148,364) |
Parity 2 (n = 1,662,148) |
Parity 3 (n = 1,118,113) |
Parity 4 (n = 655,962) |
Parity 5 (n = 340,006) |
Parity ≥6 (n = 270,928) |
All parities (n = 6,195,521) |
Lactation ended normally (TC = 0) | 77.4 | 70.3 | 62.4 | 56.0 | 51.1 | 45.6 | 67.7 | Lactation ended with abortion (TC = 8) | 0.9 | 0.7 | 0.6 | 0.6 | 0.5 | 0.4 | 0.7 | Sold for dairy (TC = 2) | 3.9 | 3.0 | 2.6 | 2.5 | 2.5 | 2.6 | 3.1 |
| Sold for locomotion (TC = 1) | 0.4 | 0.7 | 1.1 | 1.6 | 2.0 | 2.2 | 0.9 |
| Sold for low production (TC = 3) | 3.3 | 4.1 | 4.5 | 4.8 | 5.3 | 6.0 | 4.1 |
| Sold for reproduction (TC = 4) | 3.4 | 4.7 | 5.0 | 5.3 | 5.5 | 6.3 | 4.5 |
| Sold for mastitis (TC = 7) | 1.7 | 3.1 | 4.7 | 5.9 | 6.8 | 7.3 | 3.6 |
| Sold for other reasons (TC = 5) | 5.7 | 8.4 | 11.4 | 13.9 | 15.8 | 18.1 | 9.4 |
| Died (TC = 6) | 3.3 | 5.0 | 7.6 | 9.4 | 10.5 | 11.6 | 5.9 |
| TABLE 4. Percentages by reason for termination and parity for JERSEY cows completing lactations between January 1, 2007, and December 31, 2008. | |||||||
| Reason for termination | Parity 1 (n = 128,485) |
Parity 2 (n = 98,890) |
Parity 3 (n = 71,595) |
Parity 4 (n = 48,055) |
Parity 5 (n = 29,078) |
Parity ≥6 (n = 30,946) |
All parities (n = 407,049) |
Lactation ended normally (TC = 0) | 78.8 | 76.3 | 70.6 | 64.0 | 59.9 | 53.6 | 71.7 | Lactation ended with abortion (TC = 8) | 0.7 | 0.5 | 0.5 | 0.5 | 0.4 | 0.4 | 0.5 | Sold for dairy (TC = 2) | 8.1 | 6.3 | 5.1 | 4.9 | 4.7 | 5.3 | 6.3 |
| Sold for locomotion (TC = 1) | 0.1 | 0.2 | 0.4 | 0.5 | 0.6 | 1.0 | 0.3 |
| Sold for low production (TC = 3) | 2.4 | 2.9 | 3.1 | 3.9 | 3.9 | 4.8 | 3.1 |
| Sold for reproduction (TC = 4) | 2.2 | 2.9 | 3.2 | 3.7 | 3.9 | 4.5 | 3.0 |
| Sold for mastitis (TC = 7) | 1.4 | 2.0 | 3.3 | 4.4 | 5.3 | 5.9 | 2.9 |
| Sold for other reasons (TC = 5) | 3.7 | 5.0 | 7.4 | 10.0 | 12.1 | 14.6 | 6.8 |
| Died (TC = 6) | 2.7 | 3.9 | 6.4 | 8.1 | 9.2 | 9.9 | 5.3 |
| TABLE 5. Percentages by reason for termination and parity for OTHER PUREBRED (Ayrshire, Brown Swiss, Guernsey, Milking Shorthorn, and Red and White) cows completing lactations between January 1, 2007, and December 31, 2008. | |||||||
| Reason for termination | Parity 1 (n = 50,189) |
Parity 2 (n = 39,209) |
Parity 3 (n = 27,375) |
Parity 4 (n = 17,153) |
Parity 5 (n = 9,785) |
Parity ≥6 (n = 9,637) |
All parities (n = 153,348) |
Lactation ended normally (TC = 0) | 74.7 | 70.8 | 65.7 | 61.8 | 57.5 | 51.7 | 68.1 | Lactation ended with abortion (TC = 8) | 0.5 | 0.4 | 0.4 | 0.3 | 0.3 | 0.3 | 0.4 | Sold for dairy (TC = 2) | 7.0 | 5.8 | 5.3 | 4.9 | 4.3 | 4.2 | 5.8 |
| Sold for locomotion (TC = 1) | 0.3 | 0.5 | 0.8 | 1.3 | 1.8 | 2.2 | 0.8 |
| Sold for low production (TC = 3) | 2.5 | 3.1 | 3.3 | 3.1 | 3.5 | 3.7 | 3.0 |
| Sold for reproduction (TC = 4) | 3.6 | 4.7 | 5.5 | 5.7 | 6.5 | 7.2 | 4.9 |
| Sold for mastitis (TC = 7) | 1.5 | 2.1 | 3.2 | 4.4 | 5.4 | 6.6 | 2.9 |
| Sold for other reasons (TC = 5) | 6.5 | 8.1 | 9.3 | 11.0 | 11.8 | 13.9 | 8.7 |
| Died (TC = 6) | 3.2 | 4.5 | 6.5 | 7.5 | 9.0 | 10.3 | 5.4 |
| TABLE 6. Percentages by reason for termination and parity for CROSSBRED (CB90 and CB50) cows completing lactations between January 1, 2007, and December 31, 2008. | |||||||
| Reason for termination | Parity 1 (n = 44,165) |
Parity 2 (n = 28,679) |
Parity 3 (n = 17,087) |
Parity 4 (n = 9,283) |
Parity 5 (n = 4,397) |
Parity ≥6 (n = 3,053) |
All parities (n = 106,664) |
