A well accepted goal of heifer raising is to calve Holstein heifers at 24 months of age weighing 1350 lb post-calving with a wither height of 54 to 56 inches. However, according to DHIA records, the average age at calving is just over 27 months and has changed very little over the last several decades. Calving heifers later than 24 months of age can result in an array of problems, including increased costs, lower milk production, lower protein production, overconditioned animals, increased calving problems, and lower lifetime production.

After weaning, heifers tend to be the most neglected group on the farm. The result is calving ages greater than 24 months. The lower amount of labor needed to care for heifers and ease of meeting nutrient needs in comparison to other groups on the farm probably contributes to the lack of attention given to developing heifers. Since there is no immediate profit in raising heifers, some producers tend to feed this group as cheaply as possible. The result is poor growth rates.

The negative impact of an improper heifer development program upon profitability of a dairy operation is not immediate. Figure 1 shows the impact upon the breakeven time (when heifer rearing costs are offset by milk sales) of a heifer calving at 24 months of age versus 28 months of age. When a heifer is born, she becomes a profit drain on the dairy operation because of rearing costs. Once the heifer calves, she begins to earn money for the producer through milk sales. A heifer calving at 24 months of age reaches the breakeven point in profitability at 46 months of age versus 58 months for heifers calving at 28 months of age. When age at first calving is delayed by four months, the breakeven point of profitability is increased by one year.

The age of a heifer at calving is affected by two factors:

• Growth rate.

• Breeding efficiency.

Heifers should be bred on weight and frame size rather than age. To achieve the proper weight and age at the same time, heifers should be provided appropriate rations. Holstein heifers should be bred when they weigh approximately 750 to 850 lb and have a wither height of 48 to 50 inches. Breeding efficiency tends to be higher in heifers. To attain a 24 month calving age, heifers must conceive at 15 months of age. If heifers have a breeding efficiency of 1.5 services per conception, breeding must be initiated at 13 to 14 months of age. To achieve the growth rate needed for breeding, the animals must have an average growth rate of 1.7 to 1.9 lb per day.

Accelerating heifer growth as a means to reduce heifer raising costs has received considerable interest and research. Several studies have shown, when done properly, accelerating the growth rates of heifers so they calve at 22 months of age can be profitable. Reducing the age of calving below 22 months is not recommended. To achieve a 22 month age at first calving, the heifer needs to average 2.0 – 2.2 lb gain per day. Gains of over 2.2 lb/hd/day have been associated with fat deposition and may decrease longevity. Feeding heifers to gain more than 2.2 lb/hd/day is not advisable. The goals of a heifer development program are given in Table 1.

Strategies to Attain a Profitable Heifer Development Program
All stages of the heifer program need to be considered to attain profitable heifer development. For the pre-weaned calf, the importance of receiving good-quality colostrum as soon after birth as possible is well established. The pre-weaned calf should be fed a good-quality milk replacer medicated with oxytetracycline at 200 grams per ton and neomycin at 400 grams per ton to aid in the prevention of scours. The feeding of saleable milk is uneconomical. The feeding of non-saleable, treated milk is not recommended because of the variability in the nutrient content.

The calf should be weaned when she is consuming approximately 1.5 lb of solid feed. The weaned calf should be fed a highly digestible starter and grower ration to stimulate development of the rumen. The starter should contain a coccidiostat and the grower should contain a growth promotant. The use of forage should be limited prior to weaning (less than 10%) and blended with the starter/grower, if possible. Several strategies should be established during the heifer development stage.

Feed Grain
The growth rates necessary for a 22 to 24 month age at first calving cannot be met by feeding forages exclusively. A grain mix must be utilized. Many producers are concerned that feeding grain to heifers may lead to
foot problems. This can occur if grain is overfed. The needs of most heifers receiving average quality forages can be met with a grain feeding rate of 5 to 6 lb which will not cause problems associated with feeding excess grain.
In addition, as the heifer gets older, the proportion of grain should be reduced as forage intake increases.

Feed a Balanced Ration
Many operations do not have rations balanced specifically for heifers. As with any animal on the farm, it is important to meet the nutritional needs of the heifer. Protein and energy are interrelated, to a great degree, to attain proper growth rates and frame size in heifers. The NRC recommendations for energy and protein may be appropriate in ad libitum TMR feeding, but these requirements should be increased 15% with other feeding systems. It has been suggested that protein nutrition is the most limiting factor in achieving normal or accelerated growth rates. VandeHarr (1998) suggests that for each Mcal of NEm in the ration, approximately 95 to 100 grams of crude protein should be included for accelerated growth rates. While this discussion has focused on energy and protein, other nutrients should not be ignored and need to be balanced in the ration.

Use a Growth Promotant
Ionophores improve average daily gain in heifers by improving energy utilization of the grains fed. Monensin (Rumensin®*) and lasalocid (Bovatec®*) are two well recognized ionophores used in heifer rations. A third dietary growth promotant, bambermycins (GAINPRO®*), has recently been approved for dairy heifers.

In a summary of 18 trials, bambermycins increased average daily gain (ADG) by 10.5% versus controls. In a summary of 10 trials, bambermycins increased ADG by 10% versus lasalocid and, in a summary of nine trials, 3.3% versus monensin. While also improving the energy utilization from grain similar to monensin and lasalocid, in situ research has shown bambermycins also increases fiber digestion.

Increase Forage Quality
Many producers feed extremely poor forages to heifers as a means to dispose of those forages. While it is a good management practice to save the best quality forages on the farm for lactating cows or young calves, the developing heifer still needs a digestible fiber source to maintain and grow a healthy rumen environment and to support growth of the animal. Forage quality can be increased by substituting good-quality forages for poorer quality forages. Forage digestibility can be increased by supplementing certain additives.

As previously discussed, in situ research has indicated bambermycins increase fiber digestibility. Also, studies showed fiber digestibility was increased by almost 20% when supplemental cobalt was provided as cobalt glucoheptanate. The use of supplemental bambermycins and/or cobalt glucoheptanate can enable the heifer to extract greater amounts of nutrients from the forages offered.

Establish a Deworming Program
Internal parasites can reduce the weight gain of a heifer substantially. A routine deworming program should be incorporated into the heifer program. This is especially true when heifers are reared on pasture, but should be considered for all heifer development systems.

Control the Environment
The maintenance requirement of heifers is increased during adverse environmental conditions. Producers should alleviate problems associated with temperature, muddy conditions, overcrowding, excess moisture, wind, etc. Fly control should also be an important part of any heifer rearing system. Gain can be severely compromised when heifers are bothered by flies.

Monitor Results
To determine if you are on the right track to profitable heifer raising, records need to be kept. Growth rate can be measured in many ways including scales, girth tapes, yardsticks, or simply estimating heights by comparing to pre-marked fence posts, etc.

Conclusion
A strong foundation is necessary to build a profitable operation. Heifers are the foundation of the dairy. The heifer development program represents an area of potential hidden losses. If a producer considers the heifers as an investment rather than a cost, the first step has been taken toward a more profitable operation. Consult with your MoorMan’s Representative to evaluate potential improvements in your heifer development program.

*Not trademarks of ADM Alliance Nutrition, Inc.