Heifer rearing is a fundamental part of the dairy industry. It represents a significant economic investment by the farmer into the future of the herd, with studies reporting that it contributes to approximately 20% of the overall expenditure of a dairy farm (Gabler et al, 2000). The target that has been quoted for this figure is 10% (Frazer LLP, 2018), with the herd replacement costs calculated as the annual expenses to obtain calving heifers minus the revenues from culled cows, divided by the amount of milk sold. The herd replacement cost is highly dependent upon the rearing costs of and culling rate within the herd (Frazer LLP, 2018). An example is shown in Figure 1.
How much does it cost to rear heifers?
Research from 101 farms across Great Britain reported that the cost of rearing a heifer from birth to first calving varied significantly between farms, from £505.10 to £2147.50 per heifer reared (Boulton et al, 2017). This variability indicates that there are significant system differences, as well as potential inefficiencies within those systems, which have potential welfare, health and economic impacts. It is worth noting that the impact of external factors, such as the rise of inflation, have had a significant impact on heifer rearing costs, resulting in the cost of rearing a heifer in 2023 being considerably higher than in 2015.
Other factors that are also related to the cost of heifer rearing are summarised in Figure 2; these will be discussed in more detail in terms of the different life stages of the heifer. Before looking at the costs associated with heifer rearing, it is important to consider the efficiencies associated with heifer rearing and how these can be measured on farm.
Key performance indicators for heifer efficiencies
Before determining which area of the heifer rearing process may be inefficient, it is worth considering the overall efficiency of the heifer rearing process. The two key performance indicators highlighted in Box 1 are based upon the idea that heifer rearing will be efficient, providing the heifer survives, grows at daily liveweight gain over the rearing period to calve in at the target of ≤670 days and then survives long enough to have produced a profit for the farm.
Box 1.Key performance indicators of the overall efficiency of heifer rearing and subsequent efficiency of performance
- Rearing efficiency: % heifers born alive that calve at or below the target of age at first calving (≤670 days of age) (target ≥85%)
- Heifer effectiveness: % heifers born alive that calve at or below the target age at first calving and complete three lactations (target ≥75%)
From Bach et al (2021)
Breaking down these points, one of the key performance indicators to determine throughout the heifer rearing process is mortality rate for the cohort of heifers born. A study of the UK British Cattle Movement Service data records from 2011 to 2018 reported that 10% of dairy heifers born alive and registered did not survive past 22 months of age, with a 3.45% on farm mortality for dairy heifers before 3 months of age (Hyde et al, 2020). Research has estimated that the cost of mortality is £310 (Kossaibati and Esslemont, 1997); however, this is most likely an underestimation of costs. Other research has proposed that the cost of mortality is £139 per animal left if the perinatal mortality is 8% (Boulton et al, 2017); again, this may not be a true reflection of the cost. The following has been suggested for calculating the specific cost of mortality on farm (Hawkins et al, 2019):
Exact cost of mortality = (Value of newborn calf + (Cost up to death × ((interest rate/365) × 60)) × mortality rate)/remaining calves
Another aspect of the efficiencies of heifer rearing is the ability to calve in at the target age of first calving of 22 months of age. The median age at first calving in the UK is reported to be 28 months of age (Sherwin et al, 2016; Eastham et al, 2018). The age at first calving has an impact on heifer rearing costs, with the literature reporting the extra costs to be around £2.87 per day over the target age at first calving, potentially having a large impact on overall rearing costs (Tozer and Heinrichs, 2001; Boulton et al, 2017). Age at first calving has also been reported to have an impact on the future survival, productivity, health and fertility (Bach, 2011; Sherwin et al, 2016; Eastham et al, 2018), and therefore impacts the efficiency of heifer performance, as well as impacting the overall rearing cost of the heifer. The ability for a heifer to calve in at 22 months of age relies heavily on the heifer reaching the key bodyweight targets at certain milestones; these are highlighted in Table 1.
