Hahahahahaha! Icelord really knows everything! I mean that in a positive way.
Even me growing up on a farm did not know that fact about pigs or dogs.

Semen Ejaculation & CollectionSexual stimulation (5-10 min restraint) of
the boar prior to ejaculation has been shown
to dramatically increase the concentration
and volume of the boar ejaculate. Sexual
stimulation initiates smooth muscle
contractions in the tail of the epididymis and
the vas deferens.
The boar usually takes 7-
15 minutes to ejaculate the 150-500 ml
volume.Imagine that. A 7-15 minute orgasm that can unload as much as half a litre of semen. Holy fuck, dude. That's every woman's wet dream, isn't it?
http://www.livestocktrail.illinois.edu/swinerepronet/publications/extension/boara&p.pdfWhen a man ejaculates he generally produces between 2 and 5 millilitres of sperm (about the same volume as a large teaspoon would hold). A pig routinely manages one litre which is 200 times as much.http://www.open.edu/openlearn/body-mind/health/health-sciences/the-science-spermDogs are superior to humans too that way.
Dog semen is ejaculated in three fractions. The first, pre-sperm fraction is small in volume (less than 5 mls) and contains few to no spermatozoa. The pre-sperm fraction is believed to cleanse the urethra of contaminants (urine, bacteria and cellular debris) prior to ejaculation. The pre-sperm is not usually collected. The second, sperm-rich fraction comes from the epididymes and testes. The sperm rich fraction is cloudy white in color and usually 0.5 – 4 ml in volume. The third fraction consists solely of prostatic fluid and contains few to no spermatozoa. Prostatic secretions lend volume to the ejaculate, assist in pushing the sperm out of the vagina and into the cervix/uterus, and provide nutrients for the sperm during their transit to the oviducts. The volumes of the first and third fractions are variable. In particular, the volume of the third fraction is controlled by the person collecting the sample, as they can choose to collect more or less of the cell-free prostatic fluid.
Prostatic fluid is normally clear in color and may range in volume from 3 – 80 ml. Volume is not an indicator of semen quality in dogs. However, the measurement of semen volume is important in the calculation of total number of spermatozoa in the sample.
http://veterinarycalendar.dvm360.com/avhc/article/articleDetail.jsp?id=727382&sk=&pageID=3