KNOWING WHAT YOU HAVE TO DECIDE WHAT YOU NEED -- PART 4

by: Stephen B. Blezinger
Ph.D., PAS

Part 4 – Animal Analyses

Over the last few weeks in Parts 1-3 of this series we have been discussing the variety of conditions and factors that can and need to be analyzed on a cattle operation. This is in an effort to understand existing conditions and determine how to best address ways to improve performance. Similarly, there are many opportunities to analyze performance or animal conditions to determine the effectiveness of management and nutritional decisions on the animal. And while there are many opportunities to evaluate animal performance and health we will focus on the primary tools here.

Reproduction

The cow is first and foremost a reproductive unit. Producing calves is her primary objective. In order to do this efficiently her nutrition, health, stress, etc. must be managed properly. Subsequently there are a variety of tools we can use pro and post-actively to evaluate this reproductive performance and should be built into the management plan.

1. Body Condition Scoring

Body condition is directly related to the cow's reproductive performance. Body condition scoring is a subjective measurement of body fat and helps estimate the likelihood of whether a cow will cycle normally and conceive when bred. Research has shown that low body condition (low body fat) will depress reproductive activity and performance. Body conditions scores below 4 are commonly seen to decrease cycling activity and conception rates. Body condition scores of 5-6 are considered optimal for most breeds. Excessive body condition (greater than BCS 8) will likewise hurt reproductive performance because it indicates an excessively fat condition. In the same manner BCS can also be used with bulls. Bulls that are too thin may not produce semen/sperm of adequate volume or quality. They may also not have the energy levels necessary to cover the typical number of cows (25 to 40 head) we would normally expect. Fat bulls may experience mobility problems and can also be too heavy especially for smaller framed cows or heifers. With either bulls or cows, a body condition score of 5 to 6 is considered ideal.

2. Pregnancy Checking

Pregnancy checking the cow herd after breeding is a valuable tool for determining the number of pregnant and open cows. While this is an “after the fact” analyses, it helps the producer identify any open cows in the herd and provides an opportunity to potentially cull those animals for lack of performance (and reduce costs) or identify if a problem exists that needs to be addressed in the herd, management, nutrition or health programs.

Several pregnancy testing options exist for the producer. The first, and most common is rectal palpation. This is the most time-honored, trusted method and lets the producer know that yes, there is a calf in a given cow. The primary limitation with this method is in the ability of the person doing the palpating. This should come with a lot of experience and even then is not infallible. Also, it is not definitive in estimating stage of pregnancy. Even a very good palpater can be off 30-60 days in estimating stage of pregnancy and thus estimated calving due date.

A second method is by ultrasound. Ultrasonography has become practical for routine pregnancy diagnosis in cattle as machines which are portable, durable and affordable have become available (and cost effective) to veterinarians, technicians and producers. A probe that emits the ultrasonic waves is inserted into the rectum of the cow. These waves bounce differently off fluids or different solid tissues. The difference in waves returning is sensed by the probe which sends signals to the machine. These are translated into an image displayed on a screen of some type. This provides an ability to actually “see” the reproductive tract, fluids of pregnancy and fetal parts results. Some pregnancy associated structures and be seen as early as nine days after conception. Reliable pregnancy detection is generally recognized after 26 to 30 days. At this stage a fetal heart beat can usually be seen assuring the viability of the fetus. The early confidence in pregnancy detection using trans-rectal ultrasonography has also led to the implementation of “resynchronization” programs. Cows are often administered reproductive hormones after a diagnosis of non-pregnant that allow cows to be rebred very quickly. Also, since the fetus can be visualized, gender determination can be performed with successful fetal sexing has been reported from 50 to 120 days.

