Cattle - Raising Small Animals - page 426

before the breeding season, some of them could attack and injure the other bulls while they
are trying to mate. But if they establish their place, the other bulls can step in and do the
breeding at the times when the dominant bull is tired. When using two or more bulls, those
that are about the same size and breed and are raised together seem to do the best.
Artificial insemination
Artificial insemination (AI) is a common choice for people who do not want to add a bull to
their herd or who want to use genes from top quality bulls. AI may be a cheaper alternative
than caring for and feeding a live bull — semen comes in containers called straws that often
sell for $20 or less, though semen from the most in-demand bulls can cost more. AI may be
more affordable if you are looking for traits from an expensive breed or rare breed; in the case
of some breeds where bulls are not available for purchase, AI may be your only option.
The downside of AI is that it is more labor intensive because you have to be sure your cows
and heifers are in heat so you can inseminate them at the right time. They must be observed
for at least 30 minutes twice a day to detect heat. This usually means watching them at morn-
ing and at night. If you notice signs of heat in a cow, breed her within 12 hours. Artificially
inseminating a cow takes some training and practice, and many farmers prefer to pay an AI
technician to perform the breeding.
The most reliable sign of heat is called standing heat , which means she allows other cattle,
including other females, to mount her as she stands. Secondary signs of heat include pacing or
restlessness. Cows in heat may group together, follow other cows, and sniff, nuzzle, or lick
the rear ends of other cows. A female that mounts other females may be in heat; this is called
riding . Rough or rubbed-off hair on the base of the tail can indicate a cow has been ridden.
Another possible sign of heat is a string of clear mucus hanging from the vulva or smeared on
the hind legs or tail. Bloody mucus can appear two to four days after a cow was in heat; if you
see this, watch her for her next heat cycle in 15 to 21 days.
You can perform pregnancy tests shortly after attempted breeding. A veterinarian tests for
pregnancy by performing a rectal palpation of the cow's uterus and ovaries. Dairy cattle gen-
erally are checked for pregnancy between 28 and 35 days after being bred; cows that are not
pregnant can be rebred. Pregnancy testing also helps you learn an expected due date. Other in-
dications of pregnancy are failure to return to heat when a cow's next heat cycle is due. Non-
pregnant cows are called open cows . Some farmers also use what is known as a clean-up bull,
whose job is to naturally impregnate cows that did not conceive with AI.