Take Home Messages

• Heifer groups are critical for optimal group and management which may require facility additions and/or modifications.
• Aggressive heifer growth programs require higher nutrient levels than in NRC (9).
• Heifers must be measured quarterly to determine if growth targets are achieved.

Once the heifer has been weaned, several options or strategies can occur on dairy farms.

1. Older heifers do not die or require care.
2. Heifers can "rough" it with low feed costs.
3. Heifers can be fed lower quality forage.
4. If heifers are fed well, they will not milk.

These options will not produce heifers that will enter the milk string at 23 to 25 months of age, weighing 570 kg (after calving), body condition score 3, and stand 135 centimeters at the withers. These goals can be modified by the dairy manager, but must be clearly defined and measured.

Grouping Heifers

Several groups of heifers are needed to optimize growth, management, and costs. Seven groups of growing heifers listed in Table 1 are based on nutrient and dry matter intake differences, competition and size differences, need to observe heifers for A.I. breeding, and meet gestation needs.

Table 1. Suggested groups for growing heifers based on age and management strategies (8).

Age guidelines in each group can be modified depending on number of heifers, facilities, and age at breeding. However, facility limitations should no be an excuse to reduce group numbers.

Accelerated Nutrient Guidelines

Three heifer rations should be developed and delivered to growing heifers. Nutrient guidelines are listed in Table 2.

Table 2. Ration guidelines for accelerated heifer growth programs adapted from 2,3)

The following guidelines can be considered when building heifer rations.

• Limit the amount of corn silage, wet haylage (> 60 percent moisture), and pasture to heifers less than 6 months of age.
• Groups 1 and 2 need supplemental grain (1 to 3 kg) for energy and protein supplement (0.2 to 0.5 kg).
• Groups 3 and 4 need supplemental grain (0.5 to 2 kg) depending on forage quality.
• Groups 5 and 6 may not need additional grain or protein supplement beyond forage sources.
• Group 7 ration can be similar to groups 5 and 6, but supplemented with higher levels of trace minerals, vitamins, and nutrients for the unborn calf.
• ALL heifers should be force fed a balanced mineral and vitamin package (not free choice) mixed with forage or grain.
• ALL heifers should be fed an ionophore.
• Trace mineral salt and mineral can be offered separately on a free choice basis (does not replace force fed minerals).

Research has clearly demonstrated that high energy ration with marginal protein intake resulted in over-conditioned heifers with decreased mammary secretory development and milk production (1,11). Hormonal shifts (lower levels of bovine somatotropin and other mammogenic hormones) lead to this negative effect. The critical time is during the pre-pubertal development time phase (4 to 10 months of age) when the mammary gland, secretory ducts, and parenchyme cells develop (7). New York research has indicated if nutrient levels are balanced and body condition scores are within acceptable ranges, mammary development (measured by milk yield) was not compromised (12).

Environmental factors can increase energy requirements beyond normal needs (Table 3).

Table 3. Added energy requirements for dairy replacement heifers (2,7).

For example, a 275 kg heifer requires 4.14 kg of TDN per day. If the heifer is housed in open housing in winter, add .14 kg TDN. If she has heavy body mud coverage, add .17 kg of TDN. If both conditions occurred, the heifer would need an additional .35 kg of grain or the heifer reduces her growth (10).

Monitoring Growth

Every dairy manager that raises replacement heifers should be measuring and monitor heifer growth. Most dairy farmers can quickly relate their rolling herd average or milk yield per day. Few managers know heifer average daily gain, weight at breeding, wither height at calving, or body condition scores. Heifer growth is the "report card" on the heifer rearing enterprise.

Large breed heifers should gain 0.7 to 0.9 kg per day after weaning while small breed heifers should gain 0.5 to 0.6 kg per day. Body condition scores should remain under 3 until heifers are bred to avoid fattening (7). Table 4 lists growth guideline for different breeds and ages of heifers.

