Page 38 - MWC 4-23-20s

The Midwest Cattleman · April 23, 2020 · P38
Cow-calf producers should record

multiple births in their herds

By Donald Stotts value of an applicable heifer
Cow-calf producers need to calf at birth and save the feed
keep recordkeeping and genetic and development costs if they
drift in mind when cattle births are aware of the high probabili-
result in twins that are a heifer ty of freemartinism.
calf and a bull calf. “Producers need to be aware
“This condition – called that in some cases there are few
freemartinism – causes infertil- if any symptoms of freemar-
ity in most of the female cattle tinism because the male twin
born twin to a male,” said Dana may have been aborted at an
Zook, Oklahoma State Univer- earlier stage of gestation,” Fre-
sity Extension area livestock king said. “These so-called hid-
specialist for northwestern den freemartins can be difficult
Oklahoma. “Freemartinism is to identify if purchased as re-
recognized as one of the most placement heifers.”
severe forms of sexual abnor- ter, fluids of the two fetuses are Freking said the ovaries of Freking and Zook recom-
mality in cattle.” mixed. This causes an exchange a freemartin do not develop mended producers cull any
Longstanding OSU recom- of blood and antigens carrying correctly and typically remain non-pregnant replacement
mendations are for producers characteristics unique to each small, sometimes very much heifers soon after their first
to write down twin births of heifer and bull. When the anti- so. In addition, the ovaries of a breeding season.
calves while they are still nurs- gens mix, they affect each other freemartin do not produce the “Also, female cattle nurs-
ing the cow, to ensure produc- in a way that causes each to de- hormones necessary to induce ing twin calves will require an
ers do not forget. velop with some characteristics the behavioral signs of heat. estimated 13% more energy
Estimates of the percent- of the other gender. “The external vulvar region intake to maintain body con-
age of beef cattle births that “Although the male twin in can range from a very nor- dition,” Zook said. “The addi-
produce twins vary. One of the this case is rarely affected by re- mal-looking female to a female tional suckling pressure on the
more famous examples – re- duced fertility, the female twin that appears to be male,” he cow will extend the post-calv-
ported in Hoard’s Dairyman, is completely infertile in more said. “Typically the vulva is ing anestrus period. Therefore,
1993 – puts the percentage at than 90% of cases,” said Brian normal except that in some an- cows nursing twins will take
about 0.5% or one in every 227 Freking, OSU Extension area imals an enlarged clitoris and longer to rebreed for next year’s
births. Research indicates ap- livestock specialist for south- large tufts of vulvar hair exist.” calf crop.”
proximately half of the sets of eastern Oklahoma. Freemartinism cannot be In some cases, producers
twins should contain both a The transfer of hormones prevented. However, it can be may want to consider early
bull calf and a heifer calf. or cells can cause the female diagnosed in a number of ways weaning of twin calves to allow
“When a heifer twin shares twin’s reproductive tract to be ranging from simple exam- the birth mother to cycle in
the uterus with a bull fetus, severely underdeveloped, and ination of the placental mem- time with the other cows in
they also share the placental sometimes even contain some branes to chromosomal evalu- the herd. Otherwise, the pro-
membranes connecting the fe- elements of the bull calf’s re- ation. ducer may be headed for man-
tuses with the dam,” Zook said. productive tract. In short, a Laurie Ann Lyon in “The agement headaches during the
A joining of the placental freemartin is genetically female Causes and Effects of Freemar- next breeding season.
membranes occurs at about but has many characteristics of tinism” indicated producers
day 40 of pregnancy. Thereaf- a male. can predict the reproductive

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