RECENT FINDINGS IN THE INHIBITION OF AVIAN SPERM SUSTENTATION 
Roy D. Crawford 
1. In the male reproductive tract. 
a) Normal sequence of events. 
The functional maturation of spermatozoa has recently 
been reviewed by Romanoff (1960). The fertilizing capacity of 
the sperm is gradually acquired as they pass through the male 
reproductive tract. According to Munro in 1938, as quoted by 
Romanoff, sperm cells taken directly from the testes yielded 
16.1 per cent fertility on insemination, those taken from the 
epididymis gave 18.8 per cent fertility, and those from the vas 
deferns were 65.5 per cent fertile. Therefore, like mammalian 
sperm, avian spermatozoa appear to undergo a period of matura- 
tion, this maturation being attained mainly in the vas deferens. 
Since the cells pass through the reproductive tract at a rapid 
rate, aging does not seem to be a major factor in the ripening 
process. According to Romanoff, the nature of the maturation 
process is not clear e- perhaps protoplasmic changes occur in 
the spermatozoa, or a protective colloidal coating may be add- 
ed to the cells as they pass through the vasa. Apparently, the 
male environment is necessary for the development of fertilizing 
capacity since immature sperm do not ripen in the oviduct. 
. Also, as in mammals, avian sperm cells do not show 
motility within the testes. Motility is acquired during pas- 
sage through the reproductive tract. The time required for 
passage varies from one to four days in the chicken, depending 
upon mating activity. According to Munro in 1938, as quoted by 
Romanoff, chicken spermatozoa may live and show motility for as 
long as 30 days if forced to remain in the vas deferens. They 
will also remain viable in ligated vasa if the testes are re- 
moved, indicating that hormones from the testis play little or 
no part in promoting their survival. 
b) Effect of frequency of collection on semen volume and 
fertilizing capacity. 
Since it has been demonstrated that avian sperm under- 
go a process of maturation before attaining full fertilizing 
capacity, it might be suspected that frequency of mating or col- 
lection of semen may have an adverse effect on fertility. It 
might be expected that with frequent ejaculation a high propor- 
tion of immature sperm would be released. 
The relation between frequency of collection and a- 
mount of semen obtained from turkey males has been studied by 
Lorenz, Wilson and Asmundson (1955, 1956). In their first 
study, they used ten sets of four brothers of the Broad Breasted 
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