Table 4. Growth guidelines for various dairy breeds (4.5).

Once heifers have achieved the proper size, they should be bred as gestation is a fixed period which can delay return on investment. Large breed heifers should weigh over 565 kg (82 percent of mature body for the herd) after calving with a body condition score of 3 to 3.25 (12). If large breed heifers grow more than five centimeters during the first lactation, these cows may direct nutrients from milk production to growth (8). One hundred kilograms of growth during the first lactation can reduce milk yield by 600 kilograms of milk (8). Poor quality forages will not allow for accelerated growth programs to be success. If heifers calve three months earlier (27 vs 24 months of age), heifer costs decrease by $130 and require fewer replacement heifers to maintain current herd size (2).

The Late Pregnant Heifer

A fourth heifer group is the springing heifer. Besides gaining 0.7 to 0.8 kg of growth (frame), she must also provide nutrients for a rapidly growing fetus. During late pregnancy, fetal and related tissue gains account for 0.6 to 0.7 kg per day of weight gain. Thus, the springing heifer should gain over 1.1 kg of scale weight per day (12). These heifers also need additional trace minerals and vitamins for the unborn calf and immune system.

Contract Raising Heifers

As dairy farms increase in size, dairy managers may raise heifers for other operations or contract to have some one else raise their heifers. Wisconsin workers (6) summarized the cost to raise heifers depending on starting weight (Table 5). These prices provide returns to labor, management, and capital. A signed contract or agreement must be completed by both parties outlining rate of gain, monthly payment schedule, payment based on gain or daily charge, responsibility for death losses, breeding program, veterinarian charges, duration of the contract, and management practices (such as dehorning, parasite control, disease control, over crowding, identification, and foot care).

Table 5. Heifers charges based on weight (6).

References

1. Capuco, A.V., J.J. Smith, D.R. Waldo, and C.E.Texroad,Jr. 1995. Influence of prepubertal dietary regimen on mammary growth of Holstein heifers. J. Dairy Sci. 78:2709.
2. Chester-Jones, H, P.C. Hoffman, and A.L. Skidmore. 1993. Optimum heifer growth for production and profit. MN Nut. Conf. p. 137.
3. Crowley, J., N.A. Jorgensen, T. Howard, P.C. Hoffman, and R. Shaver. 1991. Raising Dairy Replacement. N.C. Reg Ext Bull. No. 265. p. 37.
4. Heinrichs, A.J., and G.L. Hargrove. 1987. Standards of weight and height for Holstein heifers. J. Dairy Sci. 70:653.
5. Heinrichs, A.J. and G.L. Hargrove. 1991. Standards of weight and height for Guernsey and Jersey heifers. J. Dairy Sci. 74:1684.
6. Hoffman, P.C. 1997. What should we charge for raising heifers? Hoard's Dairyman Magazine. Mar 25. p. 235.
7. Hoffman, P.C., and D.A. Funk. 1992. Applied dynamics of dairy replacement growth and management. J. Dairy Sci. 75:2504.
8. Hutjens, M.F. 1992. Development of dairy replacement heifers. AFIA Liquid Feed Symp. p. 64.
9. National Research Council. 1989. Nutrient requirement of dairy cattle. 6th rev edition. Nat. Academy Sci. Washington, D.C.
10. Price, S, P.C. Hoffman, and J. Barmore. 1994. High and dry heifers...faster gains, lower cost. Hoard's Dairyman Magazine. Sept 25. p. 645.
11. Sejrsen, K., J.T. Huber, H.A. Tucker, and R.M. Akers. 1982. Influence of nutrition on mammary development in pre- and post puberal heifers. J. Dairy Sci. 65:793.
12. Van Amburgh, M.E., D.M. Galton, D.G. Fox, D.E. Bauman, L.E. Chase, H.N. and R.W. Everett. 1994. Effect of pre-puberal growth rate in Holstein heifers on first lactation milk yield. J. Dairy Sci. 77:185. Suppl 1.