Reasons that cows in Dairy Herd Improvement programs exit the milking herd (2018)

H.D. Norman, L.M. Walton, and J.W. Dürr

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TABLE 1. Percentages of lactations (ALL BREEDS and CROSSBREDS) having reason for termination by breed.
TABLE 2. Percentages of lactations (ALL BREEDS and CROSSBREDS) for all cows leaving the herd for other than dairy purposes by reason for termination and breed.
TABLE 3. Percentages of HOLSTEIN lactations by reason for termination and parity.
TABLE 4. Percentages of JERSEY lactations by reason for termination and parity.
TABLE 5. Percentages of AYRSHIRE, BROWN SWISS, GUERNSEY, MILKING SHORTHORN, and RED & WHITE lactations by reason for termination and parity.
TABLE 6. Percentages of CROSSBRED lactations by reason for termination and parity.
TABLE 7. Percentages of lactations for all HOLSTEIN cows leaving the herd for other than dairy purposes by reason for termination and parity.
TABLE 8. Percentages of lactations for all JERSEY cows leaving the herd for other than dairy purposes by reason for termination and parity.
TABLE 9. Percentages of lactations for AYRSHIRE, BROWN SWISS, GUERNSEY, MILKING SHORTHORN, and RED & WHITE cows leaving the herd for other than dairy purposes by reason for termination and parity.
TABLE 10. Percentages of lactations for all CROSSBRED cows leaving the herd for other than dairy purposes by reason for termination and parity.

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For decades, dairy producers have designated reasons why Dairy Herd Improvement Association (DHIA) recorded cows leave the milking herds. Information given when cows complete lactations or are removed from the herds place the animals into 4 destination codes (DC): remained in herd, sold for dairy, sold for slaughter, or died. Those removed from the herd are given more descriptive codes called termination codes (TC). The TC system has had codes added across time and in addition choices offered to producers vary slightly between dairy records processing centers (DRPC). All DRPCs include TCs on each lactation record when forwarding them to the national cooperators' dairy database. The frequencies of the codes are provided annually to describe reasons for voluntary and involuntary culling as they have substantial economic impact on producers. Rate and reason for culling also provide beneficial information for economic studies on dairy management.

Currently there are 2 TC codes for cows that remain in the herd when their lactation ends, and 9 choices (TC codes) for cows that leave the herd. For cows that stayed in the herd, the TC indicates whether their lactations ended normally (TC=0) or ended unexpectedly as a result of an abortion (TC=8). For those cows "sold for slaughter", 7 TC choices provide detailed information about why they left the herd.

Historical summaries of survival of U.S. dairy cattle have been reported by Nieuwhof et al. (1989) and Hare et al. (2006). Those studies grouped cows by calving year and tracked them until they left the herd. That method provided comprehensive information, but unfortunately results using this approach are dated due to having to wait until all animals in the original group leave the herd. An alternative approach (used here) provided more current information by summarizing reasons cows left the herds last year. This report is based on lactations with completion dates between January 1 and December 31, 2018. Results using this method are impacted considerably by annual fluctuations in milk and feed prices.

Selected summaries are provided by parity and breed (including crossbreds). The number of crossbreds has increased over the last decade. 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 sire and an F1-crossbred dam of 2 other breeds; the CB50 group was predominately backcross offspring from an F1 dam and a sire from 1 of the F1 parent breeds.

Table 1 shows the frequency of codes by breed disregarding parity. The percentage of cows that stayed in the herd after completing their lactations averaged 63.8% (63.6 had lactations ending normally and 0.2 had lactations ending with an abortion) across all groups. Breeds ranged from 61.1 to 65.4%; Jerseys and Ayrshires were highest, Holsteins were at 63.4%. Crossbreds were higher than purebreds with 66.5% of CB50s and 66.6% of CB90s remaining in the herds for an additional lactation. All purebred and crossbred groups had 0.1 to 0.4% of their lactations ending with an abortion.

TABLE 1. Percentages of lactations (ALL BREEDS and CROSSBREDS) having reason for termination by breed (2018). ¹Breed is designated on individual cow records, and cow's breed is used to determine herd counts. For example, a Holstein herd with a few Jersey cows would be included in the herd count for both Holsteins and Jerseys. Thus, the total number of herds across all breeds is much higher than the actual number of herds in Dairy Herd Improvement programs.

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Because of breed differences in the percentage of cows remaining in the herd, percentage sold for various other reasons was often inversely related. Across all groups, the cows coded as sold for dairy was 4.9%; percentage of Holsteins and Milking Shorthorns were the extremes for purebreds at 4.4% and 9.6%, respectively. Percentages of crossbreds sold for dairy was 6.4 and 8.0%. Across all groups, unspecified reasons, low production, reproduction problems, and mastitis/high somatic cell score (SCS) accounted for 9.2, 6.8, 4.7, and 4.1%. Crossbreds were similar to Jerseys in percentage reported culled for reproduction and intermediate to Holsteins and Jerseys in percentage sold for locomotion. Percentages of crossbreds sold for low production was higher than the average percentage of most purebreds. The percentage of Guernseys that died was high (7.9%). The lowest percentage of animals coded died was for Milking Shorthorn and crossbreds (4.3 to 4.5%). Since genetic evaluations for Cow Livability became available, we are now observing a substantial decrease in the number of cows dying while in the milking herd.

