• Topics: Dairy and Poultry Sciences  | Dairy Nutrition  |  Animal Sciences  |  Harris, Barney, Jr. 

Feeding and Management of Dairy Heifers¹

HEIFER GROWTH RATES

Retardation of growth below recommended levels as shown in Table 1 tends to shorten the productive portion of the heifer's life. In some herds heifers frequently reach three years of age before first calving. The boarding bill for such heifers may become quite large.

Acceleration of growth above two pounds per day is also undesirable since lifetime milk production and longevity decrease. Tennessee studies show increased fatty infiltration of the mammary gland and reduced number of alveolar cells available for milk synthesis. Greatest harm apparently occurs during pre-puberty (prior to first heat) with little to no detrimental effect on mammary growth post-puberty (from about 11 months on). Michigan State studies suggest that feeding high levels of energy to accelerate growth from breeding to calving does not inhibit formation of mammary secretory tissue, and would probably allow maximum lifetime milk yields.

HEIFER FEEDING PROGRAMS

When calves are older (8 to 10 weeks of age) and are consuming 4 to 5 pounds of calf starter daily, a more simple and economical grain mixture may be used Table 2.

Table 3 shows the amount of crude protein, total digestible nutrients, calcium and phosphorus needed for young growing heifers to make acceptable weight gains. A calf pasture should contain a good supply of clean water and some shade. Clip the mature plants and weeds occasionally. Mature plants are less palatable and less nourishing than younger growing plants. Calves on pasture should be supplemented with some grain and minerals. A complete mineral mixture containing about 20 to 30% salt, 8 to 10% phosphorus and 14 to 18% calcium may be used. Also, one part trace mineral salt mixed with one part defluorinated phosphate provides extra minerals. The minerals should be provided in a container or trough that provides heifers free access.

A feeding program should give the dairy heifer every opportunity to develop a healthy and strong body. A well-developed heifer has a far better chance of becoming a good producer than one poorly fed and cared for. Varying amounts of roughage and grain may be fed during the growing period, with the amount of grain based on the desired growth rates. A great deal of flexibility is possible during this period and similar results can be obtained by following one of several feeding plans.

There is no one best grain mixture for young dairy calves and growing heifers. A 14% grain mixture for dairy cows is satisfactory as a growing ration for older calves. This is true even though the grain mixture may contain some cottonseed hulls and urea. The level of urea (0.5% of DM intake) as recommended for mature cows also applies to growing heifers.

Pasture Feeding

Heifers are usually turned to pasture at five to six months of age and should receive grain supplements, the amount depending on the condition of the heifers. Generally, two to five pounds of grain per day is needed for good growth. If the pasture contains some legumes, such as clover, a grain mixture containing 12 to 14% protein is adequate. If the pasture consists of grasses, millets, etc. The grain supplement should contain from 15 to 16% protein.The desirable growth rate for large breed heifers (Table 1) from birth to 14 months is about 1.7 lb/day. At 14 months these heifers should weigh about 700 lbs.

WHEN TO BREED

Optimum time for first breeding depends on the feeding program and management system. Size is more important than age in determining when heifers should be bred. Often heifers are bred to freshen at a particular time of the year to increase milk sales when supply is low and price favorable.

Well-fed heifers can be bred at 14 to 15 months of age and should weigh about 750 pounds (Holstein and Brown Swiss). At this size, conception should be good with little to no increase in calving difficulties. During the nine month gestation period, heifers should gain from 400 to 500 pounds, 130 pounds of which is calf weight and associated tissue. Until three months of age the average rate of gain is seldom over one lb per day, so an average daily gain of 1.8 lb per day is recommended from 3 to 14 months in order to obtain the desired breeding size of 750 to 800 lbs at 14 to 15 months of age. The suggested sizes and ages at which heifers are usually bred are given in Table 4.

A recent Iowa study compared age at calving on milk production of all first-lactation (305-2x-ME) heifers from 2124 herds (DHI records). The results are shown in Table 5.

There is considerable cost in both time and money in rearing replacement heifers to first calving. Calving of replacement heifers at 23 to 24 months minimizes the cost of raising replacements and allows dairy farmers to begin receiving a return on investments without affecting lifetime production.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other extension publications, contact your county Cooperative Extension service.

U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Millie Ferrer, Interim Dean.

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