Beef Cattle Heifer Development
The economic importance of beef cows having a
live, healthy calf to market every 12 months is obvious and has been emphasized in many publications. Heifer
management is the cornerstone of the overall program. This is based on the premise that heifers that are given an
opportunity to get off to a good start are more likely to be productive, profitable cows the remainder of their
lifetimes. Proper growth and development of replacement heifers will aid in their ability to deliver and raise a
healthy first calf and then rebreed for the subsequent calf crop. Two factors must be considered with replacement
heifers: 1) they are expensive and (2) the management of first-calf heifers affects their productivity for the
remainder of their lifetimes. Inadequate development of replacement females will be paid for eventually, either in
terms of a larger feed bill or in terms of an open cow (natures way of catching up). Lower rebreeding rates for
heifers compared to mature cows are normal through the second calf. When the demands on the heifers are studied,
reasons for difficult rebreeding become apparent. The heifer up until maturity, at about five years of age, must
grow and at the same time lactate and produce a calf. The loss of incisor teeth between the ages of 18 months and
four years is an added handicap that reduces their ability to graze. It is difficult for heifers to make up growth
during any of the critical first years.
Uniform calf crops are the result of shortened breeding seasons. Shortened breeding
seasons for the entire cowherd must start with the replacement heifers. Shortened breeding seasons for the
replacement heifers require that the manager/owner of those heifers must think of the heifers as a group as well as
individuals. The objective is to have the entire compliment of replacements bred closely in time and 3 weeks or
more before the adult cows.
Heifer Development from Birth to Weaning
In most beef cow-calf operations, the early development of the replacement heifers is
trusted entirely to the heifers’ mothers. However, some cattlemen use creep feeds to boost calf gains while they
are still nursing the cows. Also occasionally some purebred operations raising embryo transfer calves will utilize
dairy cows as surrogate mothers and these calves are exposed to large quantities of milk while growing. Even though
the cost effectiveness of these practices of these practices are often debated, there is little doubt that they
will increase calf gain.
A hidden expense, that may occur in a few instances, comes as a result of increased
body condition in young heifer calves while still nursing their mothers. Heifers that become extremely fat from
high energy creep feeds or very heavy milking mothers have been shown to have reduced milking ability of their own
when mature. Mammary development is in a critical stage from two or three months of age until about nine months, or
just before puberty. If a calf is storing considerable amounts of extra fat during that time, excessive fat can be
deposited in the mammary gland and inhibit its development. On the other hand, a certain minimum amount of fat is
necessary for the gland to grow, so underfeeding can inhibit development as well.
Beef producers need to look within their herds and observe heifer body condition if
they are using high energy creep feeds or dairy-based recipient cows. Because of the differences in birth weight
and frame size it is impossible to recommend a common average daily gain that would be appropriate for all young
heifers. Therefore monitoring the body condition (fatness) of the heifer calf through visual appraisal may be the
most practical way to evaluate the potential likelihood of excess fatness. Creep feeding calves with a self-limited
amount of high protein feed (such as soybean meal) can allow most heifer calves to grow adequately without concern
for extreme fatness. One such creep-feeding program has been described by OSU beef nutritionists as the "Oklahoma
Silver" program. Heifer growing programs that encourage maximum growth without excessive fatness will allow the
young heifer to get off to a good start and brings her to the next critical growing segment.
Sound research data is now available to recommend that replacement heifers need not be
implanted with a growth stimulating implant. Implanted heifers had no decrease in calving difficulty and in some
studies had slightly reduced fertility. Heifers implanted at birth and close to puberty had larger reductions in
reproductive performance. In those instances where ranchers cannot choose which will be replacement heifers at
calf-working time, there is a practical solution. Implant those younger, lighter half of the heifers that are very
likely to be candidates to sell at weaning time. Leave those heifers that have greatest chance to be replacements
UN-implanted. If at a later date you choose to keep a few heifers that were implanted at 2 months of age, there
should be no real consequence other than the wasting of the implant. Do not re-implant heifers that you plan to
Early immunization for blackleg and malignant edema at approximately 2 months of age
will be appropriate in most areas for all calves including those that become replacements. If heifers are to be
vaccinated for brucellosis, be certain to do this between 4 and 10 months of age. It is advisable to vaccinate
heifers nearer the younger age if possible. Other immunizations should be done 3 to 4 weeks prior to weaning.
Booster injections can be given at weaning time. Often just one more booster with a modified live vaccine at a year
of age will provide lifetime protection against the respiratory diseases. Visit with your local veterinarian about
the need to vaccinate replacement heifers for:
- Infectious Bovine Rhinotracheitis (IBR)
- Parainfluenza –3 (P13)
- Bovine Virus Diarrhea (BVD)
- 7-way clostridial
- Internal and external parasite control
Fortunately many of the above immunizations are now included in combination
vaccinations. Use the one that is most appropriate for your herd health history and local disease situation.
Weaning stress can result in serious health problems, especially respiratory disease.
Heifers that are affected with respiratory disease and pneumonia often have significant lung damage, do not grow
and develop properly, and must be culled prior to breeding.
Approximately 1.5 times as many heifers as will actually be needed for replacements
should be selected on the basis that they will be between 13 and 15 months of age at the beginning of the
heifer-breeding season. This will allow for some culling based upon lack of adequate growth, small pelvic area or
failure to become pregnant during the breeding season.