Six Stud Holstein bulls were selected to study the effect of zinc on semen quality,enzymatie activities,zinc and testosterone concentrations in the serum or seminal plasma.

• 试验选用6头荷斯坦种公牛，研究了锌对性反射时间、精液品质、精清酶活性及血、精清锌与睾酮浓度的影响。