Heifer Growth Strategy 

Growth, inventory, economics and data-informed management for better replacements 

FIELD GUIDE | HEIFER GROWTH | BOVISYNC MANAGEMENT 

In brief 

Breeding decisions should not rest on age alone. Age at first calving remains useful, but it is only useful when heifers reach the correct proportion of herd mature body weight before breeding and enter first lactation with enough size to perform. For many dairy heifer programs, that means approximately 55-60% of herd mature body weight at first breeding and about 80-85% after calving, with final values adjusted for breed, mature cow weight, genetics and management system. [3,5,6] 

Growth below target can be expensive even when the average age at first calving looks acceptable. It can add days on feed, increase replacement inventory, and reduce first-lactation performance. In a UW-Madison analysis of a large Holstein herd, the heaviest first-lactation cows at 30 days in milk produced 11 to 12 lb (5.0 to 5.4 kg) more milk per cow per day during early lactation than the lightest group. [6] 

BoviSync helps make heifer exceptions and trends visible before they become larger problems allowing timely management intervention. Weight data can be compared with expected weight, and breeding pen reports can include a unique BoviSync item AGE55MBW, the age at which each heifer is expected to reach 55% of mature body weight and ExpMatureWt item or expected mature body weight for an individual animal. This value originates from breed averages and can be adjusted using genomic or pedigree information related to body size where available. Reviewed alongside health, breeding eligibility, inventory stage, survival, cohort completion and later lactation performance, these records give management teams a clearer view of whether heifers are progressing as expected. The system is most valuable when reports are reviewed routinely, not only after a problem is already obvious. 

Executive Summary 

Heifer rearing is one of the largest investments in a dairy business. Penn State Extension describes replacement animals as typically 15 to 20% of milk production costs and commonly the second or third largest production-cost category after feed and, in some herds, labor. That cost is carried for many months before the animal enters the milking herd, so growth targets should be tied to whether heifers are heavy enough and mature enough for breeding for that herd, and to the economic return of the rearing program, not to calendar age alone. [1] 

The objective is not simply to calve heifers as young as possible. The objective is to raise enough suitable replacements, breed them when they have enough size and sexual maturity, calve them at an appropriate body weight, and avoid placing underdeveloped animals into first lactation. The mature body weight of the herd is the reference point with a first-breeding target of 55-60% of herd mature body weight and a post-calving target near 80-85% giving managers a practical way to assess whether the heifer is ready for the next stage. [3,5,6] 

Producers are sometimes lulled into a false sense of security with compensatory growth, or that the heifer will catch up. But missed growth has several forms of cost. A direct cost comes from additional non-productive days before calving. Iowa State University Extension estimated 2024 heifer rearing cost at $2.65 per head per day before labor and $3.15 with labor; at $3.15 per day, a 60-day delay costs about $189 per heifer before allowing for housing pressure or lost management flexibility. UW-Madison Extension also estimates that each month beyond 24 months age at first calving costs about $82 per heifer. [5,8] 

The production cost of poor growth is not limited to just delayed calving. Weight after calving is associated with first-lactation performance. UW-Madison Extension reports that every pound of missing body weight post-calving can cost about 7 lb (3.2 kg) of milk production, and its analysis of a 6,692-cow Holstein herd showed materially higher early-lactation milk from heavier first-lactation cows at 30 days in milk. Those figures should be treated as practical benchmarks rather than universal predictions, but they make the scale of the issue clear. [5,6] 

Growth, health, reproduction and inventory should always be reviewed together as calfhood respiratory disease and diarrhea can influence growth, the likelihood of reaching insemination, the number of inseminations needed, survival to calving and first-lactation performance. BoviSync provides a practical structure for the analysis of those records along with breeding eligibility, cohort completion and later performance. [9,12,13] 

Purpose and scope 

This paper provides a practical framework for farms and advisers who want to improve heifer growth, heifer inventory control, age at first calving and return on replacement investment. It does not replace calf care protocols, nutrition advice, veterinary direction or reproductive management. Its role is to show which data should be collected, how it should be interpreted, and how BoviSync can support routine decisions rather than one-off troubleshooting. 

