Reproductive Problems
Any reproductive complications in a beef cow represent economic losses to the producer, including
veterinary charges, extra labor and drugs, and non-uniform lots of calves due to delayed rebreeding.
We use the term anestrus to refer to any period during which cows are not experiencing estrous
cycles. The most common cause is pregnancy. Veterinarians can determine whether a cow is pregnant by
examining the reproductive tract. Cattle are also anestrus during the postpartum period, which is the
period immediately following calving, or parturition. In beef cows that are suckling calves, this
period varies, but it may last as long as 60 to 100 days.
Reproductive Disorders
A variety of physical, environmental and nutritional disorders can cause an interruption in the
estrous cycle - and effective reproduction. For reference, go
to Reproductive Anatomy.
- Dystocia
Causes can be hereditary, nutritional, infectious, traumatic or some combination of these.
- Ovarian cysts
Ovarian follicular cysts are structures that develop from follicles that fail to ovulate. The cysts
are usually 2.5 to 4.0 cm in diameter, but they may be much larger. Some cows with ovarian cysts
exhibit intense sexual behavior or nymphomania. Most cows with ovarian cysts, however, are anestrous.
- Nutrition
Poor nutrition can impair or prevent secretion of gonadotropic hormones, resulting in anestrus.
Nutritive deficiencies that decrease appetite - phosphorus, cobalt, and possibly iron, iodine and
B vitamins - can be particularly damaging. Substantial weight loss due to poor nutrition or illness
can stop normal cycling.
- Temperature
Cows often lose appetite and energy in very hot weather. They may cycle but not display estrus well
in hot weather.
- Age
Young cattle usually have a slightly shorter estrous cycle than older animals.
Reproductive Infections
A variety of bacterial and viral pathogens are responsible for some of the most common reproductive
problems. In most cases, effective antibiotic treatment or hormone therapy can provide a solution.
- Metritis
Also called inflammation of the uterus, this disease increases the calving-to-conception interval by
approximately 18 days. Although minor uterine infections may clear up without any treatment, metritis
can be life-threatening. Symptoms include fever, depressed appetite, lowered milk production and
foul-smelling uterine discharge. Archanobacterium pyogenes, Escherichia coli, staphylococci
and mixed infections are generally implicated (SOURCES: Morrow 1969, Successful A.I. ... 1999).
- Endometritis (Pyometra)
Pyometra is one form of metritis. This is a chronic infection of the uterus. The animal usually has
an accumulation of fluid in the uterus and a corpus luteum on the ovaries.
- Reproductive diseases
Many viral and bacterial diseases can affect fertility. They include vibriosis, brucellosis,
leptospirosis, bovine viral diarrhea (BVD) and infectious bovine rhinotracheitis (IBR or "red nose").
Many of these can be prevented by an effective vaccination program.
Postpartum Complications
The period before and after calving is the most stressful in a cow's reproductive life. The
complications listed below often appear in combination, along with reproductive infections such as
metritis, to make up what has been described as a "postpartum disease complex."
- Retained placenta
This problem has many causes, including abortion or early birth, hard labor, twins, excitement during
calving, stress at calving (high temperatures, for example), uterine torsion, infections (brucellosis,
leptospirosis, infectious bovine rhinotracheitis [IBR], mycotic infections), or nutritional problems.
A retained placenta adds an average 19 days, or one missed estrous cycle, to the number of days open.
- Uterine prolapse
In uterine prolapse, the whole reproductive tract turns inside out and protrudes from the vulva.
Uterine prolapse usually occurs at or shortly after calving. Treatment for this condition should begin immediately. A veterinarian should be consulted.
- Displaced abomasum (DA) (Commonly seen in dairy cows)
The abomasum, or true stomach, positioned between the cow's omasum and small intestine, can be
displaced by:
- changes in position of the abdominal organs
- increased gas production due to diet
- lack of movement in the gut associated with hypocalcemia, mastitis, metritis or ketosis
More than half of the cows that develop DA also have some other disorder. Cornell researchers found
that the risk of getting DA was:
- 6.6 times higher for cows with retained placentas
- 11.9 times higher for cows with uncomplicated ketosis
- 13.8 times higher for cows with primary, secondary or nervous ketosis
(SOURCE: Successful A.I. ... 1999)
About 80 percent of abomasal displacements occur within 1 month of parturition.
- Ketosis
A metabolic disease of lactating cows that occurs shortly after calving. During heavy lactation, the
cow uses glucose to produce lactose. If the demand for glucose exceeds the supply available from the
diet or liver stores, the body raids its own fats. Ketosis results from the metabolism of these fats.
Ketosis is usually associated with a depressed appetite due to metritis, mastitis or abomasal
displacement.
Cows affected by ketosis usually have:
- abnormally low levels of glucose in their blood (hypoglycemia)
- excess ketone bodies in the blood (ketonemia) and urine (ketouria)
- inappetence
- lethargy or excitability
- weight loss
- depressed milk production
- (sometimes) lack of coordination
(SOURCE: Merck Veterinary Manual, 1991)
- Acidosis
Acidosis is an acid-base imbalance caused by excessive production or ingestion of organic acids.
Ketoacidosis (ketosis plus acidosis) can be caused by pregnancy ketosis and lactation ketosis.
Clinical signs of acidosis include dehydration, diarrhea, anorexia, fever, excessive salivation,
panting and central nervous system depression. Sodium bicarbonate and replacement of fluids can
correct acidosis.
Acidosis often leads to laminitis (inflammation of the lamina of the hoof), one of the most frequent
causes of lameness. Big, infrequent meals only make the problem worse (SOURCE: Successful A.I.
... 1999).
The most effective management strategy for ketosis, acidosis and laminitis is prevention. This means
providing proper nutrition before and after calving. Dr. Jerry Olson recommends these management practices:
- Feed appropriate transition rations, starting 2 to 3 weeks before calving, so that cows can
adjust gradually to new rations.
- Formulate rations carefully, providing at least 21 percent of dry matter as acid detergent
fiber (ADF), and at least 28 percent as neutral detergent fiber (NDF). At least 18 percent of NDF
should come from forage. No more than 40 percent of rations should be nonstructural carbohydrate
(NSC).
- Feed coarsely chopped forage.
- Add buffers if necessary.
- Minimize heat stress.
(SOURCE: Successful A.I. ... 1999)
 entire article (printer friendly)
|
|
|