This is noticed at six month of pregnancy. This may be due to heat stress, genetic or use of drugs and mostly due to brucellosis a bacterial disease in cow. This transmitted to human in man it reduces undulating fever, swelling of testis and in woman it cause abortion. Long term antibiotic treatment and sexual rest is the solution. Purchase cows after brucella testing. Grow your own herd. You can vaccinate young female calves. Brucella vaccine is given at 6 month of age once. The immunity is lifelong. The vaccinated cow show positive test. There are abortion due to vibriosis at early stage of pregnancy. This infection spread by natural service so go for AI.
Retention of placenta
After the calving the placenta is not expelled. This is due to low level of estrogen so infect pregnant once only and consult your veterinary. This may be due to brucellosis. The use of selenium and vitamin E may help if it is due to the nutritional deficiency. Usually the placenta is dropped with an hour of calving. It placenta is manually removed then antibiotic be used consult your veterinarian.
Prolapse of Vagina
After conception at the pregnancy of 4 month of the vagina is noticed. It is like the football bladder. This may be genetic, nutritional, it may be allergic, involuntary contraction of uterus and above all due to the stress. This has to be pushed back immediately because once it is out it swells then it is difficult to push back. Once it is out there may be injury, immediately consult your veterinarian. The antihistaminic, and antispasmodic drugs are helpful. The veterinarian may suture vagina. But there are every possibility of re-occurrence.
Prolapse of Uterus
In case of prolapse of uterus the whole uterus is inside out. You can see cotyledons and placenta attached to it. This has to be pushed back immediately. Call your veterinarian. The solution to the problem is to select best bull and use the sexed semen. When the cow is pregnant with female the size is small and small calf will not create problem you may try Jersey semen because the Jersey female calves are small.