The emphasis is on U.S. dairy operations and U.S. extension or industry sources wherever possible. International and global peer-reviewed work is included where it adds useful evidence. 

Glossary of key terms 

1. Why heifer growth strategy matters 

Replacement heifers carry cost long before they contribute milk income. Feed, labor, housing, bedding, health inputs and capital are committed through the growing period, and the return depends on how many heifers calve, how soon they become productive, and how well they perform once they enter the herd. 

Growth is one of the controls that keeps that investment on track. If heifers grow too slowly, first service and first calving are delayed. If they are bred by an arbitrary calendar age before reaching sufficient body size, the farm may still achieve pregnancy but freshen an undersized heifer. If the farm raises more replacements than it needs, those animals may have sale value, but they use feed, space, labor and working capital while they remain in the system. 

For that reason, heifer growth should not be treated as a weight-only topic. It should be reviewed with calf health, reproduction, inventory movement, semen strategy, genetics and cohort completion. The practical questions should always be whether the farm is producing enough suitable replacements that reach breeding and calving at the planned size, without carrying avoidable delays or surplus inventory. 

2. Use mature body weight as the reference point 

Age is an easy metric to follow, but it is not a reliable substitute for size and maturity. Extension guidance and industry benchmarks consistently point toward herd-specific mature body weight rather than a single age or breed-table assumption. The herd reference should come from a sample of mature cows in the same management system, ideally third lactation-or-greater cows in mid-lactation or more than 100 days in milk. [3,5,6] 

The following targets in table 1. are working benchmarks, not universal rules and they need to be checked against breed, herd mature size, genetics, housing, ration design and veterinary or nutritional advice. 

Table 1. Key heifer growth benchmarks by stage 

Penn State gives practical Holstein breeding-weight examples around 750 to 800 lb (340 to 363 kg) when that reflects about 55% of mature body weight. Jersey examples are commonly nearer 525 to 575 lb (238 to 261 kg), depending on herd mature size. Those figures should be treated as examples, not fixed targets. The stronger method is to calculate the farm target from the actual mature cow weight in that herd. [2,3] 

Many well-managed farms work around a 22- to 24-month age at first calving, provided heifers meet size targets. A lower age at first calving is not a saving if it creates an underdeveloped first-lactation cow. A 2026 Journal of Dairy Science meta-analysis is useful here because it reinforces that strategies to reduce age at first calving must be evaluated against production, risk of dystocia and reproductive outcomes rather than treated as automatically positive. [15] 

Average daily gain is best reviewed at each growth phase. Preweaning growth, the post-weaning transition, puberty, breeding weight, pregnancy and pre-calving development each place different demands on the heifer. The target-growth approach starts with desired age at first calving and mature cow size, then calculates the gain needed from the current weight to breeding and from breeding to calving. [23] 

3. What is lost when growth is below target 

The most visible cost of slow growth is extra time before calving. Each farm should use its own heifer rearing cost, but published budgets help set the scale. Iowa State University Extension estimated 2024 rearing cost at $2.65 per heifer per day before labor and $3.15 with labor. At $3.15 per day, a 60-day delay costs about $189 per heifer. Across 100 delayed heifers, that is about $18,900 before accounting for facility pressure, feed storage, lost replacement flexibility or market effects. [8] 

UW-Madison Extension provides a similar practical reference point: each month beyond 24 months age at first calving costs about $2.75 per heifer per day, or $82 per month. The exact cost will vary by farm, but slow growth still adds non-productive days and increases the number of heifers carried in the pipeline. [5] 

Replacement margin loss: completion-adjusted cost 

Replacement economics should also be adjusted for animals that enter the rearing program but never calve. A useful farm-level calculation is replacement margin leakage: the cost of getting a heifer to calving, divided by the proportion of heifers that actually complete the program. In simple terms: effective cost per calved heifer = (daily rearing cost x age at calving in days) / heifer completion rate. 

