Infertility is the diminished or absent capacity to produce viable offspring. There are many other causes of infertility in cattle which even makes tracking diagnosing as well as treating a challenge. We all know that he goal of a breeding program should be to have maximum number of cows bred in a 65 day breeding season. If pregnancy/calving rates are below this, finding out why is important. There are both infectious and non-infectious causes of infertility.
Non Infectious Causes of Infertility
- Failing to use a bull that has passed a breeding soundness exam
- Insufficient bull numbers for cow numbers and environment
- Bull(s) with poor libido which may cause failure to serve
- Failure to mount may be caused by:
- Foot rot
- Overgrown hooves
- Weak pasterns
- Back pain
- Failure to serve properly (no intromission) may be caused by:
- Persistent frenulum
- Penile haematoma
- Short penis
- Failure to thrust may be caused by:
- Back pain
- Return to service of females may be due to:
- Poor sperm quality
- Overuse of the male
- Abnormal testicles
- Abnormal epididymis
- Abnormal accessory sex glands
The most common cause of infertility in beef herds is poor cow nutrition. Over conditioning can also be detrimental, especially in heifers, but is far less common a problem. Body condition before calving, after calving, and at breeding can all contribute to infertility. Cows that calve thin but are gaining at breeding will have better conception rates than cows that remain thin. However, cows that maintain good body condition throughout pregnancy will have the best chance of breeding back. Most commonly protein and energy are deficient in beef cattle diets. But vitamin and mineral deficiencies can also cause infertility. Infertility, poor vaccine response, diarrhea, weight loss, poor growth, weak calves and calf health problems can all stem from copper deficiency.
Stress can cause pregnancy wastage at any stage of gestation. Low stress handling when processing cattle will minimize this problem. Heat stress is also a major cause of infertility, especially early in pregnancy. High humidity exacerbates heat stress and would be expected to impact conception rates even more. Extending you breeding season late into the summer to get extra cows bred is probably a futile exercise.
Finally, genetics and other environmental factors play a role in infertility. Selection for other production traits can sometimes lead to selection against reproductive ability. There are breed differences in reproductive efficiency, especially when comparing Bos taurus to Bos indicus breeds. In general, Bos indicus breeds are superior in subtropical climates, but have later puberty and longer inter-calving interval than Bos Taurus breeds. There are wide variations between individuals, so selecting for early maturity and shorter inter-calving interval will increase efficiency over time. Even if heifers are fed properly once they are born, nutrient deprivation in utero negatively impacts their future fertility.
Bulls should have a breeding soundness exam prior to each breeding season. Even if a bull passed last year, there is no guarantee he will pass this year. Bull infertility due to heat stress is a major problem. Although there are general rules for how many bulls are needed for a group cows, this varies highly between herds. The age of the bulls, single vs. multi sire breeding groups, terrain and climate can all affect how many bulls are needed. Young bulls, particularly in breeding groups with older bulls, will not service as many cows as mature bulls. If bulls are not used to the heat, they may spend more time in the shade than servicing cows due to lack of libido. A breeding soundness exam does not test libido, so bulls should be watched to make sure they are breeding cows once they are turned out.
Infectious and Toxic Causes of Infertility in Cattle
- Campylobacteriosis (Vibro)
- Infectious Bovine Rhinotracheitis (IBR)
- Bovine Viral Diarrhea Virus (BVD)
Infertility is one of the most frustrating problems to try to diagnose. Many times the actual disease or problem (infertile bulls for example) occurs many months before cattle are palpated for pregnancy or begin calving. There is no one test like a blood sample that will test for all of the diseases or problems. Each cause/disease has different procedures required for diagnosis. To diagnose Leptospirosis, urine samples are needed. To diagnose Trich and Campy, specific tests from bulls are required. Although blood samples may help diagnose IBR and BVD in unvaccinated herds if the samples are taken at the proper time, in many instances blood samples are not helpful. The placenta and fetus are the best samples for diagnosis of late term abortions. A good overall herd health history is also important to look for other problems that may be related and help narrow down the list of potential problems.
- Buy virgin bulls or test for Trichomoniasis and Campylobacter
- Have sufficient bull numbers for cow numbers and environment
- Observe cattle closely during breeding season for bull libido and repeat breeding in cows
- Sound nutrition program, including minerals
- Maintain cow body condition and a properly functioning immune system
- Minimize stress, particularly during handling
- Cull cows that are not reproductively sound
- Palpate for pregnancy
- Pregnancy check via rectal palpation by a veterinarian can identify problems early and make diagnosis of problems more likely
- Raise or purchase only virgin heifers as replacement females
- Purchasing open non-virgin females is a risk for Trichomoniasis and Campylobacter
- Purchasing bred females is a risk for introducing BVD
Vaccination and Biosecurity
- A good vaccination program will help prevent major reproductive losses from infectious causes
- Because vaccination is not 100% protective and because there are disease that can’t be controlled through vaccination, a good herd biosecurity program is necessary.