Table 1. Recommended targeted bodyweights for heifers during the rearing phase
| Stage of rearing | Target % of adult bodyweight (kg) | Target age (weeks) |
|---|---|---|
| Post weaning weight | 18 | 12 |
| First service weight | 60 | 56 |
| Calving in weight | 90 | 96 |
The industry has historically recommended growing calves at a linear rate of 0.8 kg/d; however, research has highlighted that this may not be the most appropriate way, both from an economic viewpoint and from optimising potential epigenetic impact. There are two main reasons for this; the first being the potential epigenetic effect that early growth has, including altering which genes are activated in terms of metabolic pathways and other body systems, such as the immune system. Research has highlighted that the daily liveweight gain during the first 2 months of life is responsible for 5% variation in production in future life (Bach and Ahedo, 2008). To put this into context, 5% variation of a first lactation heifer who gives 9000 litres in 305 days is the equivalent of 450 litres in the first lactation, which is £225 at 50 p/litre. At £3000/tonne for commercial milk replacer, £225 is the equivalent of an extra 75 kg of commercial milk replacer, which is the equivalent of 500 litres of commercial milk replacer mixed at 150 g/litre. A normal calf fed 6 litres per day at 150 g/litre and weaned by 10 weeks would normally consume ~90 litres over her pre-weaning period. This increase in future production is hypothesed to be related to there being a higher concentration of oestrogen within mammary gland cells.
The other aspect of heifer effectiveness is the survival of cows within the herd to the third lactation. Improving the longevity has several impacts on the herd, which includes:
- Decreasing the number of heifer replacements required on the unit and therefore increasing the number of calves that can be sold as beef calves and decreasing the overall heifer rearing costs per annum.
- Decreasing the overall methane production from heifer rearing, as youngstock on a farm has been reported to contribute 19–33% of the total enteric methane of a herd (Knapp et al, 2014), dependent upon the age at first calving and culling rate.
- Optimising the profitability of the cows – it has been reported that cows do not produce their maximum yield until fifth lactation and therefore herds with shorter lifespans do not optimise on the maturity costs (De Vries and Marcondes, 2020).
Using a simple mathematical model, the economical optimal longevity is fifth lactation, based on the five main drivers of herd economics (genetic opportunity cost, herd replacement cost, lack of maturity cost, aged cow cost, and calf value opportunity cost) (De Vries and Marcondes, 2020).
Pre-weaning calves
The pre-weaning period is the most expensive part of the heifer's life, mostly because of the expense of the milk feeding, and comprises several components, as summarised in Figure 3. However, it is important to consider the impact on health and welfare of the heifer, as well as the overall feed conversion efficiency. Feed has been reported to be 48.5% of the pre-weaning costs (Boulton et al, 2015), with a study from the USA reporting that feed cost on 44 farms ranged from $29.06 to $259.17 per pre-weaned calf (£24.17 to £215.59) (Heinrichs et al, 2013). Factors that impact the cost of the pre-weaning period include age at weaning, kg of milk fed per day, milk price and price of commercial milk replacer per tonne. While the feed costs are hugely variable, the key outcome to monitor for the feed costs is the £ spent to gain 1 kg of weight gained. An example is highlighted in Table 2 based on a farm who fed different amounts of commercial milk replacer, where the cost per kg gained decreased when the calves were fed more commercial milk replacer.
Table 2. Impact of an autumn block calving herd changing from feeding at 12.5% to 15% commercial milk replacer in pre-weaning calves
| Diet | Commercial milk replacer fed per day (kg) | Total commercial milk replacer fed over 8 weeks (kg) | Cost of commercial milk replacer fed over 8 weeks (£)* | Median daily liveweight gain (kg/d) | Weight gained by 8 weeks of age (kg) | Cost per kg of weight gained (£) |
|---|---|---|---|---|---|---|
| 6 litres at 125g/litre | 0.75 | 40.5 | 97.20 | 0.60 | 33.6 | 2.89 |
| 6 litres at 150g/litre | 0.90 | 48.6 | 116.64 | 0.80 | 44.8 | 2.60 |
Another aspect to consider is the impact of disease on the economics, as it has the potential to impact mortality rates (discussed above), as well as having an impact by itself. The literature reports that cost of diarrhoea is £58 per case and £43 per case (Andrews, 2000); however, these are likely to be gross underestimates because of a lack of knowledge of the number of animals subclinically affected, as well as the permanent effects this had on future health and production. A systemic review on the impact of calfhood bovine respiratory disease has highlighted that these heifers were likely to have a decreased daily liveweight gain of 0.067 kg/d (over 22 months, this is equivalent to 44.89 kg), were 2.30 times more likely to be removed before their first calving and would produce 121.2 kg less milk (£60.60 at 50 p/litre) (Buczinski et al, 2021). This is hypothesised to be the result of a decrease in ability to transfer oxygen from the lungs to the blood, and therefore a subsequent decrease in the amount of oxygen available for metabolism, reducing the amount of energy released from the ingesta.