Using the Iowa State 2024 cost of $3.15 per heifer per day, a 24-month heifer at roughly 730 days has a base rearing cost of 730 x $3.15 = $2,300. If 10% of heifers do not complete the program, the 90% completion rate increases the effective cost to $2,300 / 0.90 = $2,556 per successful calved heifer. The 10% loss rate therefore adds about $256 to every heifer that does calve. [8] 

If age at first calving slips by 60 days, the calculation becomes 790 x $3.15 = $2,489, or $2,489 / 0.90 = $2,766 after the same completion-rate adjustment. The 60-day delay therefore costs about $210 per successful calved heifer, not just the simple 60 x $3.15 = $189, because the delay is also carried through the non-completion rate. 

The less visible cost is the milk production that may be left behind when heifers enter the milking herd underdeveloped. In the UW-Madison "Weight or wait?" analysis, first-lactation Holstein cows were grouped by weight at 30 days in milk. The lightest group averaged 1,126 lb (511 kg), while the heaviest averaged 1,412 lb (640 kg). The heaviest group produced 11 to 12 lb (5.0 to 5.4 kg) more milk per cow per day than the lightest group at weeks 4, 8 and 12 of lactation. Weight at 30 days in milk, rather than age at first calving by itself, was the better indicator of early-lactation performance. [6] 

UW-Madison Extension also gives a useful rule of thumb in that every pound of missing body weight post-calving can cost about 7 lb (3.2 kg) of milk production. A 100 lb (45 kg) post-calving weight deficit therefore represents about 700 lb (318 kg) of milk at that benchmark. That should not be used as a universal forecast, but it is a clear warning against calving heifers at the target age if they are below the required size. [5] 

Farms invest in genetic progress long before a heifer enters the milking herd. Sire selection, sexed semen strategy and the increase in genetic merit only gain economic value when the heifer survives, calves at the right size and has the conditions needed to express her potential. A high-merit heifer that is undergrown at calving may not fully deliver the production, fertility or longevity gains the farm has already paid to create. 

4. Growth and reproductive performance 

Poor growth affects reproduction in more than one way. Undergrown heifers may reach puberty later, enter the breeding pen later and extend age at first calving. Other heifers may be bred by age and conceive even though they are still materially below target. In that second case, the farm may not see an obvious heifer fertility failure, but the penalty can appear later as a lighter fresh heifer and weaker first-lactation performance. 

The BoviSync knowledge base article Heifer Size at First Breeding, describes AFB as a common threshold for first breeding and notes that heifers should be bred after reaching 55% of mature body weight and about 90% structural growth. DCHA similarly states that heifers should begin breeding at 55% of herd mature body weight, with a target to freshen at 22 to 24 months when body weight targets are met. [3,9] 

Reproductive performance should therefore be reviewed by weight status as well as age. A group can have acceptable pregnancy results while still leaving milk behind in the first lactation if too many animals are freshening below target size. Conversely, a low conception or pregnancy rate in the breeding group may reflect growth spread, delayed puberty, poor heat expression, health history or data capture issues rather than a single reproductive cause. 

Table 2. DCHA defines the 21-day pregnancy rate as the percent of eligible heifers that become pregnant in a given 21-day period. Numeric targets shown are from the publicly available 2023 fourth edition. Confirm against the current member-only DCHA edition where available. [3,4] 

Table 3. Reproductive measures to review alongside heifer growth 

5. Measure weight well enough to make decisions 

The value of a growth target depends on the quality of the weight data behind it. Visual estimates are not precise enough when timing of first insemination, stocking density, pen moves and inventory planning depend on relatively small differences in growth. Heart-girth tapes can be useful where scales are not available, but they should be treated as estimates and used consistently. Direct weighing with calibrated platforms, chutes, alley or parlor systems remains the preferred standard. [21,22] 

