  BeefTalk:
That Cow Wasn’t Supposed to Calve Today
By Kris Ringwall, Extension Beef Specialist,
NDSU Extension Service
For most beef producers, the final days of the last trimester of pregnancy
for their cow herd is here. For some early bird producers, calves are already
bucking and jumping. Winters like this one are great (keep your fingers crossed)
and temporarily lay to rest all the discussion of when to calve.
Often, producers question when a particular cow is due. Most producers have a
handy calving table that projects the calving date of the cow based on the day
she was bred. For example. the IRM Pocket Reference guide shows a cow bred May
21 is due to calve on March 1.
In recent years, the North Dakota State University Dickinson Research
Extension Center has targeted March 1 as the start of the calving season. Do the
cows begin calving on March 1? Unfortunately, the cows do not read the tables.
Basically, a cow will calve when she and her calf decide the time is right.
We have all seen the old cow that gets up, lays down, gets up, lays down,
walks over to the corner, walks back, lays down, twitches her tail and calves
two weeks later. Or the cow with no udder that calves in what seems to be
minutes and successfully produces a normal, well fed day-old calf.
A current trend is to advertise cows for sale with predicted calving dates.
These dates were projected based on ultrasound measurements and are used to
imply the cows or heifers should calf over a period of seven to 10 days.
Establishing the age of a developing fetus with ultrasound is very accurate but
gestational age and calving date have little in common.
At the center, ultrasound records help us sort cows based on 21 day
reproductive cycles. No attempt is made to actually guess which day a cow is
going to calf.
In reviewing cow records, center research specialist Keith Helmuth compiled
all the cows with absolute breeding dates and sire of calf. In other words, 462
cows were artificially inseminated, and conceived to the unit of semen she was
inseminated with. Because of the different breeds used, the parentage of the
calf is not questionable. No DNA test or judge was needed to identify the
father.
Of these 462 cows, the average gestation length was 282.5 days. Of the 426
cows, only 87 actually calved on the expected date. These cows were expected to
calf 283 days after breeding or March 1st. In reality, the first live calf
arrived Feb. 11, then one on the 13th and one on the 16th. Three calves arrived
on Feb. 17, three on the 19th, one on the 20th, three on the 21st, nine on the
22nd, eight on the 23rd and a rush on the 24th produced 17 calves.
The calving crew is starting to sweat. On the 25th, 19 calves were born, 36
on the 26th, 38 on the 27th, 39 on the 28th and finally the due date, March 1,
87 calves were born. More sweat, despite the cold weather. On March 2, 53 cows
calve, on the 3rd, 25 calves, on the 4th, 16 calves, on the 5th, 22 calves, on
the 6th, 20 calves, on the 7th, 15 calves, and on the 8th, only four calves.
Just as there appeared to be a let up, on the 9th, 15 calves were born, on the
10th, 12 calves, and on the 11th, one calf. Finally, a slow down and the season
finished with two calves on the 12th, three calves on the 13th, four calves on
the 14th, and one calve each on the 15th, 16th and 17th. The last two calves
were born on the 19th of March.
All 462 cows conceived on the same day, but the calving season lasted 32
days. Approximately, 80 percent calved within a 11 day window, 95 percent in a
19 day window and 98 percent within a 28 day window. If you want to bet me you
know when your cow is going to calf, I will bet you she won’t calf on the day
she is due. Cows don’t calve in a 7 to 10 day window, no matter who thinks
they should.
Happy calving. May you find all your ear tags.
Your comments are always welcome at www.BeefTalk.com.
For more information, contact the North Dakota Beef Cattle Improvement
Association, 1133 State Avenue, Dickinson, ND 58601 or go to www.CHAPS2000.COM
on the Internet. In correspondence about this column, refer to BT0078.
###
Source: Kris Ringwall, (701) 483-2427, kringwal@ndsuext.nodak.edu
Editor: Tom Jirik, (701) 231-9629, tjirik@ndsuext.nodak.edu
Click here for a printable PDF version of this graphic.
(5KB b&w graph)
Click here for a printable EPS version of this graphic.
(76KB b&w graph)
Click here for a EPS file of the BeefTalk logo suitable for
printing.
(100KB b&w logo)
When Will Cows Calve?
462 Cows All Bred on May 21
---------------------------------------------
Number of Percent
Dates Cows Calved Calved
---------------------------------------------
February 24 - March 6 372 80%
February 20 - March 10 439 95%
February 13 - March 14 456 98%
February 11 - March 19 462 100%
---------------------------------------------
---------------------------------------------
|
