Animal Gestation and Incubation

On average, the gestation period or length-of-pregnancy of a cow is 285 days long. This is similar to the pregnancy period of a woman, which is closer to around 9 months or ~260 days.

However, actual gestation period of a cow can range from 270 days to 295 days, depending primarily on breed[s], age, body condition and nutritional health. Gestation period is also controlled by genetics, but not rate of maturity. The rate of maturity is more to do with the age a bovine reaches when it starts to put fat down, not muscle, and has very little to nothing to do with reproductive characteristics including length of gestation.

Here are some rules of thumb to remember when trying to figure out how long your cows or heifers will be pregnant for:

• Heifers that are pregnant for the first time will most likely have a little longer gestation period than older, mature cows. This is typically because heifers are still growing themselves and have to put energy into growing a calf AND their own bodies, including the formation and maturation of their udder.
• Cows with poorer fertility (or have a tougher time getting bred again after giving birth) may have a longer gestation period than those with good fertility (or those that have settled during the first part of the breeding season after a 45 to 60 day rest period).
• Usually small cows have a shorter gestation period than big cows, but not always. For instance, Texas Longhorns have a longer gestation period than South Devons, but TL's are smaller in size and lighter in weight than SD's. However, this might be applicable if comparing Jerseys with Charolais or moderate-framed Angus with Chianina.
• Thin cows may have a shorter gestation than normal-condition cows, and fat cows may have a longer gestation than normal-conditioned cows.
• Females that have more masculine characteristics may have a longer gestation than those females that are more feminine in conformation.

Please see the related questions below for various breeds and their consequential length of gestation.

The stages of gestation are divided into three periods, all around 3 months and 5 days each:

1. First Trimester - Day 0 to Day 94
2. Second Trimester - Day 95 to day 189
3. Third Trimester - Day 190 to day 285

The simple answer is: You do not. A vet and qualified animal care authorities are the ONLY persons who are able to euthanize an animal in a painless and stress-free way, so take it to a vet or local animal shelter, but do not try to do anything by yourself. Many vets provide home visits if you are not comfortable in taking your cat to the vet practice. This allows the cat to die in the comfort of its own home.

Please bear in mind, anything you try to do yourself may only cause the animal suffering and pain, and that's hardly 'humanly' euthanizing is it? A vet can do this with NO suffering to the animals what so ever, its over in literally under a second or 2, and that's as it should be.

Another Answer

If you feel your cat needs to be euthanized due to a medical issue, a visit to the vet could save his/her life. Many health problems can be treated and curbed which adds months or even years onto a cat's life. If health is not the reason, then take your cat to a shelter. I'm sure they'll find someone who will accept him/her with love and open arms. Keeping your cat from living a happy healthy life that he/she deserves is inhumane in itself.