Lactation ended normally (TC = 0) | 80.8 | 76.0 | 67.6 | 61.6 | 57.6 | 51.4 | 73.9 | Lactation ended with abortion (TC = 8) | 0.6 | 0.5 | 0.4 | 0.5 | 0.5 | 0.3 | 0.5 | Sold for dairy (TC = 2) | 4.3 | 3.5 | 3.8 | 3.9 | 3.0 | 4.2 | 4.0 |
| Sold for locomotion (TC = 1) | 0.3 | 0.6 | 0.9 | 1.1 | 1.5 | 1.7 | 0.7 |
| Sold for low production (TC = 3) | 2.6 | 3.0 | 3.6 | 4.1 | 4.4 | 3.9 | 3.1 |
| Sold for reproduction (TC = 4) | 2.4 | 3.5 | 3.9 | 4.1 | 4.4 | 4.8 | 3.2 |
| Sold for mastitis (TC = 7) | 1.9 | 3.1 | 5.0 | 6.5 | 8.2 | 9.8 | 3.6 |
| Sold for other reasons (TC = 5) | 4.3 | 5.7 | 8.1 | 9.9 | 11.4 | 14.1 | 6.3 |
| Died (TC = 6) | 2.8 | 4.1 | 6.5 | 8.3 | 9.0 | 9.8 | 4.7 |
As expected, percentage of cows sold for dairy purposes generally decreased as parity increased regardless of breed because younger animals are in higher demand because of longer expected usefulness. Lactations ending with an abortion decreased with parity as was noted by Miller et al. (2008b). In contrast, cows leaving the herd for most other reasons increased with parity. The trends across parity are clear and consistent for Holsteins, which have the greatest numbers. Holstein cows sold for mastitis increased from 1.7 to 7.3%, and those sold for other or unspecified reasons rose from 5.7 to 18.1%. The percentage of Holstein cows that died increased from 3.3% for parity 1 to 11.6% for parities ≥6. A similar increase with parity was also reported by Miller et al. (2008a).
Tables 7 to 10 show corresponding percentages by parity based on only animals that left the herd except for those sold for dairy purposes. In all 4 breed groupings, sold for "all other reasons" accounted for the highest reason for exiting (29.3 to 33.8%). This could represent any reasons not designated, or simply indicate no reason was given. Most likely, it is a combination of both. Died was the next most frequent code assigned in all breeds (20.9 to 24.8%), usually followed by sold for reproduction (14.0 to 19.1%). Sold for low production (11.7 to 14.5%) and sold for mastitis (11.1 to 16.6%) were the next most frequent reasons for leaving. Two codes added to the TC list recently were used infrequently; these were sold for locomotion problems (1.6 to 3.1%) and sold for udder problems (0.0%). Perhaps there was no comparable code within the DRPC input that translated into AIPL code for the latter.
| TABLE 7. Percentages by reason for termination and parity for HOLSTEIN cows leaving the herd except for dairy purposes between January 1, 2007, and December 31, 2008. | |||||||
| Reason for termination | Parity 1 (n = 382,611) |
Parity 2 (n = 432,761) |
Parity 3 (n = 383,789) |
Parity 4 (n = 268,323) |
Parity 5 (n = 155,964) |
Parity ≥6 (n = 139,194) |
All parities (n = 1,762,642) |
| Sold for locomotion (TC = 1) | 2.2 | 2.6 | 3.2 | 3.8 | 4.3 | 4.2 | 3.1 |
| Sold for low production (TC = 3) | 18.5 | 15.8 | 13.2 | 11.8 | 11.5 | 11.6 | 14.5 |
| Sold for reproduction (TC = 4) | 18.9 | 18.1 | 14.5 | 12.9 | 12.0 | 12.2 | 15.7 |
| Sold for mastitis (TC = 7) | 9.7 | 12.0 | 13.8 | 14.5 | 14.9 | 14.3 | 12.7 |
| Sold for other reasons (TC = 5) | 31.9 | 32.3 | 33.3 | 34.1 | 34.4 | 35.2 | 33.1 |
| Died (TC = 6) | 18.8 | 19.2 | 22.0 | 23.0 | 22.9 | 22.5 | 20.9 |
| TABLE 8. Percentages by reason for termination and parity for JERSEY cows leaving the herd except for dairy purposes between January 1, 2007, and December 31, 2008. | |||||||
