http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Semen parameters, spermatogenesis and hormone concentrations in stallions subjected to long-term estrogen administration
Eight pony stallions were paired by estimated daily sperm
output (DSO) and randomly assigned to one of two treatments.
Stallions received 44 []g/kg BW estradiol cypionate (ECP) or
an equivalent volume of physiological saline solution on
alternate days during the breeding season. Blood samples
collected immediately preceding each injection were assayed
for luteinizing hormone (LH), estradiol-17[] (E2) and
testosterone (T). Semen collected at 3.5-d intervals was
evaluated for spermatozoal motility, total number of sperm
per ejaculate and seminal plasma E2 (SE2). Prior to and
after four, eight and 12 wk on treatment, DSO was determined.
Data were separated into nine 10-d periods for statistical
analysis. As expected, E2 was higher (p<.05) in the ECP-
treated group after 20 d (period 2) of treatment and for the
remainder of the experiment. Although, E2 was higher (p<.05)
in the C group prior to treatment, there was no difference
between groups after 10 d of treatment. ECP stallions had
higher (p<.05) DSO after 30 d on treatment. After 40 and 50
d (periods 4 and 5), ECP stallions demonstrated higher
(p<.05) total sperm per period. This was preceded by higher
(p<.05) LH concentrations for ECP stallions after periods 1
and 2. There were no differences (p>.05) in SE2 between
groups after periods 1 and 2. Between 30 and 70 d, ECP
stallions had higher SE2 concentrations. Elevated SE2 in ECP
stallions was moderately correlated to total sperm per period
(r =.53). No differences (p>.05) were seen between 30 and 60
d for LH, after 60 d for DSO or after 60, 70 or 80 d for
total sperm per period. ECP stallions had higher (p<.05) DSO
and total sperm per period after 90 d. Additionally, LH
remained higher (p<.05) in the ECP group after 60 d. Seminal
plasma E2 was higher (p<.05) in ECP stallions after 90 d.
There were no differences between the two groups for
testicular cell data. Elevated LH concentrations in ECP
stallions demonstrated that estrogen treatment did not
inhibit LH in this study. Treatment with ECP did not have a
detrimental effect on potential DSP in this study.
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Includes bibliographical references: pages 49-53.