A third pregnancy determination method is by blood test. In the 1980's proteins were discovered in the blood of pregnant cows that are produced by the conceptus. The first of these proteins to be developed into a commercial test for pregnancy is called “Pregnancy Specific Protein B” or PSPB. This protein is now known to be produced by the placenta. Other products produced by the conceptus and present in the blood soon after pregnancy begins are a group of compounds called “Protein Associated Glycoproteins” or PAGs. The substance called Protein Associated Glycoprotein 1 or PAG1 can now be detected by a commercial test. These pregnancy associated compounds can be detected in the blood of some cows in the first couple of weeks of pregnancy. However, development of practical tests means dealing with systems that are functional commercially and individual cow variation. In the end, the commercial tests now available claim reliable pregnancy detection at 28 or 29 days after conception. Blood tests for pregnancy in cattle in the US have been available commercially since 1992. Two companies currently market the tests in the US (BioPRYN- Biotracking LLC, Moscow, Idaho; PAG- IDEXX Labs, Westbrook, Maine; and DG29- Genex, CRI, Shawano, Wis.). Until recently both tests have been laboratory tests. Blood samples for these laboratory tests are taken in the field, mailed to a laboratory and results from the test are returned in a few days. Same day service has recently become available. Also newly available are field tests that can be done at a veterinary clinic. None of these are a “cow-side” test that can be done at the farm while cattle are still confined for blood collection. One of the challenges to use of the pregnancy protein blood tests is time after a pregnancy terminates that the substances persist in the cow's blood. Research indicates that it takes 60 to 70+ days for these proteins to clear the cow's blood. Any time earlier than this can give a false pregnancy reading. Early losses of pregnancy may also give a false positive test result. One company reports an approximate five percent false positive rate due to pregnancies that are lost soon after the test is made or had already been lost when the blood sample was taken. (Whittier, Proceedings, Applied Reproductive Strategies in Beef Cattle, 2013).

Obviously there are pros and cons to each test and selection of a particular method should best meet the farm's needs.

3. Bull Fertility Testing

Another time honored analysis is bull fertility testing. Since the bull is 50 percent of the calf production equation it is critical that bulls be fertile. Bulls should be tested 45 to 60 days prior to placement with cows to be bred to insure sperm and semen quality and quantity is adequate, that no abnormalities or injuries might be present or that any condition may exist that could diminish a given bull's abilities to service the cows for which he is responsible. In some cases this requires a trip to the veterinarian although if the operation deals with a significant number of bulls it may be more cost effective to simply have the vet come out and handle this at the ranch. It is critical that proper facilities be available to restrain the bulls when handling.

Nutritional and Health Analyses

From time to time it becomes necessary to evaluate various parameters in the animal. In many cases these are used to assist in diagnosing a particular problem that has arisen but in other cases these can be used to determine the effectiveness of a given management, nutritional or health program.

1. Mineral analyses

Producers routinely analyze soils, forages and water for mineral content. In many cases, however, minerals are not effectively absorbed by the animal which can create problems in performance, health and reproduction. A common occurrence is a copper deficiency in animals where high levels or sulfur molybdenum or iron (or some combination) is consumed. Mineral analyses are most accurately assessed using a liver biopsy although blood analyses are more common. The problem with analyzing blood is that for many minerals it does not accurately indicate the animal's true mineral status. Many minerals are highly transient in the blood. Thus a blood analysis showing “adequate” may not reflect an almost complete depletion of a given mineral in the animal's liver which has been mobilizing that mineral for some time due to excessive stress levels. While liver biopsies are more invasive and more expensive they are, by far, more accurate.

2. Internal parasite analyses

Every operation requires a good comprehensive parasite control program. In many cases however, the infestation level or resistance to specific control compounds may overwhelm the program's ability to control a given worm or other parasite. In many cases a simple fecal sample can reveal the effectiveness or lack thereof with a given deworming or parasite control product. Periodic evaluation of deworming programs is advised to insure that the product or program used is truly effective in a given program. In many cases simply collecting manure samples and taking these to the vets office can provide an indication of the parasite load in a given group of animals. This then helps determine if or what changes may be necessary to improve parasite control.

Conclusion

On farm analysis is an important part of management. By measuring the various parameters we've discussed the producer has improved information regarding what conditions need to be “helped,” where problems may exist, what is being done correctly, what is being overdone and where opportunities exist to improve performance or save money.

Copyright 2016 – Dr. Stephen B. Blezinger. Dr. Steve Blezinger is a nutritional and management consultant with an office in Sulfur Springs, TX. He can be reached at (903) 352-3475 or by email at sblez@verizon.net. For more information please visit us at Facebook/Reveille Livestock Concepts.







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