Table 2 shows the percentages derived from only animals that left the herd excluding those sold for dairy purposes. This gives a clearer picture of the relative importance of the various reasons for exiting. Unfortunately, for 29.4% of all cows leaving the herd, the reason was unspecified (24.3 to 34.1%), the highest in every group except for the crossbreds. Low production was the next most frequent code assigned for Holstein and Jersey cows exiting the herd (20.9 and 26.2%). Reproduction problems was the second most frequent code assigned for four of the remaining breeds (19.3 and 23.2%), except Guernseys. Death was a frequent code for all groups (15.7 to 24.6%). Mastitis/high SCS was also an important cause for departures (8.1 to 16.1%).

TABLE 2. Percentages of lactations (ALL BREEDS and CROSSBREDS) for all cows leaving the herd for other than dairy purposes by reason for termination and breed (2018). ¹Breed is designated on individual cow records, and cow's breed is used to determine herd counts. For example, a Holstein herd with a few Jersey cows would be included in the herd count for both Holsteins and Jerseys. Thus, the total number of herds across all breeds is much higher than the actual number of herds in Dairy Herd Improvement programs.

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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. Breeds other than Holsteins and Jerseys were combined because of small numbers, especially in later parities. The 2 crossbred groups were combined also. Clear differences across parity are evident for all groupings whose lactations ended normally as each were less likely to complete the lactations as they aged. Although 73.0% of Holsteins remained in the herd when lactation 1 ended, those percentages dropped to 66.7, 57.9, 49.1, 42.1, and 36.0 as lactations 2 through ≥6 ended. Likewise, Jerseys remaining was 68.5, 71.2, 64.5, 58.0, 50.8, and 43.5%. Other breeds and crossbreds declined as well across lactations, from 71.8 to 43.7% and from 71.3 to 43.7%, respectively.

The probability that lactations were terminated by abortion was low (0.1 to 0.3%) for all lactation and breed groups. The frequency of recorded abortions has declined from 0.7% in 2007 and 2008 (Norman et al., 2009) to 0.2% in 2018. Percentage sold for dairy purposes in Holsteins declined from 5.6% in lactation 1 to 3.7% during lactations ≥6 as younger cows are preferred due to their longer expected life.

Because of the declining percentage staying in the herd and sold for dairy across parities, one would expect those leaving the herd for other reasons to increase. The trends across parity are clear and consistent for Holsteins. Holstein cows sold for mastitis/high SCS increased from 1.9 to 9.5%, for locomotion issues from 0.7 to 4.1%, for low production from 5.4 to 9.8%, and for reproductive problems from 3.8 to 6.8%. The largest increase was for those sold with reason unspecified, from 6.3 to 18.8%. The percentage of Holstein that died increased from 3.0% during lactation 1 to 11.3% during lactations ≥6. The percentage of cows of the other breeds that left for these five reasons increased across parities as well.

TABLE 3.Percentages of HOLSTEIN lactations by reason for termination and parity (2018).

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TABLE 4. Percentages of JERSEY lactations by reason for termination and parity (2018).

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TABLE 5. Percentages of AYRSHIRE, BROWN SWISS, GUERNSEY, MILKING SHORTHORN, and RED & WHITE lactations by reason for termination and parity (2018).

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TABLE 6. Percentages of CROSSBRED lactations by reason for termination and parity (2018).

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Tables 7-10 show the percentages of Holstein, Jersey, other breeds, and crossbred cows, respectively, assigned to the various termination codes by lactation number for all animals that left the herd except for those sold for dairy purposes. "Sold for unspecified reasons" accounted for the highest percentage of exiting (24.6 to 33.5). This could represent all reasons not designated, or simply indicate no reason was given; most likely more of the latter. One would hope that a large percentage of the cows given the termination code "sold for unspecified reasons" would be coded with a more descriptive reason in the future as it would improve the evaluation accuracy of traits like Cow Livability. Sold for low production (13.0 to 34.3%) and died (14.1 to 22.3%) were common code assigned in the 4 breed groups, as was sold for reproduction (9.0 to 19.4%), and mastitis/high SCS (8.9 to 17.6%). A code added to the TC list recently, sold for locomotion, had considerable variation across breed and parity groups (1.0 to 7.2%). Sold for locomotion averaged across groups increased from 3.3% in first lactations to 6.2% in lactations ≥6. Jerseys had fewer locomotion departures than the other breeds. Dairy producers should be encouraged to furnish more complete and accurate recording of termination codes as they are used to improve evaluation accuracy in their own herd and across the entire industry. Reducing the number of cows with termination code "unspecified reasons" would produce significant genetic gain in the U.S. dairy cattle population.

TABLE 7. Percentages of lactations for all HOLSTEIN cows leaving the herd for other than dairy purposes by reason for termination and parity (2018).

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TABLE 8. Percentages of lactations for all JERSEY cows leaving the herd for other than dairy purposes by reason for termination and parity (2018).

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TABLE 9. Percentages of lactations for AYRSHIRE, BROWN SWISS, GUERNSEY, MILKING SHORTHORN, and RED & WHITE cows leaving the herd for other than dairy purposes by reason for termination and parity (2018).

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TABLE 10. Percentages of lactations for all CROSSBRED cows leaving the herd for other than dairy purposes by reason for termination and parity (2018).

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.

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.

Norman, H.D., J.R. Wright, and J.E. Lombard. 2009. Reasons that cows in Dairy Herd Improvement Programs exit the herd. AIPL Research Report CULL1 (9-09).

We wish to acknowledge the contribution of the dairy producers who supplied data for this report through their participation in the Dairy Herd Improvement (DHI) program and the dairy records processing centers (DRPC) that processed and relayed the information on to the Council on Dairy Cattle Breeding (CDCB).