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AgridianDairy KB

Cull rate

Definition

Section titled “Definition”

The cull rate, better called the herd turnover rate, is the number of adult cows that leave the herd in a year (sold plus died) as a percentage of the average adult cow inventory. Fetrow et al. 2006 recommend “herd turnover” for this combined measure, with sold and died reported separately inside it, because “cull” is used loosely for both.

Removals are commonly split by reason:

  • Voluntary (economic) culling: the cow is healthy enough to keep but is replaced by a more profitable heifer: low production, surplus cows, dairy sales.
  • Involuntary culling: the cow leaves because of a problem: failure to conceive, mastitis, lameness, injury, disease, death.

The split depends on recorded sale reasons and is imprecise: most cows have more than one problem, and “low production” often follows a disease. Fetrow et al. 2006 suggest recording the main problem that triggered the removal decision.

Early-lactation removals (sold or died ≤ 60 DIM) are almost all involuntary and are a transition measure (see fresh cow KPIs).

Relationship to replacement rate

Section titled “Relationship to replacement rate”

In a herd with stable size, cows leaving must equal heifers entering, so the turnover rate equals the replacement rate. A growing herd has a replacement rate above its turnover rate. Raising more heifers than the planned turnover needs usually forces more voluntary culling or heifer sales.

Formula

Section titled “Formula”

Plain text:

Turnover (%) = (cows sold + cows died) in 12 months / average adult cow inventory over the same 12 months × 100


Sold rate (%) = cows sold / average adult cows × 100
Death rate (%) = cows died / average adult cows × 100


Early-lactation removal (%) = cows sold or died ≤ 60 DIM / cows calving in the cohort × 100

LaTeX:

\mathrm{Turnover} = \frac{N_{\text{sold}} + N_{\text{died}}}{\bar{N}_{\text{adult cows}}} \times 100

For a period shorter than a year, use cow-days (as in adult cow mortality) or report the actual period rather than annualizing one month.

How to pull it in DC305

Section titled “How to pull it in DC305”

Removals are SOLD and DIED events, usually with a remark code for the reason (and sometimes for dairy vs beef sale). Reason codes vary by herd; check the herd’s private dc305-vocab mapping. Removed cows may be in a separate archived file and must be included.

EVENTS\D SOLD ID LACT DIM FOR LACT>0     SOLD events, with remark (reason)
EVENTS\D DIED ID LACT DIM FOR LACT>0     DIED events, with remark (cause)
LIST\D ID LACT DIM SELDT DIEDT FOR LACT>0     cows that left, with sold date (SELDT) and died date (DIEDT)
ECON\IR                                  inventory report with cull rate
ECON\ID                                  past / yearly cow inventory summary (for the denominator)
COUNT FOR LACT>0                         adult cows on hand

EVENTS lists live animals only by default. Removed cows need \D (animals that have left the herd) or \B (live and left); animals already moved to the archive file need \L. \S prompts for the date window (\S### starts

days ago); event tables default to the last 365 days.

Section titled “days ago); event tables default to the last 365 days.”
  • Tabulate removals by reason code, by lactation (1, 2, 3+) and by DIM band (0–30, 31–60, 61–150, 151–305, 306+).
  • Count cows sold to another dairy separately; they are not health failures.
  • Denominator: average of monthly adult cow counts (lactating plus dry) for the 12 months. See cow count definitions.

Typical range

Section titled “Typical range”

Herd context: US Holsteins, freestall or dry-lot.

Measure Typical Goal
Annual herd turnover (sold + died) 30–40% depends on herd strategy
Deaths as share of all removals 15–25% lower is better
Removals ≤ 60 DIM, share of calvings 6–10% < 8%
Removals ≤ 60 DIM, share of all removals 20–30% < 25%

US reference: in NAHMS Dairy 2014, 28.4% of cows (as a share of January 1 inventory) were permanently removed alive and another 5.6% died, about 34% turnover in total, with deaths about one-sixth of removals. Live removals were about 24–26% in 1996–2007 (NAHMS trends report, tables F.2.b and F.3.b).

There is no single “right” turnover: a herd with good cow health and cheap heifers may choose high voluntary culling. The useful targets are low involuntary and early-lactation removals, not a low total.

Common mistakes

Section titled “Common mistakes”
  • Leaving deaths out. “Cull rate” sometimes means sales only. Say whether deaths are included.
  • Using the end-of-year cow count as the denominator. In a growing herd this misstates turnover; use the average over the period.
  • Counting dairy sales as culls. Selling springers or cows to other dairies is turnover, but not a health or fertility failure.
  • Trusting reason codes too far. “Low milk” or “other” often hides a disease. Look at DIM at removal alongside the code.
  • Annualizing one month. Culling is seasonal (heifer supply, prices, heat-stress fertility). Use a rolling 12 months.
  • Including heifers. Heifers that die or are sold before calving belong in heifer survival, not adult turnover.
Section titled “Related”