Oklahoma Cow/Calf Corner

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Well-known member
Jan 20, 2007
LaRue, Ohio
Anaplasmosis Prevention

Glenn Selk, OSU Extension Animal Reproduction Specialist

"Preg" Check and Cull Replacement Heifers Early
Glenn Selk, OSU Extension Animal Reproduction Specialist

Anaplasmosis Prevention
By Glenn Selk

Anaplasmosis is an infectious disease of cattle caused by a blood-born organism.  Anaplasmosis causes a severe anemia because of the destruction of red blood cells.  Poor performance, abortion, and even death can result from anaplasmosis.  The organism that causes anaplasmosis is moved from animal to animal by transmission of infected blood.  In most cases, anaplasmosis is spread by biting insects that take on a blood meal from an infected animal and then move to a susceptible animal.  Insects are not the only cause of anaplasmosis transmission.  Unclean vaccination needles, and surgical tools (such as dehorners) have also been shown to cause outbreaks of anaplasmosis.

Make sure that equipment is cleaned of all blood between uses. Medicated mineral mixes have been useful in reducing the risk of anaplasmosis on Southern Plains ranches.  Chlortetracycline (CTC) consumed at the rate of 0.5 mg / pound body weight daily during tick and horse fly seasons will help prevent sickness due to anaplasmosis.  CTC may be administered in medicated feed; salt-mineral mixes offered free choice, and medicated blocks.  Most producers will choose to purchase commercially prepared medicated mineral mixes or blocks for use during the vector season.  They certainly want to read and follow the label instructions closely.  Read the label to see that it is in fact "labeled" for anaplasmosis control.  A consistent and appropriate intake of the mineral is critical to a successful anaplasmosis prevention program.  Cow calf operators will want to monitor mineral consumption closely to be certain that the recommended amounts are being consumed by the cattle. 

Placement of mineral feeders and blocks can aid in achieving optimum mineral intake.  Place them in areas where cattle spend a lot of time. Minerals should be placed in loafing areas, near water sources, in shady areas, or any other location that tends be a popular place for the herd to congregate.  Summer often becomes a busy time of year for ranchers (especially during haying season).  Don't forget to check the mineral feeders or blocks to be certain that they are supplying the minerals that your cows need.  If you suspect that an animal in your herd has anaplasmosis, call your veterinarian for help with treatment.

"Preg" Check and Cull Replacement Heifers Early
By Glenn Selk

Many Oklahoma ranchers choose to breed the replacement heifers about a month ahead of the mature cows in the herd.  In addition, they like to use a shortened 45 to 60-day breeding season for the replacement heifers.  The next logical step is to determine which of these heifers failed to conceive in their first breeding season.  This is more important today than ever before.

As the bulls are being removed from the replacement heifers, this would be an ideal time to call and make arrangements with your local veterinarian to have those heifers evaluated for pregnancy in about 60 days.  In two months, experienced palpaters should have no difficulty identifying which heifers are pregnant and which heifers are not pregnant (open).  Those heifers that are determined to be "open" after this breeding season, should be strong candidates for culling.  Culling these heifers immediately after pregnancy checking serves three very economically valuable purposes. 

1) Identifying and culling open heifers early will remove sub-fertile females from the herd.  Lifetime cow studies from Montana indicated that properly developed heifers that were exposed to fertile bulls, but DID NOT become pregnant were often sub-fertile compared to the heifers that did conceive.  In fact, when the heifers that failed to breed in the first breeding season were followed throughout their lifetimes, they averaged a 55% yearly calf crop.  Despite the fact that reproduction is not a highly heritable trait, it also makes sense to remove this genetic material from the herd so as to not proliferate females that are difficult to get bred. 

2) Culling open heifers early will reduce summer forage and winter costs.  If the rancher waits until next spring to find out which heifers do not calve, the pasture use and winter feed expense will still be lost and there will be no calf to help eventually help pay the bills.  This is money that can better be spent in properly feeding cows that are pregnant and will be producing a salable product the following fall. 

3) Identifying the open heifers shortly after (60 days) the breeding season is over will allow for marketing the heifers while still young enough to go to a feedlot and be fed for the choice beef market. The grading change of several years ago has a great impact on the merchandising of culled replacement heifers.  "B" maturity carcasses (those estimated to be 30 months of age or older) are very unlikely to be graded Choice and cannot be graded Select.  As a result, the heifers that are close to two years of age will suffer a price discount.  Currently non-pregnant, yearling 875 pound heifers (shortly after a breeding season) are selling for about $94 per cwt.  Therefore an 875 pound, culled replacement heifer is worth about $822.    Non-pregnant two-year old cows are selling for about $65 to $70 per cwt.  Open two-year old cows (those that could have been identified shortly after the breeding season) that weigh 1000 pounds would only sell for about $700 next spring.

The average expense for owning the cow is about $1 per day.  So the total loss of keeping the open heifer would be about $200 in feed and forage and another $122 in lost value.  The grand total expense for not culling open replacement heifers in today’s market is about $322 per head.  Therefore, it is imperative to send heifers to the feedlot while they are young enough to be fed for 4 to 5 months and not be near the "B" maturity age group.

Certainly the percentage of open heifers will vary from ranch to ranch.  Do not be concerned, if after a good heifer development program and adequate breeding season, that you find that 10% of the heifers still are not bred.  These are the very heifers that you want to identify early and remove from the herd.  It just makes good economic business sense to identify and cull non-pregnant replacement heifers as soon as possible.