All embryos of mammals are set to become female. The existence of a single gene on the Y chromosome persuades the development of the testes in an embryo. This makes the embryo become a male.
1. Pig:
Sperm/Ejaculation: 60-80 billion
Description: Sexual Development in boars (male pigs) is triggered by the Y chromosome and the androgen. At between 20 and 40 days old, Y chromosomes allow germ cells and the male reproductive tract to divide. It takes about 5 weeks for sperm to produce and 2 weeks to go through epidermis.
2. Zebra:
Sperm/Ejaculation: 40 billion
Description: By 48 months, Zebras ejaculate this amount of sperm. Spermatozoa first appears at 31 months.
3. Donkey:
Sperm/Ejaculation: 14.5 billion
Description: When a female horse is mating with a male donkey (jack), a mule is conceived. When a female donkey mates with a horse stallion, then a hiney is conceived. Jacks are the ones that have larger testicles than stallions. It also takes 5-30 minutes for a jack to complete the breeding act.
4. Horse:
Sperm/Ejaculation: 11 billion
Description: Poor health causes a stallion (male horse) to have poor semen levels. The sex glands are not required to provide seminal fluids. The vesicular glands are the most difficult to palpate because they are shrunken before teasing.
5. Bull:
Sperm/Ejaculation: 5-10 billion
Description: Bull sperm is made up of various substances such the acid Taurine. This should not be confused with the Taurine in drinks. This in fact is artificially made.