As the stallion ejaculates, the AV should be lowered to allow the semen to run into the collection bottle. Upon completion, drain the water to let the remaining semen drain into the collection bottle. Then keep the semen in an incubator until evalu-ated. Evaluate each ejaculate to assure the maximum number of normal, progressively motile spermatozoa. Volume is simply the total amount of gelfree semen in a single ejaculate and is usually measured in milliliters.
Concentration is determined by using a hemocytometer or spectro-photometer.
Concentration is important because it influences total sperm output and insemination dose if arti-ficially inseminating. Most stallions will ejaculate approximately 7 billion spermatozoa. Motility should be determined as soon after collection as possible. To do so, put a drop of semen on a warm slide, covering it with a warm cover slip and estimating the percent of normal progressively motile spermatozoa using a microscope. Progressively motile spermatozoa is defined as those sperm cells that are swimming straight across the microscope screen and having normal morphology.