The practical objective is not to weigh constantly. It is to collect reliable weights at ages that change management decisions. Birth or entry, weaning, 6 months, 9 to 10 months, pre-breeding, pre-calving and freshening are common checkpoints. A weight at 9 to 10 months is particularly useful because it improves the estimate close enough to breeding age to identify slow-growing heifers before the breeding pen is affected. [6,9] 

Table 4. Practical weight checkpoints for heifer growth management 

Before treating a single low ADG as a potential nutrition issue, check that the weight data is reliable and whether the same pattern appears in other heifers from the same pen or cohort. One slow-growing heifer may need individual follow-up; a group of heifers falling below target points to a management issue that needs wider review. 

6. Health records explain growth and completion 

Health records add value because growth is often affected before the weight report shows it. Calfhood respiratory disease, diarrhea, navel infection and other early-life health events can reduce gain, delay breeding eligibility and increase the chance that an animal leaves the pipeline before calving. Health events should therefore be reviewed with weights and cohort completion, not treated as a separate health file. 

Abuelo, Cullens and Brester studied 2,272 female calves in a large dairy herd where heifers with preweaning bovine respiratory disease were less likely to be inseminated or reach first calving. Preweaning diarrhea was associated with more inseminations to become pregnant, a 50 g/day (0.11 lb/day) reduction in ADG and a 325 kg (717 lb) reduction in first-lactation 305-day mature-equivalent milk. [12] 

U.S. NAHMS-related work also supports the link between calf management, health and preweaning growth. Shivley and colleagues evaluated ADG in Holstein heifer calves across 102 operations in 13 states as part of the NAHMS Dairy 2014 calf component. The broader point for farm review should be disease frequency, treatment records and weight data all read together when growth targets are missed. [13] 

Figure 1. Birth Cohort Scorecard Report - BoviSync for reviewing heifer health, growth and removals. Grouping heifers by birth month makes it easier to see whether disease pressure, growth performance and early removals are changing over time and whether a problem is limited to one cohort or part of a wider pattern. 

7. Inventory planning with sexed semen and beef-on-dairy 

At publication date, the market value of purchased replacements places an even greater need for efficient management of the heifer program. Replacement planning starts with the herd’s future requirements and needs to account for herd turnover, planned herd size, reproductive performance, calf survival, heifer attrition, and target age at first calving. If these measures are not reviewed together, the farm can raise too many heifers, leave itself short of replacements, or make management decisions that do not match future herd requirements and goals. 

Cost when replacements are short 

Replacement shortage creates a second form of margin leakage. If slow growth, death loss or weak completion leaves too few fresh heifers, the farm may have to keep lower-value cows longer, buy replacements or reduce beef-on-dairy use to rebuild dairy heifer numbers. The hidden cost is often the margin lost from cows that should have left the herd but remain because no suitable replacement is available. 

Simple calculation: lost cow value = cows retained because replacements are short x margin loss per cow per day x extra days retained. For example, if 20 cows should have been culled, each gives up $2/day of margin compared with the cow that should replace her, and they stay an additional 90 days, the lost margin is 20 x $2 x 90 = $3,600. That is not booked as a heifer-rearing expense, but it is caused by replacement shortage. 

University of Maryland Extension gives a useful example of how later calving increases replacement demand. In a 100-cow herd with a 30% cull rate and 10% heifer non-completion rate, the number of heifers needed each year rises from about 30 at 22 months AFC to about 33 at 24 months AFC. In a larger herd, or where housing and feed are already tight, that difference has practical consequences: more animals must be carried in the replacement pipeline before they generate milk income. [17] 

USDA NAHMS Dairy 2014 reported an overall average age at first calving of 25.0 months, while also stating that the recommended range is 20 to 24 months. More than half of operations had an average AFC of 24 months or less, and those operations accounted for 77.0% of heifers, reflecting lower AFC on larger operations. Although the report is older, it remains a useful U.S. benchmark for understanding how age at first calving varies across farm size. [7] 

Sexed dairy semen, a beef-on-dairy strategy and an increasing amount of genomic testing, make the need for replacement planning to be more precise, and increases the importance of regular inventory monitoring. Higher genetic merit animals can be prioritized for dairy replacement matings and retention. Lower-priority animals may be better suited for beef-on-dairy matings, sale or non-retention, depending on the farm market and replacement position. Beef-on-dairy should add value without weakening the future supply of dairy replacements. 

