Sekoni V O, Rekwot P I, Bawa E K
National Animal Production Research Institute, Ahmadu Bello University, PMB 1096, Shika, Zaria, Nigeria.
Trop Anim Health Prod. 2004 Jan;36(1):55-64. doi: 10.1023/b:trop.0000009528.91525.01.
Detailed studies of sperm morphological abnormalities were carried out on 12 Zebu x Friesian crossbred bulls used in a study of the effects of trypanosomosis. Four bulls were infected with T. vivax, another four with T. congolense, while four served as controls. The infected bulls developed chronic trypanosomosis. All the bulls initially had very low sperm morphological abnormalities that were within acceptable limits for fertile animals. After infection there was a rapid and progressive increase in all sperm abnormalities. Spermatozoa of infected bulls were highly deformed with multiple morphological defects. Mean percentage pre-infection baseline values prior to infection for acrosomal, sperm-head, detached heads, proximal cytoplasmic droplets, distal cytoplasmic droplets, sperm-tail, midpiece and total sperm morphological defects ranged between 0.1 +/- 0.1 for acrosomal and 8.3 +/- 3.2 for total morphological abnormalities in the semen of the bulls. All the infected bulls developed sperm morphological abnormalities of more than a mean of 40.0% from the 4th week after infection until the end of the investigation and were considered unfit for breeding. At 7 weeks post-infection (PI) until the end of the study (12 weeks PI), the controls had a mean of less than 5% sperm morphological defects, while the infected bulls had 100%. Mean percentage values of sperm morphological defects throughout the duration of the investigation for control bulls were low and within the normal range for fertile bulls. These values differed significantly (p<0.001) from the elevated values of the infected bulls. The results show that trypanosomosis due to T. vivax or T. congolense infection can render Zebu x Friesian crossbred bulls unfit for breeding within a very short time. The resultant infertility could be of economic importance in trypanosomosis-endemic sub-Saharan Africa where Zebu x Friesian crossbred bulls are kept.
对12头用于锥虫病影响研究的泽布牛×弗里斯兰杂交公牛进行了精子形态异常的详细研究。4头公牛感染了活泼锥虫，另外4头感染了刚果锥虫，4头作为对照。感染的公牛患上了慢性锥虫病。所有公牛最初的精子形态异常率都很低，处于可育动物的可接受范围内。感染后，所有精子异常情况迅速且持续增加。感染公牛的精子严重变形，存在多种形态缺陷。在感染前，公牛精液中顶体、精子头部、分离头部、近端细胞质滴、远端细胞质滴、精子尾部、中段以及总精子形态缺陷的平均百分比基线值，顶体为0.1±0.1，总形态异常为8.3±3.2。从感染后第4周直到调查结束，所有感染公牛的精子形态异常率均超过平均40.0%，被认为不适于繁殖。在感染后7周（PI）直到研究结束（12周PI），对照组的精子形态缺陷平均低于5%，而感染公牛则为100%。在整个调查期间，对照公牛精子形态缺陷的平均百分比值较低，处于可育公牛的正常范围内。这些值与感染公牛升高的值有显著差异（p<0.001）。结果表明，由活泼锥虫或刚果锥虫感染引起的锥虫病可使泽布牛×弗里斯兰杂交公牛在很短时间内不适于繁殖。在饲养泽布牛×弗里斯兰杂交公牛的撒哈拉以南非洲锥虫病流行地区，由此导致的不育可能具有经济重要性。
