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1. the thick whitish fluid containing spermatozoa that is ejaculated from the male genital tract
2. another name for sperm



a thick, viscid, opalescent, and whitish fluid ejaculated during copulation by human males and males of other animal species. Constituents of semen are spermatozoa and seminal fluid.

Semen contains proteins (including enzymes and nucleopro-teins), lipids, carbohydrates, vitamins, prostaglandins, sodium salts, potassium salts, calcium salts, and other organic and inorganic substances. Semen production commences during puberty, reaches its peak at maturity, and diminishes toward old age. The quantity discharged varies from species to species. Men ejaculate 2–6 milliliters (ml), bulls an average of 4–5 ml, stallions 60–100 ml, boars as much as 250 ml, and rams 1–1.5 ml.

The potency of semen depends on the quality and quantity of spermatozoa. The quantity of spermatozoa in animal semen varies, totaling approximately 30 percent in rams, approximately 14 percent in bulls, and approximately 7–8 percent in boars and stallions. It may even vary in the same animal, depending on the animal’s conditions of existence. Seasonal secretion of semen is characteristic of most invertebrates and some vertebrates, including fish, amphibians, reptiles, and many birds and mammals. Some diseases are characterized by semen lacking (azoospermia) or deficient in spermatozoa (oligospermia) or by semen with spermatozoa that are motionless (necrospermia) or malformed (teratospermia).

Semen analyses are used in forensic medicine and in determining the causes of sterility. In agriculture, an appraisal of the quality of semen is important for the artificial insemination of farm animals, as are the methods used for diluting, storing, and transporting the semen.



The fluid that carries the male germ cells. Also known as seminal fluid.
References in periodicals archive ?
In addition to using sexed semen on your best cows, inseminating the rest of your herd with high-quality beef sires will produce a calf that the beef market requires which will result in even greater profit.
Montaner first found the potential positive effect of continued semen exposure in 2015.
This study has focused on the following area: (a) determination of testis size and semen characteristics of Gurcu goats (b) detection of changes in testicular, spermatological parameters values, and testosterone levels, as well as seminal plasma phospholipase A2 levels during breeding and nonbreeding seasons.
Two days after symptom onset, viral RNA was higher in semen (1.04 x 105 copies/mL) than in blood (9.4 x 103 copies/mL); RNA was detectable for up to 100 days in blood and 168 days in semen (Figure).
Overall results showed that 2mM/ml concentration of selenium improved chilled and frozen thawed quality of semen than control and other treatment groups.
The objective of the current study was to predict the selection proportion in SD pathway after applying their sex sorted semen for heifers.
The power is in the genes hence a farmer must select bull semen that will impart this power to the daughters of his cows and heifersProductionOverall milk production determines a herds income.
Toby Hedworth QC asked of a black top: "Was there any match for Mr Olding's semen?" The forensic scientist said: "It was DNA matched to that of Mr Stuart Olding."