BoviSync inventory, pregnancy, survival, completion and cohort reports can show whether sexed semen, beef-on-dairy and retention decisions are producing enough suitable replacements without filling facilities with animals the herd does not need or leaving the dairy short.  

Figure 2. Replacement pipeline concept. The useful question is not only how many heifers enter the system, but how many move through each stage on time, at target weight and without avoidable loss. 

8. Genetics, genomics and mature size 

Mature body weight targets should reflect the herd’s own cows and the genetic direction of the replacement group. In herds using genomic testing, sexed semen and deliberate dam selection, the next generation of heifers may not have the same mature-size profile as the current herd average. This is where genetic information can help refine growth targets, provided it is used carefully. 

Body Weight Composite is relevant because it provides a genetic indication of body size and dairy form. Holstein Association USA describes BWC as including body size dimensions and dairy form, and U.S. genetic evaluation resources identify it as a published trait related to body size. It should not be used to chase larger cows without considering fertility, production, health, feed efficiency and longevity. [11] 

Growth management helps make mature size visible in day-to-day decisions. Selection strategy still needs a balanced breeding objective. Larger animals may carry higher rearing and maintenance costs, while undersized first-lactation animals may give up production. The best target is therefore herd-specific targeting animals large enough to support performance, but not larger than the farm’s economics, housing and feed system can justify. 

9. How BoviSync supports routine management 

In practice, BoviSync allows weights to be reviewed alongside health events, reproductive status, inventory movement and later performance. That makes it easier to see whether slow growth or suboptimum performance is an individual exception, a group pattern or a wider management issue. 

The BoviSync knowledge base article describes a heifer-size approach built around expected mature body weight and the age at which a heifer reaches 55% of that value. The heifer-size model uses a Gompertz growth curve, a birth-weight assumption of 5.6% of mature body weight, and a mature-weight estimate adjusted by breed average and genomic or pedigree information where available. The difference between measured and expected weight can be carried forward using the BoviSync item WghtPhnDif in weight reports, improving later expected weights for that animal. [9,10] 

For implementation, the BoviSync knowledge base article describes heifer voluntary waiting criteria based on the greater of 390 days of age or the date the animal reaches 55% of mature body weight. A weight after 9 to 10 months of age improves the estimate of when the heifer is likely to meet first-service eligibility. This allows group management to remain practical while slow-growing heifers are handled as exceptions rather than being bred by age alone. [9] 

BoviSync reports for routine review 

Figure 3. Weight Analysis - Birth to Weaning Report - BoviSync –  This report shows whether calves are achieving expected preweaning growth by comparing birth weight, weaning weight, days between weights and average daily gain across birth cohorts and individual animals. Example data only 

Figure 4. Survival Past 24 Months Report - BoviSync. Cohort survival makes attrition visible by age and birth period. Example data only. 

Figure 5. Heifer Completion Rate Report - BoviSync. Completion rate and age at first calving help show whether births are converting into calved replacements. Example data only. 

Figure 6. Birth Cohort Completion Rate through 3 lact Report - BoviSync. Longer-term cohort retention connects heifer management with lifetime return. Example data only. 

Figure 7. BoviSync weight-item view. An example of some of the many growth items available in BoviSync for both general and bespoke analysis.  Expected mature weight, measured weight, AGE55MBW, AGE63MBW and phenotypic difference can be reviewed together. Example data only. 

