With the arrival of spring, thoughts of working cattle begin to stir in most beef cattle producers’ minds. However, with the amount of time it takes to round up the herd and the aggravations associated with herd work, these are not often pleasant thoughts. The last thing a producer wants to do is add time and cost to an already difficult, expensive, and exhausting day or days of work. In this light, it is easy to see why one important management practice frequently overlooked or neglected by many beef producers is pregnancy examination. According to the 1997 National Animal Health Management Survey (“NAHMS”), only one fifth of cow/calf producers have their cows checked for pregnancy although the benefits easily outweigh the cost.

The most obvious benefit of knowing which cows are open is cost savings. A pregnancy examination will typically average $5 per head but carrying an open cow over the winter may cost several hundred dollars in hay alone (not to mention mineral, supplemental feed, vaccines, and dewormers that add additional carrying costs). Knowing who to sell allows one to make good marketing decisions such as:

1. Weaning calves early and selling culls when the cull market is high
2. Selling open heifers when they are younger and still fit the feeder market
3. Sorting off and feeding thin cows to bring a higher price and sell more pounds

Beyond the marketing aspects, pregnancy checking can be a tremendous decision making tool. Cows can be grouped into early or late season calvers and fed accordingly. Scours vaccine can also be administered at the right time to optimize colostral antibodies for the calf. Pregnancy exams are also important for the measurement of herd health and reproductive status. More open cows than expected (more than 5% open at pregnancy check) may indicate an abortion problem caused by an infectious organism such as the IBR or BVD viruses. It could also be an indicator of a sexually transmissible disease such as vibriosis or trichomoniasis. Nutritional deficiencies including a lack of energy, trace minerals, and/or protein may delay estrus and conception due to poor egg development and subsequent ovulation, resulting in open cows. Occasionally damage to the reproductive tract due to a difficult birth may result in a cow that will not breed back. Infertile bulls may be discovered at pregnancy checking time although hopefully too many cows regularly returning to heat would be noticed prior to the end of breeding season. However, in a herd observed infrequently or in a far off pasture, bull problems can easily be missed. Animals that are detected open early can then be immediately returned to aggressive breeding programs using other reproductive technologies.

Pregnancy examinations can be accomplished by several different methods including rectal palpation, ultrasound or a blood test. Rectal palpation performed by an experienced veterinarian can estimate the approximate stage of pregnancy and can be detected 35-40 days after breeding. Veterinarians use the art of palpation of fetal membranes, position of the uterus, size of the cotyledons and size/strength of pulse in the uterine arteries to determine pregnancy status and length of gestation. Disadvantages to palpation are few and often exaggerated. Rough handling of the fetus or membranes early in gestation has been associated with abortion but it is difficult to differentiate these from the “normal” amount of expected embryonic loss. Another concern is blood borne diseases such as anaplasmosis and bovine leukemia virus that can be transmitted cow-to-cow by blood present on an examination sleeve used in multiple cows. Bovine practitioners are very aware of this danger and change sleeves when blood is present or some doctors use a new sleeve on each cow.

Ultrasound can detect pregnancy earlier than palpation (around day 27 in the hands of a skilled operator) but is more expensive-largely due to the cost of the equipment. It can provide more detailed information such as viability of the fetus, presence of twins and sex of the calf and it is considered extremely accurate. Both ultrasound and palpation provide immediate answers so cows can be sorted from the chute without handling multiple times.

A blood test (“BioPRYN”) is commercially available that detects a protein produced by the placenta which is detectable in serum. Heifers and cows can be tested at 30 days or later after breeding but a cow must be at least 90 days post calving due to residual protein from the previous pregnancy. The blood must be drawn and sent to a participating laboratory for results so cows would need to be sorted at a later date after results were reported. BioPRYN is advertised as 99 percent accurate when it identifies open cows at least 30 days post breeding with less than 1 percent showing false-open (false-negative). Correct open detection is very important because giving prostaglandin to a pregnant cow will often cause abortion. The falsepregnant (false-positive) rate for the test is approximately 5 percent. There are many ways a producer can detect early pregnancies in his herd and multiple benefits available from this management tool. Producers are encouraged to work with their local veterinarian to schedule this valuable service. With so many potential benefits for one relatively small cost, it is one of the easiest economic decisions for a cow-calf producer to make.

Source: Dr. Michelle Arnold, Large Ruminant Extension Veterinarian, University of Kentucky