Influence of unilateral castration and increased plane of nutrition on sexual development of Holstein bulls. II. Histologic development of the testes.
Sixty-five Holstein bull calves were assigned in an experiment to determine the effects of unilateral castration (UC) at 1 week of age and of two levels of nutrition after 6 months on reproductive development to 16 months. Five animals were killed at 1 wk and half the remainder UC at that age. Groups of 5 in all factorial groups were killed at 2, 4, 8 and 16 months. Tubular diameter increased with age (P<.01) and at 8 and 16 months with UC (P<.01). Epithelial area at 8 and 16 months increased with age and UC (P<.01). The percents of tubular and intertubular tissue varied with age (P<.01) with the tubular tissue having its highest value at 8 months. Indexes of both total tubular and intertubular tissue were increased with age and UC (P<.01). The number of type A spermatogonia per cross section of stage 1 tubules of 16-month bulls was increased by UC (P<.05).
Barnes
M A
MA
Department of Animal Industries University of Connecticut Storrs, Connecticut 06268 USA.
Riesen
J W
JW
Woody
C O
CO