10. Review cadence and data reliability 

Heifer programs are easier to manage when the same core records are reviewed regularly. Weights, health and treatment events, pen moves, ration changes and service criteria need to be considered together, because each can affect growth, breeding timing and replacement inventory flow. A short, regular review is usually more useful than waiting until the herd is either short of replacements or carrying too many late heifers. 

Table 5. Practical review points for weight checkpoints for monitoring heifer growth management 

Average age at first breeding is useful, but it can hide the distribution of performance within the average. The review should show whether most heifers are reaching first service within a reasonable window, or whether the same average is being created by a mix of early, on-time and late animals. Where the spread is wide, the next question is whether the delay is limited to individual heifers or affecting whole cohorts. 

Reports are only as reliable as the data behind them. Missing weights, duplicate weights, obvious incorrect weights, weights entered against the wrong animal, unrecorded disease events and pen moves can all distort heifer performance reports. Recording events in the pen or at the chute through the BoviSync mobile app, increases accuracy and efficiency of data capture. Each farm should agree who records key events, when they are entered and how often reports are reviewed, so that management decisions are based on current and dependable information. 

Conclusion 

Age at first calving is an important measure, but it is not enough on its own. A heifer programme also has to produce enough suitable replacements, with animals reaching first service at the right weight, calving with enough body size and staying in the herd long enough to repay the cost of rearing and capitalize on the genetic investment. Age targets are useful, but they can give a false sense of progress if they hide poor growth, uneven development, weak cohort completion or a replacement pipeline that does not match future herd need. 

This is where regular weight measurements have value. Mature body weight should be based on the herd’s own cows wherever possible, and heifer weights should be checked at the points where key management decisions are made, including grouping, breeding, pregnancy confirmation and pre-calving. When those weights are reviewed alongside health events, breeding history, pregnancy outcomes and cohort movement, managers can see whether heifers are genuinely on track or whether a reasonable average is masking animals that are already falling behind. 

Slow or inconsistent growth adds financial costs by extending the rearing period, increases the number of animals held in the replacement pipeline and can limit first-lactation performance. It can also reduce the value of genetic investment, because high-merit animals still need the right development environment to express their potential. The cost of a weaker heifer programme is therefore not just the extra time before calving. It may also be seen in lost milk, poorer fertility, shorter herd life and fewer meaningful selection choices. 

In practice, the value of the records comes from seeing these areas together rather than in isolation. BoviSync uses unique items in reports that predict appropriate timing and age at first service, it brings weights, expected weights, health records, reproductive status and outcomes, inventory movement, cohort completion and lactation performance all into the same review. That makes it easier to see whether a problem sits with individual animals, a particular cohort or if there is potentially a wider management bottleneck in the program. It also gives managers the chance to act earlier, before the outcome appears as increased AFC, overcrowded pens, replacement shortages, forced retention of low-margin cows or fresh heifers that are not ready to perform. 

The aim is not simply to calve heifers younger. It is to raise the right number of well-grown, productive replacements at the right time for the farm. 

Appendix A. Operating targets and management thresholds 

These are working thresholds, not universal rules. They should be checked against herd mature body weight, breed, genetics, housing, nutrition, growth history and veterinary or nutritional advice. 

Appendix B. Mature-body-weight conversion examples 

The table below shows how breeding and calving targets change as herd mature body weight changes. Values are rounded to the nearest 5 lb and nearest kilogram. 

Appendix C. Simple farm-level calculations 

References 

1. Penn State Extension. Heifer Economics. Published 2025. Accessed 21 May 2026. 

2. Penn State Extension. Monitoring Dairy Heifer Growth. Updated 3 December 2025. Accessed 21 May 2026. 

3. Dairy Calf & Heifer Association. Gold Standards: Performance and production standards for dairy calves and heifers, fourth edition. 2023. 