| Reason for termination | Parity 1 (n = 16,015) |
Parity 2 (n = 16,655) |
Parity 3 (n = 17,015) |
Parity 4 (n = 14,718) |
Parity 5 (n = 10,186) |
Parity ≥6 (n = 12,596) |
All parities (n = 87,185) |
| Sold for locomotion (TC = 1) | 0.9 | 1.2 | 1.5 | 1.7 | 1.8 | 2.6 | 1.6 |
| Sold for low production (TC = 3) | 19.2 | 17.1 | 13.0 | 12.7 | 11.0 | 11.7 | 14.4 |
| Sold for reproduction (TC = 4) | 17.5 | 16.9 | 13.4 | 12.0 | 11.2 | 11.0 | 14.0 |
| Sold for mastitis (TC = 7) | 11.4 | 11.8 | 13.9 | 14.4 | 15.2 | 14.6 | 13.4 |
| Sold for other reasons (TC = 5) | 29.5 | 29.5 | 31.2 | 32.7 | 34.6 | 35.9 | 31.9 |
| Died (TC = 6) | 21.6 | 23.4 | 27.1 | 26.5 | 26.2 | 24.3 | 24.8 |
| TABLE 9. Percentages by reason for termination and parity for OTHER PUREBRED (Ayrshire, Brown Swiss, Guernsey, Milking Shorthorn, and Red and White) cows leaving the herd except for dairy purposes between January 1, 2007, and December 31, 2008. | |||||||
| Reason for termination | Parity 1 (n = 8,872) |
Parity 2 (n = 9,025) |
Parity 3 (n = 7,841) |
Parity 4 (n = 5,656) |
Parity 5 (n = 3,704) |
Parity ≥6 (n = 4,226) |
All parities (n = 39,324) |
| Sold for locomotion (TC = 1) | 1.7 | 2.4 | 2.9 | 4.0 | 4.8 | 4.9 | 3.1 |
| Sold for low production (TC = 3) | 14.2 | 13.5 | 11.5 | 9.4 | 9.2 | 8.4 | 11.7 |
| Sold for reproduction (TC = 4) | 20.6 | 20.5 | 19.2 | 17.4 | 17.1 | 16.5 | 19.1 |
| Sold for mastitis (TC = 7) | 8.7 | 9.0 | 11.3 | 13.2 | 14.2 | 15.0 | 11.1 |
| Sold for other reasons (TC = 5) | 36.6 | 35.0 | 32.3 | 33.3 | 31.1 | 31.6 | 33.8 |
| Died (TC = 6) | 18.2 | 19.6 | 22.7 | 22.6 | 23.7 | 23.6 | 21.2 |
| TABLE 10. Percentages by reason for termination and parity for CROSSBRED (CB90 and CB50) cows leaving the herd except for dairy purposes between January 1, 2007, and December 31, 2008. | |||||||
| Reason for termination | Parity 1 (n = 6,315) |
Parity 2 (n = 5,740) |
Parity 3 (n = 4,809) |
Parity 4 (n = 3,161) |
Parity 5 (n = 1,705) |
Parity ≥6 (n = 1,346) |
All parities (n = 23,076) |
| Sold for locomotion (TC = 1) | 2.4 | 3.1 | 3.2 | 3.2 | 3.8 | 3.9 | 3.1 |
| Sold for low production (TC = 3) | 18.2 | 14.8 | 12.9 | 11.9 | 11.3 | 8.8 | 14.4 |
| Sold for reproduction (TC = 4) | 16.9 | 17.7 | 13.8 | 12.1 | 11.3 | 10.9 | 15.0 |
| Sold for mastitis (TC = 7) | 13.0 | 15.3 | 17.9 | 19.2 | 21.2 | 22.2 | 16.6 |
| Sold for other reasons (TC = 5) | 29.8 | 28.6 | 28.9 | 29.2 | 29.3 | 31.9 | 29.3 |
| Died (TC = 6) | 19.7 | 20.5 | 23.2 | 24.5 | 23.2 | 22.2 | 21.7 |
References
Hare, E, H.D. Norman, and J.R. Wright. 2006. Survival rates and productive life of dairy cattle in the United States. Journal of Dairy Science 89:3713–3720.
Miller, R.H., M.T. Kuhn, H.D. Norman, and J.R. Wright. 2008a. Death losses for lactating cows in herds enrolled in Dairy Herd Improvement test plans. Journal of Dairy Science91:3710–3715.
Miller, R.H., M.T. Kuhn, H.D. Norman, and J.R. Wright. 2008b. Factors that affect abortion frequency in dairy herds in the United States. Journal of Dairy Science 91(E-Suppl. 1):8(abstr. T21).
Nieuwhof, G.J., H.D. Norman, and F.N. Dickinson. 1989. Phenotypic trends in herdlife of dairy cows in the United States. Journal of Dairy Science 72:726–736.
Powell, R.L., H.D. Norman, and J.L. Hutchison. 2008. Breed composition of the United States dairy cattle herd. Journal of Dairy Science 91(E-Suppl. 1):7(abstr. T17).