As discussed in Figure 2, there are many factors that can be used to determine the cost of pre-weaning calves; these are summarised in Figure 3, with an example shown in Table 3 for a herd rearing 50 heifers (time period birth to 10 weeks of age).
Table 3. Example herd for calculating costs of a pre-weaned heifer (birth to 10 weeks old)
| Factor | Different costs (where applicable) | Total | |||
|---|---|---|---|---|---|
| Initial value of the calf | £200 | ||||
| Pre-weaning feeding | Commercial milk replacer: 6 litres/day at 15% = 57 kg fed at £2400/tonne = £137 | Concentrates: 53 kg fed total at £350/tonne = £18.55 | Straw: 3 kg fed at £60/tonne = £0.18 | £155.73 | |
| Housing | Electricity: 100 kwh/year at 28 p/kwh = £0.08/day = £5.60; water consumption: 0.8 p/day = £5.60 | Bedding costs: 200 kg at £60/tonne = £12 | Housing depreciation: £0.07/day = £4.90 | Slurry: 7.0 litres/day up to 91 days: £0.15/day = £10.50 | £38.60 |
| Labour | 2 hours/day for 25 calves at £12.50/hour | £1 per heifer/day for 10 weeks | £70 | ||
| Vet and medical spend | Diarrhoea: 12 cases/100 calves/year at £58 per case = £7/at-risk calf | Bovine respiratory disease: 56 cases per 100 calves/year at £43/case = £24/at-risk calf | Vaccinations: intranasal at £7.42/calf | Failure of passive transfer: 14 cases/100 cows/year at £50/case = £7/at-risk calf | £45.42 |
| Mortality | Mortality rate was 4% with animals dying at approximately 7 days of age | Cost up to death: feed (£15.36), housing (£2.66), veterinary (£58): £76.02/heifer | Interest rate: 3% | Or alternatively two deaths at £310 out of 50 calves (£12.40) | £17.03 |
| Total cost | £526.78 | ||||
Costs of rearing a calf from weaning to bulling
While heifers are frequently ignored post-weaning, this is an important time in a heifer's life economically, as this is when the cost per kg of growth can be the cheapest. This is related to heifers commonly being fed a cheaper diet (3 kg of concentrate and ad lib straw), while still having a high feed conversion efficiency (3–4 kg dry matter intake can result in 1 kg of growth) (Bach et al, 2021). For this reason, it has been advocated to have a target daily liveweight gain of 1.2 kg/day, as the calves have the capacity to convert a cheap feed source into lean growth. For example, a calf fed 3 kg of concentrate per day and 1 kg of chopped straw costs £1.11 per day at £350 per tonne of concentrate and £60 per tonne of straw. The energy from 3 kg of concentrate is approximately 34 MJ, which is enough energy for a 120 kg heifer to grow at 1 kg/day; thus the cost per kg of daily liveweight gain is £1.11. It is important for a herd from an economic point of view to consider the diet of post-weaning heifers and what the potential growth rates are from the diet fed at certain stages of the rearing process. This is because poor daily liveweight gain during the early rearing phase can result in an expensive feed bill to meet the target bodyweights during the later rearing stages, as a result of the feed conversion efficiency decreasing with age (Table 4). An example of daily liveweight gain targets based on the diet fed for a spring block calving herd is shown in Table 5; for this to work, farms need to be committed to regular weighing of heifers.
Table 4. Overview of diet and feed conversion efficiency of heifers during rearing
| Stage | Main dietary constituent | Estimated feed conversion efficiency (dry matter intake:daily liveweight gain) |
|---|---|---|
| Pre-weaned calves | Milk | 2:1 to 2.5:1 |
| Weaned calves | 25% forage | 3:1 to 4:1 |
| Young heifers | 50% high quality forage | 4:1 |
| Older bulling heifers | Total mixed ration | 6:1 to 7:1 |
| Older pregnant heifers | Poor quality forage | 8:1 to 15:1 |
Table 5. Example of target daily liveweight gain for a spring block calving herd, based on potential daily liveweight gain from diets fed at different stages of rearing process
| Age (weeks) | Time of year | Potential diet | Kiwi Cross cows | |
|---|---|---|---|---|
| Target daily liveweight gain (kg/d) | Proposed bodyweight at the end (kg) | |||
| 0–4 | February | Milk | 0.7 | 50 |
| 4–8 | March | Milk and concentrate | 0.9 | 75 |
| 8–12 | April | Concentrate and straw | 0.9 | 100 |
| 12–18 | May–June | Grazing and concentrate | 0.8 | 123 |
| 18–26 | July–August | Grazing | 0.8 | 167 |
| 26–37 | September–October | Grazing | 0.8 | 229 |
| 39–56 | November–February | Fodder beet and silage (over wintering) | 0.55 | 294 |
| 57–65 | March–May | Grazing | 0.7 | 334 |
| 66–91 | June–October | Grazing | 0.7 | 456 |
| 92–100 | November–December | Fodder beet and silage (over wintering) | 0.5 | 484 |
| 101–104* | January | Transition ration | 0.4 | 495 |
| Target calving weight (kg) (at 90% adult bodyweight†) | 495 | |||
adult bodyweight is taken from the mean bodyweight of third lactation cows from that specific farm.
