Nutrition
Early Spring Nutritional Challenges of Spring-
Calving Cows
By Glenn Selk, Oklahoma State University
Late winter and early spring
is the most challenging time
of the year for the nutrition of
the spring-calving beef cows.
Unless cool season grasses are
available, this is a season where
maintaining or gaining body
condition on spring calving
cows is really quite difficult.
Warm season grasses have not
yet begun to grow. Dormant
grass (what little is left) is a
low-quality feed. Cows cannot,
or will not, consume a large
amount of standing dormant
grass at this time year. If the
only supplement being fed is
a self-fed, self-limited protein
source, the cows may become
very deficient in energy.
Remember, the instructions
that accompany these self-fed
supplements. They are to be fed
along with free choice access
to adequate quality forages.
There is another factor that
compounds the problem. A
small amount of winter annual
grasses may begin to grow
in native pastures. These are
the first tastes of green grass
many cows have seen since
last summer. The cows may try
to forage these high moisture,
low energy density grasses,
in lieu of more energy dense
hays or cubes. The sad result
is the loss of body condition
in early lactation beef cows
64 | APRIL 2019
just before the breeding
season is about to begin.
Body condition at the
time of calving is the most
important factor affecting
rebreeding performance of
normally managed beef cows.
Nonetheless, condition changes
after calving will have more
subtle effects on rebreeding
especially in cows that are in
marginal body condition. Body
condition changes from the
time the cow calves until she
begins the breeding season
can play a significant role in the
rebreeding success story. This
appears to be most important
to those cows that calve in
the marginal body condition
score range of “4” or “5”.
An Oklahoma trial (Wettemann,
et al. , 1987 Journal of Animal
Sci., Suppl. 1:63). illustrates the
vulnerability of cows that calve
in the body condition score of
5. Two groups of cows began
the winter feeding period in
similar body condition and
calved in very similar body
condition. However, after
calving and before the breeding
season began, one group was
allowed to lose almost one full
condition score. The other group
of cows was fed adequately to
maintain the body condition
that they had prior to calving.
The difference in rebreeding
rate was dramatic (73% vs 94%).
Again, this illustrates that cows
that calve in the body condition
score of 5 are very vulnerable to
weather and suckling intensity
stresses and ranchers must
use good nutritional strategies
after calving to avoid disastrous
rebreeding performance.
Cows should calve in moderate
to good condition (scores
of 5 or 6) to ensure good
rebreeding efficiency.
Ideally, cows should be
maintaining condition during
mid to late pregnancy and
gaining during breeding.
The goal of the management
program should be to achieve
these body conditions by
making maximum use of the
available forage resource.
Continue feeding a source of
energy, such as moderate to
good quality grass hay free
choice and/or high energy
cubes until the warm season
grasses grow enough to
provide both the energy and
protein that the lactating
cows need. Yes, the feed is
high-priced. But the cost of
losing 21% of next year’s calf
crop is even greater. I