In all my previous articles I have been writing about pets, giving an impression that am an exclusive small animal vet. Noo! I’m a Veterinarian! That means, any animal that’s presented to me wouldn’t leave unattended, bring a lame horse and you take home a sound horse, bring a cow with dystocia and you go home with the cow and a calf, bring a rabbit with mucoid enteropathy and take home a jumpy bunny, bring a parrot with psittacosis and go home with a eupnoeic parrot (breathing normally), bring a crocodile with ………..any animal whose pathophysiology is within the boundaries of my cerebrum I cannot leave it unattended, those out of it are referred to another vet. This time I want to break up that notion and give up something about our ‘milk factory’; the cow. Its reproductive cycle (heat/estrus).
Heat/estrus refers to the period when cows or heifers are willing to be bred. The time interval from one heat to the next (estrus cycle) in cattle is 18-25 days depending on the follicular waves recruited in the cycle. Heat detection therefore involves identifying cows and or heifers showing behavioral signs consistent to being on heat, these signs are hormonally controlled. They are due to the activity of the ovary. The signs are usually an indication of an imminent release of an egg from the ovary(ovulation) ready to be fertilized. Detecting and interpreting these signs will help in the timing of the insemination.
Heat in cows should be observed twice a day. It has been shown that most of the heat in cows occur during the night; 60% of the heats occur during the night and hence can easily be missed. The stockmen should therefore be trained to identify cows on heat fast so as not to miss heat. Missed heats translates to a wasted 25 days and a consequent interference of the calving interval.
Bulls; cows/heifers in late pregnancy, and those with ovarian abnormality like cystic ovarian disease aid in the identification of cows in heat even those with silent heat. This is because they have high estrogen hormone and are therefore very responsive to cows in heat. When bulls are used unless natural service is employed in the farm they should not be allowed to mate. In some farms vasectomized bulls are used specifically to identify cows on heat, they are not able to successfully make a cow conceive as their vas deferens is ligated and cut (vasectomy).
In some intensive dairy farm technology has been employed to detect heat. This involve fitting pedometers to the cows in the farm, the pedometer records the cows’ activity. Cows on heat are very restless and active, this is recorded by the pedometer; animal is traced and inseminated on time.
What then are the signs to look for on the cows on heat?
The signs below are arranged with increasing intensity from early estrus to standing heat, when ovulation is very near.
- Mucus discharge from the vulva.
- Restlessness and fighting other cows.
- Jumped on by other cows, but not standing still.
- Sniffing and licking vulva of other cows.
- Resting chin on the rump of another cow (be cautious when you spot saliva mats on the rump of cows in the farm)
- Jumping on other cows.
- Jumping on the front end of other cows.
8. Standing heat. (stand still when jumped on by another cow)
By Dr. Ngetich (BVM, UoN)
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Weaned Japanese Spitz Puppies Duly vaccinated and dewormed