In terms of calculating the heifer rearing costs, it is very similar to those discussed above for the pre-weaning costs; costs include feed costs, vet and medical spend, mortality, housing costs and labour. The time periods that this is split up into will depend upon on the individual farm and what is easiest.
Accounting the costs of fertility in maiden heifers
A good fertility performance is essential for reducing the cost of heifer rearing, as a delayed conception increases the number of days which the heifer is reared for (and therefore costing money), as well as increases the likelihood of the heifer being culled as a result of infertility, either as a maiden heifer or in subsequent lactations because of an increased age at first calving (Bach, 2011; Sherwin et al, 2016; Eastham et al, 2018). The costs of the conception itself are highlighted in Box 2.
Box 2.Example calculating cost of conception per heifer in the group
- Semen costs per heifer, based on a conception rate of 60%: mean 1.6 straws at an average of £20/straw = £32
- Time for artificial insemination and heat detection: 40 minutes/day for a batch of 15 heifers at £12.50/hour = £0.56 per heifer/day for the duration in that group
- Pregnancy diagnosis: approx. £8/pregnancy diagnosis
- Medical intervention: five injections of Estrumate: £0.48/heifer in group
What about the time to pay this back?
Research has suggested that heifers must survive to at least second lactation to payback the rearing costs to the farm. A study investigating the longevity of Irish heifers calculated that 8535 kg of milk would be required to break even, based on a mean margin over variable cost of €0.17/kg and the approximate cost of rearing a heifer of €1451 per heifer (Archer et al, 2013). This would therefore take a minimum of one lactation and generally more. This finding was echoed in a UK-based study, where the mean number of days after first calving to breakeven point was 530 days, which was approximately 1.5 lactations before profit was made (Boulton et al, 2015).
A target for first lactation heifer production is at least 80% of the adult herd yield; for example, first lactation heifers should produce 6400 litres if the adult cows are producing 8000 litres in 305 days. If a heifer was to produce 6400 litres in her first lactation, at 50p/litre, then she would have given £3200 of saleable milk. At which point, if the heifer cost £2000 to rear, then it would mean that there was £1000 to cover her first lactation costs. The first lactation costs include feed, labour, housing, parlour running costs, pregnancy costs, disease costs and mortalities or culled cows; these costs could easily be more than £1200 in many dairy systems. It also worth considering the role of the milk price in this payback time, as if the milk price was 40p/litre, then the heifer would have produced £2560 of saleable milk; this results in £560 to cover her first lactation costs.
Conclusions
Heifer rearing can be an expensive and inefficient process on farms, with huge economic variation between different farms having been highlighted. It is important for farmers to determine the replacement costs of the unit, to determine where the inefficiencies are within the system, as this will have an impact on the health and welfare of the individual heifers, as well as the sustainability and productivity of the farm. The role of the veterinary surgeon is to aid the farmer in setting targets for their heifers, based on their farming system, and reviewing the heifer performance, including economics. There is the potential for veterinary surgeons to have an impact on the heifer rearing process in terms of health, welfare and performance, as well as reducing inefficiencies and rearing costs on farm.
KEY POINTS
- The economics of heifer rearing is massively variable between dairy farms in the UK and needs to be determined on a farm-by-farm basis to determine the areas of inefficiencies.
- Feed costs have a large impact on rearing costs; however, the metric to determine its impact, which is £ spent per kg of bodyweight gained as expensive feed, can be used in an efficient manner, providing it is supported with the desired daily liveweight gain.
- Any heifer exiting the herd before the start of her second lactation will not have covered her rearing costs and transfers that debt to surviving heifers, increasing the payback time.
- Veterinary surgeons have a role in aiding farmers to set targets for heifer performance and reviewing performance indicators, including those relating to longevity.