Beef  Reproduction 
and Hormones of the Bull
L. L. Wilson and C. W. Foley, Animal Sciences Department
This publication is designed as a teaching aid for the intensified cattle reproduction schools conducted by the Indiana Cooperative Extension Service. It is also included in the Beef and Dairy Production Handbooks for County Extension Workers. The purpose of these publications is to help producers more clearly understand the structure, functions and abnormalities of the reproductive organs of cattle.
female's reproductive tract. Other secondary functions of the various parts of the bull’s tract are to: (1) manufacture fluids which are necessary to carry and nourish the sperm, and (2) produce certain chemical substances (hormones) which are necessary for normal development and maintenance of a bull.
Organs of the bull
Introduction
If a cow fails to conceive after one or a series of services, or she aborts or loses a calf at birth, a loss is created. This loss results from having fewer salable calves or prospective herd replacements, selling nonpregnant but otherwise productive cows for slaughter prices, non-uniform calf crops, and higher labor requirements per cow. In dairy herds, the largest loss is in reduced milk production because of a longer calving interval.
Low' reproductive efficiency may be the fault of either the bull, cow, or overall management. Sterility applies to an animal that cannot reproduce; infertility applies to the animal that is neither normally fertile nor totally sterile.
The primary purpose of the bull's reproductive organs is to produce and transport the male reproduction cells or sperm to the
The reproductive or genital system of the bull (shown in Figure 1) is composed of the scrotum, testes, duct system, accessory glands, penis, and sheath.
The scrotum is a sac or pouch in which the testes are suspended below the body cavity. The scrotum has two functions: (1) provides protection for the testes, and (2) regulates the temperature of the testes. The scrotum maintains the temperature of the testes between 6 and 10 degrees Fahrenheit below the body temperature. It does this by relaxation or contraction of the scrotal muscles. For instance, in cold weather, these muscles contract and pull the testes closer to the body for added warmth.
The testes or testicles are paired oval structures suspended within the scrotum with the aid of the cremaster muscles. Inside each testis, sperms are produced in thousands of microscopic tubules (seminiferous tubules). The cells which line these small tubules divide and form immature sperm which are
Beef Section • Animal Sciences Department Cooperative Extension Service, PURDUE UNIVERSITY, Lafayette, Indiana
AS-360 Jan. 1967
~ Reproductive Organs