4. Dairy Calf & Heifer Association. DCHA updates its Gold Standards. Press release, 5 May 2026. Accessed 21 May 2026. 

5. University of Wisconsin-Madison Division of Extension. Heifer maturity matters. Accessed 21 May 2026. 

6. Lauber MR, Fricke PM. Weight or wait? How defining breeding eligibility of heifers impacts first-lactation milk production. University of Wisconsin-Madison Division of Extension. Accessed 21 May 2026. 

7. USDA APHIS Veterinary Services. Dairy 2014: Dairy Cattle Management Practices in the United States, 2014. 2016. 

8. Iowa State University Extension and Outreach Dairy Team. Heifer Raising Costs in 2024. Accessed 21 May 2026. 

9. BoviSync Knowledge Base, White Papers. Heifer Size at First Breeding. Accessed 21 May 2026. 

10. France J, Dijkstra J, Dhanoa MS. Growth functions and their application in animal science. Annales de Zootechnie. 1996;45(Suppl. 1):165-174. 

11. USA Cattle Genetics and Holstein Association USA. Individual traits and Body Weight Composite resources. Accessed 21 May 2026. 

12. Abuelo A, Cullens F, Brester JL. Effect of preweaning disease on the reproductive performance and first-lactation milk production of heifers in a large dairy herd. Journal of Dairy Science. 2021;104(6):7008-7017. doi:10.3168/jds.2020-19791. 

13. Shivley CB, Lombard JE, Urie NJ, Kopral CA, Santin M, Earleywine TJ, Olson JD, Garry FB. Preweaned heifer management on US dairy operations: Part VI. Factors associated with average daily gain in preweaned dairy heifer calves. Journal of Dairy Science. 2018;101(10):9245-9258. doi:10.3168/jds.2017-14022. 

14. Gelsinger SL, Heinrichs AJ, Jones CM. A meta-analysis of the effects of preweaned calf nutrition and growth on first-lactation performance. Journal of Dairy Science. 2016;99(8):6206-6214. doi:10.3168/jds.2015-10744. 

15. Lean A, Gunn A, Quinn J, Lean I, Breinhild K, Golder H. Meta-analysis of the effects of age at first calving on production outcomes, calving difficulty, and reproduction in dairy heifers. Journal of Dairy Science. 2026. doi:10.3168/jds.2025-27004. 

16. Penn State Extension. The Importance of Heifer Inventory. Published 2025. Accessed 21 May 2026. 

17. University of Maryland Extension. Managing Heifer Inventory on the Dairy. Updated 23 February 2022. Accessed 21 May 2026. 

18. Fricke PM, Lauber M. Optimizing use of sexed semen in dairy herds. University of Wisconsin-Madison Division of Extension. Accessed 21 May 2026. 

19. Holden SA, Butler ST. Review: Applications and benefits of sexed semen in dairy and beef herds. Animal. 2018;12(s1):s97-s103. doi:10.1017/S1751731118000721. 

20. Hawkins A, Burdine KH, Amaral-Phillips DM, Costa JHC. Effects of housing system on dairy heifer replacement cost from birth to calving. Frontiers in Veterinary Science. 2020;7:625. doi:10.3389/fvets.2020.00625. 

21. van Dijk J, Eagle SJ, Gillespie AV, Smith RF, Holman AN, Williams HJ. Visual weight estimation and the risk of underdosing dairy cattle. Veterinary Record. 2015;177(3):75. doi:10.1136/vr.102955. 

22. Sherwin V, Hyde R, Green M, Remnant J, Payne E, Down P. Accuracy of heart girth tapes in the estimation of weights of pre-weaned calves. Veterinary Record Open. 2021;8:e16. doi:10.1002/vro2.16. 

23. Van Saun RJ, Abuelo A. Feeding Dairy Calves From Weaning Through Maturation. MSD Veterinary Manual. Reviewed/revised December 2025. Accessed 21 May 2026. 

24. Dairy Cattle Reproduction Council. Focus on Heifer Size to Determine Age at Breeding. 2017.