Reasons that cows in Dairy Herd Improvement programs exit the milking herd (2016)

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

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TABLE 1. Percentages of cows (ALL BREEDS and CROSSBREDS) completing lactations.
TABLE 2. Percentages of cows (ALL BREEDS and CROSSBREDS) leaving the herd except for dairy purposes.
TABLE 3. Percentages of HOLSTEIN cows completing lactations.
TABLE 4. Percentages of JERSEY cows completing lactations.
TABLE 5. Percentages of AYRSHIRE, BROWN SWISS, GUERNSEY, MILKING SHORTHORN, and RED & WHITE cows completing lactations.
TABLE 6. Percentages of CROSSBRED cows completing lactations.
TABLE 7. Percentages of HOLSTEIN cows leaving the herd except for dairy purposes.
TABLE 8. Percentages of JERSEY cows leaving the herd except for dairy purposes.
TABLE 9. Percentages of AYRSHIRE, BROWN SWISS, GUERNSEY, MILKING SHORTHORN, and RED & WHITE cows leaving the herd except for dairy purposes.
TABLE 10. Percentages of CROSSBRED cows leaving the herd except for dairy purposes.

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For decades, dairy producers have designated reasons why cows leave the milking herds through Dairy Herd Improvement Association (DHIA) recordings. 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/salvage, or died. Those removed from the herd are given more descriptive codes, i.e., termination codes (TC). The TC system has added codes 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 before forwarding to the national dairy database. The frequencies of the codes are provided annually to describe reasons for voluntary and involuntary culling as they have considerable economic impact on producers. Rate and reason for culling also provide beneficial information for economic studies on dairy management.

Currently there are 2 TC choices for cows that remain in the herd when their lactation ends, and 10 choices (TC codes) for cows that leave the herd. For cows that stayed in the herd, the TC indicates whether their lactations ended as planned (TC=0) or ended unexpectedly as a result of an abortion (TC=8). For those cows “sold for slaughter or salvage”, 8 more TC choices provide more detailed information about why they left the herd.

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 cows by calving year and tracked them until they left the herd. That method provided comprehensive information, but unfortunately any results using this approach are quite 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, 2016. 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 64.4% across all groups. Purebreds ranged from 62.6 to 67.2%; Milking Shorthorn and Ayrshires were highest, Holsteins were at 64.0%. Crossbreds were higher than most purebreds with 67.4% of CB50s and 67.1% of CB90s remaining in the herds for an additional lactation. All purebred and crossbred groups had 0.2 to 0.4% of their lactations ended by an abortion.

TABLE 1. Percentages of cows (ALL BREEDS and CROSSBREDS) completing lactations by reason for termination and breed (2016). 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, total number of herds across breeds is 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 other reasons was often inversely related. Across all groups, the cows coded as sold for dairy was 3.7%; percentage of Holsteins and Ayrshires were the extremes for purebreds at 3.3% and 6.9%, respectively. Percentages of crossbreds sold for dairy was 4.6 and 5.2%. Across all groups, unspecified reasons, low production, reproduction problems, and mastitis/high somatic cell score (SCS) accounted for 9.6, 6.1, 4.5, and 4.5%. Crossbreds were intermediate to Holsteins and Jerseys in percentage reported culled for reproduction and for locomotion. Percentages of crossbreds sold for low production was slightly higher than the average percentage of all purebreds. The percentage of Holsteins and Jerseys that died was similar (5.5% and 5.7%). The lowest percentage of animals coded died was for Milking Shorthorn (3.3%).

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 30.3% of all cows leaving the herd, the reason was unspecified (25.5 to 32.7%), the highest in every group. Low production was the next most frequent code assigned for Holstein, Jersey, and crossbred cows exiting the herd (19.0 to 24.6%). Reproduction problems was the second most frequent code assigned for the remaining breeds except Guernseys (21.3 to 24.5%). Death was a frequently used code for all groups (12.7 to 23.0%). Mastitis/high SCS was also an important cause for departures (8.5 to 15.8%).

TABLE 2. Percentages of cows (ALL BREEDS and CROSSBREDS) leaving the herd except for dairy purposes by reason for termination and breed (2016). ¹Breed is determined from individual cow records, and cow's breed is used to determine the breed for herd counts. For example, a Holstein herd with a few Jersey cows would be included in the herd count for both Holsteins and Jerseys. 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 purebreds, and Table 6 for crossbreds. Purebreds other than Holsteins and Jerseys and crossbreds groups were combined because of small numbers, especially in later parities. Clear differences across parity are evident for all groupings as each were less likely to complete the lactations as they aged. Although 74.3% of Holsteins remained in the herd when lactation 1 ended, those percentages dropped to 66.8, 57.9, 50.1, 43.7, and 37.8 as lactations 2 through ≥6 ended. Likewise, Jerseys remaining was 71.4, 70.9, 65.0, 57.7, 51.9, and 44.2%. Other purebreds and crossbreds declined as well across lactations, from 72.7 to 48.1% and from 76.0 to 43.5%, 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 0.3% in 2016. Percentage sold for dairy purposes (3.3 to 6.7%) generally decreased as lactation number increased 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 2.0 to 9.6%, for locomotion issues from 0.7 to 4.0%, for low production from 5.0 to 8.9%, and for reproductive problems from 3.7 to 6.3%. The largest increase was for those sold with reason unspecified, from 6.4 to 19.0%. The percentage of Holstein that died increased from 3.0% during lactation 1 to 11.5% 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 cows completing lactations by reason for termination and parity (2016).

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TABLE 4. Percentages of JERSEY cows completing lactations by reason for termination and parity (2016).

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TABLE 5. Percentages of other purebred cows (AYRSHIRE, BROWN SWISS, GUERNSEY, MILKING SHORTHORN, and RED & WHITE) completing lactations by destination category, reason for termination, and parity (2016).

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TABLE 6. Percentages of CROSSBRED cows completing lactations by destination category, reason for termination, and parity (2016).

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Tables 7-10 show the percentages of Holstein, Jersey, other purebred, 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. Within all 3 purebred groups and parities, “sold for unspecified reasons" accounted for the highest percentage of exiting (25.8 to 33.1%). 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 accuracy of the new trait Cow Livability. Died (14.5 to 23.6%) and sold for low production (11.4 to 29.9%) were the next most common code assigned in all breeds, usually followed by sold for reproduction (8.2 to 20.3%). Mastitis/high SCS (9.4 to 19.4%) was the next most frequent reasons for leaving. A code added to the TC list recently was assigned infrequently, sold for locomotion (0.8 to 6.9%). Dairy producers should be encouraged to furnish more complete and accurate recording of termination codes as they are likely to be used to improve evaluation accuracy in the future.

TABLE 7. Percentages of HOLSTEIN cows leaving the herd except for dairy purposes by reason for termination and parity (2016).

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TABLE 8. Percentages of JERSEY cows leaving the herd except for dairy purposes by reason for termination and parity (2016).

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TABLE 9. Percentages of other purebred cows (AYRSHIRE, BROWN SWISS, GUERNSEY, MILKING SHORTHORN, and RED & WHITE) leaving the herd except for dairy purposes by reason for termination and parity (2016).

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TABLE 10. Percentages of CROSSBRED cows leaving the herd except for dairy purposes by reason for termination and parity (2016).

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).