Читать книгу Bovine Reproduction - Группа авторов - Страница 53

Spermatogenesis is a highly proliferative and regulated developmental process of multiple germ cell divisions to increase their number and subsequently differentiate to spermatozoa in the seminiferous tubules (ST) of testes. Spermatogenesis is essential for species conservation and genetic diversity within the species [1]. For cattle farming, spermatogenesis yields target spermatozoa for genetic improvement in production potential. Traditionally, the bull has been truly called half of the herd on account of his spermatogenesis. A bull produces more calves per year per herd than a cow. The bull contributes to the genetic and production potential of the herd more extensively and perpetually than does the cow. If the replacement heifers are maintained, the bull affects the production potential of the herd for about 25 years [2]. Spread of male germplasm through artificial insemination is the major tool for genetic improvement in cattle production. In the United States, adaptation of artificial insemination led to a 4.5‐fold increase in milk production per dairy cow on average from 1940 to 2009 [3].